On Emergy

Tom Wayburn

Emergy and Transformity

We begin by recognizing that, although availability accounts for entropy, its usefulness varies from one energy source to the next.  (Both Gibbs availability and Helmholtz availability are defined in Appendix I.  If the reader thinks of them as simply energy, he won’t go too far astray.)  A joule of Gibbs availability from diesel fuel is worth more than a joule of Gibbs availability from sunlight.  In fact, it takes about 40,000 joules of sunlight to produce a joule of diesel fuel.  The availabilities of common fuels, especially renewable fuels, must be referred to an agreed upon standard.  Emergy analysis, developed by Howard Odum, the famous ecologist, assigns standardized values to fuels and other things of interest to society.  His reference standard is one joule of sunlight.  Emergy measured in emjoules is the Gibbs availability of the sunlight, measured in joules, required to produce, by an optimal process, (1) fuels; (2) other energy sources such as wind or fresh water in mountain lakes; (3) natural resources such as grass, trees, petroleum, and other fossil fuels; (4) manufactured objects, (5) human resources; (6) information; and (7) any other objects of economic interest that can be associated with an identifiable quantity of sunlight.  In Table 2-1, typical transformities necessary to compute emergies based on sunlight are given [ 7].  [Note.  Figure, table, and reference numbers refer to Chapter 2 of On the Preservation of Species.]

 

Table 2-1.  Solar Transformities

(solar emjoules per joule) [7]

Item

sej/J

Sunlight

1

Wind kinetic energy

623

Unconsolidated organic matter

4,420

Geopotential energy in dispersed rain

8,888

Chemical energy in dispersed rain

15,423

Geopotential energy in rivers

23,564

Chemical energy in rivers

41,000

Mechanical energy in waves and tides

17,000-29,000

Consolidated fuels

18,000-40,000

Food, greens, grains, staples

24,000-200,000

Protein foods

1,000,000-4,000,000

Human services

80,000-5,000,000,000

Information

10,000-10,000,000,000,000+

The transformity of sunlight is, of course, unity.  The entry for wind kinetic energy says that 623 joules of sunlight are required to generate 1 joule of kinetic energy in wind.  (Wind has about 40 joules of thermal energy, which is not available to us, per joule of kinetic energy.)  Each joule of geopotential energy in dispersed rain requires 8,888 joules of sunlight according to Odum.  Presumably, some portion of this falls into mountain lakes, etc., which, in turn, feed mountain streams and rivers and may be used to produce hydroelectric power.  The entry for geopotential energy in rivers is 23,564.  (How it can be known to five significant figures I cannot say.  I surmise that it has been computed that 8,888/23,564 (equal to approximately 0.377) is the fraction of dispersed rain that ends up in rivers.)  The emergies of food, greens, grains, and staples must account for the rain they require, the sunlight they absorb in photosynthesis, any fossil fuel that is used in their cultivation and transportation, etc.  Each joule (of availability) such foods contain requires from 24,000 to 200,000 joules of sunlight – depending, I suppose, on whether they grow wild in the consumers backyard or are farmed by a giant agri-business and shipped half way around the world.  I am not certain of the exact interpretation intended and I will try to get a clarification from Prof. Odum.  The reader realizes that a meal of greens from the green grocer, which might contain 21 million joules of Gibbs availability, has an emergy that might be as high as 4.2 trillion solar emjoules.  The case of human labor is interesting too.  I consume energy at the rate of about 0.1 kilowatts when I work.  That’s 100 joules per second.  If I work one hour using all of the knowledge I have acquired through some very expensive (no doubt overpriced) schooling (partly paid for by the reader), the emergy cost of that hour could be as high as 5 E109 solar emjoules per joule times 3600 seconds per hour times 100 joules per second times 1 hour  =  1.8 E1015 solar emjoules.  (That’s 1.8 million billion emjoules.)  So, these are some pretty expensive words you are reading!

