A CRITICAL DISCUSSION OF THE  STERN AND IPCC ANALYSES OF CARBON EMISSION MITIGATION POSSIBILITIES AND COSTS.

19.1.10

 Energy & Environment, 2010, Vol. 21, No. 2, 49 – 73.

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SummaryAbstract:  Like the Stern Review the IPCC Working Group 3 Reports have been taken as showing that the greenhouse gas emissions problem can be solved at negligible cost, primarily by development of alternative energy technologies.  The lengthy Fourth Assessment Report summarises the findings of many studies, rather than present analyses that can be clearly assessed.  The argument in this paper is that most and probably all of the studies drawing conclusions about the mitigation potential of alternatives are invalid because they do not consider the possible limitations to renewable energy sources, nuclear energy and geo-sequestration.  They are economic modelling studies which take the cost of a unit of carbon mitigation and multiply this by the amount of mitigation required, without regard to the difficulties and limits affecting the extent to which these sources can be scaled up.   If the greenhouse problem is to be solved by resort to these technologies then the magnitude of the scale-ability problem is huge [MB1] .  This paper argues that there are major reasons why the alternatives cannot be scaled up sufficiently, and that it is not possible to explain how the anticipated 2050 energy budget could be met without exceeding safe greenhouse limits [MB2]  .  If this analysis is sound Stern and the IPCC have been seriously misleading and the greenhouse problem cannot be solved at any cost in a society that is committed to affluent living standards and economic growth. The discussion accepts the climate science in both sources, and does not dispute the desirability of moving to renewable energy.

Keywords: Greenhouse, IPCC, Stern, Garnaut, mitigation, renewable energy.

The Reports from the Third Working Group of the IPCC Third Assessment Report, (IPCC, 2001, hereafter TAR) and Fourth Assessments (IPCC, 2007, hereafter referred to as 4AR) align with the Stern Review (2006) and the Garnaut Report to the the Australian government (Garnaut, 2008) in asserting highly optimistic conclusions regarding the possibility and cost of solving the greenhouse problem.  Stern states “…climate change mitigation is technically and economically feasible with mid-century costs likely to be around 1% of GDP…” (2006, p. 240.)  The IPCC Third Assessment Report’s conclusion is, “In 2030 macro-economic costs for multi-gas mitigation, consistent with emissions trajectories towards stabiliszation between 445 and 710 ppm CO2-eq, are estimated at between a 3% decrease of global GDP and a small increase, compared to the baseline.” (IPCC 2001, Table 3.) The Fourth Assessment Report says, “In 2050 global averaged macro-economic costs for multi-gas mitigation towards stabilization between 710 and 445 ppm CO-eq, are between a 1% gain to a 5.5% decrease of global GDP.”  (Barker, Quereshi and Koehler, 2007, Table 6.)

These conclusions have received extensive global publicity and appear to have been taken as crucial and confident givens in official and popular thinking about the nature of the Greenhouse problem and the steps that are appropriate for dealing with it.  (E.g. Sachs, 2007.)

This paper argues that both these conclusions are mistaken.  The argument is not one of degree, i.e., that the cost and difficulty will be significantly greater than is foreseen by these two studies.  The argument is that the greenhouse problem cannot be solved without large scale reductions in the volumes of economic production and consumption taking place, and therefore cannot be solved at any cost within a society committed to affluent “living standards”, maximum levels of economic output, and economic growth.  If this argument is valid then policies premised on the Stern and IPCC reports are likely to be seriously mistaken.it would be difficult to exaggerate the seriousness of the policy mistakes that will be premised on the Stern and IPCC reports. [MB3] 

It will be argued that the major fault in both analyses is to do with the appropriateness of using of what are referred to as “top down” and ”bottom up” economic modelling analyses.  Loosely speaking the former take the present cost of a unit of carbon mitigation (e.g. replacing a coal-fired power station with a wind farm) and multiply this by the number of such units that would be needed to solve the whole problem. “Top down” approaches apply a similar logic to the effects of measures applied to the whole economy, such as the imposition of a carbon tax.

The fundamental mistake in the use of these approaches lies in the assumption that there are no limits to the extent to which the various strategies can be applied or scaled up to the magnitude that would be required to deal with the total carbon emission volume envisaged.  For instance it is possible to build one 1000 MW wind farm at a certain cost, but that does not mean it will be possible at any cost to find enough sites to build several hundred times as much wind capacity as has been established to date or integrate this into electricity supply systems. .   It will be explained that there are reasons why this assumption that technical limits can be ignored is invalid with respect to all the mitigation strategies considered by these reports, reasons to do with quantity, physical and ecological limits, and integration and technical problems.

A critique of the Stern Review has been detailed separately (Trainer, 2007a) and will only be referred to briefly in thisThis paper which will focus on the Working Group 3 reports from the IPCC Third and Fourth Assessments.   THowever as the IPCC does not suggest proportions of total energy use to be accounted for by different sources at a future date.  S some of Stern’s assumptions for these will be loosely used here.

The following critique does not deal with or question the climate science embodied in the IPCC Reports from Working Groups 1 and 2, or in the Stern Review.  These are accepted as valid and valuable scientific and political contributions documenting the urgency of the problem (although reasons to think they ujnderestimate the seriousness of the situation are noted.).  This paper is only focused on the conclusions in Working Group 3 reports regarding mitigation possibilities and costs deriving from the use of economic models which do not deal with the crucial “scale-ability” considerations. [MB4]       

            The magnitude of the mitigation task.

It is important to begin with an understanding of the magnitude of the mitigation task, the way this depends on the energy and emission target assumed, and the question of what might constitute a safe target.

a.    The energy target assumed.

It is commonly assumed that in view of current rates of increase in energy consumption, especially driven by the rapid growth of some Second and [MB5] Third World economies, by 2050 demand for energy services couldwill be approaching 2.5greater than twice times as  present demand.as great as at present.  The IEA (2004) expects a 71% increase by 2030, which roughly indicates an increase from the early 2000s c. 450 EJ to c. 1100 EJ by 2050.  (The values taken in this paper are for early 2000s and will be somewhat low now.)  This aligns with Stern’s assumption that by 2050 carbon dioxide emissions will rise from 23 GT p.a. to 61 GT/y under a business as usual projection (2006, Fig. 9.3.).  ABARE (undated) projections are similar. The IPCC Fourth Assessment Working Group 3 also assumes an approximately 70% increase by 2030 for business as usual (80% is stated in the Technical Summary, Fig. 4.25, p, 48.)  Extrapolating  to 2050 loosely indicates 1100 EJ, although IPCC WG3 projections are somewhat lower.  Mahoney and Honnery ()review estimates of the 2050 demand and conclude that it is likely to be in the region of1000 EJ. For working purposes this paper will take 1100 EJ as the approximate amount of energy to be provided in 2050.

Of his expected 61 GT/y of CO2 produced in 2050 by a “business as usual” or “baseline ” projection, Stern assumes 10.75 GT/y will be avoided via greater efficiency in energy use.  This corresponds to 18% or 198 EJ of the expected 2050 1100 EJ “business as usual” primary energy demand.  For the purposes of the present discussion a much more optimistic assumption will be made, i.e., that 25% of the total baseline energy demand (not just carbon based inputs) can be eliminated by increased efficiency of use etc. This figure is common although debatable but will be used here without assessment for illustrative purposes. It means that energy sources would have to provide 825 EJ of energy services. 

It will also be assumed that 25% of energy services (after allowing for conservation) will be in the form of low temperature heat, from solar panels (although this is not plausible for high latitude regions in winter.)

If the proportions of energy services assumed here for transport and electricity generation are much the same proportions as at present in rich countries then transport energy would require 290 EJ and electricity 205 EJ in 2050. 

It will be assumed that by 2050 world population will be 9 billion (although it could take somewhat longer to reach this figure.)  . The expected level of energy supply in 2050 would therefore provide all the world’s people with about 122 GJ per person of primary energy, which is half the present Australian per capita consumption, but might be only about 20% - 25% of the probable Australian 2050 use if the anticipatedpresentgiven the expected energy growth trends continue..  (ABARE, undated.).

If we take the above 2050 projection for Australian energy consumption per capita in 2050 and if 9 billion were to rise to that per capita amount of energy consumption then world energy production might have to be in excess of 4,0500 EJ, possibly 8+10 times as great as in the mid 2000sat present.  In other words, if we were to take as our target an equitable world providing enough energy to give all people the amount per capita that Australians are currently heading for likely to have byin 2050, the target would have to be around 4+ times as high as that assumed by Stern. [MB6] 

Thus the mitigation task involved and the plausibility of strategies depends greatly on the energy target taken and the underlying equity assumptions.  Stern’s target is much less difficult than it might have been because it is well below an amount of energy that would enable all people to have present, let alone expected, rich world consumption.

b.  The carbon emission target.

