mailto:dave@lafn.org More energy articles by David LawyerThe "company town analogy" which I thought up in Aug. 2007, was a major breakthrough which brought significant changes. Then in Sept. 2007 I realized the dual nature of output energy from a mine: caloric and embodied and finally think I've got a better understanding of it which I'm in the process of explaining (including formulas for feedback). I plan to deal with the energy flow balancing problems that happen when company towns are placed in a transportation network. See Network of Company Towns. I'm also pondering the ultimate purposes of energy. See What are the Ultimate Purposes of Energy?.
In Apr. 2008, I realized that I had failed to show how to account for renewable energy and also failed to emphasize that the required input to a "black box" per unit output is not in terms of embodied energy but in terms of real energy and real commodities. As fossil fuel becomes more and more difficult to extract from the earth, the amount of embodied energy per MJ of fuel will increase. Likewise for the embodied energy in other goods. So more embodied energy to "black boxes" will be required per unit output in the future.
I'm perhaps 1/2 done writing, researching, revising and proofreading this multifaceted and complex article. In addition to the problems mentioned in the above paragraph, you'll likely find some typos, some lack of continuity, repetition of arguments, poor organization, some lack of clarity, and failure to fully evaluate and compare the various accounting methodologies. But since much of it is valid and useful in its present form, I'm leaving it on the Internet. Even when it's 100% finished, I hope to continue to come up with some new ideas and clarify old ideas so it will still be sort of a working paper for some time. But if you do find factual errors, let me know.
If you're not already aware of just how significant this problem is, see Appendix: Motivation
When someone does a task (such as working at a paid job) it takes energy, but how much? How should the energy content of human labor be defined? It's easy to just calculate how much nutritional energy is expended by calculating the Calories of food energy one burns. But for every Calorie of food one eats it takes roughly 10 or more Calories of fuel energy to make, transport, and cook the food. See Appendix: Fuel to Make Food. But isn't much of what one does when one's not working used to support ones work? For every hour one works, about 1/2 hour of sleep at night is required which also burns Calories. So perhaps all the energy used to keep a worker healthy and happy should be allocated to the energy expended at work. This is not just food energy but includes the energy it takes to build and maintain housing, transportation, and other infrastructure as well as provide services to the worker such as government, medical, financial, repair, and retail trade services. Thus the energy input needed for human labor may be quite high.
In opposition to this view is the argument that a worker is going to be alive and use up energy in living, regardless of where he works, including the case where the worker was or will be unemployed. This will be called the "alive anyway" argument. This point of view, which implies the energy cost of human labor is low, has serious problems with it which will be discussed later. to-do.
Now returning to the high human energy cost point of view. The energy cost of services of course includes the energy cost of the human labor that provides these services. Not only that, but the service workers themselves require services, etc., etc. Should not some (or all) of this human energy be allocated to the worker who receives such services, thereby enabling him/her to be more productive at work? And again, the energy that these service people expend is not just caloric food energy since they also require shelter, clothing, transportation, information, education, etc., all of which require energy.
This human energy expended to support human life and work becomes embodied in people (and is called "embodied energy"). It's far more than just the caloric value of their physical bodies or the direct chemical energy it takes to create and maintain those bodies (human capital). Even the knowledge people store in their brains took a lot of energy for them to acquire, in addition to the energy it took by society to create and pass on such knowledge. In writings about embodied energy it is usually described as embodied in physical goods or services. But for this article it's embodied (or embedded) in human beings too. See Appendix: Embodied Energy.
At first glance it seems that trying to find a reasonable method of allocating energy to human labor is an overly complex and subjective task which is difficult to comprehend. But there's a way to frame the problem and to transform the economic geography of the problem so as to make it clear how the energy flows. It's what I call the "company town analogy" where all the people and capital needed to produce something are concentrated in an isolated "company town". This model will show that the energy cost of human labor is high, thus implying that something is wrong with the "alive anyway" argument.
First we'll make a simple model and later extend it so that it will be both more realistic and cover more situations. This will result in relaxing some of the restrictions imposed by the simple model.
The simple "company town" model is to take a production facility like a factory, farm, or mine and place it inside an isolated "company town". The town will be solely devoted to the production of just one good from that factory, farm or mine. The sole product made in the company town (such as automobiles, food, or coal) will all be exported out of the town to the rest of the world. The town also houses all the workers needed to make that product including the workers' families and service people needed to provide services to the workers. Into the town (from outside) will come all the goods needed to support the town and its one industry. The town will have a fixed boundary fence and only one gate thru the fence for goods to enter and exit. After the town is populated with people, people do not flow across the town boundaries. To maintain steady population, babies, children and families are raised inside the town. As people retire from work in this company town, they continue to live in the town until they die. It's postulated that the town be in a steady state equilibrium with only enough capital goods flowing into the town to replace worn out capital and with births equalling deaths so as to keep population fixed.
This company town is intended to be a model of production in the real world of today and to use approximately the same amount of energy to produce the product made in the town. Thus the lifestyles of the people who live in the company town should mirror the lifestyles in real society. For example, the long commutes by auto that take place in the real world will continue to happen in the company town even though they would not otherwise be necessary due to the compactness of most company towns.
A company town could, in some cases represent a vertically integrated industry such as the production of corn-ethanol which requires a town with both farms to grow the corn and an industrial plant to turn the corn into ethanol.
Here's the ways the simple company town model will be extended later on to permit:
While the model will give the same results if flows in and out of the town were just across its boundary, a fenced boundary with a gate make it easier to visualize. For the single commodity "company town", there is only one flow out the gate and that's the product made by the town factory, farm, or mine. If the output flow is an energy good, like ethanol, coal, or crude oil, then the energy content of the input flows combined must be less than the output flow if the town is to yield a positive "energy return on energy invested" (EROEI or ERO). If it can't yield a positive return, then this town is parasitic on the rest of the world for energy and requires an energy subsidy from the rest of the world but contributes nothing to pay for this subsidy since it only "exports" one commodity to the rest of the world.
The energy flowing into the town includes the energy embodied in the consumer goods for all the people in the town. Also, the supplies, equipment, and energy for the industry in the town flow into it and these all contain embodied energy. The input flow includes goods to maintain and replenish the infrastructure in town including housing, transportation, commercial and public buildings, etc. Utilities like electricity, natural gas, and water flow into the town thru the meters at the town gate.
What about the case where the output of the town is not an energy good? It would seem that the energy embodied in the output should be equal to the energy embodied in the input, just like the case when the output is an energy good like ethanol or coal. But to establish this we`ll need to wait until later when we connect up all the inputs and outputs of many company towns into a network.
This model makes it clear that to produce the commodity that the town exports, not only must the production workers in the town be supported 24 hours a day, 7 days per week, but all the other people in the town must be supported too: medical workers, utility workers, retail trade workers, financial service workers, government employees, homemakers, children, teachers, retirees, etc. All of the material support for the town comes from outside the town thru the town gate. It represents the input energy cost of obtaining the exported commodity. The part of this material support that supports the lives of the people in the town represents the human labor energy cost of producing the export commodity.
Since the energy flows into the town from outside become embodied in the output good of the town, the more energy-intensive the lifestyle of the people in the town, the higher the energy cost of producing the output of the town. This is assuming that the higher input energy to the town is less than fully compensated for by higher worker productivity.
The flow of goods and services into the town also supports "surplus activates" not essential to the production of the town's product. "Surplus activities" in the town include waste (or all types), criminal activity, harmful drugs, gambling, luxury goods, and the support of parasitic people: non-working owners of assets in the town, people on "welfare", prisoners, people wrongfully receiving disability pensions, the homeless, etc.
One may claim that since these surplus activities don't contribute to the output production of the town, we shouldn't count these energy inputs. But if the town is to mirror the real social structure of society, these surplus activities exist and do accompany production.
It would be of interest to look at two models, one where we have an ideal society with a minimum of "surplus activities". Human nature being what it is, there will likely always be some waste, cheating, criminality, etc. The other model would represent the "surplus activities" of the real world.
The support of government, whose services are allocated to the output to the town product, includes both local town government and the town's share of county, state, national, and international government. This obviously includes the military including the support of national troops at home and abroad including support of any military or "peacekeeping" units of the United Nations. The justification for this is that for the town to be safe from possible harm, military protection and law enforcement of international scope is needed. Although such activity actually takes place outside of the town, the model assumes that the town's share of such activities takes place within the town based on the concept of placing everything needed to support the production of the town within the town. Thus there will be some military, troops, United Nations personnel, etc. living in the town. For the support of such personnel, there will be an input flow of goods to the town, including military equipment and supplies. Counterproductive military expenditures (such as possible the Vietnam and Iraq wars) should be classified as waste under the previously mentioned "surplus activities". Of course non-local governments provide much more than just military services so the town's share of all of these will be located in then town and there will be input flows of goods and energy to support them.
For labor that contributes to production, what is the energy content of it? In the company town, all the inflows of goods, other than those that are direct input to the town's one-product (exported commodity) industry, are for support of the people in the town. The town's population consist of the production workers who make the town's single product and the people dependent on the production workers: service workers, spouses, children, retirees, etc.
Let's define the gross energy per person as the total energy used by society divided by the total population. For the U.S. the energy used per persons is about 120 times food calories. See Food-calories are what percent of fuel energy. In the examples, a figure of 100 times food calories is used. But this figure needs to be increased a few fold to account for the service workers and dependents that are needed by production workers.
The example of a mining town in the next section will present a more concrete example of the energy flows of a company town. This mining example illustrates general principles applicable to the energy flows of all other kinds of goods and services so you don't want to skip it even if you have no interest whatsoever in mining.
This example is for a hypothetical coal mining operation at a remote location. But it illustrates the general case for a plant or firm that exports its product to the rest of the world outside the company town. It will also look at the question of "energy return on energy invested" = EROEI. Before starting up the coal mining operation, It will be necessary to build a mining town to house the miners and recruit both miners and support personnel to populate the town. The town will produce only coal and export it to the rest of the world.
