A critique of Jacobson and Delucci’s proposals for a world renewable energy supply.

7.7.2011

Ted Trainer.

Conjoint Lecturer, Social Sciences and International Studies, University of New South Wales, Kensington, 2052. F.Trainer@unsw.edu.au Tel. 61 02 93851871.

Abstract:  Jacobson and Delucci have recently put forward a detailed case in support of the claim that renewable energy sources can meet total world energy demand.  The following argument is that this proposal is unsatisfactory, primarily because it does not deal effectively with the problems set by the variability of renewable energy sources, and also because its analysis of investment costs is inadequate.

Keywords:  Renewable energy. Intermittency. Limits to growth.

Advocates of renewable energy technologies frequently refer to the many available and potential ways of reducing the effect of variability of renew able energy.  However they usually do not show that these could be combined to enable constant energy delivery to the grid despite the magnitude of the shortfalls that typically occur in supply from renewable sources.  Jacobson and Delucci (2011a, 2011b) list possible strategies but do not show that these can provide the necessary quantities of energy to plug gaps in supply.

It is firstly necessary to outline the nature and magnitude of the general problem of variability confronting renewable energy sources. 

            The magnitude of the variability problem.

There are periods when there is close to no wind blowing anywhere in a large region, and these times can last for many days.  Weather tends to comes from the west in large “synoptic patterns” and these can leave the entire continent of Europe under conditions of intense calm, cloud and cold for a week at a time. Lenzen’s review of renewable energy (2009) includes three plots which make the magnitude of this problem evident.

Lenzen’s graphs from Oswald et al, (2008) make the magnitude of the problem clear.  It shows wind energy availability over the whole of Ireland, UK and Germany for the first 300 hours of 2006, i.e., in mid winter, the best time of the year for wind energy.  For half this time there was almost no wind input in any of these countries, with capacity factors averaging around 6%.  For about 120 continuous hours UK capacity averaged about 3%.  During this period UK electricity demand reached its peak high for the year, at a point in time when wind input was zero.

Soder et al. (2007) provide a similar plot for West Denmark in mid winter, again one of the best wind regions in the inhabited world.  For two periods 2 and about 2.5 days there was no wind input at all, and in all there were about 8 days with almost no contribution from wind energy. 

Clearly these periods of calm are not rare and of minor significance.  For several days in a winter month in good wind regions there would have to be almost total reliance on some  other source.  The capital cost implications of having a back up system capable of substituting for just about all wind capacity are rarely focused on.

Lenzen’s third plot is for the whole of Germany, again showing hardly any wind input for several days in a row. (See also E.On Netz, 2004.) 

Davey and Coppin (2003) make the same point for Australia, for instance indicating that for 20% of the time a wind system integrated across 1500 km from Adelaide to Brisbane would be operating at under 8% of peak capacity.  Mackay (2008, p. 189) reports data from Ireland between Oct. 2006 and Feb. 2007, showing a 15 day lull over the whole country.  For 5 days output from wind turbines was 5% of capacity and fell to 2% on one day. At times the Danish wind system contributes almost no electricity.  Similar evidence is given by Coelingh, 1999, Fig. 7, Sharman 2005, and Mackay, 2008, p. 189.  Given that electricity is only about 25% of rich world energy consumption, advocates of a completely renewable energy supply would need to explain from which source around 99% of demand is to be met on these occasions.

The problem can be discussed in terms of “capacity credit” and “loss of load probability”, but these can obscure the central issue.  “Capacity  credit” refers to “...the fraction of average capacity that is reliably available during peak demand.” (Lenzen, 2009, p. 92.)  The south Australian electricity supply agency estimates that for its wind supply system this value is only 3-4%.  However ”reliably” in this context means 95% probable and the crucial point concerns what can happen in the remaining 5% of the time, which is 17 days of the year.  As the above cases show it is very likely that what can happen is the occurrence of long periods with negligible wind.  The probability of a loss of load event might e very low, but if and when it happens the entire wind contribution would have to be made up by some other source, and as Lenzen notes the capital cost of this provision should be accounted to the wind system.