Sunlight-based emergies have the disadvantage that they are large and known only very roughly.  Moreover, gross estimates are used to evaluate the fuels we use most frequently.  We don’t know how many joules of sunlight must be expended by the most efficient process to produce one joule of alcohol from biomass.  Undoubtedly, the optimal process has yet to be discovered.  These are deficiencies in emergy analysis.  They can be remedied somewhat as will be shown.  Howard Odum recognized that the value of manufactured goods can be quantified in terms of the energy consumed to produce them.  What we owe to the genius of Howard Odum is beyond our powers to compute (even in units of emjoules) – it is truly priceless.  That said, I must warn the reader that the use to which I put his gift is my responsibility alone.  If my implementation of his ideas, which, for the most part, corresponds to my personal taste and inclinations, turns out to be defective, the blame lies solely with myself and does not reflect upon the merit of his original conception and the great body of his vast and rapidly growing scientific legacy.

If we wish to do economics based on emergy, we need to assign emergies to capital goods and other manufactured objects.  Let us see how to do this in a thought experiment involving an imaginary ideal process.  In this process, the only input is energy (availability); no raw materials are used or, put another way, the raw materials are not considered to have any value – maybe negative value – like toxic waste or raw sewage, but we won’t take credit for it.  The process produces one product.  We wish to compute the emergy of that product produced by an optimal process.

 

Figure 2-1a.  Energy balance for ideal process

Figure 2-1b.  Availability balance for ideal process

Figure 2-1c.  Emergy balance for ideal process

 

In Fig. 2-1a, we depict the energy balance for our process.  We don’t show the product coming out, which is assumed to carry negligible energy.  All of the energy entering is reduced to junk heat.  In Fig. 2‑1b, availability enters and nothing comes out, since junk heat has no availability (in this analysis) and neither does the product, which can’t even be burned.  The lost work term provides closure for the availability balance.  Finally, in Fig. 2-1c, the emergy balance is shown with the transformed availability entering, measured as emergy, and the product carrying an equal amount of emergy along with it into the economy – even though all of the availability was consumed as junk heat.

In the case of a similar process that produces the same unit product but is less than optimal, more emergy is required at the input, and the difference between the input and the output is lost.  Thus, as in the Combined First and Second Law (Appendix I, Eq. I-6), emergy can be destroyed.  Can it be created?  Not in this corner of the universe – at least not at the present time.  We get it from the sun, which, presumably, loses much more than it creates.  I have no idea where it came from.  (One might as well say it came from God for all I know; but, most people have no idea what I mean by that word, which, apparently, cannot be used without doing at least a little harm.)  In this chapter, we are not permitted to pursue this question further.

In their earlier work [6], Howard and Elizabeth Odum measured emergy in fossil-fuel equivalents.  Emergies used to evaluate industrial economies might be computed more easily by taking the transformity of crude oil or even methane as unity.  If we are moving toward an electrical basis for energy analysis, it might be better to take one joule of 60 cycle (Hz), 110-volt alternating current (AC) as the unit of emergy – or, perhaps even better, 3,600,000 joules ( = 1 kWhr).

Efficiency

Definitions

Manufacturing

Emergy efficiency is emergy out divided by emergy in.  This efficiency is 1.0 for an optimal manufacturing process because the emergy of the output is defined to be the emergy of the inputs.  For a less than optimal process, the emergy efficiency is the emergy of the inputs to an optimal process over the emergy of the inputs to the process under investigation.  One can have negative energy efficiency; but, emergy efficiency, applied to manufacturing processes, lies between zero and one.

Energy Production

The emergy of the product is not known

If we are the first to investigate a new process to produce a new alternative fuel, this process must be taken to be optimal as we have none other with which to compare it.  Therefore, the emergy of a new alternative fuel would have to be just the sum of all of the emergy costs  – both direct and indirect – that go into the process.  [An example of an indirect cost is the pro-rata share of the commuting costs of the tax consultant (A) that should be charged to the pyrolysis worker (B) because the man (C) who serves B lunch had his taxes done by A.]  We shall always compute an emergy efficiency of 1.0 in the case of a process to produce a new product, or any product the emergy of which has not been investigated previously, the inputs to which are standard energy sources.  But, if the sum of the exergies of the inputs, all of which are primary fuels, exceed the exergy of the new fuel, the process is infeasible from the viewpoint of sustainability.  In this case or in the case where the emergy of the new energy product is much higher than the emergies of comparable fuels produced by other means, the only justification for the process is that we cannot do without the product and there is no other way to get it.  This can be done under singular circumstances, but it cannot be done in general.