Normally the criteria on whether or not to go ahead with the project would be profitability. Will the cost exceed the income obtained by selling the coal? For it to be profitable, it would seem that it also must have a positive return on the energy invested in the project (EROEI). So let's examine the EROEI question: Will the coal exported from the mine contain more energy than the energy used to operate the mine and provide for the miners, including energy depreciation of capital investment in the mine, housing, and utilities, etc.?
It will take energy to build a mining town and to provide amenities. The project will require not only miners but service personnel to provide services to the miners: medical workers, food workers, utility workers, repair people, store clerks, government workers, etc. It will also require that a flow of consumer goods (including food), hardware and building materials, transportation vehicles, etc. be sent to the mining town to support both the miners and their service workers. Actually, if it's going to be a sustainable society in the mining town, the miners will need to reproduce and raise children so the town needs to support not only miners and service workers but also their spouses and children. And the retirees from the town need to be supported. The first model to be presented will neglect families and retirees but later models will include them.
This is a model of energy flows for a plant producing a single good. In this case it's a mine producing coal and is shown in Figure 1 below. Flow are the flow of energy per day per miner. It shows energy flows of mostly embodied energy. One unit of flow is the energy needed to maintain one person (about 100 x 2500 kcal/day or about 1.4 GJ/day). See energy per capita. Flow volumes marked with a "*" are flows from world outside of the mining town. The output flow of 4 units of embodied energy is marked with a "+" to remind one that to this embodied energy one may add the caloric value of the coal mined by one miner. The utility of the coal only depends on it's caloric value and not on the embodied energy used to mine it. It's assumed that for each miner, 0.5 of a service worker is required to provide services to the miner. Likewise, each service worker requires the services of 0.5 of a service worker.
____________________ ________________ 1 | Production Worker| 2 | Plant | 4+ i--->| (miner) |---->| (mine) |-----------> | |__________________| |______________| Product (coal) *2 | /\Services to /\ ------->-------| 1| Production Worker | Industrial Supplies, Consumer Goods | 1 __________|________ *2| Parts, Machinery, +Housing, |--->| Service Worker |-->--i | Energy, etc. +Utils, etc. | (server) | | |_________________| | 0.5 | 0.5 | |---<----| Services of Service Worker to Self (note all flows are energy, 1 = gross energy for one person) Figure 1: Company Town Energy Flows
The "Service Worker" shown in Fig. 1 represents the total services provided by a large number of service workers, since only a tiny percentage of an actual service worker's total working time is devoted to the miner. Likewise for the part of the service worker that provides services to the service worker that serves the miner. Since each service worker actually requires some services from a large number of other service workers, each of which require services and so on ad infinitum, it's likely that the "service worker" in the figure represents the amalgamation of services provided by millions of service workers. Many of these services are provided by telecommunication such as financial information, printed and internet information, etc.
Note per Fig. 1 that to support the miner, one service worker (server) is required. But we previously stated that the miner only needs 0.5 servers. There's no conflict here since a server also needs services and the 0.5 of a server will require 0.25 of a server to support her. Then this 0.25 of a server will require 0.125 of a server, etc, etc. The infinite series sum of all this ( 1/2 + 1/4 + 1/8 + ...) is one server. Thus a whole server is needed even though the miner only uses the services of 1/2 of a server. This is equivalent to the service worker needing to use 1/2 of her service effort to provide services to herself so she is only able to offer the surplus half of her services to the miner. The miner is charged the full energy cost of this server. This is represented by a flow of 1 from the server to the miner. If there wasn't a miner there would be no need for this server.
The loop of value 1/2 in Fig. 1, which flows both from and to the service worker, represents the work that the server does for herself. One might ask why the service energy input to the miner is 1 but the service energy input to the server is only 1/2 (provided by herself).
If a miner requires one server, why doesn't each server require another service worker? Well, a service worker that only provided services to others would in fact need another server to provide her with surplus services. But in the miner example, just 1/2 of a server provides all her services to the miner so then another 1/2 of a server is needed to provide surplus services to the 1/2 server serving the miner. Another way of stating this is that a server that provides herself with all her needed services doesn't need any other server to provide these service needs for her.
The miner has a total input energy flow of 2 while the server has a total input energy flow of 1 1/2. Yet the external input energy flow to support these 2 persons is just 2 (1 per person) as it should be. How can the total input energy flow to these 2 persons be 3 1/2 ( 2 + 1 1/2 )? Because some of the original input energy obtained from outside the mining town is "recycled" within the mining town. All the outside-world energy input to the server gets recycled into the energy input of the miner. Half of the energy input to the server gets recycled to herself (as shown in the loop). This is an example of a general principle for embodied energy: the sum of all the energy inputs to people can be much larger than all the energy produced in society.
This recycling of energy could also be called "pass thru" It's something like recycling paper. The total production of paper can be much larger than the original production of paper from wood pulp, etc. due to recycling. Something like this happens in the natural world of wild animals where the total input calories eaten by animals is greater than that supplied by plants, since some animals eat other animals thus recycling food energy.
Embodied energy itself is not a benefit but a liability since it represents here the fuel energy required to make commodities. The specific embodied energy (per unit of good) is known as the "embodied energy intensity". For example, if a kilogram of flour takes 200 MJ of energy to produce (including human energy) then we say it has an embodied energy intensity of 200 MJ/kilogram. If it takes 10 kcal of fuel to create 1 kcal of food, then the EEI is 10/1 = 10 kcal/kcal or just a factor of 10 (unitless).
Fig. 1 shows a total input of embodied energy to the mining town of 4, but this is only true if the input flows of goods to the town have assumed fixed embodied energy intensities. A more precise model would specify the inputs to the town in terms of quantities of real goods and not in terms of embodied energy. Then if we know the embodied energy intensity (EEI) of each such good, we merely multiply each input flow by its corresponding intensity and sum the results to obtain the total input embodied energy. In this case, if the EEI's of the input commodities change then the efficiency of the town's output changes: high input EEI result in a high output EEI and conversely. Before inserting this town into a network of "company towns" with each town supplying goods to other towns, the inputs need to be specified in terms of real values. But even without this, the model is of significant use in illustration the accounting for human labor.
For example for Fig. 1 suppose the 4+ output is 4 units of embodied energy plus 4 units coal fuel energy (caloric). Then the total embodied energy output is 8 but there is only 4 units of useful output flow so the EEI is 8/4 = 2 MJ/MJ. This means that to get 1 MJ of output, it takes 2 MJ of fuel from the earth. This result holds only because the inputs are specified in units of embodied energy. But if instead we specified inputs in terms of real quantities, then the EEI of 2 for the output of the town would vary with the EEI of the inputs to the town. For example if the input to the town was specified as 4 units of real fuel energy, then this could be obtained from the 4 units of fuel energy output. The result would be no net energy output from the town with the EEI of infinity for the zero net output. The meaning of this is that as the net output is reduced by increasing the input requirements to almost 4, the EEI become arbitrarily large (approaches infinity).
This pertains to all energy flow charts like Fig. 1. People and organizations pay for energy flows going to them, so the flow of money is in the opposite direction to energy flow. Thus money flows in the reverse direction of the arrows. The flows of energy may be flows of goods or flows of human mental and/or physical energy. One may take the ratio of the flow of money to the flow of energy and find a "price" for the energy (say in $/MJ). If a certain flow of energy increases due to an increase in the flow of an item (a good or service) the flow of money increase proportionately.
Since a good contains more that just embodied energy, part of the price one pays for a good is to pay for its non-energy content, unless one believes in the "energy theory of value". But there is also an "energy and material theory of value" which would include the value of scarce minerals contained in the good which becomes embodied in the good just like energy does.
Since there is often statistical data available for the flows of money but not for embodied energy, there is a temptation to try to estimate the unknown flow of energy from the known flow of money. To do this one needs is an estimate of the flow ratio of energy to money ("energy price").
In most cases, neither purchasers nor sellers of goods and services try to explicitly evaluate the embodied energy contained in an item. But indirectly, the price of an item reflects (to a certain degree of approximation) the embodied energy. Actually, the %/MJ will vary from item to item but it may not be feasible to estimate this variation. So one can attempt to estimate an average "energy price" and use it to find an estimate for the flows of embodied energy. This is frequently done.
The service worker in Fig. 1 actually represents the whole collection of service workers (servers) in the company town and the miner represents all of the miners, including management and office staff. But it's simpler just to make the chart for one miner and one server that would need to be a jill-of-all-trades if there was actually only one server.
But the service economy includes not only the labor of servers but the consumption of material goods needed for services. For example, the provision of medical services includes not only doctors, nurses, and secretaries, but consumes office space, utilities, medical equipment and supplies (including medicines). Where are these shown in Fig. 1? They are part of the consumer goods, etc. input to the miner and service worker. These material goods are part of what is called here energy per capita while the service worker's labor is not part of this per capita energy since it's recycled energy.
Why are services different than goods in this model? It's because services are part of the local company town economy and are not exported to the outside world. It's also possible for a company town to be built around a company that exports services such as providing customer support by telephone or a resort for out-of-town tourists.
The flow chart only shows those services where the server works for pay. Most people provide some of their own unpaid services such as preparing their own food instead of eating out. Do-it-yourselfers also provide their own services for home and auto maintenance and repair, etc.
For the mining town, the coal output energy flow has 2 parts to it: The flow of the coal itself which may be represented in energy terms by its caloric value and the virtual flow of embodied energy used to mine the coal (4 units, including 2 units of human energy of the miner). The caloric value of the coal represents it's use value. But the embodied energy to make the coal, represents the energy it took to mine the coal (including human labor). The total embodied energy is the sum of these values and is consumed when the fuel is used. If we look at a fuel (such as coal), caloric energy is generally a benefit while the embodied energy to make it is a cost. This distinction will be dealt with later when a network of company towns is discussed. See Dual nature of output energy
What this model shows clearly is that all the energy used by both the miner and the service worker must be counted. If the energy supplied to this mining town is not paid back by the coal output, then the mining town must receive an energy subsidy from elsewhere. This would be nonsensical since the purpose of the mine is to supply net energy to the rest of the world.
So for the mining to be profitable for society there needs to be a substantial energy gain which means a positive energy gain (the ratio of energy returned to energy invested should exceed one). This means the energy flow of coal out should hopefully be significantly larger than 4. But even if it yields a positive return on energy invested, it's not necessarily socially beneficial since burning coal results in pollution (including CO2 which causes global warming) and deprives future generations from using it due to depletion.