A similar problem associated with higher penetrations of wind and solar is to do with periods of over-supply and dumping.  Lenzen (2009, p, .94) reports Hoogwijck et ,al. 2007 as finding that “...the amount of electricity that has to be discarded grows strongly for penetrations  in excess of 25-30%.”  If wind and PV were to contribute 25% and 30% of electricity then on sunny and windy days they would be generating more than twice average demand.  Some degree of system “over-sizing” will probably make sense but the capital cost implications are easily overlooked.  System capital costs should be divided by electricity delivered, not generated, to arrive at a realistic system capital cost per kW.  The Zero Caron Australia proposal involves solar thermal input that regularly reaches twice the amount that can be used, but this is not taken into account in capital costing.

Jacobson and Delucci expect 50% of energy to come from wind.  Again no attempt is made to explain where energy is supposed to come from during the kinds of weather events described above which can last for several consecutive days.  There is reference to the use of hydrogen but the magnitude of the implications for storage and the very large scale losses due to the energy-inefficiency of this path (see below) are not discussed, let alone quantified.

Solar energy availability exhibits similar variability.  Most obviously, even on a sunny day PV panels can provide no energy for about 16 hours of that day.  Renewable energy enthusiasts tend to discuss in terms of average supply and demand, whereas it is the times of unusually high or low supply and demand which set the limits.  At the best Australian sites winter DNI averages around 5.7 kWh/m²/d but in particular months it can average 40% below this value, i.e., 3.42 kWh/m²/d.  (See ASRDHB 2006, RREDC undated, Kaneff and Hagen 1991, NASA, 2010.)  This means that on about half the days in such a month it would be even lower.

Maxima or peaks in demand are also crucial.  Energy supply infrastructures typically have to contain 30-50% more generating plant than would meet average demand, in order to cope with peak demand.  In addition, the two events can coincide.  That is demand can peak in periods of low renewable energy source availability. Such events are not unusual in winter.  For instance Victorian winter energy demand peaks during periods of calm accompanied by low temperatures. Note in the plot from Oswald mentioned above in 2006 UK electricity demand reached its highest point for the year on a day when there was no wind contribution. When demand peaks the generating capacity required can be c. 1.5 times that which could meet annual average demand, and again these are periods in which it might not be possible to meet more than a negligible fraction of that demand from wind or solar source.  These are periods when almost all demand would have to be met by other than solar and wind sources, setting significant implications for the amounts of redundant plant required and total system capital costs, unless this can be done via very large scale energy storage; see below.

            Jacobson and Delucci’s solutions.

Jacobson and Delucci recognise the general variability problem but state that it can be overcome by the technologies they list.  The following argument is that their discussion of these options is superficial and far from convincing, and that these technologies are not capable of solving the general variability problem.  The crucial issue here is quantitative; i.e., the extent to which particular technologies can deal with variability and whether or not all combined can add to a sufficient capacity to get around the difficulties set by variability. 

First it is important to again make the general point that that Jacobson and Delucci assume 50% of energy needed will come from wind.  However Lenzen’s review (2000) concludes that only 20+% of electricity, as distinct from total energy, can be supplied by wind due to integration difficulties created by its variability.  Jacobson and Delucci do not deal with this contradiction.

The strategies they list will be discussed in turn.

1.    “Interconnect dispersed generators.”

The half page explanation of this strategy begins by stating that connecting renewable energy sources  “...smooths out electricity supply –and demand—significantly.”  A paragraph then refers to a study in which variation in modelled wind output from 16 turbines over a month was found to be even less than that for hydroelectricity output.  The final paragraph explains that connecting PV sites also reduces variability. 

These brief statements make the well-known observation that interconnections do reduce variability in supply from individual solar and wind devices, but they fall far short of a satisfactory case for the claim connecting sources can make a sufficient contribution to overcoming the variability of renewable sources.  In particular Jacobson and Delucci do not explain how renewable can deal with those climatic events referred to above in which both sun and wind are contributing little or nothing for days at a time.  As was discussed above, a number of studies document the magnitude of this problem in modelled and actually observed systems connected across large distances.  When most of Europe is experiencing calm and cloudy conditions over large regions for days at a time the crucial question is not whether input from wind and sun has been “smoothed out”, it is whether there is any significant input at all from these combined sources.

