Biofuels, Solar and Wind as Renewable Energy Systems_Benefits and Risks Episode 1 Part 9 pps

sector needed to deliver the required energy carriers – the energy consumption ormetabolism of the energy sector; and ii Net Energy to Society – used for theproduction and consumption of

sector needed to deliver the required energy carriers – the energy consumption (ormetabolism) of the energy sector; and (ii) Net Energy to Society – used for theproduction and consumption of “non-energy goods and services” - the energy con-sumption (or metabolism) of the rest of the society.

In spite of an unavoidable level of arbitrariness in the calculation of EROI, thisscheme indicates clearly the tremendous advantage of fossil energy over alternativeenergy sources (for more see Giampietro, 2007a) In relation to the costs of produc-tion of energy carriers, oil has not to be produced, it is already there Moreover, inthe previous century it was pretty easy to get: the EROI of oil used to be 100 MJper MJ invested, according to the calculations of Cleveland et al (1984) For thisreason, in the community of energy analysts there is an absolute consensus aboutthe fact, that the major discontinuity associated with the industrial revolution in allmajor trends of human development (population, energy consumption per capita,technological progress) experienced in the XXth century was generated by the ex-treme high quality of fossil energy as primary energy source (for an overview ofthis point see Giampietro, 2007a) This means that to avoid another major disconti-nuity in existing trends of economic growth (this time in the wrong direction), it iscrucial that when looking for future alternative primary energy sources, to replacefossil energy, humans should obtain the same performance, in terms of useful workdelivered to the economy per unit of primary energy consumed

As explained earlier a very high EROI means that the conversion of oil into anadequate supply of energy carriers (e.g gasoline) and their distribution absorbs only

a negligible fraction of the total energy consumption of a society This small head makes it possible that a large fraction of the total energy consumptions goes

over-to cover the needs of society, with very little of it absorbed by the internal loop

“energy for energy” Moreover, due to the high spatial density of the energy flows

in oil fields and coal mines the requirement of land to obtain a large supply of fossilenergy carriers is negligible Finally, waste disposal has never been considered as

a major environmental issue, until acid rain deposition and global warming forcedworld economies to realize that there is also a sink side – beside the supply side -

in the biophysical process of energy metabolism of whole societies As a matter offact, so far, the major burden of the waste disposal of fossil energy has been paid

by the environment, without major slash-back on human economies Compare thissituation with that of a nuclear energy in which uranium has to be mined, enriched

in high tech plants, converted into electricity in other high tech plants, radioactivewastes have to be processed and then kept away (for millennia!) both from the hands

of terrorists and from ecological processes

The narrative of the EROI is easy to get across: the quality of a given mix ofenergy sources can be assessed by summing together the amount of all energy in-vestments required to operate the energy sector of a society and then by comparingthis aggregate requirement to the amount of energy carriers delivered to society

By using this narrative it is easy to visualize the difference that a “low qualityenergy source” can make on the profile of energy consumption of a society This

is illustrated in the two graphs given in Fig 8.4 (from Giampietro et al., 2007).The upper part of the figure – Fig 8.4a – provides a standard break-down of the

profile of different energy consumptions over the different sectors of a developedeconomy Total Energy Throughput (TET) is split into the Household sector (FinalConsumption) and the economic sectors producing added value (Paid Work sector –PW) The economic sector PW is split into: Services and Government, ProductiveSectors such as Building, Manufacturing, Agriculture (minus the energy sector) andthe Energy Sector (ES) The example adopts an average consumption per capita of

300 GJ/year and an EROI> 10/1 This entails that only less than 10% of TET goes

into the energy sector Let’s assume now that we want to power the same societywith a “low quality primary energy source” For example, let’s imagine a system

of production of energy carriers with an overall output/input energy ratio of 1.33/1.The lower part of – Fig 8.4b (right side) – shows that for 1 MJ of net energy carriersupplied to society this energy system has to generate 4 MJ of energy carriers Asmentioned earlier, the huge problem with primary energy sources alternative to oil is

that they have to be produced, and they have to be produced using energy carriers.