For society to be sustainable it must reproduce itself. This means that both the miner and service worker needs to support a family with children to replace both them and their spouses when they die. While due to the current overpopulation it may be desirable to have less children, eventually generating the replacement amount of children (slightly greater than 2 per woman) will be needed for human life on earth to be sustainable.
So to this mining town we need to add families with children and then estimate the energy inflows from the outside world that it will take to support them. Here's an example based on the addition of families to the previous no-families mining example.
Comparing this with Fig. 1 shows that the flow of input consumer goods, housing, and utilities has doubled from 2 to 4. This has assumed that with families, the mining town's population doubles. If the both the miner and service worker take a spouse and has 2 children then the number of people quadruple. But in reality, adding families may only be equivalent to about doubling the population because:___________________ _______________ ?6 2 |Production Worker| 4 | Plant |-----------> i--->|(miner) & Family |---->| (mine) | Product (coal) | |_________________| |______________| *4 | /\ Services to Production /\ ------->-------| 2| Worker's(miner's) Family | Mining Supplies, Consumer Goods | 2 _________|________ | Machinery, and +Housing, |--->| Service Worker |-->--i *2| Energy +Utils, etc. | and Family | | 1 | |_________________|--<--| 1 Services of Service Worker to Self (note all flows are energy, 1 = flow of energy per capita Figure 2: Company Town Energy Flows (includes families
See Appendix: Number of Service Workers per Production Worker for some mathematical derivations and examples.
In this example, the energy flow to the miner & family due to services has doubled from 1 to 2. The additional person represents a fraction of a (non-employed) spouse plus a fraction of a child. But the provision of services to the miner family is still only 1/2 of a service worker (the same as just for the miner alone). The reason the energy flow doubles is because the miner's family now has to bear the burden of the additional energy to support the service worker's family. The miner's family of 2 persons (including the miner) is assumed to require no more services than the miner alone since the miner's spouse provides some services to the family and herself. Likewise for the service worker family: only 1/2 of a service worker is needed for each such family.. It's doubled in energy value (from 0.5 to 1) since due to the energy cost of supporting a family, the energy cost of a fixed amount service work has doubled.
The services that the newly added spouses provide for their families are not shown in the flow chart but the services that the service worker provides for herself is still shown. The policy for energy flow diagrams here is to only show flows that take place in the marketplace. The service worker serving herself is taking place in the market since the service worker actually represents a composite of a large number of service workers who get paid for their services.
So the result of this example is that the energy flows for support of the town residents has doubled from 2 to 4. Even though the amount of service work provided by paid service workers hasn't changed, the flow of service energy has doubled due to the higher energy cost of labor now that families need to be supported. The amount of labor the miner provides to the mine hasn't changed a bit, but energy cost of his labor has doubled for the same reason.
What happens to people that become disabled, perhaps due to a mine accident or retire because they become too old to work effectively? We'll call such people "retirees". Their support is also considered to be the responsibility of the mining town where they worked. Thus more consumer goods from outside the town and services from within the town will be needed to support them. This is also another energy cost of mining. Here's a modified flow chart to include them:
This example assumes that one retiree would need only 1/2 of the services that a miner needs. So the 1/2 retiree only needs 1/8 of a new service worker directly implying 1/4 of a new service worker is required to provide her surplus service to the retiree. This also implies that another 1/4 of spouse/children are added to the service worker family. The result is one more unit of consumer goods energy input flow, split equally between the retiree and the service worker family.___________________ _______________ 2 |Production Worker | 5 | Plant (mine) | *7 i--->|(miner) & Family |---->| |------------> | |__________________| |_______________| Product (coal) *5 | /\ /\Service to Production /\ ------->-------| | 1 2|Worker Family | Mining Supplies, Consumer Goods | 2.5 | _______|_______________ *2| Machinery, and +Housing, |------|-->| 1.25 Service Worker |-->--i | Energy +Utils, etc. | | | & Family | | | | |_____________________|--<--|1.25 Self-Services of |0.5 \ | of Service Worker | 1\SS Tax 0.5|Service to Retiree | \____________\/____ |------->| 1/2 Retiree | 0.5 |_________________| (note all flows are energy, 1 = gross energy for one person> Figure 3: Company Town Energy Flow: families and retiree
The reason why the retiree needs less services than the miner is because the retiree has time to perform some services for himself. At the same time, a retiree will likely require more medical services.
The energy output of the retiree is labeled "SS Tax" meaning "Social Security Tax" This energy flow goes to the miner who pays a social security tax (flowing in the reverse direction) to support the retiree. It may seem like a fictitious energy flow since the retiree isn't providing any energy or service to the miner, at least not at this time. But in the future when the miner retires, the reverse flow of SS tax that the miner paid should entitle the miner to a forward flow of energy to the retired miner in the form of services and consumer goods. So there is a real energy flow to the miner, but it will be delayed until he retires (or becomes disabled).
The first example presented was a mining town but it's important to look at other examples.
The company town may be based on a manufacturing factory and all it's employees and servers for the factory workers. In this case one is asking the question: What is the embodied energy content of the production from the factory? All the energy supplied from outside to the factory town is allocated to the product make by the factory. For multiple products, one would need to attempt to allocate the separate inputs required for each product.
Using the example of Fig. 1 for the factory case, the output flow of 4 associated with the product is just the input energy flow to the factory town. To be energy-self-sustaining the output product flow must be sold (exchanged for other goods and energy) that will provide an input energy flow of at least 4 ( = 2 + 2 ). Likewise for Figs. 2 and 3 where the output energy flow contains the embodied energy of the sum of all the input energy flows.
The same model (Figs. 1 to 3) is applicable to farming with an isolated farming community where the farm town included the surrounding farms All (or almost all) of the farm products are exported to the outside world. All the services to farmers and their families (besides the services provided by their spouses and children) are obtained from service workers that live in the town. And the farm labor is of course provided by people within the farm community.
To produce ethanol from corn requires both farms to grow the corn and a plant (factory) to produce the ethanol. So to study the energy flows, lets put all the economic activity to make ethanol (the ethanol economy) in one place and call it the ethanol community. It will consist of a combined farming/ethanol-plant town and include surrounding farms that grow corn. Like the other models, the only export from this community is ethanol and all the material goods sent to support this town are ultimately for the purpose of producing ethanol. This example shows that we can put "vertically integrated" industries into a bounded isolated community for analysis.
Since the solar energy which helped make the ethanol is renewable the total energy of the output may be just the embodied energy it took to make the ethanol. So when the ethanol is burned, all the energy that's consumed is just its embodied energy provided that the ethanol production has not degraded the soil. In other words the ethanol production process should provide for replenishment of nutrients to the soil (including humus) and preventing topsoil loss. This will make the EEI of ethanol higher. Another issue is the clearing of native vegetation (by burning) to provide farmland for growing ethanol. This will not be accounted for here but the release of carbon dioxide into the atmosphere by such burning is a significant side issue.
A National Park has boundaries and exports the service of recreation to the outside world via the visitors who visit it. It's sort of another type of "company town". Not all visitor consume the same energy since ones who camp out in the park use less energy than the ones who stay in lodging, since they are not charged with the energy depreciation on their lodging and don't utilize "hotel services". This is an exception to the simple model since park visitors are allowed to cross the boundaries of the "resort town".
While the U.S. government classifies electricity as a service, the generation of electricity in a power plant will be classified as production of a good. The good is electrons supplied by wires at a substantial voltage between wires. Without a voltage, electrons by themselves are worthless. The electrical workers involved in maintaining the power distribution in "company towns" are service workers. The production workers at the power plant export electricity to the outside world (outside of the "power plant town") while the local electrical workers don't export electricity.
A freight railroad provides a transportation service to industry. The transportation is represented by a service input flow to the plants served by rail in various other company towns. This is not the flow of goods that the railroad brings to the company towns but the flow of service that the railroad provides by transporting and delivering the goods.
The "company town" for rail freight consist of a railroad line, including the railroad tracks, yards, stations, and assorted railroad towns strung out along the railroad line to house the railroad workers, and their servers and families. etc.
Freight in railroad cars flows across the boundary of the railroad line at the ends of the line, etc. where the railroad freight cars pass from one railroad line to another line. But this doesn't count as a flow in the flow chart if what enters the railroad also leaves the railroad. What does count are goods like locomotive diesel fuel, replacement rails, repair parts, etc. that enter the railroad but don-t exit it since they are consumed by the railroad. It's assumed that each railroad line does its fair share of maintenance of the railroad cars that travel on more than one rail line.
In the Company Town Analogy it was implied that the "company town" is supposed to concentrate economic activity from diverse locations into a single town. Thus the "company town" model represents the dispersed economy of the real world associated with the production of the product made by the plant in the company town.
This economy also includes the housing and infrastructure needed for such workers. Then we claim that the models of Figs. 1 to 3 are also applicable to this dispersed "company economy". The reason why the "company town" model looked at an isolated town was so that the energy flows into and out of that town could be easily identified and understood as pertaining to the single commodity produced in the plant (a mine, factory, resort, etc.) in that town. It's easy to visualize the boundary of the model and observe the flows across the boundary. But real commerce is most always more complex.
So let's suppose that we take an isolated company town, remove the fence around it and open it up so that now outsiders can move in. For example, people who work for other industries outside the company town start to move in. Then some of these new entrant workers may start to receive services from the service workers that formerly served the company town plant workers. As this happens some plant workers, still needing the same amount of services, will start to receive them from new service workers brought in to serve the new entrants. This may be thought of as a "service worker swap". It doesn't change the basic model. But now, the service worker boxes in Figs. 1-3 represents the service work from a wide variety of service workers. Since may service workers will now be serving both the original inhabitants and the new entrants, only the portion of their services which (directly or indirectly) provides service to the original town plant workers will be counted. So now the plant economy is only part of the economy of the company town since new economic activity is taking place there. But the model is still valid for the plant economy.