2.  “Use complimentary and non-variable sources to help supply match demand.”

The point made in this section is that “...when the wind is not blowing, the sun is often shining, and vici versa.”  Again this is true but is of little consolation when neither source is available for days at a time.  In addition the implications for plant redundancy and capital costs are overlooked. 

It is often said that “...the wind is always blowing somewhere”, without recognition of the implications.  If the wind is blowing strongly today in region A and the total wind sector contribution is to be supplied by that region today, then it will have to contain enough wind generating plant to meet that contribution.  If tomorrow the wind is only blowing well in region B then that region will also have to contain enough generating capacity to meet the whole wind contribution.  Thus in every region which might be the only one where the wind is strong on a particular day we would need sufficient capacity to meet the whole wind quota.  In other words, to be able to always meet the wind quota would require several times the amount of plant needed to make wind’s average annual contribution, and most of it would be idle much of the time.  Also, for much of the time the whole system would be producing far more than could be used.

The main “non-variable” alternative energy source referred to is geothermal.  Even the renewables-optimistic WWF Energy Report, (2010), and  Jacobson and Delucci themselves only assume geothermal can contribute about 4% of world energy.  Australia has much better hot dry rock heat resources than the rest of the world but it is not yet clear how effectively they can be tapped or at what energy return value.  It will require considerable amounts of energy to bore holes 5 km deep through rock, fracture rock at depth, pump water down and force it 500 metres across to the nearest rising hole.  It is not known what will be the temperature and rate of flow of the water that comes up, and what generation efficiency these will enable.  In addition in Australia there will be the dollar and energy costs of constructing very long transmission lines from the deserts where the hot rock is located.   The only operating plant in Australia (not at the most promising location) can transform into electricity only 6% of the heat energy in the water, one sixth the efficiency value for a coal-fired power station. Early in 2010 the much-publicised Geodynamics venture in South Australia abandoned its efforts, writing off $350 million. 

3. “Use smart demand-response management to shift flexible loads to better match available ... generation.”

The value of this strategy depends on the proportion of total load that is flexible, and this is likely to remain quite limited.  Some heating and cooling functions can draw on heat energy stored for days, but all domestic and commercial energy use makes up only about 16% of total energy use, so their heating and cooling demand would probably be well under 10% of all energy.  There would be virtually no scope for shifting the timing of electric vehicle battery recharge (see below), or of most energy-intensive industrial uses.  Some industrial processes such as ammonia or cement manufacture do in principle allow postponement, e.g., until summer, but this means expensive plant sitting idle some/much of the time.  Energy-intensive kilns and furnaces cannot be switched on and off to follow short solar and wind peaks.  These functions do not add to a large fraction of energy demand.

Jacobson and Delucci assume that the charging of electric vehicle batteries is “flexible”.  “...most electric vehicles would be charged at night.”  This is problematic as at night winds tend to be low and there is no input from PV systems. 

Thus it is not likely that “smart, demand-response management” could make much difference to the general situation, let alone in those periods when there is negligible sun or wind in the region for days at a time.

4.  Store electric power.

Again the importance of quantitative argument is evident, but this is not given.  Jacobson and Delucci list a number of ways in which electricity can in effect be stored, but these fall far short of being capable of storing the quantities required.  The main options Jacobson and Delucci list will be considered in turn.

Pumped water storage.

The gaps left by intermittent sources can be filled to some extent by electricity generated by water that has been pumped up into dams.  However the capacity compared with demand is very limited.  World hydro-electric generation meets only about 15% of electricity demand, and the 10.7 EJ/y contribution is not likely to be doubled.   Hydro electricity has been c. 9% of electricity supply in Australia but has fallen to 6% in recent dry years.  It can provide only 18% of demand for a short period in Australia. 

However reference to hydroelectric capacity is misleading because it refers to water released in a once-through flow from a high dam, whereas pumped up storage is not possible unless there is also a low dam close by to hold the large volume of water to be pumped.  Thus the main limit is to do with how many dams have or could be given adequate low dam capacity.  The sea can be used as the low “dam” but this sets problems to do with seepage of salt into the ground at the high dam sites.  This is why a proposal in South Australia was abandoned.