The 2050 carbon emission target Stern adopts corresponds to18 GT/y of carbon dioxide p.a., or 4.8 GT/y of carbon.  There are grounds for regarding this as much too high.  The most common view in recent years seems to have beenis that if serious ecological consequences are to be reduced to a low (but still worrying) probability, then global temperature should not be allowed to increase by more than 2 degrees over the 1990 level.  According to Baer and Mastrandrea (2006) and Hoehne (2006), to reduce the probability of such an increase to 9 – 16% would require carbon dioxide emission to be reduced to the vicinity of 5.7 GT/y by 2050, an 80% reduction, and to almost zero by 2100. The IPCC’s 4AR estimate of the range of emissions permissible for the 450 ppm target  is 5.7 - 14 GT/y by 2050, but their diagrams at Fig. SPM 7 and Table SPM 5, (p. 16) indicates state that for a 2 – 2.4 degree rise emissions must be kept between 4 and minus 15 GT/y by 2100. According to Baer and Mastrandrea (2006) and Hoehne (2006), to reduce the probability of a 2 degree increase to 9 – 16% would require carbon dioxide emission to be reduced to the vicinity of 5.7 GT/y by 2050, an 80% reduction, and to almost zero by 2100.  In other words the longer term goal probably has to be the complete elimination of emissions. [MB7] 

It is very likely that before long these targets will be regarded as much too high.  There is increasing evidence that the IPCC’s  expectations regarding climate change have been too conservative.  In the two years since the 4AR observed warming effects, including arctic ice melting, ocean acidification and sea level rise, are reported to be trending at or above the maximum expectations.  tending to occur  and that effects are tending to occur well before they were predicted, most obviously accelerating arctic ice melting, atmospheric CO2 increase, and sea level rise.  (Garnaut, 2008, p. 21.)  The 4AR did IPCC has not yet not attempted to take into account the effects of feedback mechanisms, such as the reduced carbon absorption capacity of warmer seas, methane release from drying tundra andor less reflection of solar energy when arctic or glacial ice retreats, primarily due to the difficulty of arriving at a  high level of  agreement across all participating nations on uncertain evidence.  (See the note under SPM 7.)   These effects are likely to be large andIt is therefore likely that in it is probablelarge. 

It is likely th that in the near future there will be considerable agreement that all emissions should be eliminated by 2050. (See for instance Hansen (2008.) is calling for acceptance of a 350 ppm atmospheric concentration target.  `Probably most influential will be the recent analysis by Meinchausen et al. (2009) which asserts a 1000 GT total cumulative limit to emissions between 2000 and 2050, if the chances of exceeding 2 degree temperature increaserise is to not to rise above 25%.  If the release is 1440 GT the probability is 50%.  The first figure in effect means emissions must taper from the present level to zero by 2050.  Yet as Meinschaussen et al. point out emissions have accelerated in recent years, increasing 20% in the last 6 years to 2006.future a responsible atmospheric concentration limit will be well under 450 ppm, and that the 2100 emission target will be below zero emissions (i.e., requiring an amount of CO2 to be taken out of the atmosphere every year.).

The basic quantities arrived at above for use in the following analysis are summarised in Table 1.              

                             ______________________________________________

                                Table 1.

World 2050 primary energy equivalent, i.e.,

assuming c. 2% p.a growth and therefore

c. x 2.5 early 2000s c. 450 EJ.                                 1100 EJ/y

Energy services enabled due to increased

conservation, efficiency of use,  etc.

(c. 25% of b.a.u. primary).                                         275 EJ/y              

Energy services or final energy to

be provided.                                  825 EJ/y                                              825 EJ

Low temperature heat, mostly water and space.       206 EJ/y

Transport energy, 35% of final.                                 290 EJ/y

Electrical energy, 25% of final.                                  205 EJ/y

Carbon Capture and Storage, assuming

5.7 GT CO2/y safe release, as

electrical energy (assuming 80% capture rate.)*        250 EJ/y                                        

…corresponding to electricity supplied                        93 EJ/y

Carbon Capture and Storage, assuming                      0 EJ

no release by 2100

Energy needed to provide 9 billion people

with the per capita amount Australians are

likely to average by 2050.                                     4000+ EJ

______________________________________________

*This assumes coal-fired power generation. Assuming gas-fired generation would more or less double the energy figure, but estimated gas resources are similar to petroleum so are not likely to be a significant long term contributor.

The IPCC “case” regarding costs of mitigation.

Because the TAR and 4AR state strongly optimistic conclusions regarding the possibility of mitigating the greenhouse problem, and regarding the negligible cost to GDP involved, it is to be expected that in these lengthy documents we would find detailed and convincing cases for these crucial conclusions.  However these are not given.  We are told that many studies support the conclusions stated, but in general a case is not put forward and supporting evidence or sources are not given.  It is therefore difficult if not impossible to check the supporting literature to confirm relevance, derivations and interpretations. There is only occasional and fleeting reference to difficulties that might be set by limits to the adoption of alternative energy sources and strategies, always without discussion of probabilities or magnitudes.  Following are some of the few statements of grounds or reasons for conclusions that can be found, included here mainly for illustrative purposes. It should be noted that these statements have not been selected as specially problematic instances.  They are representative of the quality of the case presented.  These are the kinds of reasons given and in most cases they are the best grounds that can be found in the Reports for the conclusions stated. [MB8] 

·      Chapter 3 of the TAR is supposed to give a summary of “…technical options to limit or reduce greenhouse gas emissions.” (IPCC, 2001, Section 1.2.3.)  At best the Chapterit gives very brief descriptions of options.  For instance only two paragraphs are given on fuel cells.  Section 3.4.4.6 provides 200 words on biofuels, stating that “…these are technically feasible.” 

·      Often we are given generalisations of the following kind;  “…there are many alternative technology ways to reduce greenhouse gas emissions, including more efficient power generation from fossil fuels, greater use of renewables or nuclear, power…” (TAR, Section 3.8.7.)

·      The crucial conclusion,   “…renewable electricity, which accounted for 18% of the electricity supply in 2005, can have a 30-35% share of the total electricity supply in 2030 at carbon prices up to US$50/tCO2-eq.”  is not derived nor are the grounds for it explained.  (Lenzen’s review ,concludes that 20% is likely to be the limit; 2009.)

·      Difficulties and limits involved in renewable energy sources are occasionally referred to, but only in fleeting comments such as the following regarding biofuels. “However, energy yields (litres oil per ha) are low and full fuel cycle emissions and production costs are high.”  (Section 3.4.4.6.)  Similarly, regarding intermittent sources…”large penetration into grids may eventually require storage and/or backup to guarantee reliable supply.  Therefore it is difficult to generalize costs and potentials.” (Section 3.8.4.3.)

·      Various references indicate that the supporting case is to be found in Summary for Policy Makers Box 3. (E.g., p. 11.) However the approximately 100 words in the box simply says conclusions are based on “top down” modelling studies.

For the purposes of this paper an effort has been made to review many of the references that are quoted by the IPCC and by Stern, in order to determine their significance.  It seems that all are modelling studies which do not discuss physical or biological limits.  This major fault is discussed below.

I have made an effort to review many of the references that are quoted by the IPCC and by Stern, in order to determine their significance.  It seems that all are modelling studies which do not discuss physical or biological limits.  This major fault is discussed below.

 The focus on potential improvements in energy use efficiency

Mitigation involves two domains, the first being reducing the energy needed to perform operations, and the second being reducing emissions CO2 produced in the process of generating energy.  The IPCC explicitly focuses its mitigation case mostly on the potential for reducing the carbon dioxide emissions from various sectors of the economy, e.g., buildings, forestry, agriculture. The 4AR Tables SPM 1 and 2  (p. 9) present a summary of the results of economic modelling studies. 

The TAR Section 3.9 (Table 3.37) is summarised as follows, “…the total potential for worldwide greenhouse gas emissions reductions…are estimated to amount to 1,900-2,600Mt/C/y by 2010 and 3,600 – 5,050 Mt/y by 2020.”   The 2020 total is stated as 23 – 42% of the amount likely under a business as usual projection.  It is made clear (p. 304) that the higher figure assumes the most optimistic estimates, which are for carbon at $100/t. Table 4.19 sets out possible contributions and arrives at a total saving by 2030 of 7.46 GT of CO2.

The specific energy-saving improvements mentioned range between about 5% to 50%.  For shipping the range is 4% - 30% (p. 75), 20% for aircraft 20%, and vehicles perhaps 50%. For the building sector the figure is 30%. These figures align with the generally assumed potential from previous discussions (although Lovins and von Weisacher, 1997, have argued that resource use per unit of economic output can be cut to one-quarter of present values.)

Fuel switching, for instance from coal to gas, is one of the main sources of saving mentioned.  However it can be argued that gas should not be a central consideration in the discussion of a long term sustainable energy future, partly because it is a carbon emitting fuel and partly because its depletion history is likely to be similar to that of petroleum although somewhat delayed. is likely to be largely exhausted later this century [MB9] .   Also fuel switching and several of the other possibilities mentioned are “one-off” options rather than continuing strategies.; they can only be made once.If by 2050 most of the “low hanging fruit” have been picked it is not likely that savings and conservation will make a major continuing contributions thereafter. [MB10] 

The possible total stated, a 7.4 GT/y reduction, is not a very reassuring prospect in view of the present 26 GT/y emission rate, the 61 GT/y rate Stern anticipates by 2050,  and the probable need to completely eliminate greenhouse gas emissions by the 2050end of the century.  Even if the most optimistic of these estimates of savings is realized, the IPCC is saying that the level of emissions in 2030 would be higher than it is now, above 30 GT/y compared with 26 GT/y.  (Table 4.65, p. 290 gives the 2030 figure as 39 GT, a 63% increase. See also SPM 10 and p. 290.)  Again this is not very reassuring in view of the above discussion of necessary goals, e.g., possibly an 80% reduction by 2050 according to the IPCC and possibly complete elimination by 2050 according to more recent estimates.