If plant workers and/or their service workers move outside of the factory town, how is this accounted for? One method would be to just expand the boundaries of the company town to encompass this even more dispersed plant economy and consider the people who were already present in the expanded region (and their supporting infrastructure) to be just like the new entrants to the "company town" as explained above. The plant economy still remains intact and is still represented by Figs 1-3. As the plant economy (of this single plant) becomes more dispersed the term "company town" is no longer applicable.
So what we have now is that instead of a plant economy consisting of an isolated company town for which we could draw a circle around on a map we now have a dispersed plant economy which one still might try to represent on a huge map by numerous small circles. But it gets messy since many service workers now only devote a small percentage of their time (directly and indirectly) to the factory workers from a certain plant. Today with the Internet, the geographic range of the dispersed plant economy may include the entire world, since a service worker located on the opposite side of the world may provide services to people in a plant economy. Such a plant economy can be defined conceptually and still represents the isolated company town (with a plant). But to graphically plot all the details of energy flows for each person and items of infrastructure would be an arduous task now that the plant economy of this one plant has become so dispersed.
So now instead of isolated plants in company towns we have numerous "plant economies" each centered around a certain plant but with geographically dispersed workers and service providers. The energy flows within this new "plant economy" are assumed to be as close as feasible to the situation in the company town and conversely.
In all these company town models, the entire flow of consumer materials and infrastructure input (including depreciation of infrastructure) is ultimately to support the workers of the town plant making the exported product produced by the town such as coal, ethanol, farm produce, product of a factory, etc. So let's estimate just how much more this energy is as compared to the amount of food calories consumed by a production worker. From Human Energy Expenditure for Production the energy to support a worker is about 100 times his food caloric energy (metabolic energy). But since the worker only works about 1/4 of the time, but burns more kcal/hr while working, we must increase the 100-times so that it will only apply to the time spent at work. Assuming that 1/3 of the kcal food intake is consumed on the job, the 100-times becomes 300-times. But then there's about 4 others (including service workers, spouses, children, and retirees) that must be supported for each worker so the 300-times becomes about 1500 times.
So it seems that for every calorie of food energy burned on the job by a typical production worker, the worker actually requires over 1000 calories of fuel energy (or about 1500 calories as estimated above). For a service worker it's also about 1500 calories also. Why? Just go through the same reasoning as above for the production worker. For every calorie the service worker burns about 100 calories of fuel is used, the service worker also requires the services of other service workers just like the production worker does, etc. So the service worker, like the production worker, consumes (directly and indirectly) about 1500 times the calories burned while at work.
However, since all the energy supplied to support the people in a company town ultimately goes to the production workers. Adding up the total energy attributed to production workers and the total energy attributed to service workers will result in much more energy than is input to the town. Doing this would be double counting since all the energy of the service workers is ultimately passed on to the production workers. One can't just add up the energy supplied to each service worker and come up with a total energy energy supplied to the service workers, since part of each service workers energy input is passed thru to other service workers. Thus there is a lot of recycling of human energy by passing energy from one person to another in the form of services resulting in the total energy input to persons being a few times more than the total energy used by society.
Before putting company towns into a network, an incremental step is to show just two company towns connected together. The output flow of each connects to the input flow of the other town. If one of these towns has an input flow of fuel from the earth, it may be considered to be the main town. Its output may be fed to the second town to be transformed into something else which is then input (fed back in altered form) into the main town.
Fuel contains both caloric energy and embodied energy. To show these flows on a network diagram one needs some well defined variables. There are sometimes equations to write down and solve which require such variables, like the MJ/day output of real fuel from a mining town.
But the situation is more complex since it takes energy to
produce fuel for society and this energy becomes embodied in the
fuel. The flow of fuel energy thus has 2 components which are
implied by the following five variables:
F Fuel flow of caloric energy in the fuel
E Embodied energy flow of embodied energy in the fuel
T = F + E Total energy flow including embodied energy
e = E/F Specific embodied energy (a ratio)
t = T/F Specific total energy; t = 1 + e
Knowing any two of the above variable enables the remaining 3 to be determined. Thus fuel flow has 2 components to it and just giving one component doesn't adequately describe the flow. Also, while the flow of caloric fuel energy is usually known, the flow of embodied energy often needs to be calculated by solving simple equations using the above defined variables.
It also need to be specified whether or not the caloric energy of the fuel comes from minerals fuels or "renewable" sources such as solar energy or hydroelectric power. For the case of renewables, the total energy T = E since the caloric energy didn't need to be removed from the earth.
For the flow of non-fuel commodities there are also two components of flow: commodity flow C and embodied energy flow E as defined above. Since most non-fuel commodities do not contain caloric energy, the total energy flow is the same as the embodied energy flow E.
For a company town that exports fuel energy to the outside world, a simple model is for it obtain all of it's input energy flow for making fuel (not the input flow from the ground) from its own output by feeding back a fraction p of it's output fuel energy to itself. This would require that the fuel town only needs its own feedback fuel F1 for input and has means for converting some of this fuel energy to consumer goods (including food) to support the lives of its residents. Thus the fuel town converts some fuel feedback energy to embodied energy in the fuel output. But since the fuel feedback comes from the output, it too contains embodied energy. Let F be both the fuel flow from the ground and the output fuel flow (not including any embodied energy). Then the total output flow is tF where t is the specific total energy, and since p of this gets fed back, T=ptF feedback fuel flow.
But possibly some of this fed back total energy (included embodied) has an ultimate purpose of supporting human life in the fuel town and thus disappears down a "Life Energy Sink". Let the c be the fraction of total fed back total fuel energy ptF which is allocated to the life energy sink so that the life energy sink flow is thus cptF. c is the sink flow fraction. All this and more is shown in Figure 4 below.
Fuel From Ground ______________________ T=cptF Life Energy Sink -------------------->| Fuel Production |---->-------> Fin | Company Town | F=Fin T=tF T=(1-p)tF i------>|____________________|---->----------i------------------> | | F2=(1-p)F | Feedback Fuel F1=pF T=ptF | Net fuel output |---<-----------------------------<----------| Figure 4: Feedback Flow of Energy from a Fuel Town
In Figure 4 we know the values of Fin (fuel in from ground), p (fraction of output energy fed back), and c (fraction of feedback allocated for ultimate use of life support). From these all the other variables may be found by formula. But first it should be clear that the value of c is subjective (will be discussed later to-do).
We know F = Fin, which assumes that the fuel mined or pumped out of the earth has about the same caloric energy value when it enters commerce as it did in the earth. So looking at the figure it's clear that if we only knew the value of t, the specific total energy of the output fuel flow F, we could readily calculate the other unknowns.
To find t, just equate the total energy inputs and output for
the fuel town:
F + ptF = tF + cptF Solving for t gives t = 1/[1 - p(1
- c)]
Energy flows of fossil fuels from the earth need to be allocated to some purpose although this is a subjective statement. They flow into the world and only a small part of this flow accumulates in the form of embodied energy in the works of man and in accumulated knowledge. The rest is expended in the lives of people and in wasteful activities. The fuel town can exist ok without a life support sink which is the same as setting c = 0. Then t = 1/(1 - p)
At the opposite extreme, if all the feedback energy is allocated to life support it means that the fuel is produced entirely by human labor since none of the feedback energy is used to support the physical plant used in oil production. In this case c = 1. Since all fuel feedback is allocated to life support, should it also be allocated as embedded energy in the fuel output of the fuel town. See Double Duty
But what difference does it really make? Regardless of how much embodied energy there is in the fuel, the output flow of fuel F from the company town remains the same regardless of the subjective value of c. The monetary cost of the fuel shouldn't depend much (if any) on the value picked for c, unless a higher value of c implies that more luxury goods are being consumed by the town's residents which is made possible by higher wages resulting in a higher price of fuel.
Figure 5 shows the case for F=1, p=0.9, c=0 (no life support sink). Given these values, it's trivial to calculate all the other ones. By picking p=0.9 it means that 90% of the fuel extracted from the earth must be fed back to the fuel town to provide energy for the extraction of the fuel (including life support energy for the town's residents). If the fuel were petroleum, it would mean that for every gallon of consumption by the rest of the world, 10 gallons of oil must be removed from the earth. This means a high amount of embodied energy E in the fuel output of the town, which is 9 times greater than the fuel output (e=9).
Fuel From Ground ______________________ -------------------->| Fuel Production | 100% of output 10% of output Fin=1 | Company Town | F=1 T=10 E=9 Fnet=0.1 T=1 E=0.9 i------>|____________________|---->----------i------------------> | | | Feedback Fuel F=0.9 T=9 E=8.1 |90% of output |---<-----------------------------<----------| Figure 5: Feedback Flow with p=0.9 c=0 => t=10
The people in the fuel town use the fuel to support their lives and the fact that 90% of fuel output is fed back means that they get a lot of life support from this since they consume much of the feedback energy. The more inefficient the production of energy by the town: the higher the feedback energy is, the more people the town supports, the more rapidly the fuel in the earth is depleted and the more pollution put into the atmosphere (worse global warming>. So what may be a benefit to the town residents is harmful to the rest of the world. Of course, if there are enough other fuel towns that are much more efficient (lower values of specific energy e and t) then the above p=0.9 (inefficient), the fuel town may not be able to sell it's fuel since it will cost too much to produce.
As fuel supplies in the earth become more and more depleted and fuel becomes more difficult to extract, then the equivalent of inefficient fuel towns something like figure 5 may become a reality. While it's very bad for the environment, in one way it's seemingly beneficial for the rest of the world. This is because the rest of the world is supplying no energy to the town and yet is getting an output fuel flow of Fnet=0.1. While its embodied energy content is 9 times this (e=9, E=0.9), the energy return on energy invested is seemingly infinite from the viewpoint of the rest of the world (which supplies no energy of any kind into the fuel town).
But there is one thing wrong with this model. The rest of the world is getting fuel from the town but providing nothing in return to the town Since money is presumably being paid for the net fuel output from the town, what does this imply? Normally, one would expect this money to flow into the town which would entitle the town to obtain a flow of goods from the rest of the world along with the embodied energy in these goods. But suppose the money goes to the owners of assets in the town who don't live in the town? One can define the town such that all the people required for the towns existence live in the town which implies that the owners of the assets of the town also live in the town. Even if corporations are present in the town, one can form a model where all the stockholders of the assets of the town live in the town. One exception would be where the government owns the town plant and uses the net output of energy (actually the money obtains from it) to subsidized some other region.