Mackay’s analysis of UK potential pumped storage sites (2008, p. 189) shows that it is only a small fraction of what would be needed, even in a country with high rainfall.

A major problem is in deciding at a point in time whether the need will be for empty high dams to store surplus energy from a coming surge in wind for instance, or full high dams to enable generation through a coming lull in wind energy.  There is also the need to keep dams somewhat empty to enable mitigation of floods, in an era in which the frequency of extreme weather events is likely to increase.  The greenhouse problem is likely to reduce hydro capacity in future.

Smil (2010) points out that stop/start generation sets problems regarding high volume water flows over long distances through tunnels connecting low and high dams. Getting large volumes moving takes energy, lowering overall efficiency.

Lang (2010) explored the feasibility of tunnelling 50+ km between two dams in the Australian Snowy Mountains scheme and found that the venture would be too expensive.  It would only generate 9 GW for 3 hours, but Australian average consumption is c. 30 GW.  Tumut 3 dam, the largest available in the Snowy region, only generates 1.5 GW.

These considerations suggest that except in unusual regions pumped storage cannot make more than a quite small contribution to the storage task that would be involved in maintaining supply through periods of protracted cloudy and calm weather. 

Compressed air energy storage (CAES).

This seems to be the most promising option but its potential is not clear.  Using electricity to compress air and then using the air to generate electricity later is claimed by some to be between 40% and 70% efficient.  However Mackay (2008) states 18%, presumably referring to systems not using added heat at the expansion/regeneration stage; see below.

Easily overlooked is the fact that we would have to pay the capital cost of at least two generating systems.  The first would be the windmills creating the electrical energy, the second would be the equally large system of compressors converting the electrical energy into compressed air.  (It is assumed that the compressing turbines can be reversed to do the subsequent regenerating.) To this generating capacity must be added the cost of the storage structures.  Fthenakis (2009) says the cost of CAES is half that of lead-acid battery storage.  If so it would be prohibitively high for very large scale use. Thus capital costs would probably be 2+ times that of the wind turbines, while energy delivered might  be 40% less than they generate, meaning that the capital cost per kWh delivered would be around 3.5 times that for a windmill supplying without storage. 

Very large storage volumes would be required to store significant quantities of energy.  According to Fthenakis (2009) there is sufficient storage space in the US, especially in the form of old gas fields.  Most other countries would have less of these.  Sorensen (2003) says 15 MJ can be stored per cubic metre, i.e., 4.16 kWh.   If this is so, then to deliver 10,560 MWh to meet night time demand from a 1000 MW plant via a 0.5 efficient system (i.e., storing 21,120 million kWh) would require a storage volume of approximately 5,068 million cubic metres, i.e., a 3mx3m mine shaft approximately 563 km long (or 1,564 km long if Mackay’s efficiency figure is valid.)  In many countries there would probably be too few caverns or old mines large enough for this form of storage to enable bulk electricity supply via intermittent sources.

The main storage task however is coping with several calm and cloudy days in a row, as distinct from providing16 hours night time supply from a PV system after a normally sunny day.   Providing a four day capacity would set a storage task more than 6 times as large.

The biggest problem would seem to be the fact that high efficiency requires the burning of gas to provide heat to the air as it expands at the regeneration stage.  In a wholly renewable energy world this will not be possible.  Solar heat could be used, but this would mean solar plant would have to be added to collect energy in the form of heat equivalent to a large fraction of the energy collected by wind, and the plant to store it would also have to be built.  Heat availability would be at its lowest in winter when wind energy for storage, and the need for stored energy, would both be at their highest.  However heat released in the compression phase might be stored for this use, although this would also involve large scale capital costs.

New batteries and capacitors.

New kinds of batteries are being developed for wind power, but the cost goal has been reported as $(US)500 per  kWh.  This would seem to be far too high for large scale use.  To store the 16,000 MWh from a 1000 MW PV power station for night time supply would cost $8 billion, some 4 times the cost of a 1000 MW coal-fired plant.

Hydrogen.