 If by 2050 most of the low hanging fruit have been picked it is not likely that savings and conservation will make a major contribution thereafter. [MB11] 

The emission scenarios given in the TAR, 4AR and Stern Review show that a rise in emissions of this general magnitude is “compatible with” (see further below) a path to stabilisation at 550 ppm by 2100 (but not at the more responsible 400 or 450 ppm.)  It would be possible therefore not to be alarmed at the increase, if there were good reasons to think that the emission rate after 2030 or 2050 can be cut dramatically. This is a major fault within the Stern report, i.e., advising that not much has to be done by 2050 to solve the problem without making it clear that a great deal would have to be done after 2050.  (See further below.) The argument in this paper is that there are not good reasons for assuming that very big reductions can be made after 2050, and that neither Stern nor the IPCC has not dealt with the issue.

Other summaries within the 4AR seem to indicate an even more unsatisfactory 2030 situation.  It is stated that of the 116 EJ electricity supply anticipated for 2030, 26.7% is expected to come from renewables, 17% from nuclear sources, and 55% from fossil fuels (pp. 255, 303.) This represents the burning of 21 billion tonnes of coal p.a., which would generate 56 billion tonnes of CO2 p.a. This again would seem to be an alarming prospect as it means that the electricity sector’s emissions alone would be more than twice the present total emissions.

It is not that the IPCC assumes that heavy dependence on fossil fuels will be offset by Carbon Capture and Storage, because the report does not expect geo-sequestration to be making a significant contribution by 2030. (Table 4.19 has it accounting for only .81 GT by then.)

To the above emission figure for electricity must be added the much larger transport quota, 35% of total energy consumption, or c. 290 EJ.  It is difficult to see why this would not raise emissions far beyond the c. 30 GT/y the report’s most optimistic studies project for 2030. In addition there would be the contribution from the generation of the remaining 40% of energy demand, although some much of this would be for space and water heating and should not be problematic (except in winter in the higher latitudes.)

Stern argues that as time goes by technical advance and “learning effects” will make it possible to improve performance and lower the costs of carbon abatement.  There will be a tendency for this to happen but there will also be a “diminishing returns” effect and there are reasons for thinking this will be the moreost powerful of the two.

The savings the Report refers to are the easiest ones to make, the “picking of the low hanging fruit” after decades of abundant cheap energy in which wasteful habits have developed.  It should not be assumed that the rate at which savings can be made in the years to 2030 can be continued thereafter. There is weighty evidence in the IPCC 4AR Fig. SPM 10 that there will be markedly diminishing returns for energy saving and conservation effort.  It shows that increasing the cost of carbon 5-fold, from $20/t to $100/t does not increase CO2 saving much, compared with the initial effect of imposing athe $20/t cost.

Although the report states that we are not on a path that would solve the problem (p.255), it is puzzling why the IPCC does not stress that the conservation and savings achievements it anticipates and which are the focus of its mitigation discussion would fall far short of a satisfactory goal.

Of course unforeseen technical advances with major effect cannot be ruled out in a discussion of this kind.  The present analysis seeks to clarify the magnitude of the problems such breakthroughs would have to solve.  Even if these were not as difficult as this analysis concludes questions remain regarding the wisdom of continuing down an increasingly energy-intensive path on the faith that technical fixes will turn up in time to avoid the difficulties that path leads to.

            The misleading goal statement.

Both the Stern Review and the 4AR have been widely taken to be saying that it will be possible  and without significant economic cost to solve the greenhouse problem.  However it is crucial to recognise that this is not what the documents are saying.  Both are actually saying that the steps we need to take by 2030  (2050 in Stern’s case), in order to be on the path that will eventually lead to stabilisation of atmospheric CO2 can be taken and will not be costly.  As has been noted above, what is not made clear in these statements that little might needs to be done by 2030/50 if the (eventual) goal is stabilisation at  550 ppm but a great deal would then need to be done after 2030/50.

Consider again the statement quoted above, “…In 2030 macro-economic costs for multi-gas mitigation, consistent with emissions trajectories towards stabilisation between 445 and 710 ppm CO2-eq, are estimated at between a 3% decrease of global GDP and a small increase, compared to the baseline.”  (See also the statement in SPM p. 19 quoted below.)  The key and misleading term here is  “consistent with”.  The statement does not say that the steps envisaged are sufficient for stabilisation; it merely says they are ”consistent with” moving to eventual stabilisation.

The fourth diagram in the 4AR SPM 7, (p. 16) makes the situation clear.  It represents emission levels necessary to achieve of the 550 ppm target and it shows that CO2 emissions might be allowed to rise to 60 GT/y by 2050 which is 2.5 times present levels.  Thus it could appear that their analysis of the 2030 situation in which emissions have risen considerably does not warrant alarm.  However the diagram shows that even to achieve 550 ppm stabilisation emissions must be reduced greatly after 2050, and by 2100 must be down to 25 GT (the centre of the range of estimates.)

Again there is a strong case that 550 ppm is much too high a target for safety.    The second diagram in SPM 7 represents what many would havenow regarded (i.e., in 2007 before the observation of unexpected warming effects)  as a more appropriate emission scenario, although it is one which still runs a considerable risk of causing more than a 2 degree rise in global temperature. It shows that emissions must not rise above 35 GT/y, by 2050 must be down to 12 GT/y, and by 2100 must be cut to minus 7 GT/y (average of the range of estimates represented.)

If generated from coal, a 12 GT/y of CO2 200050 achievement would correspond to the provision of 12 GJ per capita for 9 billion people, around 5% of present Australian per capita energy consumption. Whereas the most optimistic studies represented in the IPCC 2030 expectations would allow use of some 300 EJ of fossil fuel without sequestration (the approximate amount Stern assumes), Fig. 4 indicates that for a relatively safe strategy the post 2050 goal must be virtually no fossil fuel energy use, (or almost total sequestration of CO2 from fossil fuel use.  (On such a possibility see below.)

It would seem to be clear therefore that both Stern and the IPCC Working Group 3 have given seriously misleading impressions regarding the magnitude of the steps that need to be taken, by taking much too low an energy provision target, by taking too high an emission target, and by not emphasising the fact that their 2030/50 targets are misleading because dramatic emission reduction must be achieved later in the century.  When these three factors are combined it is evident that the task these reports should have focused on is many timesfar more difficult than the 2030/2050 task they have set themselves.

            Can the non-fossil sources be scaled up sufficiently?

Given the need for almost complete elimination of emissions, and the limits to savings and energy use, the only options are the very large scale geo-sequestration of carbon from coal use, and/or use of nuclear energy, and/or reliance on renewable energy sources. This leads to the crucial issue of “scale-ability”, i.e., can these sources be scaled up sufficiently.  This question is almost completely ignored by Stern, the IPCC, and ABARE (2007) and the more recent Garnaut Report (2008).  The issue firstly requires a critical discussion of the use made by these studies of economic modelling.

The non-economic determinants; the invalidity of the economic modelling.

Both Stern and the IPCC are led to overlook the problem of scale-ability by basing their optimistic cost conclusions solely on ”top down” and “bottom up” economic modelling.   Studies of the former kind ask what it costs to generate 1kKW by wind for instance, and multiply this by the number of kWh required from wind in a  particular scenario.  “Top down” approaches estimate general effects on the economy from the imposition of a tax or quota, such as carbon taxes and caps. Thus the 4AR says, “Modelling studies show carbon prices rising to 20 to 80 US$/tCO2-eq by 2030 and 30 to 155 US$/tCO2-eq by 2050 are consistent with stabilization at around 550 ppm CO2-eq by 2100.”( IPCC, 2007, SPM. p. 19.) 

Stern’s Figure 9.4 shows that 2050 energy supply is assumed to be made up of specified proportions of nuclear, wind, solar, CCS, etc.  The essential logic of his cost argument involves taking each of these sources, finding what the cost would be to replace 1 kW of coal-fired generating capacity, and multiplying this by the amount of coal-fired energy the source in question is assumed to replace in 2050.  (Likely technical advances and changes in present costs are taken into account.) 

Thus Stern arrives at the conclusion that by 2050 the total cost of replacing sources generating 43 GT of CO2 will be about 1% of GDP p.a.  (Other economic modellers have criticised Stern, especially for incorrect assumptions about the discount rate, and concluded that the cost will be much lower than Stern states; e.g., Toll, 2006, and Nordhaus, 2007.)

