Remote solar PV vs small nuclear reactor – electricity cost comparison

It is often claimed that small-scale renewable energy, such as solar photovoltaic panel arrays, will fill an important future energy niche by providing much-needed electricity to developing nations and other remote regions (such as the outback of Australia). That’s a seemingly reasonable argument, but how do the numbers stack up? Below, Gene Preston (SCGI member) provides some easy-to-follow calculations (currency is in US dollars/cents). The results might surprise many:

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A friend of mine at the University of Texas and I were talking about his desire to develop a presentation for educators in Africa to use in estimating energy costs. He has just 3 hours for his presentation. He wants the teachers to be able to do the economics calculations themselves. I suggested he narrow down the discussion to just a comparison of solar versus small scale nuclear. Here’s what I came up with:

Solar – Lets go low tech with fixed solar panels. The cost is $8/watt (W) and runs about 14% of the time (its capacity factor). You will need energy storage, which costs $1/W + $.4/Wh (that is, 40c per watt hour**).

Lets say that we develop a solar system to serve a 5 kW peak load with an average load of 1 kW. The daily energy demand will be 24 kWh and peak load is 5 kW. This could be a few houses or a small school with some PCs. To produce the average amount of energy needed will require 1/.14 = 7.14 kW, so lets say 8 kW just to put in a little extra energy production factor. The 8 kW will cost $8/W (for 8000 W) = $64000. The energy storage system will cost $1/W (5000) = $5000 for the electronics and switchgear plus $.4/Wh (24000) = $9600 for one day’s energy usage. I would double this and install two days of storage just to be safe, which would cost $19,200.

Therefore the cost of the 5 kW peak demand solar system is:

$64000 for the panels (only half this cost is the PV array)

$5000 for the storage system electronics

$19200 for the batteries (2 days storage)

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$88000 for the entire system. (see what I mean about this being a rich person’s energy source?)

Let’s calculate the cents per kWh energy cost. Assume a loan at 6% annual interest rate to pay for it. Assume the system has a 20 year life.

A = PW [(i)(1+i)^n] / [(1+i)^n-1] where A is the annual payment, PW is the present cost of the system, i is the interest rate of .06, and n=20 years.

Then A = (88000)(.06)(1.06)^20 / [1.06^20 - 1] = .08718 (88000) = $7672.24 annually.

The energy produced annually is 24 kWh/day (365 days/y) = 8760 kWh. The cost per kWh = 767,224 cents per year / 8760 kWh per year = 87.6 cents per kWh. (first wow — that’s expensive!)

What about if we instead generated this energy from small nuclear reactors? First, some examples/references:

The Pebble Bed Modular Reactor would have been in South Africa but there is local opposition

This is an interesting discussion of micro reactors, especially the Russian Navy’s design

This information paper from the World Nuclear Association shows the huge number of small-scale reactor technologies being considered

Here is an IEEE paper on small nuclear (2, 5, 10 and 20 MW reactors)

The objective of many of the above references is to get the nuclear power cost down to about 10 cents per kWh. Suppose we could buy into nuclear at $5000 per kW (that’s the estimated cost of the Babock & Wilcox small nuclear plant [called 'mPower'], for a 125 MWe plant). The 1 kW of nuclear power portion of the small plant would run all the time so one kW would have an average energy based on the calculations for the solar plant. All we have to do is replace the $88000 with $5000 in the previous “A =” calculation.

Therefore the small nuclear program energy cost is .08718 (5000) (100) / 8760 = 5 cents per kWh. (second wow — that’s low cost!)

However we will need some peaking power to get 5 kW peak load. We can use the battery storage system to get the peaking power. We only need 4 kW since we will have the 1 kW nuclear running all the time. Also, the energy storage need only be about 4 hours at the most at 4 kW (conservatively). The peaking power using nuclear energy is $4000 for electronics + .4 (16000) for batteries = $10,400. Note that the peaking power system costs twice as much as the base load nuclear generation. The total cost is about $15,000 and the energy cost is about 15 cents per kWh.

This small nuclear + peaking system is only about 18% the cost of the solar + storage system.

This is an example of how anyone can, fairly easily, go through the economics calculations for solar and nuclear. Such an exercise would probably an eye opener for them, and dispel the myth that solar is ‘free energy’ or even a cheap source of power. But how are they to afford any type of power plant if they do not have industries that need power and produce income for them?

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**This estimate is based on presentations given by Xtreme Power Inc.

Solar thermal questions

To round out the controversial critique of solar power started here, I reproduce below the most detailed critical analysis I’ve read on solar thermal electricity. It’s written by a University of NSW academic, Ted Trainer. I’d strongly encourage you to read his full 44-page set of arguments on the inability of renewable energy to sustain an energy intensive society (an earlier version of which was reviewed last year on BNC — this provides an updated summary of his 2007 peer-reviewed book on this topic, published by Springer).

For context Ted and I agree on many things, but not all. We both acknowledge the seriousness of the climate crisis and the magnitude of the sustainability problems caused by humanity’s overexploitation of natural environments. We differ in that Trainer sees only one viable solution — a rapid, planet-wide ‘power down’ of civilisation to some ’simpler way’ (read here for his well-mapped-out thesis).