The emergy of the product is known

Case 1.  If  the inputs are not of the same type as the product but each of them has a known emergy, the emergy efficiency is the known emergy of the product divided by the sum of the emergies of the inputs.  This is the situation (described below) where electricity is used to produce hot water.  This is definitely a suboptimal process as hot water can be produced with less emergy by burning fuel.  If the emergy efficiency is computed to be greater than one, the older process that determined the emergy of the product under investigation is sub-optimal; and, the emergy of the product can be reset to the sum of the emergies of the inputs to the new process.  It may not be expedient to discontinue production by the older process immediately because of compelling reasons not to shut down the older facilities – not the least of which is the time delay before new facilities can be built.

Case 2.  If the inputs are all the same type as the product, we have the standard feasibility analysis wherein it is to be determined whether or not the process will continue to run if all energy inputs are taken from the product stream.  Working backwards, let us assign an emergy of one emergy unit (MU) to one kilowatt-hour of whatever form of exergy, call it Eo, is produced by the process under investigation.  Then, let us calculate the emergies of the inputs to our process under the hypothesis that the optimal processes that produce our inputs consume energy of type Eo only, unless some other form of energy (call it E2) is available that would be wasted if we did not consume it.  If the emergy efficiency is less than 1.0, the process is infeasible, by which we mean that it would be unsustainable unless it were subsidized by an infusion of fossil fuel, for example.  Such a process will consume more fossil fuel than it saves.

Matching Problems

After all, we have no idea if even one sustainable primary energy technology exists other than firewood itself.  (We would prefer not to burn firewood directly, because of the smoke, even if it turns out that global warming (from carbon dioxide) is not a problem.)  In any case, when we analyze our first sustainable energy process, we have no right to imagine that a less expensive sustainable energy source exists that can be “matched” to that process.  We cannot make use of predictions concerning the distribution and usefulness of our form of primary energy or any other.  In other words, we must do our determination of feasibility with only occasional reference to the matching problem that will be solved subsequently.

Thus, it is, in fact, Eo, itself, that must carry the burden of the direct and indirect costs with few exceptions.  On the other hand, if we have sustainable electricity, probably we would use electric cars, which are much more efficient consumers than gasoline or diesel cars, regardless of the emergy costs associated with building the cars and providing the electricity.  Workers commuting back and forth to work will consume about one-third the energy budget of a gasoline-powered car.  We do not use electric cars currently because, with 1997 technology, we would consume more fossil fuel making electricity for electric cars than gasoline cars consume on the road.  [A good case can be made that the reason we do not use electric cars in 1997 is that oil companies have conspired to prevent us from doing so, but it is not necessary to make so reckless an accusation to advance the thesis of this essay.  This book is about radical social change.  It is singularly lacking in sensational conspiracies.]  It takes about three kilowatt-hours of fossil fuel to produce one kilowatt-hour of electricity in a modern power plant even with cogeneration.  Thus, one-third (of the energy consumption of a comparable gasoline-powered car) is the break-even point for cars powered by electricity from power plants – not that we wish to use fossil fuel even when we can use less of it than the comparable budget for sustainable forms of energy.  [Probably, in an economy whose only primary energy is electricity, hydrogen from electrolysis of water would be the fuel of choice (or the precursor of the fuel of choice) for applications that cannot use electricity.]

Accounting for Ancillary Energy Sources

Occasionally, one of the producers (Process A) that supplies our emerging primary energy technology produces an ancillary energy source, E2, that will be wasted if it is not used.  For definiteness, let us imagine that Eo is 110-volt, 60-Hz alternating current (AC) and E2 is a stream of hot water at 500 K.  Suppose that E2 can be used by another part of the system (Process B) whose purpose it is to produce Eo.  In this case, the emergy associated with E2 is irrelevant because it will cancel out.  Of course, we must charge Process B for whatever emergy costs are associated with the equipment necessary to make E2 available.  If, instead, E2 is used in a non-energy process (Process C) to make widgets, we must assign an emergy to it.  We shall evaluate the emergy of  E2 according to how much reversible work Process C can obtain from it, which we shall compute next.  This is called the exergy although, in the case of a stream of hot water, the exergy corresponds to the Gibbs availability, which is discussed in Appendix I.