That is, a process of production of primary energy sources must use energy carrierswhich have to be converted into end uses This fact entails a double energetic cost(to make the carriers that will be used then within the internal loop to produce theprimary energy required to make the energy carriers) That is, this internal looptranslates into an extreme fragility in the overall performance of the system Anynegative change in this loop does amplify in non-linear way A small reduction ofabout 10% in the output/input ratio – e.g from 1,33/1 to 1,20/1 implies that the netsupply of 1 MJ delivered to society would require the production of 6 MJ of energycarriers rather than 4MJ (for more on this point see Giampietro and Ulgiati, 2005)

Fig 8.4a The pattern of metabolism across compartments of a developed society with a “high

quality” primary energy source (EROI>10/1)

Fig 8.4b The pattern of metabolism across compartments of a developed society with a “low

quality” primary energy source (EROI< 2/1)

Let’s image now to power the same society illustrated in Fig 8.4a (a developedsociety) using a “low quality primary energy source” (EROI= 1.33/1) and keeping

the same amount of energy invested in the various sectors (beside the energy sector).The original level of energy consumption per capita for the three sectors described

in Fig 8.4a is 279 GJ/year, which is split into: (i) 90 GJ/year in Final Consumption(residential & private transportation); (ii) 63 GJ/year in Service and Government;and (iii) 126 GJ/year Building and Manufacturing and Agriculture In this case,the energy sector – when powered by low quality energy sources – would have toconsume for its own operations 837 GJ/year per capita Then, when combining theenergy consumed by the rest of society and the energy consumed by the energysector the total energy consumption of the society would become 1,116 GJ/year percapita – an increase of almost 4 times of the original level! Obviously such a hypoth-esis is very unlikely It would generate an immediate clash against environmentalconstraints, since the industrial and post-industrial metabolism of developed society

at the level of 300 GJ/year per capita has already serious problems of ecologicalcompatibility, when operated with fossil energy However, the environmental impactwould not be the only problem There are also key internal factors that would makesuch an option impossible Moving to a primary energy source with a much lowerEROI than oil would generate a collapse of the functional and structural organi-zation of the economy In fact the massive increase in the size of the metabolism

of the energy sector would require a massive move of a large fraction of the workforce and of the economic investments right now required in the other sectors of theeconomy A huge amount of hours of labor and economic investment will have to be

moved away from the actual set of economic activities (manufacturing and servicesector) toward the building and operation of a huge energy sector, which will mainlyconsume energy, material and capital for building and maintaining itself.

8.2.2 The Combination of Biophysical and Socio-Economic

Constraints Determines a Minimum Pace for the Throughput

to be Metabolized

Due to the organization of metabolic systems across different hierarchical levelsand scales, there are “emergent properties” of the whole that cannot be detectedwhen considering energy transformation at the level of the individual converter Insocio-economic systems, these “emergent properties” may be discovered only whenconsidering other dimensions of sustainability – e.g the characteristics of social oreconomic processes determining viability constraints – which are forcing metabolicsystems to operate only within a certain range of power values To clarify this pointlet’s discuss an example based on an analysis of the possible use of feeds of differentquality in a system of animal production This example is based on the work ofZemmelink (1995)

In the graph shown in Fig 8.5 numerical values on the horizontal axis (e.g A1,A2) represent an assessment of the quality of feed (based on nutrient and energycontent per unit of mass) They reflect the given mix of possible feed types whichare available in a given agro-ecosystem: (i) dedicated crops or very valuable by-products = high quality; (ii) tree leaves = medium quality; and (iii) rice straw =low quality Therefore, moving on the horizontal axis implies changing the mix ofpossible feed types “Very high quality feed” implies that only dedicated crops orvery valuable by-products can be used; “very low quality feed” implies that alsorice straw can be used in the mix The points on the curve represent the size of theherd (e.g S1, S2, on the vertical axis on the right) The diagonal line indicates therelation between levels of productivity (pace of the output) of animal products –i.e beef – (e.g P1 and P2 on the vertical axis on the left) and the “quality” of feedused as input for animal production (e.g the point A1 and A2 on the horizontalaxis) When using only animal feeds of a high quality one can get a high level ofproductivity (boost the output), but by doing so, one can only use a small fraction ofthe total primary productivity of a given agro-ecosystem This analysis describes anexpected relation between: (i) productivity in time (power level – on the vertical axis