If there is a flow of goods into the town to pay for the oil output, how is the flow diagram (Figure 4 and 5) modified? The energy associated with this input flow of goods is not needed for the production since the feedback of 90% of the energy production fully supported the town's production. Thus it must be used for surplus goods and capital accumulation. It would be represented by a sink for the ultimate consumption of energy for its ultimate purpose.
Perhaps a better way to portray the model of Figures 4 and 5 is to not require that the fuel town also be able to convert fuel feedback into goods needed by the town. To achieve this we can envision a "multi-output" company town in the feedback loop. This multi-output town has fuel as a single input and makes all the goods needed by the fuel town, including consumer goods, industrial supplies, etc. This multi-output (one input) town makes all sorts of goods (including food) for both it's residents and the residents of the fuel town. To mirror society, we'll assume that the small-scale production of the town is just as efficient as the large scale production in the real world.
An example of such a "fuel town" with a "multi-output town" is shown in Fig. 6 below where the numbers represent energy flow: E is embodied energy and F is fuel caloric energy (in units of say a TJ/day).
Fuel From Ground ______________________ -------------------->| Fuel Production | F=2 E=2 F=1 E=1 F=2 | Company Town |---->----i----------> i------>|____________________| | Net Fuel Output Goods to | ______________________ | p=0.5 Support People| E=2 | Multi-output | F=1 E=1 | and Plant |---<---| Company Town |----<----| Fuel to "Feedback" Town |____________________| (Feedback Town) Figure 6: Feedback Flow of Energy from a Fuel Town
It's assumed that all of the energy supplied to the fuel town (except energy from out of the ground) is embodied. It seemingly takes E=2 units of embodied energy input to the fuel town to to extract F=2 units of fuel energy. So it seems like there is no gain in energy. Except that the E=2 embodied energy has a datum of the the earth. (See Energy Datum) but the F=2 excludes any embodied energy and has the fuel town fuel output as a datum. Since these two datums are different, they are not comparable. To correct this error we must use the same datum.
Using the fuel output of the fuel town as a datum, we would have E=0 output from the fuel town (no embodied energy) and thus have only F=1 input to the Mult-ouput town which gets transformed into E=1 output of embodied energy which goes into the fuel town. Thus for E=1 of embodied energy input the fuel town supplies an output of F=2 of fuel so one unit to energy in gets two units out resulting in a gain in energy. Except that there's of course a loss of the two units of energy (F=2) extracted from the earth.
From the point of view of the rest of the world, the town-pair supplies the world with F=1 of energy and requires no input energy from the rest of the world so it's seemingly infinite return on energy invested since no energy is invested. But there is a cost: The F=1 flow to the rest of the world implies a flow of one unit of energy to the rest of the world, but the depletion of energy in the earth is F=2 units along with the pollution resulting from burning these 2 units of energy. Note that like before, this Model neglects sale of net output Fnet
When one tries to use the above model where there is no fuel output to the rest of the world, it would seem that the flow of embodied energy becomes infinite. The input flow of energy from the ground continues to be 2 but there is no output flow. This would imply that since energy is not lost (fuel energy burned becomes embodied energy) then energy must be somehow stored in the two towns. But the model has no storage facilities. Where does the energy go to? Well, the fuel supports the lives of the people in the two towns. This life support can be represented by embodied energy flowing out of the towns which disappears into a network sink.
Fuel From Ground ______________________ E=1* -------------------->| Fuel Production |---->----> Life of residents (sink) F=2 | Company Town | i------>|____________________|---->----i p=1 Goods to | ______________________ | F=2, E=1*, T=3 Support People| E=2 | Multi-output |----<----| Fuel to "Feedback" Town |---<---| Company Town | E=1* |____________________|---->----> Life of residents (sink) (Feedback Town) Figure 7: Feedback Flow of Energy from a Fuel Town; no Net Output
An example is shown in Figure 7 above. The two units of embodied energy, E=2, input to the fuel town, does double duty in the fuel town. It supports the lives of the residents which use their lives for the output of fuel. Thus the E=2 should be counted twice as output: once for supporting the lives of the residents and again for enabling the output of fuel. But that would violate the rule of conservation of energy by having energy output flows exceed the flow of input energy. So in the figure only the input of E=2 is allocated to the outputs and each such output is marked with a * (E=1*) to indicate this. The non-sink output of the fuel town is thus F=2, E=1*. So E=1* is one half of the (double-counted) embodied energy.
This assignment of fuel energy to double-counted embodied energy is in conformance with the "principle" that all fuel energy, even if in embodied form, ultimately goes somewhere and doesn't get multiplied or double counted. However this conservation of fuel energy principle doesn't necessarily imply that if E=2 (embodied energy) is doubled, the result is two of E=1*. It might be E=1.2* and E=0.8* etc. which would also satisfy the conservation of fuel energy since it represents two units of fuel energy. Thus in general, when a unit of embodied energy, E, becomes double-counted, the result is E=x and E=y wheres x and y are non-negative numbers that sum to the embodied energy input, that is: x >= 0, y >= 0, and x + y = embodied energy input.
However one can't arbitrarily assign values to x and y within the constraints. This is because the flow of "embodied fuel energy" to the sinks must be equal to the input flow of fuel energy from the earth. The E=1* satisfies this requirement for the example of Figure 7. But having the life-support sink for the fuel town have flow E=0.8* with E=1.2* for the multi-output town also satisfies this requirement. But it seems reasonable to make each E=1* so that the embodies energy going to each sink due to life support has the same amount of embodied fuel energy.
To-do: Treat non-fuel goods similar to fuel with both a utility component, and an embodied energy component.
This model will discuss the quantification of human energy in the U.S. economy using a simple feedback model. The final output will be only surplus goods and services. But first, we'll present the simple model where the final output is both consumer goods and surplus. and neglects human energy (no feedback). Later it will be corrected to include human labor, where only the surplus goods and services are the final output.
The figure below shows U.S. economy as a black box with an energy input flow F and output flow O. The economy is assumed to be in a steady state condition with no net capital accumulation. The input flow is the flow of energy from oil wells, coal mines, natural gas wells, etc. The economy (black box) takes this input energy (and other raw materials) and converts them into finished products and services. Also input is solar radiation and falling water used for hydroelectric power but this is not shown in the Fig. 8.
Output flow O is the energy content of the final consumer goods and services consumed by people. For example the goods: food, clothing, shelter, recreation, personal autos (and the gasoline to run them), luxury goods, etc.; and the services: medical care, sales clerks, government, etc. All the input energy is allocated to the output consumer goods and services. Most of the output energy is in the form of embodied energy. But some is in the form of actual energy, such as gasoline which in addition to its heat value, contains the embodied energy used to produce it (oil well drilling, refining, transportation, etc.)
______________________ F (input energy) | O = F | O (output energy) ------------------>| The U.S Economy |--------------------> (Energy of fuels) |____________________| (Energy in consumer goods & services) Figure 8: Energy Flow in US Without Feedback
The production and consumption of intermediate goods (such as lumber to build houses or glass for automobile windows) all happens within the black box of the U.S. economy. For industrial processes that use energy, much of the input energy becomes waste heat, but all this input energy is allocated to the output goods of the industry. So the energy which was turned into waste heat still winds up as embodied energy in the output. Of course, some of this output is intermediate output which becomes the input of some other industry inside the black box. Thus the input fuel energy F equals the final output energy O. Actually, both the output energy O and the input energy F are energy flows and for the U.S. are roughly 100 exajoules per year. See Total fuel energy We'll often omit the word "flow" when discussing input, output, and feedback energy but it should be understood that it's actually a flow.
While the flows in the above diagram represent energy (mostly embodied) one may think of the flows as being consumer goods, and labor with these flows being measured in terms of energy flow. In other words the amount of each consumer good or unit of labor is measured by the amount of embodied energy it contains. Except that consumer fuels will have both embodied energy plus potential heat energy.
The next step is to account for human energy which is shown in Figure 9 below.
In this section "goods" will often be used to mean both goods and services. "Surplus" goods are goods and services which are not necessary to support maintain, and reproduce the labor force. Surplus goods consist of luxury goods (such as yachts and second homes, etc.), waste (such as gambling, recreational drugs, and government waste)), and capital accumulation (not counting the requirements of replacement of existing but depreciating capital goods).
The method used here is to show the human labor feedback energy flow as being outside the "Production Economy" black box. The final output of consumer goods and services (including some capital goods) is spilt into two parts: surplus goods with energy flow S, and the goods necessary to support working people with energy flow L. Since humans must reproduce, educate and raise children to sustain the labor force, all the energy needed for this is included in the human labor energy flow L. The energy embodied in the consumer goods and services, both of which are consumed by workers, is then expended during the labor of the workers and becomes embodied energy in the products they make and the services that they provide. It is thus another energy input to the economy and adds to the fuel energy input F resulting in a total energy input of F + L.
This labor energy L represents positive feedback since it adds to the fuel energy F. Note that like the simple model without feedback, the input energy to the economy is equal to the output energy: F + L = O. But O splits into surplus and necessary energy so O = S + L. Let p be the percentage (or fraction) of the output energy O which supports the workforce. In other words L = pO. The rest of O must go for Luxury of S = (1 - p)O. Note that if p is not fixed, this model is invalid. Later on we'll show why it seems reasonable to let p be fixed in value.