Jacobson and Delucci include in their list of storage strategies using renewable sources to produce and store hydrogen.   They do not explore the implications of the low energy efficiency of this path.  The energy efficiencies of a) producing hydrogen from electricity, b) compressing, pumping and distributing it, and c) re-generating electricity via (expensive) fuel cells are, optimistically, .7, .8 and.5, meaning that for each kWh the wind turbines generated would deliver .28 kWh to use via this path.  Again the implications for capital cost are significant, in effect multiplying the cost of generating plant per kWh delivered via hydrogen by 3.6.   

To these costs those of the hydrogen producing and storage plant would need to be added.  If the strategy is to store in hydrogen for the regeneration of electricity almost as much generating capacity would be needed in the form of fuel cells as in the form of wind turbines, and their cost per kW of generating capacity is far higher than that of wind turbines. 

Jacobson and Delucci assume that liquid fuel for aircraft and other uses would be provided via liquid hydrogen.  They do not discuss the implications of gaseous or liquid hydrogen use for quantities of plant, embodied energy costs or capital costs. As will be emphasised below, the limits to renewable energy are set primarily by capital costs, due largely to the need for redundant generating plant, not by accounting focused on energy supply and demand budgets of the levelised cost of electricity produced.

It is not clear whether thorough embodied energy accounting would show any net benefit in the hydrogen path, especially when liquid hydrogen or fuel cells are involved.  If the energy needed to construct all equipment for dealing with the hydrogen was subtracted from the .28 kWh energy content of the hydrogen produced by 1 kWh of electricity, or from the .14 kWh of liquid hydrogen (requiring cooling plant), and if the embodied energy cost of renewable plant is around 10% (a probable figure for solar thermal, see Lenzen 1999), then it is possible that it would take about as much energy to provide the hydrogen as contained in it.

The remaining storage strategy Jacobson and Delucci mention, the use of electric vehicle batteries, is listed by them as their fifth item.

5. Store in electric vehicle batteries.

Jacobson and Delucci regard this as an “...especially promising”’ option.  Their one-paragraph account does not deal with the following issues supporting the conclusion that this strategy is not likely to be able to make a significant contribution to the general storage problem.

The main problem with this strategy is that vehicle batteries need to be fully charged when they are to be used, which is typically twice a day.  This sets difficulties re the time available to carry out the various processes involved.  It would take time to recharge the batteries from the drive to work, then there would be the storage time until the energy is needed, and the time that use takes, then it would take time to recharge the battery again to be ready for the drive home from work.  At present it can take 7 hours to recharge a battery.  It is therefore difficult to see how an electric vehicle battery could be available for a useful length of time to perform a general electrical system storage contribution.

Many car users could not predict confidently when they were likely to want to use the car, and would set safety margins reducing the available time.  Vehicles would be most available for storage at night, but electricity demand falls markedly at night so there would not be that much need for storage then.  Winds tend to be lower at night, and there would be no PV input.

The main need for stored energy does not occur within a single day but involves sequences of cloudy and calm days, and it is not evident how vehicle batteries could make any contribution to solving this problem, because they need to be fully recharged twice a day.

The capital cost of a system would have to include the cost of two separate transformers (from 240 v to 12 v), battery chargers and inverters for supplying to the 240 v mains, for every vehicle.  One set would need to be where the vehicle was parked overnight and the other where it was parked during the day.

According to Smil (2010, p. 29), Lithium batteries deteriorate in the field quickly and have to be replaced in 2 – 3 years.  He says a set for a car costs $35,000. However  Jacobson and Delucci estimate future cost at $(US2011)7,980 -17,310, assuming recycling of Lithium, and believe that in future a set will last 15 years.  High ambient temperatures worsen performance and life.  

The limitation set by a 7 hour charging time could be eliminated by battery swap systems at “refuelling” stations.  However this would double the quantity of batteries required, with significant effects on system energy costs, and the availability of materials.

Finally there are the economic implications for the car owner.  If he pays 13c/kWh for the electricity to charge his battery, loses some of this in charging and sells the remainder back to the grid at the c. 5 c/KWh which other electricity suppliers are paid he is not likely to want to be involved in the scheme.  This suggests that participants would have to be paid at least three times the wholesale price received by other generators, and probably significantly more to compensate for the shortening of battery life due to the additional charging and discharging cycling.