Consider Process D, which produces a continuous stream of hot water at 500 K.  The inputs to Process D are cold water, whose Gibbs availability may be taken to be zero, and 1 kilowatt of 110-volt, 60-Hz AC.  Since electricity can be converted to work with a very high efficiency, we set the power term in the rate form of the energy balance equation to precisely 1 kilowatt.  It may be used to lift a weight or it may be converted to heat completely.  Let us divide Process D into two control volumes to facilitate analysis.  The first control volume, D1, consists of an ideal electric heater.  The energy balance equation, presented in Appendix I, is

                            Eq. I-1

It is easy to see from Eq. I-1 that, for D1, which is a steady-state system, Qout = Win, or, in terms of  rates,

Next, consider a control volume, D2, consisting of the space within Process D through which the water flows.  The inputs to Process D2 are cold water with zero availability and the heat from the electric heater, which for the water should be written Qin.  The output is hot water at 500 K.  To see that the availability of the hot water is the output of a Carnot engine the high temperature reservoir of which is the hot water and the low temperature reservoir of which is cold water at 300 K, we write the Availability Balance (Combined First and Second Laws) for Process D2.  The Availability Balance Equation is

                                                                                                                                                 Eq. I-5

or in rate form

where, for a steady-state process, the term to the left of the equal sign is zero; and, for a reversible process, the rate of lost work term is zero.  Moreover, the availability of the water entering is zero, the heat out is zero, and both work terms vanish to give

This shows that the exergy of the hot water is equal to the Gibbs availability.  (To find the exergy for fuels one must subtract the Gibbs availability of the combustion products from the Gibbs availability of the fuel.)  If, instead, we had transformed the availability in the hot water to 110-volt, 60-Hz AC, we would not have been able to do it with anything like the efficiency of a Carnot engine.  Perhaps we would have been able to obtain 0.2 kilowatts, i.e., one half of the Carnot efficiency, which is rather optimistic.

[Note.  If we set the emergy of E2 equal to the work in the form of Eo that was required to produce E2, we will be cheating Process C of the emergy spent to make the emergy of E2 available to Process C.  This will result in overvaluing widgets.  Moreover, we will not be charging Process A for degrading 1 kW of electricity.  If we set the emergy of E2 to only 0.2 MU, the electric power that could be produced from E2 by a heat engine and generator set that performed with one half the Carnot efficiency, we will be undervaluing widgets because this value for the emergy of E2 is much lower than the proper pro-rated share of the Eo that supplies Process A.  Since we set the emergy of  E2 equal to the reversible work that Process C can obtain from it, namely, its exergy, we are making Process C, itself, responsible for such inefficiencies as Process C may incur (above and beyond the inefficiencies mandated by Nature).  Exergy, which in this case is equal to the Gibbs availability, is a measure of the usefulness of E2 to Process C.  I do not see how we can do better.]

Finally, let us consider two processes (1 & 2) and two choices for a standard emergy unit (a & b):

·        Case 1a  Producing electricity from hot water with 1 MU = 1 kilowatt-hour (kWhr) of 110-volt, 60-Hz AC:  The transformity of hot water is 0.5 MU/kWhr because the exergy (and availability) of the hot water from which 0.2 kWhrs of electricity can be produced is 0.4 kWhrs under the assumptions of our example.  When the reference energy is the most concentrated primary energy technology in the spectrum of providers, the transformities all lie between zero and one.  This is in contradistinction to solar emjoules with transformities greater than one and sometimes very large.

·        Case 1b  Producing electricity from hot water with 1 MU = 1 kWhr of Gibbs availability of hot water:  Since we require 0.4 MU to produce 0.2 kWhrs of electricity, the transformity of electricity is 2.0 MU/kWhr electricity.

·        Case 2a  Producing hot water from electricity with 1 MU = 1 kWhr of 110-volt, 60-Hz AC:  If this process were optimal, the emergy of the hot water would be 1 MU because the emergy of the product of an optimal process is equal to the emergy of the input, but this is not an optimal process.  The emergy of hot water is only 0.4 kWhrs times 0.5 MU/kWhr = 0.2 MU.  Therefore, the emergy efficiency is 0.2 MU / 1 MU = 0.2.