______________________ F (fuel) F + L | O = F + L | O S (surplus goods) -------->i-------->| Production Economy |---->----i----------> | |____________________| | S = O - C = (1 - p)O | ______________________ | | | Consumer goods | | |----<----| become labor: L=C |----<----| L (labor) |____________________| C (consumer goods to workers) C = O - S = pO (note that F, L, O, S and C are all flows of energy, say in J/yr) Figure 9: Flows of Energy (mostly embodied) with Labor Feedback
This model is like what one finds in some textbooks on electronic circuits or control theory. It's like an amplifier with a gain of one and with a fraction p of the output fed back to the input as positive feedback. Given an input energy flow F and fraction p, one can readily solve for O, L, C, and S in terms of F and p. First, solve for O: In F + L = O, substitute pO for L (since L = C = pO). This gives: F + pO = O which upon solving for O gives O = F / (1 - p). Now since S = (1 - p)O, substituting for O gives S = F. Since C = pO, we get L = C = Fp / (1 - p) by substituting for O and noting that L = C. This shows the rationale for having p constant. L is directly proportion to F. For example, if fuel flows double so do labor energy flows. The model assumes that the labor to turn energy into consumer goods is directly proportional to the amount of energy. In other words constant productivity of labor. Also implied is that if needed, due to increased energy input, more workers can be obtained from elsewhere, and conversely. Here's the figure again with these results included and an example for the case where p = 0.8.
______________________ assume p = 0.8 F (fuel) F + L | O = F + L | O = F/(1-p) = 5*F -------->i-------->| Production Economy |---->----i----------> S = F | 5*F |____________________| | S = F = O - C = (1 - p)O | ______________________ | S (surplus goods) | | Consumer goods | | |----<----| become labor: L=C |----<----| L (labor) |____________________| C=4*F (consumer goods to workers) L = C = 4*F L = C = O - S = pO = Fp/(1-p) (note that F, L, O, S and C are all flows of energy, say in GJ/yr) Figure 10: Feedback Energy with Equations and Example (p = 0.8)
The results may seem strange at first, but they make sense when one thinks about them. For the example shown in Figure 10 where there isn't much surplus and p = 0.8, then O = F / (1 - p) or O = 5*F. Since L = C = pO then L = C = 4*F. This means the output energy flow O is 5 times the input energy flow F and the feedback labor energy flow L is 4 times F. How can energy flows, all resulting from the input fuel flow, be a few times larger than the energy of that fuel flow?
Labor energy flow is much higher than "total" energy flow due to feedback. It's something like say a circular swimming pool that has circulating water flowing round and round in the pool. The water represents energy. The pool also has an input pipe with water (energy) flowing into the pool and an outlet pipe with water flowing out of the pool with these inlet and outlet flows equal. So the flow within the pool of the water circulating round and round may be much larger than the input or output flows of the pool. In this analogy, the pool includes the feedback loop for labor energy. However, don't carry this analogy too far, since the mathematical flow model used here assumes no storage of energy and the pool and pipes of course store energy (represented by the water). But while this analogy shows that it's feasible to have such high flows of energy, it doesn't explain what it really means.
But note that since S = F (regardless of what p is) the output of surplus energy is equal to the input fuel energy. The final output S is only surplus goods and all the input fuel energy F is allocated to this final output. But since only 20% of consumer output goes for surplus goods, then the energy content per dollar of goods is about 5 times what it would be if human labor were neglected and there was no feedback of consumer goods (which would just flow out of the system). Let's call the embodied energy content per unit of good the "energy intensity" of a good. Using a dollar's worth of goods as a "unit", the energy intensity is in units of embodied energy per dollar (in units of say J/$). Similarly for human labor, let its "energy intensity" be the Joules per dollars worth of labor at prevailing wage rates (J/$).
If the energy intensity of surplus goods is high, so will be the energy intensity of the consumer goods needed to support labor. This is because if we could be more efficient and support labor with less consumer goods (perhaps due to higher quality of the goods), then some of the consumer goods that formerly supported the work force could be diverted from workers to surplus goods. Since these goods are interchangeable with surplus goods, they must have the same high energy content (energy intensity) as surplus goods. Thus the consumer goods to support labor has high energy intensity, just like surplus goods and thus the labor effort made possible by such consumer goods must have high energy intensity. An economist might say that we must account for the "opportunity energy cost" of workers' consumer goods since they have an alternate use as surplus goods.
Summarizing: In this model, the energy of human labor, including all the consumer goods and services that support labor (and the reproduction of labor) is an intermediate good. The only final output is surplus goods (including waste and capital accumulation). All the fuel energy input is allocated to the this final output which explains why it has such high energy intensity.
This model is equivalent to the case of a worker requiring additional workers for his support. If all workers are equally productive and require the same amount of energy to support their living, then the example with p=0.8 is saying that for every person engaged in producing surplus goods 0.8 of a worker is required to produce the necessary consumer goods for him. But that 0.8 of a consumer-goods worker isn't producing anything for his own support so he needs 0.8 x 0.8 of another worker to provide for his support. And so on, ad infinitum. But its easy to show that this geometric series sums to 4 showing that it ultimately take 4 non-surplus workers (consumer-goods workers) to support one surplus-goods worker.
It's obvious that the feedback model is something like the model of a large network of company towns. But in many company town models, the surplus goods are consumed right in the company towns, except for capital goods accumulation. On the contrary, the feedback model explicitly shows the flow of surplus goods. The feedback model has service workers within the economy and doesn't show the distinctive role that local service workers play in supporting production workers. Add-more later.
In order to apply the company town analogy to the world (or to a self-sufficient nation) we need to create a huge number of company towns to make everything used by people and industry. Then all the company towns become nodes in a transportation network where the output of each company town is spit up into a large number of flows of the same good and each such flow flows along a transportation route which connects to the input of some other company town. Thus the outputs of company towns become the inputs of other company towns although it's possible that some of the output of a company town might flow to that same town's input. But in order to do this the specific inputs to each town in terms of the amount of input required for unit output needs to be specified for each town.
There's major unresolved problems: What are the energy sinks for embodied energy? What are the ultimate purposes for energy? And there's more questions like the above. I'm working on these questions but I fear that some of the answers are likely to be subjective.
THIS IS PARTLY WRONG: SORRY. It's been only partly fixed.
This dual nature of energy flow out of a company town exists when the output good is itself energy. The output of an energy producing company town (such as a coal mine, oil field town, or ethanol community) is a fuel which has value due to its caloric energy content. But there's also embodied energy that went in to the inputs to the company town that produced the fuel. In non-energy company towns this embodied energy is the only energy output. But for a energy company town there is also the caloric energy output based on the caloric value of the output fuel.
These two types of energy output, embodied and caloric represent different things. The caloric value of the coal represents it's use value or utility. But the embodied energy represents the energy cost of making the fuel available. Caloric energy represents a benefit while the embodied energy represents an energy cost it took to get the fuel. Cost and benefits don't usually add. But if you were to burn the fuel the amount of energy destroyed is the sum of the embodied and caloric energy.
A flow of fuel energy needs to have 2 values to the flow: the caloric energy of the fuel and the embodied energy of the fuel. A technological process like using the fuel energy to make something will require a certain amount of caloric energy, regardless of what the embodied energy is. Yet the total energy used up by using the fuel is the sum of the caloric and embodied energy.
So if there is to be a positive energy gain, the heat value (caloric) of the fuel (neglecting transportation costs) will have to more than the value of the caloric and embodied energy that went into producing the fuel. If the net energy gain is small then a lot of fuel is being burned to produce a small amount of net energy gain. This can be a disaster for the environment since it will release much pollution into the environment to obtain just a little energy. For the case of atomic energy supplying the energy inputs from the external world to the mining town, there may no be release of much pollution if all goes well, but if it doesn't it can be very polluting.
Yet even if there is no energy gain, there is still support for the life of the human beings in the fuel company town. Consider the case where the flow of caloric energy of the fuel is equal to the embodied energy flow (equal to the total input energy flow) and there is thus no energy gain (zero energy return on energy invested). Yet the output fuel flow could become the input to another company town (with diverse output products) which would convert this input into an output flow suitable to support the fuel town. Thus we have sustainability (until the fuel is depleted) with zero energy gain from the fuel town. But there is no surplus energy flow either. Surplus is needed for capital accumulation and advancement of knowledge, etc.
If one wanted to only have the United States in the network of company towns, one would need to account for imports and exports. One could create a special super-company-town for this purpose. Into it would flow all goods and services to be exported and out of it would flow all goods and services which are imported. One would need to assume that trade is balanced so that the energy content of the imported goods would be assigned the energy content of the exported goods. Since in reality, the US is running a huge foreign trade deficit this balancing of energy flows of export-import is not valid.
The actual imbalance of trade results in a huge energy imbalance of flow from the rest of the world to the United States. It's like an energy "subsidy" to the U.S. from the rest of the world. But it's not really a subsidy since the U.S. is in debt to foreign countries (including U.S. equities held by foreigners)to pay back this imbalance deficit and this implies that eventually the situation will reverse and there should be a huge energy subsidy flow from the U.S. to the rest of the world. Except that it's difficult to envision how such a reverse flow will be feasible which implies that the U.S. may just default on it's debt one way or another. But if such a default happens, then the energy subsidy flow is likely to come to a halt.
So the area under study will be called the "economy" which is assumed to be the economy of a mostly self-sufficient country as the United States or the Soviet Union were at one time.
The company towns should be mutually exclusive and exhaustive. This means the following: Exclusive: production firms and people in the economy should be counted only once. Exhaustive: the people in all the company towns should account for all the people in the economy and the outputs should account for all the outputs of material goods and exported services.
The problem is to estimate the net energy change for society if a new job is created and a person starts working. This should also be equal to the energy change if the same job is eliminated. But the above statement of the problem is inadequate since one needs to specify what to keep constant and what may vary. It also may depend on what the person placed in the job was doing previously.
One way to look at this is to estimate the energy required to support this person sustainably. The worker receives pay for work and uses it for life support which consumes embodied energy in food, clothing, shelter, health care, etc. including embodied energy in services. A diametrically opposed point of view would reason the`at since the person who gets the job was already being supported and thus consuming energy, little (if any) additional energy life support is required. This situation is complex and will be examined later on fix-me.
Note that this section uses a person-day as a measurement of labor. But strictly speaking, marginal cost should be measured where the change in labor is very small, such as only a second of labor time per day. So when we talk about creating a job, what we actually mean is slightly increasing labor time (say be a second), then estimating the energy cost of this second to find the J/sec of energy cost, and then converting to units of energy per person-day of labor.