These considerations align with the impression Lenzen’s review (2009) expressed, i.e., that is that not much excess wind energy is likely to be storable in vehicle batteries. 

           6. “Forecast weather to plan energy supply needs better”.

It is stated that this “...gives operators more time to plan ahead for a backup energy supply when variable energy source might produce less than anticipated.” (p.1173.)

Again the claim is true, but can make little difference regarding the main problems.  Even perfect forecasting capacity would bring virtually no greater ability to deal with those periods of several days at a time when solar and wind input is negligible.  Some flexible demand could be postponed but it has been argued that this would be a quite small proportion of total demand.

In conclusion, it would seem clear that combining the options Jacobson and Delucci list would provide little capacity to store the quantities of electricity routinely needed, let alone to cope with those long periods in which there is little sun or wind energy.

The usually overlooked need for redundancy.            

Optimistic claims re the potential of renewable energy (e.g., Stern, 2006, The World Wide Fund for Nature, 2010, Zero Carbon Britain, 2007, Greenpeace, 2010, Zero Carbon Australia, 2010), typically fail to recognise the need for large scale redundancy in generating capacity, caused by the fact that often one or more component systems will not be contributing much if anything.  For instance, when the availability of solar energy is low, enough wind capacity for instance would have to have been built to make up that deficiency.  When there is little wind there would have to be on hand sufficient solar generating capacity to meet the deficit.  Thus total system capital cost might be several times what at first seemed to be required. 

This shows that the crucial questions regarding renewable energy supply are not clarified by information on the “levelised cost” of a kWh from the various sources, nor by figures on their average annual contributions.  What matters most is the capital cost of the quantity of plant required to cope with a) periods of minimal or zero energy availability, b) periods of maximum demand, and c) the required amount of plant redundancy to cope with variability which at times reduces or eliminates contributions from one or more components of the total system. 

The issue is illustrated by Stern’s Fig. 9.4 (2006) which attributes 8% of future energy supply to wind. The typical procedure is to multiply such a quantity in kWh by a levelised cost for a kWh of wind energy, and to regard the result as the cost of the wind component in the proposed total supply system.  What this fails to recognise is that  there will be times when there is little wind and then there will have to be enough extra solar capacity to compensate for this, and there will be times when solar input is low and there will also have to be enough extra wind (or other) capacity to plug that gap.  The total system will therefore need much more wind plant than would be sufficient to generate 8% of total annual demand.  (Lenzen briefly notes the need to add the cost of backup to the cost of a system component such as wind, but does not emphasise the magnitude of the implications for system capital costs.)

Thus the common practice of focusing on levelised costs in estimating total system capital costs leads to serious underestimation of system costs. Attending to peak capital costs kW(peak) are similarly misleading.  Some expect the capital cost per peak kW for coal and solar thermal electricity plant to be about the same by 2030 (e.g., Jacobson and Delucci.)  However a coal fired power station averages an output that is about .8 of its peak capacity, whereas for a solar thermal power station the figure is around .2.  In other words for each to deliver at a constant 1 kW rate the solar thermal plant would have to be four times as large as one capable of delivering 1 kW at peak insolation, so the capital costs in relation to average or constant energy delivery are not well indicated by the commonly quoted peak ratings.  They refer to a peak output which the solar thermal plant achieves only for a small fraction of the time.

 Investment costs.

Jacobson and Delucci estimate that their scheme would cost in the vicinity of $100 trillion over twenty years, meaning an annual investment cost of $5 trillion.  It is not pointed out that an investment of $5 trillion p.a. would be more than 11 times the early 2000s $450 billion p.a. total global energy investment sum. (Birol, 2003, Pfuger, 2004.)  Nor is it made clear that this sum would have to be paid in perpetuity, as plant would need to be rebuilt after its lifetime had expired. (Jacobson and Delucci refer to the IEA’s assumption of 20 year lifetimes, but they assume 30 years. IEA, 2008.)