on the left); (ii) ecological efficiency (utilization of the available biomass – on thehorizontal axis); (iii) stocks in the system (the size of the herd – on the vertical axis

on the right) in animal production This emergent property of the whole determiningthe viability and desirability of different types of biomass depends on both: (i) therequired level of productivity (determined by the socio-economic context) – theeconomic break-even point on the vertical axis on the left; and (ii) the characteristics

of the agro-ecosystem (the set of biological conversions and the ecological context).This study confirms that the need of operating at a high level of productivity implies

Fig 8.5 Feed quality and net productivity of animal production

reducing the ecological efficiency in using the available resources That is, when thesocio-economic constraints force to operate at a very high level of productivity, alarge fraction of tree leaves and all available rice straw can no longer be considered

as feed, but they will result just waste

This analysis provides a clear example of the need of contextualization for physical analysis That is, when looking only at biophysical variables we can onlycharacterize whether or not a feed input of quality “A1” is an input of “adequatequality” for a system of production of beef operating at a rate of productivity P1.However, the ultimate decision on whether or not the level of productivity P1 isfeasible and desirable for the owner of the beef feed-lot cannot be decided using onlythis biophysical analysis The viability and desirability of the level of productivityP1 depends on the constraints faced on the interface beef feed-lot/rest of society.This evaluation of desirability has to be done considering a different dimension

bio-of analysis In this case, the acceptability bio-of P1 has to be checked using a economic dimension (the position of the economic break-even point on the verticalaxis on the left) This viability check has to do with the evaluation of the pace ofgeneration of added value (linked with the level of productivity P1) required for theviability of the production system

socio-In conclusion, the very same feed input of quality “A1” can be either: (1) fectly adequate for that system of animal production in a given social context (e.g

per-in a developper-ing country); or (2) not acceptable, when movper-ing the same biophysical

process from a developing country to a developed country That is, a change in thesocio-economic context can make level P1 no longer acceptable When forced tooperate at a higher level of productivity (e.g P2) to remain economically viable, theowner of the feed-lot would find the feed input of quality “A1” no longer either vi-able or desirable In biophysical terms, the feed input of quality “A1” would remain

of an adequate quality for sustaining a given population of cows, but no longer of an

“adequate quality” for sustaining, in economic terms, the threshold of productivity,required by the owner of the feed-lot to remain economically viable

The set of relations described in the graph of Fig 8.5 is based on well knownbiological processes for which it is possible to perform an accurate analysis of thebiological conversions associated with animal production Yet, due to the complex-ity of the metabolic system operating across multiple scales, and due to the differ-ent dimensions of analysis which have to be considered, the concept of “quality

of the energy input to the whole system” depends on: (1) the hierarchical level

at which we decide to describe the system – e.g the cow level versus the wholebeef feed-lot level; and (2) the context within which the system is operating (inthis case on the economic side of the animal production system) When consideringalso socio-economic interactions, there are emergent properties of the whole (theperformance based on multiple criteria mentioned by Carnot), which can affect theviability or desirability of an energy input (the minimum admissible feed qualityfor achieving an economic break-even point) These emergent properties can af-fect the admissible pace of the metabolism of the whole, and therefore induce abiophysical constraint (the need of reaching a certain threshold of power level)within a particular conversion process (the transformation of feed into beef at thehierarchical level of the whole production system) This can imply that what is aneffective energy input, when operating at a lower power level (in this example themix of feed of quality “A1” in Uganda) is no longer a viable or desirable energyinput when operating in the USA That is, even when the biophysical parameters

of the system remain completely unchanged – keeping the same cows, the same set

of potential energy inputs for the feed, the same techniques of production – it is thecoupling with the external context – beef feed-lot/rest of society – that will affect thebiophysical definition of “quality” for what should be considered as a viable energyinput