First let's look at what happens if a new production worker is added to a "company town" as previously defined. It assumes that either the company town has full employment or that the unemployment rate is fixed. The additional energy which needs to be supplied to the town is the energy per capita of the new worker plus a few other dependent people: servers, spouses, children, and retirees. Thus it's a few times the energy per capita with a total of approximately 0.1 Gcal/day (giga calorie) or about 300 times the rate of caloric intake per day of the worker's food of about 3Mcal/day (3000 kcal/day). See Calories eaten per day.
But if a new job is created in the company town, where does the new worker come from. Since population in the town is constant, people born in the town are just replacements for townspeople who die and don't provide an employee for a new job. So there are two possibilities: the new employee comes from outside the town or the new employee is a extra person born in the town in addition to the births which are replacements for deaths. to-do
Another method of estimation is as follows: Let's consider the case of a firm named F that can produce the same output with either: one additional employee or a fixed amount of additional energy input. An economist would call this the "marginal rate of substitution for the "production function" of this firm where energy is to be substituted for labor. This energy input is assumed to be "pure" energy that contains no embodied energy and thus no human energy. It's like the enterprise is located next to an oil seep in the earth and it can use this oil for energy but nevertheless has to pay for the oil.
It's also postulated that the total output of goods and services remains the same in the short run, otherwise any scheme that reduced such output could save energy. However energy inputs to industries are allowed to vary as an impact of the creation of this new job. We also assume that no additional capital is required to support this new job. Firm F thus has two alternatives: one more employee or a fixed rate of additional energy input (due to not hiring a new employee). In both cases, the output of the firm F is the same. Which alternative for firm F will use less energy? We will examine both the short run impacts and long run population impacts. The short run is perhaps a month or so and the long run is many years.
Three cases will be considered:
If unemployment is at a fixed rate (and population constant) an unemployed person finding a job is accompanied by an employed person losing a job. In this case, in order to maintain constant output, more energy must be used by the firm that loses an employee which isn't replaced. However the hiring firm F reduces their energy consumption by hiring this new employee. In economics one might say that there is an opportunity energy cost to pay since more energy is now required to maintain output by the firm F that lost the employee. Remember that most of the energy saved or lost is in the form of embodied energy of goods.
For example, if the new employee redesigns the manufacture of goods so that the goods will last longer, the production of them can be reduced to keep the output constant, resulting in less energy. Note that if a good lasts longer, it's value increases, so to keep the value of output constant, less physical output of goods is needed.
This result using the company town model is similar for a worker switching jobs from one company town to another company town. The worker, along with his dependents and servers just move from the old company town to the new one. Thus there's no change in consumer goods energy input costs for the two company towns as a whole, except that the town where the worker quit now has to import more energy so as to maintain constant output.
So the energy cost of providing this new worker is called the "marginal rate of substitution" of energy for labor in the industry losing the worker. This should be approximately the same as the worker's wage, which covers payment for the support of all the servers and dependents required by the worker. So this is about the same as the huge amount of energy as predicted by the company town model for the case where there one only looks at the company town that took on a new resident worker along with the worker's servers and dependents.
A simple example for this case is where an unemployed person gets the new job. But an equivalent situation can happen if the new job is filled by someone who quits an existing job, and that existing job is filled by someone who quits another job, etc., etc. but ultimately, someone quits a job that get filled by someone who was unemployed.
Unemployed persons will likely have less income and likely live more frugally. Such living uses less energy. For example, the unemployed person may have time to do things to use less energy such as repair broken possessions rather than purchase new, etc. and eat cheaper food (which takes less energy to make). Since the unemployed person has more free time, he has opportunities to use time to save energy such as repairing things instead of discarding them and buying new. In an extreme case he may even be homeless and save the energy normally used for housing. When the person gets the new job and has more income, the person is likely to live less frugally and thus use more energy. So there is usually an energy cost to hiring an unemployed person.
In most cases, an unemployed persons lives at least partially off the labor of others (a subsidy), such as workers that work for companies which pay unemployment insurance taxes. When the unemployed person gets a job and becomes self supporting, then the subsidy by other workers is reduced and more of the products of their labor are available for consumption by these workers. Another way a saying this is that if an unemployed person goes to work, more is produced resulting in more energy consumption
fix-me Suppose someone in a company town is fired from his job thus increasing unemployment, but the input flows of consumer goods don't change so that the fired person is still supported with his previous standard of living. To maintain constant output of the town's industries, a new hire from outside the town, along with his dependents and servers need to enter the town, resulting in a significant increase in energy input with no increase in output. The marginal rate of energy intensity (increase in energy input per unit increase of output) is infinite. In the previous extreme case where the unemployed person gets a job and maintains his standard of living, the marginal rate of energy intensity is zero (more output for the same energy input). So while it's possible to find extreme cases, these are not typical.
Since energy and global warming are long run issues, we are especially concerned with long run effects. For a developed country, More jobs available will likely increase birth rates to provide workers to fill those jobs, and conversely. Economic conditions do influence birth rates in modern countries such as the low birth rates in the United States during the great depression and in Russia in recent times due to the depression in Russia. Thus in the long run, creating a job may mean that there will be a few more people to provide energy for and conversely. The company town model itself doesn't address the issue of long run population change.
Let's look at the case of domestic work animals such as horses. If one maintains a work horse using feed produced using fossil fuels, then that energy obviously is assigned to the useful work done by the horse. Also, the non-feed energy needed for maintaining the horse counts also. If we don't need the horse anymore, then we can sell the horse to someone who does and will pay for the cost of sustaining the horse. If there are excess horses and little demand for them, then we can breed less horses and thus save the energy required to maintain the horse. The surplus horses could be put out to pasture until they dies of old age, or we could even kill the horses for horse meat. Thus for a horse, in contrast to humans, the long run impact would be saving of the total energy used to maintain the horse.
The situation for slaves is intermediate between the case for horses and non-slave humans. If slavery were legal today, the slave owners might be able to control the reproduction of slaves. Thus if one less slave is needed, there would be a lower birthrate for slaves and conversely. Thus all the energy required to maintain and reproduce a slave would be charged to the services and goods produced by the slave.
This is the crux of the problem of determining what counts as an intermediate good in an Input-Output model. If we can find the ultimate purposes for energy use, then all energy used by society may be assign to these purposes, then other uses of energy are just to produce intermediate goods and services. Such intermediate production assigns the energy it uses into the embodied energy of the intermediate goods and services. But the ultimate purposes are like sinks in energy flow. The energy used by them disappears and is lost forever. By assigning all the energy to the ultimate purposes, these purposes become very energy intensive and great energy savings can be achieved by reducing these ultimate outputs.
Modern society produces energy and it's use needs to be accounted for in terms of the ultimate purposes for which it is used. For example, one might say that an ultimate use of energy is to provide automobile transportation. But if the automobile is used by a firm to produce a good or service, should not that transportation energy be assigned to that good or service produced? And if that good or service is not a final output (i.e. an ultimate purpose of energy) then one needs to look for ultimate purposes further along in the embodied energy flow chain.
A very simple energy economy is one without human beings and even more elementary is an energy economy with only plants (and perhaps some bacteria to help decompose dead plants). In this case the purpose of the sunlight energy provided to the plants is just to grow the plants. Insofar as some of the plant material becomes trapped in the earth is is converted to fossil fuels, one could claim that one purpose is to create fossil fuels and another purpose is to generate oxygen from carbon dioxide, thus creating a planetary atmosphere more suitable for future animal life. Since animal life evolved from plant life, one could claim that an ultimate purpose is to prepare the way for evolution into animals and ultimately human beings.
If we add animals to this world of plants, and if some animals are carnivores and eat other animals, then what is the purpose of the solar energy that provided energy to the plants and ultimately to the animals. Since the animals depend on the plants for their survival, one purpose of the solar energy is to support animals. But what about the purpose of supporting plants? The animals don't eat all the plants so part of the purpose of the solar energy used must be to support plants. So the ultimate purpose is to support both plants and animals.
After some of the animals evolve into people, then the ultimate purpose of the solar energy would seem to be the support of plants, animals, and people. Some might claim that the single purpose is to support people and that the population of humans could be so large that there is no place left for wild animals and plants. But don't people have a lot to learn from observing the life of wild animals and plants? And isn't there also a recreational aspect? Does wild nature have a right to exist even if it were of little or no benefit to humans? Thus how to allocate the solar energy depends in part on ones philosophy of the relation of humans to the natural world.
The extraction and use of mineral fuels such as coal, petroleum, natural gas, and uranium is done by human beings and not by wild animals or plants. Thus it would seem that the purpose of this energy is to support human life. A simple allocation model would be to allocate all of this mineral fuel energy to the consumer goods used by people which are made possible by the consumption of these fuels. In other words the ultimate use of the energy would be to support human life with food, clothing, shelter, etc.
Another point of view is that much of the support of human life is merely a means to an end. Humans use a significant part of their lives to work and help produce goods and services. They are thus something like machines. You provide them with food, clothing and shelter and they produce surplus goods: luxury goods for the rich (and sometimes not-so-rich); capital goods for industrial capital accumulation; works of art, music, science, literature; recreational goods; etc. Then the ultimate use of energy is to supply surplus goods to society. In this scenario, the energy is allocated to a smaller subset of goods than the allocation in the above paragraph which includes food, clothing and shelter. Thus the embodied energy intensity (EEI) of the surplus goods is very high.
How does this apply to a company town which produces fuel for it's output? While the fuel itself is not the ultimate use of that fuel energy, from the viewpoint of the world at large the fuel town gets energy input from the embodied energy of the consumer goods flowing into the town (plus industrial goods and energy) and outputs only fuel. The human labor and support of all the people in the town is just part of the production process and is an energy cost input for the obtaining of the exported fuel output.
But let's look at this from the point of view of the residents of the fuel town. Their livelihood comes from the extraction of fuel, they exchange the fuel they produce for consumer goods. For them, the ultimate use of the fuel they extract is to support their lives in the town. In a sense, the embodied energy supplied in consumer goods to the town is used twice: once to provide fuel output due to the labor of the people and again to support their lives. Work has a dual purpose: It both produces output and provides a livelihood for the workers. A unit of embodied input energy can both flow into an ultimate purpose sink of supporting human life and also be converted into fuel due to the labor of the workers.