At first sight this might appear to be a straight forward and sound approach, i.e., determining the unit cost and multiplying this by the number of units needed.  However this approach involves the crucial assumption that measures that can be taken now on a small scale can be geared up by the required (huge) amount.  It will be explained below that with respect to all of the replacement technologies involved in the IPCC’s and Stern’s analyses this assumption is highly dubious or false. Achievement of the quantities of energy supply stated in Table 1 above and in Stern’s Fig. 9.4 would involve very large scale application of alternative energy technologies.  When this issue is attended to difficulties and limits that have little or nothing to do with economics or dollar costs become apparent.  These problems are to do with the physical and biological limits and difficulties associated with energy technologies and the quantity and integration limits that the alternatives to fossil fuels run into when very large scale use is taken into account.  It will be explained that when these issues are considered it becomes evident that to rely on top down or bottom up economic modelling in this area is inappropriate and leads to conclusions that are incorrect and conducive to seriously mistaken policies.  The modelling studies listed by the IPCC reviewed for this paper do not make reference to these issues: see for instance, ABARE, 2007, Zhou, (undated), Edenhoffer, Lessmann and Bauer, (2005), Toll, (2006), Fischer and Morgenstern, (2006), Van Vuuren, Eickhout, Lucas and den Elzen, (2006), Weyant, 2006, Nordhaus, 2007, Barker, et al., (2005), Clarke, et al., (2006), Barker, Qureshi and Kohler, (2006).

            Difficulties and limits involved in alternative energy technologies.

This failure would seemappears to be due in large part to the fact that there has been almost no literature focusing critically on the basic question underlying this issue, i.e., the limits to the use of renewable energy. There seems to have been only one book previously published on the topic, i.e., Howard’s The Solar Fraud (2003).  Trainer 2003, 2005 represent early and partial attempts to clarify aspects of the issue.  Renewable Energy Cannot Sustain A Consumer Society, (Trainer 2007), offers a more detailed summary and interpretation of evidence accessible in the early years of this century.  Trainer (2007c) advances the analysis in the light of more recent evidence.  More recently Mackay (2008) and Lenzen (2009) add detailed support for the critical thesis.  (A number of reports have set out to show that renewables can meet all energy demand, but these are typically not critical discussions and in my view do not deal satisfactorily with the difficulties.)  It is therefore not surprising that in the absence of any substantial literature on the topic analyses of the potential for carbon emission mitigation have proceeded without recognising any need to consider possible limits to the contribution renewables could make.

Following are notes on some of the severe problems of “scale-ability” encountered when the limits to renewable energy are explored.  It should be kept in mind that the magnitudes of the tasks focused on here and those the IPCC and Stern have taken on are much less than is that involved in enabling an energy affluent world for all without encountering causing a greenhouse problem.

            Wind.  Stern expects wind power to provide 62 EJ in 2050. This is about 150 times as much electricity wind contributed when he wrote.  (taking AWEA figuresCoppin, 2008.)  It is not plausible that enough sites could be found, on-shore or off-shore, within tolerable distances of population centres.  Trieb (a strong believer in renewables) estimates European wind potential as about 2 EJ/y from onshore sites and another 2 EJ/y from offshore sites. (Trieb, undated, p. 48.)  Lenzen’s review states a similar conclusion. (2009).  Some European regions are probably close to their limits now.  Note also that a very large increase in wind capacity would mean use of decreasingly favourable and increasingly distant sites, and therefore a reduction in the present average capacity and significant loss in long distance transmission.  Lenzen’s review points out that although the global wind resource is very large, most of it is in distant regions such as Siberia, Northern Canada and Patagonia, an only around 5% is close to high demand regions.

The IPCC’s Table 4.2 assumes global wind potential is 600 EJ, 10 times as great as Stern assumes, without explanation or discussion of sites or transmission issues.  (For some other questions re the Table see Note 1 below.)  Lenzen concludes that wind will not provide more than about 20% of electricity demand,  because integration difficulties accelerate beyong that point. (2009.)  Stern’s assumed quantity corresponds to 30% of 2050 world electricity given in Table 1 above.

            Biomass.  Stern’s figure 9.4 indicates access to 110 EJ of biomass energy.  This is optimistic as it corresponds to 8650 million ha when all cropland totals only 1,400 million ha.    Estimate of global biomass lenergy potential vary greatly.  Hoogwijck concludes that 4.5 billion ha couldan be devoted to this purpose and over 1000 EJ/y could be harvested. (Lenzen, 2009.)  (The plausibility of this claim is problematic as there are only about 8 billion ha of productive land.), Field, Campbell and Lobel on the other hand estimate a maximum global biomass fuel harvest of onlyf 27 EJ/y without causing unacceptable ecological effects.

Very large scale biomass energy production would have to come predominantly from cellulosic inputs.  Chapter 5 of Trainer 2007 reports what seem to be the most plausible estimates, i.e., that the yield for very large scale cellulosic biomass production is not likely to exceed 7 tonnes per ha, and that ethanol production is likely to be around 7 GJ net per tonne of biomass. (Fulton, 2005.) If 1000 ha could  be used the yield would be c. 50 EJ/y of ethanol.

It should be noted however that there is doubt whether it will be economically or technically viable to produce ethanol from woody inputs. (Augenstein and Benemann,  2007.)  Land, forest and water resources are already stretched and likely to deteriorate, population is going to increase by 50% and food demand by a greater amount, and the greenhouse problem is likely to reduce yields markedly. 

Stern’s figure 9.4 indicates access to 110 EJ of biomass energy.  This is optimistic as it corresponds to 860 million ha when all cropland totals only 1,400 million ha.  ItStern’s figure would yield only c. 363 EJ of transport fuel, or 4 3.7GJ per person for 9 billion, when Australian Transport consumption is about 65 GJ per person, and rising.

These figures indicate thatHowever biomass is not likely to make a marked contribution to enabling rich world liquid fuel levels to be achieved by all. If all 9 billion people were to consume the per capita quantity of oil plus gas Australian’s now consume p. a., via ethanol from cellulosic inputs, a plantation area of around 23 billion ha would be needed, on a planet with only 13 billion ha of land (Trainer 2007, Chapter 5.)

Nuclear energy.  If we take the proportion of energy demand Stern assumes will be met by nuclear reactors, 115 EJ would be provided.  This is about 14 times the world's present nuclear contribution.  If At that rate of use the estimates of Uranium resources commonly quoted, (e.g., ISA, 2006, p. 33, Lenzen, 2009)by Leeuwin and Smith (2003, 2005) and Zittel (2007), are correct they would be exhausted in less than than a decade.  (The IPCC 4AR Table 4.2 lists Uranium resources 3 times as great,. This is because low grade ores are included.  The ISA report estimates these as 10 Mt and discusses the factors producing a declining energy return rate with low grade ores, such as the fall decline in the extraction rate as grade falls.  There is also the effect of the “mineralogical barrier” encountered with low grade ores.  In view of these factors it is presently uncertain what quantity of energy that could be derived from poorer ores at a satisfactory net energy return, even when . Thorium resources are generally assumed.  Lenzen (2009,  p.50) concludes that to be comparable to Uranium when low grade ores are included.  These figures indicate that present nuclear technology might continue to provide c. 8 EJ /y for 85100 years, yielding a cumulative total of 7800 EJ.  This should which must be compared with the 1000 EJ/y target assumed in this discussion.

The Integral Fast Breeder Reactor could alter the outlook significantly but at this point in time its feasibility and potential remains uncertain, especially with respect to fuel availability.  If the conventionally assumed capacity to derive 70 times as much energy from Uranium via breeders compared with burners is applied to the quantity of Uranium probably extractable from ores over .001% (Lenzen, 2009, Leeuwin and Smith, 2005, Fig. 2.), a total energy yield of 70,000 EJ is indicated.  This would probably meet world energy demand from 9 billion living on the per capita energy consumption rate Australia is heading towards by 2050 (currently at 2+% pa. growth), for less than 20 years.  These figures do not take into account the decline in Uranium extraction rate as ore grades fall (which might be to 20% at .001%.), or the possi bilityh of an 8 year doubling rate. (Lenzen, 2009.)   Adding Uranium in bomb grade material, c. 13,000 t and in reactor waste, 130,000 t (ISA, 2008, p. 33 ) would not alter the outlook markedly.  TheseSome of these estimates are speculative but they indicate caution re the assumption that the IFBR promises abundant energy.

(and refers to a quantity 50 times as great, which assumes fuel recycling and breeder technology).

            Geo-sequestration.  Although not a renewable technology it is appropriate to discuss the geo-sequestration of carbon dioxide (or or CarbonCoal Capture and Storage, CCS) here as it is often seen as the solution to the greenhouse problem, and a large assumed role for it would reduce the load on renewables.   The IPCC does not expect geo-sequestration  to have been implemented significantly by 2030 but Stern assumes that by 2050 CCS will account for 18% of the 43 GT of carbon dioxide saved, i.e., 7.7 GT/y.

CCS is currently being practised on a small scale but there is little evidence on which to conclude that it can be effective on a vastly greater scale, or safe over long periods.  Demonstration projects will take place at ideal sites, and might not indicate effectiveness at the many less than ideal sites that would eventually have to be used.  CCS is only applicable to stationary generating sources and would therefore not apply to possiblyat least 4 60% of carbon fuel use.   It is likely to have an energy cost between 10 and 40% of energy output. (IPCC, 2007, Chapter 4, p. 24), and between .1 and 1% of the CO2 stored is likely tomight leak out each year.  (Torvanger, Kallbekken and Rydal, 2004.)

