A CRITICAL DISCUSSION OF THE IPCC ANALYSES
|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|
|Energy services enabled due to increased conservation, efficiency of use, etc. (c. 25% of b.a.u. primary).||275 EJ|
|Energy services or final energy to be provided.||825 EJ|
|Low temperature heat, mostly water and space.||206 EJ|
|Transport energy, 35% of final.||290 EJ|
|Electrical energy, 25% of final.||205 EJ|
|Carbon Capture and Storage, assuming 5.7 GT CO2/y safe release, as electrical energy (assuming 80% capture rate.)||250 EJ|
|corresponding to electricity supplied||80 EJ|
|Carbon Capture and Storage, assuming no release by 2100||0 EJ|
|Energy needed to provide 9 billion people with the per capita amount Australians are likely to average by 2050.||4000+ EJ|
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 are the best grounds that can be found in the Reports for the conclusions stated.
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 it gives very brief descriptions of options. For instance only two paragraphs are given on fuel cells. Section 184.108.40.206 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.
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 220.127.116.11.) 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 18.104.22.168.)
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.
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.
Mitigation involves two domains, the first being reducing the energy needed to perform operations, and the second being reducing 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 1900-2,600Mt/C/y by 2010 and 3600 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, 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 it is likely to be largely exhausted later this century. Also fuel switching and several of the other possibilities mentioned are one-off options; they can only be made once.
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 end 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. 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.
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 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 sectors 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 geosequestration 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 muchlarger 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 reports most optimistic studies project for 2030. In addition there would be the contribution from the generation of the remaining 40% of energy demand, although much of this would be for space and water heating and should not be problematic (except in winter.)
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 most 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 the $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.
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 Sterns 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 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 too high a target for safety. The second diagram in SPM 7 represents what many would now regard 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, 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 times more difficult than the 2030/2050 task they have set themselves.
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). The issue firstly requires a critical discussion of the use made by these studies of 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 1KW 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.)
Sterns 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 IPCCs and Sterns analyses this assumption is highly dubious or false. Achievement of the quantities of energy supply stated in Table 1 above and in Sterns 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 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).
This failure would seem 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., Howards 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. (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 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 figures.) 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.) 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.
The IPCCs Table 4.2 assumes global wind potential is 600 EJ, 10 times as great as Stern assumes without explanation. (For some other questions re the Table see Note 1 below.)
Biomass. Sterns figure 9.4 indicates access to 110 EJ of biomass energy. This is optimistic as it corresponds to 850 million ha when all cropland totals only 1,400 million ha. 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.) 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. Sterns figure would yield only c. 33 EJ of transport fuel, or 3.7GJ per person for 9 billion, when Australian Transport consumption is about 65 GJ per person, and rising.
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 worlds present nuclear contribution. If the estimates of Uranium resources commonly quoted, e.g., by Leeuwin and Smith (2003, 2005) and Zittel (2007), are correct they would be exhausted in less than a decade. (The 4AR Table 4.2 lists Uranium resources 3 times as great (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 Coal 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 at least 40% 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 to 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.
According to Hendricks, Graus and van Bergen (2004), the best estimate of available land sites is 1700 GT. (The IPCCs uncertain estimate of the maximum theoretical potential is 6 times as great; see Metz, undated.) If 9 billion people were to have the probable 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. If the 2050 emission limit is 5 GT/y, if geo-sequestration captures 80% of CO2 generated, then 25 GT/y could be generated, corresponding to about 250 EJ of primary energy or 80 GJ of electricity. This would provide 9 billion people with 7 GJ per capita p.a., about 20% of the present Australian per capita electricity consumption, leaving none to meet transport demand. Note again that by 2100 no release of CO2 is likely to be permissible, which would eliminate use of geo-sequestration because it cannot capture all CO2 generated. Also 250 EJ of primary energy from coal would be about twice the present rate of use which some think will see coal supply plateau within two decades. (Energy Watch, )
Solar PV. It would be possible to build and site the 110 EJ of solar capacity Stern 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.
Solar thermal: Could the capacity of solar thermal systems to store energy get round 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 orignetation goes 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, reported by Dey and Lenzen (1999) at 4% of lifetime energy output. 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.
When these factors are applied to DNI data for Central Australia, which could be the best site in the world, it is possible that a continuous 24 hour flow of less than 10 W/m net of all energy costs would 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/m (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 200s 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 more effective than troughs, primarily because they can face the sun directly all 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/m flow. (Davenport, 2008.) The US Mod 1 and 2 systems have been reported to deliver at a lower rate, the equivalent of 18 W/m averaged over a mid winter month. (Sandia, undated.) Peak output from these dishes would be in the range of 250 W/m.
These 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. European and US dish developers therefore do not regard heat storage via dishes as viable.
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.
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/day with hardly any hours over 700 W/m. (Further climate evidence is given in Trainer 2008.)
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 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 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. This means that if sun and wind are to be large contributors to electricity supply little or no reduction can be made in coal or nuclear capacity, as there will be times when almost all of it will be needed.
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 6% of Australian electricity.)
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) 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. Sterns Figure 9.4 reveals this assumption and it therefore represents a fuel budget but not a capital or plant budget. His scenarios 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. When multiplied by the inverses of their capacity factors to arrive at capital cost per delivered kWH 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%, nowhere near enough for safe CO2 emission rates. No provision 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.
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.
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 Sterns 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 If 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.
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. The following analysis is based on the table on p. 4 above.
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 80 EJ of safe coal use via CCS as derived above,15 EJ of hydroelectricity (a questionable doubling of the present amount), and 55 EJ each of wind and solar. This could be 70 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 Sterns 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 t he form of petrol.) Let us take Sterns 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 157 EJ/y, requiring at least 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.)
Hydrogen powered transport would probably double the amount of electricity to be generated, to 408 EJ, given Bossells 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.
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 164 EJ, 20% 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.
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 (and that target would enable a per capita use that was only half the present Australian figure and one-quarter of the amount Australians are likely to be using by 2050.)
The argument has been that the IPCCs conclusions about 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 Reports 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 4ARs 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 to 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 considered, there seems to be no way that the anticipated 2050 global energy budget can be provided. 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. Like the Stern Report the IPCC Working Group 3 Reports have given 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 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 half a century that consumer societies are fundamentally unsustainable, the Stern Review and the IPCC Working Group 3 Reports have reinforced the dominant faith and have therefore seriously reduced the chances of the situation being recognised or of effective strategies being adopted.
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 worlds people. For example the Australian per capita ecological footprint of about 7 ha is around 10 times as large as the worlds productive land area would permit for 9 billion people.
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 worlds 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 there is virtually no recognition that this could be a problem.
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. The 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 an economic growth. It s 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. 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 IPCC and 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 hat 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 around .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.
You can get the original document here:
http://candobetter.wikispaces.com/space/showimage/Trainer-IPCC-CRIT-1jul08.doc Ted Trainer
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