·        Case 2b  Producing hot water from electricity with 1 MU = 1 kWhr of Gibbs availability of hot water:  Similarly, if an electrical heater were the best way to heat water, the transformity of electricity would be 1 MU/kWhr because it requires 1 kWhr to produce 1 MU of hot water.  If we assume, for the sake of this discussion, that passive solar heaters are not available, the optimal way to obtain hot water is by burning fuel.  Since it requires about 3 kWhrs of fossil fuel to produce 1 kWhr of electricity.  The transformity of  fossil fuel is about 2 MUs per 3 kWhrs of fossil fuel on a hot-water basis, i.e., the transformity of fossil fuels relative to 500 K hot water is 0.667 MU/kWhr.  We are assuming that it is easier to produce electricity from 500 K hot water than from fossil fuel, which neglects the high temperature at which fossil fuel burns.  Nevertheless, there will be some losses in making super-heated steam from fossil fuels but far less loss than we would encounter in allowing heat transfer between flame temperature and 500 K as discussed in the section on Irreversibilities and lost work in Appendix I.

The solution of the matching problem will determine the role of transformities in evaluating various forms of (high-grade) energy.  Notice that, nowadays (and as long as it has been used), electricity has been produced by consuming other forms of high-grade energy that might just as well have been conserved if they were scarce and electricity were abundant.  If, someday, we should enjoy a feasible solar energy technology, we would have electricity that had been produced without destroying a competitive and extremely valuable form of energy, namely, fossil fuels.  In that case, perhaps it would be better to denote two different types of electricity with two different transformities:  (i) electricity produced from contemporaneous sunshine (renewables) and (ii) electricity produced from sunshine stored over millions of years (fossil fuels).  The transformity of electricity from fossil fuels would be about one-third the transformity of electricity from renewables.  After all, if you have electricity but you need fuels, you cannot continue to assign a higher emergy value to renewable electricity.

Example

Suppose we wish to produce 110-volt, 60-Hz, alternating current (AC) electricity, Eo, by means of photovoltaic cells.  One emergy unit then is one kilowatt-hour of Eo.  An emergy flow diagram for this thought experiment appears in Figure 2-2 below.  Since, ultimately, we must determine if this technology is feasible or not, we will assume that Eo is the only form of primary energy available.  Therefore, we will employ this form of energy for most of our production needs.  Moreover, we must assume that the suppliers of goods and services will employ our product as well.  Also, most suppliers have some known emergy costs associated with manufactured items – from paper clips to electron scanning microscopes.  Since the emergies are known, either because Eo has been used always or because it is easy to convert the emergies to what they would be if Eo were used, no further emergy analysis is required.  Let us denote these emergies Cn, where it is understood that Cn will take different values depending on where the symbol appears.  Some of the emergy inputs are not even labeled; i.e., they may include indirect costs that are rarely considered in the peer-reviewed literature.  For example, it is assumed that the pro-rata emergy expenses of all people involved in the project in any way whatever are included among these inputs including their living expenses.  For a detailed discussion of this point see “Energy Flow in a Mark II Economy”.

 

Figure 2-2.  Illustration of simplified primary energy process to demonstrate ERoEI calculation

Suppose, though, that, in some process that supplies one of our inputs, passive solar energy can be employed to provide hot water, E1.  The manufacturing facilities that produce the passive solar energy apparatus must be assumed to employ 110-volt, 60-Hz AC; nevertheless, under this assumption, we might be able to produce hot water (E1) the exergy of which is 1 kWhr by employing only 0.7 MU, say, of Eo .  We may take credit for the transformity of 0.7 MU/kWhr hot water.  Suppose, further, that 0.1 kWhrs of E1 is required for each MU of Eo produced.  The emergy cost of this input is only

 

All such emergy inputs will be summed.  If they exceed one, the process under investigation is infeasible (under present circumstances).

Suppose, in addition, that one or more of the processes providing our inputs can deliver high-temperature waste heat, E2, in the form of hot water carrying 0.05 kWhrs of Gibbs availability per MU of Eo produced, with only 0.01 MU of capital and operating costs per MU of primary energy produced.  This energy may be regarded as free since it is both produced and consumed in equal quantities during the production of one MU of Eo, however we must charge the process 0.01 MU for the additional expense of recovering it.  If we hypothesize a world wherein all the primary energy is electricity from photovoltaic cells and the emergy input exceeds the output, our hypothesis is untenable.  But, if we had employed Odum’s definition of emergy without the modifications just described, the emergy associated with the energy produced by the most efficient sustainable energy technology we could devise would have been precisely equal to the emergy of the inputs, which would give no information whatever about the feasibility of the proposed sustainable energy technology.