A major difficulty concerns the availability of storage sites. It will be assumed here that very large volumes of CO2 should not be placed in the deep ocean as the long term ecological effects could not be foreseen confidently, especially in view of changes to ocean currents etc. likely to be caused by the greenhouse problem.  Global warming is reducing the capacity of sea water to absorb carbon.  Deep ocean waters circulate and eventually carbon dioxide placed in them will be released to the atmosphere again.    (Lenzen , 2009, refers to these difficulties.)                                                                                                                            

According to Hendricks, Graus and van Bergen (2004), the best estimate of available land sites is 1700 GT. (The IPCC’s uncertain estimate of the maximum theoretical potential is 6 times as great; see Metz, undated.)  If 9 billion people were to have the possirobable 2050 Australian per capita energy consumption of 500 GJ/person and if CCS dealt with 20% of this, annual CO2 production would be 96 GT and the storage capacity might only last 18 years. 

However the main problem with geo-sequestration is that it is not likely to extract more than 80% - 90% of the carbon dioxide generated at the power station. According to Hazledyne, (2009) when all sources are taken into account, including fugitive emissions from mining, the figure is 75%.  Nor can it be applied to other than stationary emission sources, and therefore it cannot include fossil-fuelled transport.

 If the 2050 emission limit is 5.7 GT/y, if geo-sequestration captures 80% of CO2 generated, then 28.5 GT/y could be generated, corresponding to about 280 EJ of primary energy or 104 EJ of electricity.  This would provide 9 billion people with 11.4 GJ per capita p.a., about one-third of the present Australian per capita electricity consumption, leaving none to meet transport demand.  Note again that by 205100 no release of CO2 is likely to be permissible, which would eliminate use of geo-sequestration because it cannot capture all CO2 generated. Also 280 EJ of primary energy from coal would be more than twice the present rate of use which some think will see coal supply plateau within two decades. (Energy Watch Group, 2007.)

Easily overlooked is the carbon cost of alternative energy sources, e.g., from the use of petroleum in the mining of minerals for their construction.  Lenzen’s review (2009) reports these as ranging between less than 1 gramme per kWhe generated, to c. 100 for PV, roughly averaging 50 g/kWhe.  If this average is assumed then generation of 619 EJ/y would produce more than 9 Gt CO2/y.  If all energy could come from alternative sources this issue would not arise, but even under ideal conditions it would take decades to reach that situation. If 50 years is assumed, and alternatives are assumed to progressively replace fossil fuels over that period, then the cumulative emissions from this source would be one eighth of the total remaining budget according to Meinschausen et al. state.

            Solar PV.  It would be possible to build and site the 110 EJ of solar capacity Stern’s Fig. 9.4 assumes, but this source too is subject to limits, due to its variability (discussed more fully below).  For instance, it would not be possible to integrate a very large amount of such a highly variable source as PV into supply systems, e.g., phasing the other components down as all the PV came on stream within an hour or so on a summer morning, and then having to turn to coal or nuclear sources at night or on a cloudy day.  Stern’s assumed PV contribution is more than 50% of electricity demand.

            Solar thermal:  Could the capacity of solar thermal systems to store energy get solveround the above storage and integration problems?  Some believe this capacity gives solar thermal technologies the potential to enable renewables to meet total electrical demand. (Trieb, undated, Czisch, 2004.)  There is no doubt that these systems will be major contributors but their capacity to deliver in winter is quite problematic. (For the detailed discussion see Trainer, 2008a.)

In winter the output of normal trough systems with north-south orignentation falls tgoes down to about 20% of summer output, or lower.  (Odeh, Behnia and Morrison, 2003 indicate a lower ratio.)  East-west trough layout improves the winter/summer ratio but the winter output remains low.  From the gross output figure a number of deductions would be made before a net delivered figure is arrived at, such as the plant operating energy cost, which Sargent and Lundy (2003) say might be 10% in future (but can be 17% at present; Section 4.3). Secondly, the embodied energy cost of the plant has to be deducted, indicareported by Dey and Lenzen (1999) to be greater than at 64% of lifetime energy output (when components in addition to the collection field are included.).  The embodied energy costs of the long distance transmission lines, for instance from Western Egypt to NW Europe, would have to be subtracted, along with the perhaps 15% loss in transmission over such long distances. (Mackay, 2008.)

 When these factors are applied to Direct Normal irradiationDNI data for Central Australia, possiblywhich could be the best site in the world, it is possible that a continuous 24 hour flow of less than 10 W/m2 net of all energy costs would is likely to be delivered from troughs to distant users.  (See Trainer, 2008, for the derivation.)  If so a plant capable of delivering 1000 MW in winter might need a collection area of more than 100 million square metres.  Taking one anticipated longer term future cost of $320/m² (Mancini et al., 2003) the plant would cost around $320 billion, excluding transmission line costs. (They put the present cost at 10 times this future cost estimate.)  A coal fired power station plus fuel (at early 2000s price) for its lifetime might cost $4 billion.  It would seem very unlikely therefore that troughs could be relied on to provide large quantities of electricity in winter, let alone to bridge gaps in supply from other renewable sources.

Solar thermal dish systems are likely to be considerably more effective than troughs in winter, primarily because they can face the sun directly all through the day. However their winter performance is also problematic.  Data on the output of a dish at Phoenix, Arizona indicates a January output corresponding to a constant 28 W/m² flow. (Davenport, 2008.)  The US Mod 1 and 2 systems have been reported to deliver at a lower rate, the equivalent of 18 W/m² averaged over a mid winter month. (Sandia, undated.)  These flows are a small fraction of peak flowsPeak output from these dishes which would be in the range of 250 W/m². 

However tThese figures are for efficient dish-Stirling generators and these could not be used if heat was to be stored, indicating that efficiency would then be considerably lower.  Heat storage would involve energy costs for pumping the heat, and most importantly, losses from the long pipe lengths between the many dishes and the power block.  In trough systems the absorber pipes perform this function and thus are heated. An early project by Kenaff (1991) moving heat a short distance to a steam generator but not involving storage achieved an annual solar to electricity efficiency of 9.1%.   European and US dish developers therefore do not regard heat storage via dishes as viable.

The most promising possibility for heat storage via dishes involves the dissociation of ammonia.  Lovegrove, Zawadski and Coventry (2006) estimate that half the solar energy collected might be available after storage.  If the solar to electricity efficiency for 400 square metre “Big Dishes” rises from the present 13.9% to 19% as is Lovegrove, Zawadski and Coventry expect, it can be estimated that this process might deliver over long distances in wWinter around 18 W/m², continuous 24 hour flow.  (This figure takes into account an estimated energy cost for plant construction and transmission line loss; for the derivation see Trainer, 2008a.)

If the overall net rate of delivery at distance in winter is 18 W/m², for a power station delivering 1000 MW the collection area would have to be c. 55 million square metres.  Lenzen (2009, p. 1129) reports the expectation that future solar thermal costs will more or less level out at one-third their present amount.  This aligns with the expectation Luzzi (2000) states with respect to fFuture costs for Big Dishes, i.e., a fall toIf it is assumed that future solar thermal dish capital costs fall to one-third of the present cost ($440,000 per dish) according to Luzzi (2000). Athe solar thermal power station would then cost $20 billion, 5.4 times the cost of a coal-fired power station plus lifetime coal (at the early 2000s cost.).  About 137,000 Big Dishes would be needed to deliver ac net 1000 MW at distance.  In mid winter one dish would be meeting the electricity demand of only 8 Australian households.

Table 1he above budget assumes a 205 EJ/y electricity supply.   If one-third of this was to come from a solar thermal sector with sufficient capacity to meet the demand in winter, 910 million Big Ddishes would be needed.  The above estimate indicates a future total cost of $100t, or $4t p.a. assuming a 25 year plant lifetime.  This is 9 times the present total world annual energy investment. (Bairol, 2003.)  (Several important cost factors have not been included in this estimate, including the cost of the ammonia storage system and the long distance transmission lines.)

Again these figures cannot be stated with confidence but they are indicative of the magnitude of the difficulties and costs that would be involved in achieving the stated budget.

 An early project by Kenaff (1991) piping heat to a steam generator but not involving storage achieved an annual solar to electricity efficiency of 9.1%.  The ANU “Big Dish” (again steam not Stirling) efficiency is reported as 13.9% (although 19% is eventually anticipated.)  If its winter efficiency declines as for dish-Stirling systems then in Central Australia in winter gross output would probably correspond to a continuous flow of 20 W/m or less, and when the additional reducing factors are taken into account a net flow closer t 10 W/m might be delivered. 

These estimates are uncertain but they indicate that satisfactory generation from heat storage via steam from dishes in winter would seem to be unlikely.