In economics there is something called joint products, like the mutton and wool from sheep. But what we are talking about concerning the fuel town is something quite different. Some of the food the sheep ate went into growing wool and other elements of the sheep's food went into growing meat. In the fuel town, the same elements of consumer goods both supported the workers lives and went into the production of the exported fuel. In other words the fuel input accomplishes two different purposes at the same time.
to-do.
It should be obvious that there will be differences of opinion as to whether or not specific goods or services should be included in the surplus good category (luxury/waste items) or whether they are necessary goods for workers. For example, what types of vacation travel are luxury and what types are needed to maintain the physical health and morale of workers?
Here are some wasteful economic activities: commercial gambling (including lotteries), civilian government waste (including unjustified subsidies), military spending wrongfully used (example: Vietnam, Iraq), most recreational drugs, waste by monopolies such as overpaid railroad train operators.
Both the problems of global warming and the depletion of fossil fuels has heightened the public awareness of the need for energy conservation. Conserving fossil fuels puts less carbon dioxide into the air and helps reduce the acceleration of global warming. It also conserves the fuels for use by future generations but unfortunately the future use of this saved fuel in the future could exacerbate global warming.
Thus it's important to be able to get good estimates on the energy it takes to produce various goods and services since people and governments often favor the goods and services that allegedly have the least energy content. For example: Does it take more fossil fuel energy to make ethanol than the energy contained in the ethanol? But a major problem in energy accounting is how to estimate the human energy it takes to make goods (such as ethanol).
As a digression: Favoring low-energy-content goods by subsidizing them is (in the authors opinion) bad policy. Using fuel energy does harm to the environment and the future. Just like smoking cigarettes is harmful, subsidizing goods that use less energy and are thus the less harmful is like subsidizing cigarette brands which are the less harmful because they contain lower levels of tar and nicotine. Such subsidy is not fair to those that don't use the product at all.
For example, someone who travels little and doesn't own an automobile is likely saving more energy than someone who drives a fuel-efficient automobile. Thus if there's subsidy for energy-efficient autos, there should be even more subsidy to people who don't even use an auto, but there isn't. Thus if government operated more rationally and didn't subsidize goods that are supposedly energy-efficient, knowing the energy content of goods would not be as important.
Many studies of energy flows in the economy simply (and erroneously) neglect the human energy factor. A recent example is the book: Environmental Life Cycle Assessment of Goods and Services, An Input-Output Approach by Chris T. Hendrickson, Lester B. Lave, and H. Scott Matthews. RFF Press, April 2006 (260 pages).
What is often called renewable energy isn't really renewable at all, since to produce "renewable energy" often requires a lot of embodied energy (including human energy) to produce.
When human beings work, play, or rest they use energy and put carbon dioxide into the air by breathing. But this carbon dioxide by itself doesn't directly contribute to global warming since the food was created by the sun shining on plants and the plants removed carbon dioxide from the air in order to get the carbon used to form the food. For the case of meat, the animals that grew to create the meat ate food generated by the sun. Thus it might seem that food is a renewable resources created by solar energy and eating it doesn't increase the carbon dioxide content of the atmosphere. But this is an illusion because to produce food the modern way requires machinery, fertilizer, transportation, and human labor that use a lot of fossil fuel energy and thus heavily contribute to global warming.
The energy content of food (measured in Calorie=kilocalorie=kcal) is food energy consumed by humans and the carbon dioxide we breathe out is a result of the digestion of this food. But for every kcal of food consumed, it roughly takes about 10 kcal of fossil fuels burned to produce it and transport it to the consumer. See Appendix: Fuel to Make Food All this also contributes to global warming. But the impact of using human energy doesn't end there. Humans, in addition to food, require clothing and shelter. Without these, they would die (at least in cold climates) and thus not be able to exert any physical or mental energy. So clothing and shelter are necessary prerequisites for human energy to be available. Note that human energy output is not just muscle power but also includes the mental energy used by people at work, study, recreation, etc. To further explain this requires explaining the concept of Embodied Energy.
So most all of both food energy and human energy is derived from fossil fuels and is thus not renewable.
Most studies either ignore human labor energy or grossly underestimate it. See Company Town Analogy which explains why human labor energy is very large.
The energy expended to make a product (such as an automobile) or a service (medical care), or an adult person is called the embodied energy of the item and is depreciated as the product, service ,or person is utilized. Just like an automobile depreciates in value as it is used and ages, so does the embodied energy in the automobile depreciate. The embodied energy of an automobile is not just the direct energy it took to assembly the automobile but includes the sum of the embodied energy of all the components that went into the automobile: light bulbs, the battery, tires, windows, human labor, etc.
Of course, each component itself is a product and contains the embodied energy of its components. And so on ad infinitum. It's really infinite because each chain of components eventually begins to loop.
But the adding up of an infinite number of values doesn't result in an infinite sum because the complicated series of numbers we add converges. For a very simple example, if we add up the series: 1 + 1/2 + 1/4 + 1/8 + ... we get 2 although there are an infinite number of terms. Synonyms for "embodied energy" include: "embedded energy", "indirect energy", and possibly "emergy".
A simple example (neglecting human labor) of a loop with 2 components is iron and coal. It requires coal to make iron since the carbon in coal combines with the oxygen in iron ore to create carbon dioxide gas, thereby removing the oxygen from the iron oxide ore and leaving just iron. But it requires iron (actually steel) to mine coal since coal mines use steel (mostly iron) to hold up the roofs of the mines, etc. Suppose that to make x tons of iron requires ax tons of coal and to make x tons of coal requires bx tons of iron So to make a ton of iron requires this many tons of coal from this 2-item loop process: a + aba + ababa + .... This is just an infinite geometric series which sums to a/(1-ab).
Another way to find this result without using an infinite series is by simple algebra. Let the total amount of coal required to make x tons of iron be cx. Let's find the value of c in terms of a and b. We have cx = ax (direct amt. of coal) + c(bax) since we need bax amount of iron to make ax amount of coal. Solving results in c = a/(1-ab), the same as obtained using the formula for the sum of an infinite series. Actually, much more coal than this is required to make a ton of iron since there are many other loops and chains involved. For example, the steel mill that makes iron uses electricity that may have been generated by coal.
Returning to the automobile example, as the auto is driven, ages, and wears this embodied energy is consumed and charged to using the auto. In other words, we deprecate the embodied energy just like we would depreciate the monetary value of the auto as it ages and as it's driven. Thus in addition to burning gasoline as we drive, we also "burn" some of the embodied energy of the auto.
Trying to calculate the embodied energy in a product such as an automobile, isn't simple. But it gets much more complicated when we try to account for the human energy expended in making something. At first glance, one might think that human energy is small compared to other types of energy, such as the energy used to fuel automobiles and keep them in motion. After all, a human being doing heavy work only exerts about 1/5 of a horsepower while an auto uses perhaps a hundred times more horsepower when it's moving. Note that in cruising on level ground at moderate speed, only a small fraction of the horsepower of an automotive engine is actually utilized and the above example is for an auto which uses only 20 horsepower for speeding along a level highway.
But if we fully count human energy, then it becomes very significant. As mentioned previously, providing humans with food, clothing, and shelter requires many times more energy than just the calorie value of the food we eat. One reason is that for every calorie of food we eat, the takes over 10 calories of fuel to create it (see Eric Hirst's Study, 1974 and David Pimentel's Study) Also, due to the inefficiency of the human body in turning food energy into muscle work, the energy requirements of human beings are even higher. Furthermore, a productive society requires a certain amount of government, transportation, buildings, and other infrastructure. And a person with a desk job needs additional exercise to stay healthy. All of these things and more are necessary to maintain a worker and require energy, mostly by using up the embodied energy in consumer goods and services provided to people.
Let's compare a human being to an automobile in terms of the energy used. An active adult needs only about 2,500 kilo-calories a day (=2,500 Calories with a capital C in the U.S.) of food. See Calories eaten per day. This is equivalent in heat value to only .08 gallons of gasoline. But when one realizes that it took the equivalent of about .8 gallons of gasoline energy to create this food it becomes more significant. Now each adult over 14 in the U.S. uses about 1.5 gallons of gasoline per day Gasoline Consumption per Adult for transportation. This is almost double the energy used to produce ones food. But when all the other energy required for living is included, then human energy consumption becomes much higher than the energy in automotive gasoline consumption. It's thus of great significance and something that should never be neglected in energy accounting although unfortunately, it often is.
As I'll explain later, human energy flows are actually much higher than implied above, due to "positive feedback" which I'll also define and explain.
Input-output analysis is formulating energy flows using vectors and matrices. It only works for a closed economy but since today the U.S. is no longer very self sufficient, one needs to use the entire world. Unfortunately, good data just isn't available.
Here's how you do input-output analysis: You partition all industries of the world into a large number of sectors so that all economic activity is covered. For every sector of the economy you define what one unit of output is. For example, for the steel industry sector the output could be defined in dollars or in tons of steel. Whatever units are chosen for output of a sector the same unit of measure must be used for the input of it to other sectors. But units may be mixed: one sector may measure output in dollars, another in tons, and another just in numbers (such as number of small automobiles). The units of output must be defined for all sectors. Money, such as dollars, is the simplest unit but not necessarily the best.
Then for sector 1 (say it's steel) you find say how many tons of coal it directly took to make a ton of steel. Then you ask how much electricity it directly took to make a ton of steel, etc. So now for steel you have a list of numbers showing how many units of the output of various other economic sectors it took to make one unit output of steel. These numbers constitute a "vector" and are called input-output coefficients (or technological coefficients). The components of such a vector often have low values of less than one (but not always). Of course, you don't stop with steel but determine these coefficients (vectors) for all sectors of the economy that you've defined. Then using these coefficients, you write a set of equations to find the inputs needed from each sector given a vector which represents the outputs of all sectors. The equation are simple linear equations and can be written in matrix form. Each such vector becomes a column in matrix A (the Leontief matrix).
The "outputs" mentioned above are the gross outputs. Part of the output of each sector is used for inputs to other sectors and the rest of the output is consumed as final output. For example, part of the electricity we generate goes to factories, offices, stores, etc to help provide for the creation of goods and services and the rest of the electricity goes to residences for final output to the public. It's not quite this simple since if you earn money while