Determination of Feasibility of Nuclear Fission

To compute the total emergy input of nuclear fission, we must consider all phases of the operation from discovery of uranium to the disposal of the decommissioned plant and the storage of radioactive materials for thousands of years.  If the sums of the emergies of the inputs, calculated according to the author’s modifications, exceed the a priori assignment of one MU per kWhr of primary energy (electricity), the process is infeasible.  (On December 27, 2005, we still don’t know if it’s feasible, since no nation has used nuclear energy without a generous infusion of fossil fuel.)  Even in the case of feasibility, if the emergy costs overwhelm the emergy costs of sustainable routes to electricity, nuclear fission should be rejected, unless our energy consumption has exceeded Maximum Renewables.

 

Figure 2-3  Rough proportional partition of economy into sectors

For the sake of simplicity, we divide the economy into four sectors, namely, energy, production (including agriculture), service, and business as shown in Fig. 2-3 and Fig. 2-4.  (Government is considered part of business; but, probably, we should separate transportation from other service categories because of the dramatically greater energy use in that sector.  The purpose of these pages is merely to suggest a methodology.)  In Fig. 2-3 we divide the sectors roughly proportionally to the share of the economy they represent, but in Fig. 2-4, to make further division of the sectors easier to see and draw, we divide the sectors into equal quarters.  To the ith sector one assigns an emergy relation for each hour worked: ei = ew,i + aieP,i , where e is the average total emergy expended per person-hour, ew is the emergy expended at the job, and a is the fraction of the personal emergy budget, ep , that must be charged to the job.  (In the case of some participants, a might be 1.0.)  This methodology is promising because employment figures are readily available and the average emergy expenditure per employee can be estimated closely enough.  One can dispense with the individual ew terms in favor of the total emergy budgets or the appropriate pro rata shares, of the participating enterprises.  (It is the sum of the aieP,i portions that is conspicuously absent from the standard Energy Returned over Energy Invested analysis in 2005.  Please see my study of a theoretical simplified economy in “Cash Flow in a Mark II Economy”.)

We then count the person-hours expended within the energy sector, Eo, both nuclear and non-nuclear that should be charged to nuclear.  For example, the work done to discover uranium, mine it, refine it, comply with regulations including getting the plant permitted are part of Eo .  (This is not the Eo of the Example (above).)  Also, the employees at a nuclear power plant drive back and forth to work and part of their personal emergy budgets, coming mostly from fossil fuels, would not have to be expended if they did not work on nuclear emergy.  But, the nuclear sector is serviced by equipment manufacturing and plant construction, which we place in the production sector.  Therefore we must count the hours expended in the production sector, P1, that must be charged to the energy sector.  The transportation of uranium ore, fuel rods, and production equipment belongs to the service sector, but the people who feed energy and production workers their lunches away from home, do their income taxes, etc. – all of those people spend emergy that must be charged to nuclear fission.  Thus, we must count hours in the service sector, S1, that must be charged to the energy sector and the production sector.  This service may include scientific research and engineering as well as window washing.  Finally, nothing gets done (in this crazy economy) without a huge amount of sales, bargaining, deal making, accounting, shuffling paper, counting beans, hiring and firing, scheming, forecasting, and telling other people what to do.  All of which costs emergy, especially the fossil-fuel emergy required to carry these people around in cars, trains, and planes.  So, we count the hours in the business sector, B1, that must be charged to the energy, production, and service sectors.

 

Figure 2-4  Accounting for emergy costs of nuclear fission

 

But, P1, S1, and B1 must be serviced by additional person-hours, E2, from the energy sector, which hours, in turn, must be serviced by the production sector, P2.  For example, accountants need computers and copying machines, paper and ink and many other manufactured items.  Economists add this to the Gross Domestic Product, but it is really overhead and should be counted as a debit – not economic growth.  This second level of hours spent in the energy and production sectors entails additional work, S2, in the service sector and all three require additional hours, B2, spent in the business sector.  Secondary person-hours are followed by tertiary hours until no new hours can be identified.  (One must count the gasoline expended by the person who cleans the floors where the paper is printed to do the income tax of the person who delivers the sandwiches to the cafeteria where the man eats who services the copying machine of the person who does the taxes for the truck driver who carries the fuel to the garage where the truck is fueled that carries the steel to the construction site where the equipment is built to maintain the nuclear power plant.  The reader gets the idea.)