The most promising solar thermal possibility seems to be to store energy via the dissociation of ammonia. (Lovegrove, et al., 2004.)  A plant of this kind is being developed at Whyalla, South Australia, but it has not been possible to get technical detail from the project developers. It seems that they are not yet clear how effective the system will be but Lovegrove, et al. estimate that under ideal conditions half the DNI energy would be available as heat after storage.  An (uncertain) derivation from these figures suggests that in winter such a system might deliver a constant flow of c. 20+ W/m over long distances, net of all energy costs.  (See Trainer 2008.) 

However there would seem to be some major problems in this strategy. The first concerns the greater structural strength required in big dishes (500 square metres at Whyalla) and thus the disproportionately greater embodied energy costs.  These seem to be three times those of the much smaller and more common European and US dish-Stirling systems. (See Trainer, 2008.) The second problem concerns the embodied energy cost of the plant to process the ammonia, especially that for storing large volumes under pressure.

Although solar thermal systems are being designed with heat storage capacity they still involve a problem of intermittency.  ln Central Australia there can be two sequences of four consecutive cloudy days in a winter month.

The third problem is to do with the frequency of occurrence of sequences of cloudy days.  Climate data for Daggett, a US dish-Stirling site, shows that one third of the days in a winter month DNI is too low for significant generation.  Runs of 4 days in a row at such levels are not uncommon, e.g., averaging 1.5 – 2.5 kWh/m^/2/day with hardly any hours over 700 W/m². (Further climate evidence is given in Trainer 2008a.)

Thus despite their capacity to store heat solar thermal systems suffer an intermittency problem, although it is not as serious as that confronting PV or wind systems. The occurrence of night time which is a major limit for PV systems will not be a significant problem given that 12 hour storage is likely to be standard practice.  HoweverIf if the solar thermal system was to average .3 of total electricity supply yet had the storage capacity to maintain its contribution through 4 calm and cloudy days, then its storage capacity would have to be 13 times as great as the 7.5 hours storage currently being built into solar thermal plant. In addition its collecting capacity would have to be considerably greater thaen that required for average output, in order to accumulate such a reserve between cloudy periods.

It should be clear from these estimates that it would not be possible for solar thermal systems to overcome the gaps in supply from other renew able  sources, resulting from intermittency of sun and wind.  For instance if it is assumed that solar thermal, wind and PV each contribute one-third of supply and, the solar thermal component has sufficient storage to meet total demand over four cloudy and calm days, thwhen this capacity would have to be some 40 times as great as the 7.5 hr storageat being built into solar thermal systems today.

Thus despite their capacity to store heat solar thermal systems suffer an intermittency problem, although it is not as serious as that confronting PV or wind systems. For instance the occurrence of night time which is a serious limit for PV systems will not be a problem.  If provision of four day storage is not acceptable then resort to back up sources will be needed perhaps twice a month in winter.

It would seem therefore that solar thermal systems would have low net output performance in winter, and suffer a serious intermittency problem despite their storage capacity.  Above all, it seems clear that there would be no possibility of them being the means for overcoming the gaps in supply from other elements in a wholly renewable electricity supply system.

            The integration problems and their implications for limits.

The most important problems confronting renewable energy sources are to do with integrating very large amounts of variable or intermittent inputs into the supply system. When the contribution of renewables is relatively low no integration difficulties might be encountered.  Indeed it is conceivable that wind or solar sources could each contribute 15% - 20% of system output without major difficulties.  As relatively small inputs from these sources varies with the waxing and waning of sun and wind the existing surplus coal and nuclear capacity can be adjusted as necessary.  Supply systems always have unused generating capacity in reserve to deal with breakdowns or unusually high peak demand and at present fluctuations in renewable contributions are small relatively to this excess capacity.  However the vision of a largely renewable energy supply system alters this situation.

The most difficult problems for renewables are set by the low solar radiation in winter, and the fact that synoptic weather patterns can leave continental areas with low winds for days at a time.  PV systems provide no energy for some at least 16 hours a day.  For several months of the year the German wind system averages around 5% of its peak capacity (E.On Netz, 2004).  The studies by Davey and Coppin, (2003), Coelingh (1999), and Oswald Consulting (2006) show that even in the best wind regions output would be low for considerable lengths of time and calms can last several days at a time.  Lenzen’s review (2009, pp. 84, 94) illustrates the way aggregating output from manyh wind farms over wide regions can leave large variation in total supply from the wind system, due mainly to the occurrence of continent-wideal climate regimes. 

This means that if sun and wind are to be large contributors to electricity supply little or no reduction can be made in the amount of coal or nuclear capacity that must be built, as there will be times when almost all of it will be needed. (Lenzen, 2009, p. 92.)

Let us assume that we have a system with an average demand of X GW, and that we build a wind system with a peak capacity of X GW and a PV system with a peak capacity of X GW. On a sunny and windy day these renewable components of the total system would be generating almost 2X GW, twice as much as is needed, so half of it would have to be dumped, or stored inefficiently as hydrogen.  (Not much of it could be stored as pumped water because hydro sources contribute only around 15% of world electricity, and relatively few existing dams could be adapted to it.  (Both low and high storage capacity is needed.)6% of Australian electricity.)  Lenzen points out the way dumping of energy from a wind system increaseshow these problems have been found to increase rapidly if wind makes up more than 20% of average supply.

On a night when winds were about average the renewable sector would be contributing about .23X GW, (i.e., the world average wind capacity according to the IPCC, 4AR, Section 4.3.3.2) but on a calm night the 2X GW of renewable capacity would be contributing nothing and resort would have to be made to X GW of coal or nuclear capacity.  Over time the wind and solar elements would contribute perhaps 40% of demand, the approximate sum of their average capacities, meaning that about 60% of demand would have to come from coal or nuclear sources.

This shows how renewable energy sources are best regarded as alternatives to coal/nuclear sources and to each other, and not as additions. To build X GW of wind capacity and X GW of PV capacity is not necessarily to have added 2X GW of generating capacity to a system, because there will be times when it will have added no capacity, e.g., on calm nights. Discussions of renewable energy often proceed as if these sources can be treated as additive.  Stern’s Figure 9.4 reveals this assumption and it therefore represents a fuel budget but not a capital or plant budget.  His scenario’s merit is that it reduces coal demand, but at an unrecognised very high capital cost in the need to retain three separate kinds of generating capacity.

The above system intended to meet X GW demand would include X GW (peak) of wind generating capacity, X GW (peak) of PV capacity, and X GW (peak) of coal and/or nuclear capacity.  The capital costs of these three kinds of plant might be $(A)1,400/kW for the coal plant (or c. $4000 adding lifetime coal cost, at the early 2000s coal price), $(A)1,400/kW for wind (although some recent constructions suggests that $(A)2,000 would be more appropriate, see Trainer, 2007, Chapter 2), and $(A)7,000/kW (incl. BOS) for PV plant. (Lenzen, 2009.)  When multiplied by the inverses of their capacity factors to arrive at capital cost per “delivered” kWhH as distinct from peak kW, the total system cost might add to 11 times that of the coal plant plus fuel cost, and it would only reduce coal use by 40%, well short of the amount needednowhere near enough for a safe CO2 emission rates. 

No provision has been is made here for the cost of reinforcing grids to cope with large flows of wind or solar power from regions that happened to be generating well at a particular time.  It is clear that the problems of integration and alternation/addition have major implications for total system capital costs.  Yet Stern and the economic modellers quoted in IPCC reports make no reference to any of these issues to do with scalability, integration, alternation, idle plant or conversion losses or the need for back up plant.

Stern’s Fig. 9.4 failsreveals the failure to take into account the need for overlapping or redundant generating capacity.  It could give the impression that PVsolar plant capable of producing 110 EJ/y or 300 PJ/day needs to be built, given that when1 square metre of PV panels typically produces .65 kWh2.4 MJ a day.  But in much of Europe in winter 1 square metre of PV panels will only produce on averagte less than .1 kWh.around .3 MJH/d,, so in order for PV to keep up its contribution then far more capacity must be available, or more of some other renewable capacity must be available to compensate for the PV shortfall.  The difference this need for redundancy makes to total plant and investment required when the effect for all renewable sources within a system is taken into account is large.  (This also points to the way levelised cost figures can be misleading indicators of total system costs.)  Lenzen (2009) notes the need to take into account the implications for back up capacity when calculating the full greenhouse gas costs of an energy source.

Would it make sense to “over-size renewable components of the system in order to reduce use of coal or nuclear energy?  It can be seen that if the wind and PV capacities were doubled then annually they would generate about 80% of demand, but much of this would have to be dumped because these sources would sometimes be generating 4X GW, four times as much as would be needed.  Thus over time they might be able to meet 60% of demand, again meaning that if this arrangement was in place globally Uranium resources would be quickly exhausted, and/or geo-sequestration sites would not last long.  Note that we would still need to retain almost X GW of coal or nuclear capacity regardless of the magnitude of the over-sizing, because there would still be some times when almost all of the renewable capacity was idle. Total system capital cost would include X GW of coal/nuclear plus 2X GW of wind plus 2X GW of PV, and coal or nuclear sources would have to meet c. 40% of total demand.

The logic evident here indicates that it would probably not make sense for any renewable energy source to constitute a proportion of total demand that was greater than its average system capacity factor (except to the extent that sources reciprocate, e.g., winds tend to be down in summer when solar is up.) It can be seen that the capital costs of total systems significantly “oversized” in an effort to cut carbon emissions to “safe” levels increase dramatically compared with the reductions achieved in the need for coal or nuclear sources.