In conclusion the question: “are crop residues useful feed for a beef feed-lot?”cannot be answered without first checking the biophysical constraints on energytransformations which are determined by the set of expected characteristics of thewhole metabolic system These expected characteristics are determined by its inter-action with its context The question about the viability and desirability of cropresidues as alternative feed cannot be answered just by looking at one particu-lar dimension and one scale of analysis According to the analysis presented in

Fig 8.5 crop residues may provide nutritional energy to cows, but their viability

and desirability depends on the severity of the biophysical constraints determined

by the socio-economic characteristics of the whole Exactly the same answer can

be given in relation to the possibility of using biomass for the metabolism of asocio-economic system

8.2.3 Economic Growth Entails a Major Biophysical Constraint

on the Pace of the Net Supply of Energy Carriers (per hour and per ha) in the Energy Sector

Let’s image that, in order to reduce the level of unemployment in rural areas of oped countries, a politician would suggest to abandon the mechanization of agricul-ture and to go back to pre-industrial agricultural techniques requiring the tilling andthe harvesting of crops by hand By implementing this strategy it would be possible

devel-to generate millions and millions of job opportunities overnight! Hopefully, such asuggestion would be immediately dismissed by political opponents as a stupid idea.Everybody knows that during the industrial revolution the mechanization of agricul-ture made it possible to move out from rural areas a large fraction of the work force.This move had the effect to invest human labor into economic sectors able to generateadded value at a pace higher than the agricultural sector This is why, no developedcountry has more than 5% of its work force in agriculture and the richest countrieshave less than 2% of their work force in agriculture (Giampietro, 1997a)

As a matter of fact, changes in the structure and the function of socio-economicsystems can be studied using the metaphor of societal metabolism The concept ofsocietal metabolism has been applied in the field of industrial ecology (Ayres andSimonis, 1994; Duchin, 1998; Martinez-Alier, 1987), in particular in the field ofmatter and energy flow analysis (Adriaanse et al., 1997; Fischer-Kowalski, 1998;Matthews et al., 2000) By adopting the concept of societal metabolism it is pos-sible to show that the various characteristics of the different sectors (or compart-ments) of a socio-economic systems must be related to each other, as if they weredifferent organs of a human body In particular it is possible to establish a mech-anism of accounting within which the relative size and the relative performance

of the various sectors in their metabolism of different energy and material flowsmust result congruent with the overall size and metabolism of the whole Thesetwo authors have developed a methodological approach – Multi-Scale IntegratedAnalysis of Societal and Ecosystem Metabolism (MuSIASEM) – originally pre-sented in several publications as MSIASM – e.g Giampietro, 1997b, 2000, 2001;Giampietro and Mayumi, 2000a,b; Giampietro et al., 1997a, 2001; Giampietroand Ramos-Martin, 2005; Giampietro et al., 2006c, 2007; Ramos-Martin et al.,2007; Giampietro, 2007a – which can be used to perform such a congruencecheck

That is, the MuSIASEM approach can be used to check the congruence between:(i) the characteristics of the flows to be metabolized as required by the whole soci-ety; and (ii) the characteristics of the supply of the metabolized flows, as generated

by individual specialized compartments An overview of the possible application

of this method to the analysis of the quality of energy sources is presented inGiampietro, 2007a; Giampietro et al 2007 Just to provide an example of the mech-anism used to perform this congruence check, we provide in Fig 8.6 an analysis ofthe energetic metabolism of a developed society (e.g Italy) in relation to the profile

of use of human activity over 1 year

Very briefly, when considering the system “Italy” at the hierarchical level of thewhole society – considered as a black box (on the right of the figure) – we can

Fig 8.6 Minimum threshold of energy throughput per hour of labor in the energy sector of a

developed country

say that 57.7 millions of Italians represented a total of 503.7 Giga hours (1 Giga=