The $100 trillion figure appears to be a correct derivation from Jacobson and Delucci’s assumptions regarding the number of wind turbines etc. required and the capital cost per kWh(p) they assume.  However some of their key assumptions are highly challengeable.  They state that their cost figures are 30% lower than those of the IEA, without adequate explanation.  More importantly, the 2050 supply target in their discussion, 11.7 TWh/y, is 15% lower than present world consumption.  Remarkably this is not explained or justified and only three scattered sentences seem to be given to it throughout the two papers.  The claim seems to be (e.g., p. 1159) that the innovations and savings involved in the proposed conversion of many functions to electricity would result in a reduction in final demand of this magnitude, but no attempt is made to show this numerically.  It is an implausible claim as the target assumed is less than half the probable 2050 world energy demand that is indicated by IEA and other projections.   (The important transport assumption, i.e., a factor 5.3 improvement due to electrification of vehicles, is quite challengeable.  Such large efficiency gain claims typically refer only to the processes between batteries and wheels and omit the energy losses in getting energy into the battery.  The reasons for regarding a factor 3 reduction as more plausible are detailed in Trainer 2010b.)  Subtracting the embodied energy costs of all components would further reduce the efficiency gain, but Jacobson and Delucci do not discuss the embodied energy costs of any renewable technology.

The appropriate beginning point for arriving at a target in exercises of this kind is the likely 2050 demand we are heading for (pre-GFC) under business as usual, which is in the region of twice present world energy consumption.  A satisfactory analysis would show numerically how various plausible conservation and conversion steps might reduce the amounts of energy needed by the industrial, transport etc. sectors feeding into this total, and then consider how renewables might enable achievement of the resulting target. Had a more appropriate target been taken the amount of plant required and the associated capital costs would have been significantly higher than those Jacobson and Delucci arrive at (for this reason alone, and others are added below.)

Trainer (2010a) derives a budget for a renewable energy capable of meeting 2050 world demand in mid-winter, and estimates that annual investment would have to be much greater than $5 trillion p.a.  The exercise did not take into account three factors that would markedly increase the required investment sum.  Firstly, no provision was attempted to deal with the variability of renewable energy sources, and had this been done the plant and capital conclusion arrived at would have been markedly higher.  That is, the contributions from renewables were based on monthly average wind speeds and solar radiation levels, whereas a more realistic analysis would have focused on the plant needed to cope with minimum wind and radiation occurrences.  Secondly, no provision was made for meeting peak demand; the supply target assumed was the annual average demand.  As has been noted, the need to cope with peak demand can require building 1.5 or more times the amount of plant needed to meet average demand. Thirdly the exercise did not take into account the cost of capital, which could double the investment figure arrived at when all other factors have been accounted.

It should also be noted that the supply target Jacobson and Delucci take would provide the world’s likely 2050 population with only around 45 GJ per person, which is only about 16% of the present Australian per capita energy consumption.  If their claim for renewable energy is that it can provide present rich world energy consumption levels to all people then the figures for plant and capital costs would be some 7 times the sum associated with their supply goal.

Unless the assumptions and/or derivations underlying the estimates above and in Trainer 2010a are significantly mistaken, it would seem to be impossibly costly to provide all people with present or anticipated rich world energy-intensive “living standards” via renewable energy.

Policy Implications?

The foregoing analysis has not been an argument against attempting to transition to full reliance on renewable energy sources.  Trainer (2010c, 2011) argues that such a transition should be undertaken as quickly as possible and that renewables can enable a satisfactory quality of life for all, but not in energy-intensive consumer-capitalist societies. 

The general “limits to growth” analysis of the global predicament identifies energy as only one of several accelerating problems that are insoluble unless the fundamental commitments of such societies to affluent “living standards” and economic growth are abandoned.  The above two sources detail the case that a radically different “Simpler Way” could be viable and attractive.  This vision embraces frugal lifestyles, small and highly self-sufficient local economies, and participatory and cooperative ways in an overall economy that is not driven by growth or market forces could be viable and attractive.  However the general failure to consider such an option is reinforced by analyses such as that of Jacobson and Delucci which appear to show that present energy-intensive consumer-capitalist societies can be sustained by renewable energy sources.

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