It is clear that the problems of integration and alternation/addition have major implications for total system capital costs.  Yet Stern, Garnaut and the economic modellers quoted in IPCC reports make no reference to any of these issues to do with scalability, integration, alternation, idle plant, energy dumping, the need for redundant alternative plant,  or the need for back up coal/nuclear plant.

            The conversion and dumping problems.

Discussions of the potential of renewable energy sources usually fail to take into account the need to convert energy from forms that are available to forms that are needed. All the major alternative energy sources, except for biomass, only produce electricity, but eElectricity accounts for only about 25% of Australian final energy consumption.  This leaves the question of where the other 75% of energy is to come from (apart from biomass), and what might be the losses of energy in conversion from one form to another. 

Conversion is typically quite energy-inefficient, meaning that much more primary energy needs to be generated than might appear to be the case. For instance fuelling transport by hydrogen generated from electricity could require generation of about 4 times the amount of energy that is to power wheels.  (Bossell, 2004.)  Stern’s Fig. 9.4 neglects this problem of conversion losses, and the IPCC does not deal with its implications.

Discussions of renewable energy contributions to total demand also typically give little or no attention to the problem of energy dumping set by the variability of renewables.  This increases the need for energy conversion and lowers average capacity factors.  Consider a system in which over time wind and PV each supply one-third of demand (i.e., .33 x total demand).  The world average wind farm capacity is .23, which means that at times output from a farm will approach 4.3 times average output.  For PV systems in good locations annual average capacity is probably about .18, meaning that on a sunny day a system will be producing about 5.6 times average output.  Now inconsider a system in which wind and PV components each contribute on average .33 of total demand, on a sunny day which is also quite windy these two components might be producing about 3.3 times total demand.  So even if the non-renewable components in the system couldan be shut down, 2.3 times as much energy as is needed would have to be dumped, or stored inefficiently as hydrogen.  This would have a significant effect on the system’s average capacity measured in terms of energy actually used. 

            Renewable energy conclusions.

At least the foregoing discussion points to a number of significant difficulties regarding the variability of renewables and the magnitude of their potential contributions. Neither Stern, the IPCC or the more recent Australian Final Garnaut Report deal with these issues.  The points made above seem to seriously challenge or clearly invalidate a number of the unexamined assumptions evident in these reports.

Thus there are major difficulties regarding the variability of renewables and the magnitude of their contributions.  (A more recent attempt to assess the limits of renewables is given in Trainer 2008b.)  Neither Stern nor the IPCC deal with these issues.  The points made above seem to seriously challenge or clearly invalidate a number of the unexamined assumptions evident in Stern’s Fig. 9.4. and the IPCC Reports dealing with mitigation.

It should also be noted that if the renewable fraction of total supply was to be large the sudden rise and falls in the renewable contribution would seem to set an impossible problem of rapid “ramp” rate for coal, nuclear or solar thermal sources. The output from these power stations cannot be raised or lowered quickly and could not follow the large and rapid changes in demand, e.g., when the whole of a very large amount of PV capacity came on stream in a period of one hour or so. Gas plant can respond more rapidly but the required changes would still seem to be formidable.   As has been stated above, iIf used on the required scale in a world attempting to maximise use of renewables  gas resources would be quickly exhausted as these are not much greater than estimated petroleum reserves.

It should be stressed that these are not arguments against the adoption of renewable energy technologies.  Chapter 11 of Trainer 2007 argues that we must move entirely to these sources and that we could live well on them, but not in a society committed to high rates of energy consumption, affluence and growth.

Attempting a 2050 world energy budget.

The unsatisfactory nature of the IPCC and Stern analyses can be made evident by attempting to explain how the 2050 1100 EJ energy budget might be composed.  Table 2 sets out the relevant figures.

Table. 2

A 2050 World Energy  Budget.

World primary energy target.                                      1100 EJ/y

Energy to be supplied after assuming 25% energy

conservation and 25% of the remainder supplied

as low temperature solar heat.                                   619 EJ/y                                                                                                                                -----------------------

Direct electricity supply.

            Required                                                         205 EJ/y

            Supply source         Coal with CCS                  93 EJ/y

Hydroelectricity                19 EJ/y

                                                Nuclear                              8 EJ/y

                                                                                      120 EJ/y

            Required from wind and solar                                                  85 EJ/y

Transport energy supply.

            Required                                                        290 EJ/y

            Supply                     Biomass

                                           (Stern’s assumption)       336 EJ/y (ethanol)

            Required from wind and solar                                                257 EJ/y

However only c. 60% of transport energy

can be electrical, i.e.,174 EJ/y.  Thus 850 EJ/y

must be converted from electricity.

If conversion efficiency is assumed,

Thus total electricity to be supplied                                               493605 EJ/y

            Supply through one winter month                                        4150 EJ

Table 2 derives the conclusion that renewable sources would have to supply 41 EJ of electricity in a winter month.  Let us explore the implications for a system in which solar thermal dishes are to supply one-third of the electricity required, in winter, i.e., 14 EJ/month.  At 18 W/m² continual flow, a 400 m² dish would deliver 7.2 kW, i.e., 5,3456 kWh/month, or 19.3 GJ/month.  Therefore to deliver 14 EJ/month, 725 million Big Dishes would be needed, and at the estimated future cost of $147,000 per dish, the total cost would be $107 t.  The annual cost would  be $4.3 t, which is 9.5 timesLet us assume the solar thermal system supplies one-third of the 50 EJ.  A solar thermal dish delivering 18 W/m2 in winter would deliver 19.2 GJ per month.  To deliver 17 EJ, 870 million dishes would be required, and assuming the above costs annual investment would be c. $3.8t, or 8+ times current total world annual energy investment.  (Bairol, 2003.)

If PV and wind were each to meet one-half of the remainingthird of the 50 EJ totalelectricity demand the investment total would more than treble.increase sustantially.  Wind would add a lesser sum than solar thermal but PV would add a much greater sum.

If the cost of energy increases significantly, as is almost certain in future years,  then the cost of most if not all other inputs into the construction of energy systems will also increase, with multiplying effects on total final costs.

Again these estimates are uncertain and are only given as indicative, but their general magnitude makes clear the importance of taking into account several factors which Stern, and the IPCC Working Group 3 and Garnaut ignore, includingespecially possible limits to energy derivable from the various renewable sources, rates of supply in winter, the difference between gross output and net rate of delivery at distance and in view of embodied energy costs, losses in conversion, and especially the need for overlapping or redundant generating capacity.

I think dump all th old…does the table say it; comment a bit??

The following analysis is based on the table on p. 4 above.

OLD

   Energy saving.  It will be assumed that energy conservation etc. effort will cut 25% off the amount demand would otherwise reach.

   Low temperature space and water heat.  It will be assumed that one-quarter of the total 206 EJ is in this category, and can be easily delivered from solar sources (although this is too optimistic for many mid to high latitude countries.)

   Electricity. From Table 1 above this sector would require 205 EJ.  Let us assume that in 2050 this is met by 104 EJ of “safe” coal use via CCS as derived above,15 EJ of hydroelectricity (a questionable doubling of the present amount), and 43 EJ each of wind and solar.    This could be 80 times early 2000s wind capacity, and it is likely that by 2100 geosequestration could not be used at all. If the lignin in biomass residues can be used after ethanol production, 5 EJ of electricity might be derived, taking Stern’s assumption of 110 EJ of primary biomass energy.  Thus we have explained the quantity of electricity needed, but we have not dealt with the huge problems of integration and back-up which actually reduce quantities that could be used.  Nuclear energy cannot make a significant long term global difference in view of Uranium resources, unless breeders and fusion are employed.

Transport :  This sector, accounting for 35% of the total, would require 290 EJ (in the form of petrol.)  Let us take Stern’s assumed amount of biomass energy, 110 EJ, which would produce about 35 EJ of ethanol. This would leave 255 EJ of transport energy to be found.  This could not be provided via the production of liquid fuel from coal as the CO2 in vehicle exhausts could not be captured.  In any case the geosequestration quota has been allocated to electricity, above.   Petrol driven cars are c. 40% energy efficient meaning that some 102 EJ would be driving wheels, and thus if electric vehicles were assumed this would be the quantity of energy that would have to reach the wheels.  However, because the energy efficiency of the electricity-to-wheels path is c. 50% (Bossell, 2004), some 204 EJ would have to be generated, almost 3.5 times the present world electricity production.  (Let us ignore the fact that air and sea transport cannot be powered electrically, except via hydrogen; see below.)

If this load is divided between wind and solar sources so that each meets half electricity plus transport demand, then to provide its fraction installed peak wind capacity would have to be 145 EJ/y, requiring around 150 times the early 2000s installed wind capacity.  (Again Trieb, undated, p. 48 estimates European combined on- and off-shore potential at c. 4 EJ.)  At Sydney average insolation 145 EJ from PV corresponds to 19 square metres per person for a world population of 9 billion.