109) of human activity in the year 1999 In the same year they consumed 7 ExaJoules (1 Exa = 1018) of commercial energy This implies that at the level of thewhole society, as average, each Italian has consumed 14 MJ/hour (1 Mega = 106)

to cover both: (i) the step of production of goods and services; and (ii) the step

of consumption of goods and services For example, more than 60% of the Italianpopulation is not economically active – e.g retired, elderly, children, students Thefraction of human activity associated with this part of the population is therefore notused in the process of production of goods and services (but it is used in the phase ofconsumption) Furthermore the active population works only for 20% of its availabletime (in Italy the work load per year is 1,780 hours) This implies that out of thetotal of 503.7 Giga hours of human activity available to the Italian society in 1999,only 36.3 Giga hours (8% of the total!), were used to work in the economic sectorsproducing goods and services In that year, almost 14 hours of human activity havebeen invested in consuming per each hour invested in producing! Let’s now see howthis profile of distribution of time use affect the availability of working hours to beallocated in the mandatory task of producing the required amount of energy carriers

in the energy sector This requires looking at what happened within the tiny 8% of

the total human activity invested in the productive sector Out of these 36.3 Gigahours, 60% has been invested in the Service and Government sector The industrialsector and the agricultural sector have absorbed another 38%, leaving to the energysector less than one percent (<1%) of the already tiny 8% of the total This is a

well known characteristic of modern developed societies, which are very complex.This complexity translates into a huge variety of goods and services produced andconsumed, which, in turn, requires a huge variety of different activities across thedifferent sectors associated with different jobs descriptions and different typologies

of expertise (Tainter, 1988)

In conclusion, in Italy in 1999, only 0.0006 of the total (not even 1/1000th!) ofthe total human activity has been used for supplying the energy carriers associatedwith the consumption of 7 Exa Joules of primary energy consumed in that countrythat year This means that by dividing the total consumption of the “black box Italy”

by the hours of work delivered in the energy sector, the performance of the energysector in relation to the throughput of energy delivered to society per hour of labor

in the energy sector has been of 23,000 MJ/hour.

It should be noted that if rather than considering Italy had we considered USAthe consumption per capita would have been much higher (333 GJ/person year or

38 MJ/hour in 2005) After adjusting for a different population structure (50% ofthe population in the work force) assuming 2,000 hours/year of work load and only0.007 of the work force – about 1 million workers* – in the sector supplying fossilenergy carriers, the resulting throughput of energy delivered to society per hour

of labor in the energy sector is 47,000 MJ/hour [* this excludes almost 1 million

workers in gas stations and trucks needed for transporting liquid fuels, which arenot included in the calculation since they are required for the distribution of fuelsindependently from the energy source used to produce them]

8.3 Using the MuSIASEM Approach to Check the Viability

of Alternative Energy Sources: An Application to Biofuels

8.3.1 The “Heart Transplant” Metaphor to Check the Feasibility and Desirability of Alternative Energy Sources

To visualize the type of integrated analysis based on the MuSIASEM approach forlinking the characteristics of the energy sector to the characteristics of the wholesociety, we propose the metaphor of a heart transplant, illustrated in Fig 8.7 (moredetails in Giampietro and Ulgiati, 2005; Giampietro et al., 2006c) Let’s imagine thatthe actual energy sector based on fossil energy as primary energy source, is the heart,which, at this very moment, is keeping alive a given person (e.g a given society).Let’s imagine now that we want to replace this heart with an alternative heart (e.g

an energy sector powered by biofuels from agricultural production) Let’s imaginethat we want to perform this transplant because someone claims that the alternative

Fig 8.7 The metaphor of the heart transplant

heart is much better (e.g it makes it possible to have “zero emission” of GHGs fromthe energy sector and a total renewability of the supply of energy carriers)

Still, it would be wise, before starting the operation of transplant, to checkwhether or not such a substitution is: (i) feasible; and (ii) desirable To do such

a check it is necessary to compare the performance of the actual heart with theperformance that we can expect from the alternative heart we want to implant.This comparison can be obtained by checking the congruence between: (A) thepace of the required flow of energy carriers determined by the characteristics ofthe whole society; and (B) the pace of the net supply of energy carriers which can

be achieved by the “alternative energy sector” we want to implant The application

of this approach is presented in the next section, which compares the performance

of the actual energy sector powered by fossil energy with the performance of anenergy sector powered by biofuels For the sake of simplicity we will focus only

on two biophysical constraints on the pace of the flow of energy carriers: (i) “therequirement of hours of labor in the energy sector to generate the required supply”versus “the availability of hours of labor which can be allocated in the energy sector

by a given society”; (ii) “the requirement of hectares of land in the energy sector togenerate the required supply” versus “the availability of hectares of land which can

be allocated to the energy sector by society” With this choice, we ignore additionalissues, which are very relevant when checking the viability of biofuels as alternativeenergy sources These additional issues should include: water demand, soil erosion,preservation of natural habitat for biodiversity