[Note in proof (2-5-97).  In accounting for emergy inputs to transportation, for example, we may take credit for the increased efficiency of electric vehicles over internal combustion vehicles, since we may assume that the emergy from the nuclear power plant is the only primary energy available.  Alternatively, we may use that emergy to produce hydrogen for fuel cells if that process reduces the proportion of emergy production that must be charged to overhead.]

This iterative accounting procedure must converge eventually because the total person-hours in the economy is finite over a finite length of time, which may not exceed the period of decay of the radioactive materials.  This difficult calculation can be carried out in principle; but, undoubtedly, excessive emergy costs will be encountered in many cases early in the process.

I cannot emphasize enough that this calculation should actually be done – at least roughly – for nuclear energy, photovoltaic energy, energy from biomass from both biological and other processes, such as pyrolysis of biomass.  The first two technologies produce electricity, my favorite choice for an absolute emergy standard; i.e., one kilowatt-hour of 110 volt, 60 Hz AC is one emergy unit (MU) even though electricity is not primary energy.  Only the assumed emergy of one MU per kWhr of pyrolysis products (or pyrolysis products that have been reacted with hydrogen to produce diesel fuel) is inconsistent with the practice of choosing electricity to be the universal standard to which all emergies should be referred.  Inevitably, some electricity must be employed in any biomass process; therefore, we must assign an emergy of 3 MU to one kilowatt-hour of availability from electricity, since we shall require (approximately) 3 kilowatt-hours of pyrolysis product to produce one kilowatt-hour of electricity, as estimated previously.  We have reverted to Odum’s original definition; and we have established a transformity of 3 for electricity.  We may not employ this emergy or transformity for electricity outside of this calculation without endangering our hope for a universal (electrical) standard for emergy.  Alternatively, we could begin this calculation by assigning an emergy of one-third MU for pyrolysis products.

If electricity were abundant, but the scarcity of diesel fuel (needed to run essential farm machinery that we could not afford to replace) had become a life-and-death crisis, we might be pressed into converting electricity into diesel fuel at a loss.  Suppose diesel fuel were produced by reacting pyrolysis products of biomass with hydrogen.  What is the transformity of diesel fuel in that case?  The analyst will want to consider carefully the assignment of emergies, exergies, and transformities in every application.

Improving Efficiency

Suppose nuclear emergy proves infeasible under the circumstances described above.  Nothing stops us from recomputing the emergy input costs in a society that has already abandoned materialism.  Suddenly, the huge overhead of business and government is gone, e.g., licensing, regulation, inspection, (graft?), exorbitant executive salaries for people who contribute about as much as Dilbert’s manager (the pointy haired guy).  (“Dilbert” is a comic strip, written by Scott Adams, that ridicules non-technical managers who “manage” technical workers generally without a clue as to what they (the “techies”) are doing.  The reason this is funny is that it is true.)

If decentralization has occurred, the costs of workers commuting will have been eliminated.  If money has been eliminated, the costs of accounting, collecting taxes, paying wages, collecting bills – even grocery bills – will have been eliminated.  If delegislation has occurred, all legal costs will have disappeared.  Ninety percent of the population will have been freed from drudgery and, since economic contingency would have vanished, they could afford to do as they pleased, which might include building a primary energy provider.

Indeed, eliminating materialism can make the infeasible feasible.  And, if the infeasible is essential to our survival, I don’t see what there is to decide (politically).

Scarcity

The results of the calculations are not critical for my case unless a per capita energy supply of 1 kW, on an electricity basis (110 AC, 60 Hz), cannot be supplied.  High-energy scenarios are rejected for reasons other than their expected impossibility.  The very low energy prognosis must be countered with much more stringent birth-control policies – one child per couple, say.  Again, one can only hope that this could be achieved voluntarily if it were necessary.  People have got to be made aware of the urgency of the situation.  They must be convinced that they are personally responsible for the outcome – and might be held accountable for their behavior.  Dissenters should be encouraged to speak openly and should be defeated soundly in public debate wherever it occurs.  Pointing out the fallacies of policies that promote population growth is one way, perhaps the best way, to teach the lesson.  Please do not let anyone make a casual remark, even, that the earth is not really over-populated without making a strenuous objection, even if you are classified thereafter as a crashing bore.

Houston, Texas

December 28, 2005