Hydrogen powered transport would probably double the amount of electricity to be generated, to 408 EJ, given Bossell’s estimates of the efficiencies and losses on that path. (That this is plausible is evident if we optimistically assume .7 efficiency of hydrogen production from electricity, .8 for distribution, and .5 efficiency for future fuel cell drive, yielding an overall efficiency of 28%.) 

Thus neither an electric nor a hydrogen powered transport option would seem to be viable, considering only quantity implications, let alone the difficulties in storing, integration and back up.

At this point in the attempt to construct an energy budget we have accounted for low temperature heat, and electricity (by making some implausible assumptions) but we are far from explaining how transport could be fuelled, and there would then be the remaining 146 EJ, 18% of the total 825 EJ energy demand to provide for.  If this was to come from wind or sun the energy losses in conversion (e.g., from electricity to hydrogen and storage) would greatly multiply the primary quantity necessary.  We have already assumed use of all the permissible coal (and that amount will not be permissible by 2100.)  We would have special difficulty explaining how we could provide the approximately half of liquid fuel demand that is not for transport, (i .e., some 60 GJ per person in Australia at present), given the above limits to ethanol from biomass, and to hydrogen.

It is evident from his discussion that conversion issues and loses are very important in the estimation of the potential of renewables.  These are not taken into account in the Stern or IPCC Reports.

If we assume a 50% conversion loss then this last 18% of energy would require generation of about 300 EJ of electricity.  If we assume CCDS will be able to capture the upper limit of the IPCC’s estimate for the possible range, i.e., 90%, and that the 2050 CO2 permissible release quantity is the IPCC mean estimate, 9 GT/y, then electricity from “safe” coal use could be 310 EJ/y (and all coal might be exhausted in 37 years.)  However this is of little significance as safe release after 2050 will probably be zero.

This failed exercise indicates that it will not be possible to achieve an expected 2050 world energy target of 1100 EJ within safe carbon emission limits.  This is despite the fact firstly that it assumes much more coal use than will be acceptable after 2050, and  secondly that the target would enable a per capita use only half the present Australian figure and one-quarter of the amount Australians are likely to be using by 2050.)

Conclusions on the three reportsIPCC Third Working Group Reports.

The argument has been that the IPCC’s conclusions in the IPCC, Stern and Garnaut  reports regardingabout the possibility and cost of greenhouse gas mitigation are seriously mistaken. To summarise the main problems, the Reports are statements of findings, not presentations of the case leading to them, making it impossible to asses in any convenient way how valid the conclusions are.  Secondly although it is stated that “The world is not on a course to achieve a sustainable energy future” (IPCC 2007, Ch. 4, p. 255), the tone is at variance with the Report’s evidence, failing to appropriately stress the magnitude of the shortfall left after conservation effort, or the difficulties renewables etc. involve, and therefore failing to emphasise the seriousness of the situation.  The 4AR’s most optimistic emission reduction expectations would be associated with a 25% increase in emissions by 2030, to c. 30 GT/y, when by their own account a relatively responsible path requires reduction to possibly a minus value by 2100.  If it was clear how such a rising trend (despite picking the low-hanging fruit) could be easily reversed after 2050 the situation might not be so disturbing, but this is not discussed let alone shown.

The conclusions on energy savings are not very impressive, mostly ranging from 5 to 50% of present energy use per unit of output.  When the effects of $20/t and $100/t CO2 prices are considered it appears that there are severely diminishing returns, i.e., that it will be easy to make significant savings initially and at low cost, but increasing the cost greatly will not add very much to achievements. 

Thus, most of the reduction task will be left to the energy generation sector, and the treatment of this sector is even less technically satisfactory, or reassuring.  There is no discussion of the potential and limits to renewables, apart from the most superficial notes, and conclusions are based on an economic modeling methodology which cannot arrive at sound conclusions because it does not refer considerto the crucial physical and biological difficulties and limits associated with renewables.  When these limits and the implications of the need to transform large quantities of energy into different forms are consideredtaken into account, there seems to be no way that the anticipated 2050 global energy budget can be achievprovided.  Again that budget represents only one-quarter of the amount needed to provide expected Australian 2050 per capita consumption to all people.

It would be difficult to exaggerate the importance of these conclusions.  The threeLike the Stern Report the IPCC Working Group 3  rReports have assertedgiven the world three highly confident conclusions.  The first is that the greenhouse problem can be solved, the second is that it can be solved at negligible cost, and the third, implicit, conclusion is that it can be solved without any need to question the commitment to affluent living standards and economic growth.  The argument in this paper contradicts has been that all these conclusions are clearly and profoundly mistaken. Whereas people within the “limits to growth” school of thought have been arguing for decadeshalf a century that consumer societies are fundamentally unsustainable, the Stern Review, and the IPCC Working Group 3 Reports and the Garnaut report have reinforced the dominant faith and have therefore seriously reduced the chances of the situation being recognised or of effective strategies being adopted.

            A radically different view of the situation and the way out.

In Chapter 10 of Trainer 2007b it is argued that the energy and greenhouse problems are only two of the increasingly serious problems consumer society is running into it, and that it will not be possible to solve these unless the commitment to affluence and growth is abandoned. Consumer society involves rates of resource use and environmental impact that are far beyond sustainable levels and could not be extended to all the world’s people.  For example the Australian per capita ecological footprint of about 87 ha is around 10 times as large as the world’s productive land area would permit for 9 billion people. (World Wildlife Fund, 2009.)

Chapter 10 also argues that even if there were not a problem of ecological sustainability the present rich world affluent “living standards” would not be possible if these countries were not taking most of the world’s resource output, thereby condemning the Third World majority to far less than their fair share.

The commitment to affluent “living standards” and limitless growth is the predominant cause of the multi-faceted global predicament we are in.  These quests inevitably generate problems of ecological destruction, resource depletion, Third World deprivation and geopolitical conflict and war.  In addition the drive for growth and affluence is damaging the quality of life and social cohesion in even the richest societies.  

Although the present levels of production and consumption are grossly unsustainable and are the basic cause of the many alarming problems, the top priority is economic growth.  Therefore there will inevitably be an accelerating rise in the magnitude of the problems over coming decades. Note that at the expected (and required) 3% p.a. rate of economic growth, by the end of the century the economies of the rich countries will be churning out 16 times as much production for sale every year as they do now.  Yet within official political circles and the general public there appears to be little oris virtually no recognition that this could be a problemof any need to reconsider the commitment to economic growth.

Chapter 10 concludes that the problems cannot be solved in a society committed to affluence and growth, and therefore that huge and radical system change is clearly needed.  It is argued that Tthe necessary vast reductions in energy and resource use and environmental impact cannot be made without dramatically reducing the present volume of production and consumption and therefore without changing from a society committed to affluent lifestyles and economic growth. It is not just that consumer/capitalist society is unsustainable, the point is that it is that it cannot be made sustainable. Unfortunately advocates of renewable energy typically reinforce the dominant belief that it can.

Chapter 11 of Trainer 2007 argues that the solution must be thought of in terms of a transition to some kind of “Simpler Way”.  (For the detailed account see Trainer, 2006.)  This must involve non-affluent (but sufficient) material living standards, mostly small and highly self-sufficient local economies (and therefore localization as distinct from globalization), zero-growth economic systems under social control and driven by need and not by market forces or the profit motive (although there might be a considerable role for markets and private firms), and highly cooperative and participatory systems.  The Simpler Way vision would enable all to live well on (extremely low quantities of) renewable energy. (A numerical case is given in Chapter 11 of Trainer, 2007.) Obviously such radical system transition could not be made without profound change in values and world view, away from competitive, acquisitive individualism, i.e., without radical contradiction of some of the core elements in Western culture.

It is not likely that changes of this magnitude will be made, especially given that it is late in the day, the required changes are radical in the extreme and their necessity is not on the agenda of official or public discussion.  It is highly regrettable that the Stern, IPCC and Garnaut Stern Reports have powerfully reinforced the dominant belief that there is no need to consider such change because the greenhouse problem can be solved without threatening the commitment to affluence and growth, and that it can be solved at negligible cost.

Note 1.   Table 4.2 of IPCC 4AR states some energy resource and use quantities that are questionable.  In the text world electricity production is given as 17,000 TWh, which aligns with IEA figures and corresponds to 62 EJ/y.  However Table 4.2 states that nuclear and hydro electricity each provide c. 26 EJ, which would mean that coal, which is actually the major contributor, would be responsible for less than 6 EJ.  Other sources indicate that the figure should be c. 8 EJ, corresponding to about 15% of electricity.  This figure is stated in the text on pages 260 and 273.

Present wind generation is given in the Table as .95 EJ but the mid 2000s figure from The American Wind Association is aroundCoppin (2008) states is .5 EJ.  The figures on p. of the 4AR and other sources represent .5 EJ. (The rapid growth rate for wind installation confuses this figure.)

Hydro potential is given as 60 EJ, but other sources indicate that this is equivalent to about 7 – 8 times the present amount.  It is commonly recognised that for ecological reasons few if any more big dams will be built in future.

 The 7400 EJ figure stated for nuclear resources is usually given not as a likely estimate but as a possible high estimate, some three to four times the more common c. 4 million tonne Uranium resource.

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