8.3.2 Checking the Feasibility and Desirability of Biofuels Using Benchmark Values

8.3.2.1 The Biophysical Constraints Over the Required Flow of Energy Carriers

Let’s first define the two benchmarks values to characterize the viability and sirability of the supply of energy carriers from the energy sector operating in adeveloped society

de-In relation to the throughput per hour of labor – that is, according to the analysisdescribed in Fig 8.6 – within a developed country the throughput of energy perhour of labor in the energy sector has to be in the range of values between 23,000MJ/hour and 47,000 MJ/hour

Coming to the benchmarks referring to the spatial density of the energy flow,Fig 8.8 provides a comparison of the ranges of power density of different pri-mary energy sources (the graph on the left of the figure) against the ranges ofpower density of different typologies of land use associated with the pattern ofmetabolism of developed societies (the graph on the right of the figure) In rela-tion to this figure we can immediately detect that the differences in these valuesare so big to require the use of a logarithmic scale It is well known that before

of the industrial revolution (before the powering of societal metabolism by fossilenergy) the number of big cities – i.e cities above the million people size – was

Fig 8.8 Power density gap between the required and supplied flows of metabolized energy

very small The percentage of urban population in pre-industrial societies was verylow As a matter of fact, when using biomass as primary energy source one has

to rely on a power density of the energy input per square meter which is muchlower than the density at which energy is used in typical land uses of urban settling(Giampietro, 2007a) In relation the requirement of a high power density of the netsupply of energy carriers, the movement from agricultural biomass to biofuel makesthings much worse, because the density of net power supply is heavily reduced

by the internal loop of energy carriers consumed within the process generatingbiofuel

In conclusion the two benchmark values for a developed country are:

throughput per hour labor in the energy sector: 23,000–47,000 MJ/hour

power density of fossil energy consumption in urban land uses: 10–100 W/m2.

8.3.2.2 The Confusion About the Energetic Assessment of Biofuels

There is a great confusion in literature, when coming to the assessment of theenergetic performance of biofuels (e.g Farrell et al., 2006; Shapouri et al., 2002;Patzek, 2004; Patzek and Pimentel, 2005; Pimentel et al., 2007) This confusion

is due to the lack of agreement on how to calculate the net energy supply of fuel from energy crops This is a crucial starting point since in a biofuel systemenergy carriers are produced (e.g in the form of ethanol or oils), but also con-sumed (e.g in the form of electricity and fossil fuels, during the production ofthe energy crop, transport and in the conversion of biomass into the final biofuel).Obviously, to be considered as an energy source the energy output of this processneeds to exceed the energy input But even more important, in relation to its fea-sibility and desirability, the requirement of land, labor and capital for generating

bio-a net supply of biofuels should not imply bio-a serious interference with the bio-actubio-alfunctioning of the whole socio-economic system In relation to this point there aretwo key issues to be considered: (1) how to handle the implications of net energy

analysis – that is, one should acknowledge the crucial distinction between gross and net production of biofuel; and (2) how to handle the differences in quality

of the different energy forms accounted among the inputs and the outputs of theprocess

1 the implication of net-supply of energy carriers – let’s imagine to have a biofuel

system, fully renewable (not depending on oil for its own functioning) and havingzero CO2emission, operating with an output/input 1.33/1 The consequences of thisfact have been discussed in Fig 8.4b This system has to produce 4 barrels of biofuel

to supply 1 net barrel to society It should be noted that by addressing the net supply

of energy carriers (a net supply of energy carriers and not a mix of input/output ofdifferent energy forms) it is much easier to appreciate the importance of adopting