In the past year Tom Blees and I have exchanged a number of emails with Ted, in which we’ve talked about Generation IV nuclear power (IFR in particular), proposing it as a potential ‘uranium-thorium bullet’ to solve the energy crisis — and, as a result, providing the clean energy to solve a whole host of global problems such as climate change, water supply, agricultural sustainability and repairing the damage we’ve inflicted on natural systems. To his credit, Ted has looked at my arguments seriously, and has come up with a range of questions on Gen IV nuclear on which he requires ‘clear and convincing information’. As such, in a future post on BNC, I intend to address his nuclear critiques. But that’ s for another day.

The examination of solar thermal electricity given below is quite detailed, yet necessarily incomplete. Reliable data are simply lacking on many critical points. At the foot of this post, I list some key knowledge gaps on which Ted seeks further data. Perhaps you can help. For now, read on!

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SOLAR THERMAL ELECTRICITY (for the reference list, see here)

Ted Trainer

The major drawback for renewable energy is the inability to store electricity from intermittent sources.  Solar thermal technologies are especially valuable because they can store heat and use it to generate electricity when it is needed.  Some believe this capacity will be the key to enable renewable energy sources to meet all electricity needs (e.g., Trieb, undated, Czisch, 2004), for example plugging gaps left by PV and wind.

Solar thermal systems are best suited to the hottest regions and it is not clear how far into the mid latitudes they can be effective, apart from via very long transmission lines.  They seem to be especially doubtful in winter, even in the best locations.  (For a more detailed discussion of solar thermal’s limits and potential see Trainer, 2008.). Trough systems will be considered first, then dishes.

Troughs

The winter electrical output for the US SEGS VI trough system is reported at about 20% of summer output. (NREL, personal communication.) Modelling for Central Australia, possibly the best solar thermal location in the world, by Odeh, Behnia and Morrison (2003) produces a figure closer to 12%.

The SEGS VI plant with its north-south troughs was not designed to maximise winter performance.  Arranging the troughs on an east-west axis, as distinct from the usual north-south axis, would raise the winter/summer ratio for energy entering a trough. (“Polar axis” alignment of troughs enables maximum energy yield, but is not feasible for large scale power generation.)  However even in good solar thermal regions the performance of east-west troughs in winter (and summer) is relatively low, compared with the summer and annual average performance of north-south troughs.  This is evident in Figure 1 from Odeh, Behmia and Morrison.  Summer thermal energy (not electrical output) entering a NS trough at Alice Springs would be 780 MJ/m/month, (in this document  “m” represents square metre) whereas in winter from and EW trough it would be 430 MJ/m/month, or 4 kWh/m/day.

The radiation data given by RREDC (undated), Meteonorm and ASRDHB, 2005,  point to the same general conclusion.  These sources indicate that Alice Springs is a better location than Egypt, receiving possibly 50% more solar energy per metre in winter.  It also seems to be a little better than the SW US.  Thus if solar thermal technologies are problematic in winter at Alice Springs they are not likely to be viable in the US or for Europe.

A critical problem for solar thermal systems is what proportion of collected heat is above the threshold level required for generation of sufficient steam pressure.  In regions where radiation is low to moderate, considerable heat energy could be collected without enabling generation of a significant amount of electricity.  For SEGS VI radiation appears to have to reach 700 W/m (DNI or direct normal irradiation, not global radiation) before generation becomes moderate, and at 500 W/m it is only about 33% of maximum.  (NREL, undated, Jones, et al., 2003, Figs. 5 and 14.) Thus if east-west trough collects 4 kWh/m/d, as Fig. 1 from Odeh, Behnia and Morrison indicates, not all of it will be at a sufficient intensity to generate electricity.

ASRDHB data show that for Alice Springs in winter the intensity of DNI per square metre entering an east-west trough averages only 408 W/m, over a 12 hour period.  It is over 700 W/m for about 7 hours.  Fig 3 from Odeh, Behnia and Morrison shows that at Alice Springs 26% of DNI received over a year is under 500 W/m and 18% under 350 W/m.  These figures suggest that the 4 kWh/m/d entering the trough is a misleading indication of electricity likely to be generated and that the actual output could be less than half this amount.

More direct evidence comes from the SEGS VI record.  Hayden (2004, p. 190 .) reports that the 2.3 million square metres of collectors average 77 MW over a year, which corresponds to a continuous flow of 33 W/m.  The above evidence is that winter performance is about 30% of the average performance, which is a solar to electricity efficiency of 10.7%.  This suggests that the winter figure would be a 24 hour average c.13 W/m.

From this very low gross output a number of factors must be deducted, the main two being the energy required to build and run the plant.  The latter energy losses, mostly for pumping fluid through the absorber, are given by Sargent and Lundy (2003, Section 4 – 3) at 17% p.a., although they estimate that in future the figure will be under 10%.

The embodied energy cost, i.e., the amount of energy needed to build the power plant, is reported by Dey and Lenzen at c. 4% of gross output for a plant of normal size in normal conditions.  However a plant capable of delivering 1000 MW in winter would have to be 2.5 times as large as one capable of this output as an annual average, so its embodied energy cost would be that much higher.

(It would then generate much more than 1000 MW in summer and the ratio of embodied cost to total output would remain c. 4%, but a problem would then be that summer output would be far in excess of demand. On problems in storing such a surplus as hydrogen see below.)

The embodied energy cost analysis of solar thermal systems must also take into account the energy cost of building and maintaining the long distance transmission lines, e.g., from North Africa to North West Europe and of transforming from DC to AC power.  The lines might add one-third to power plant dollar cost.  (Czisch, 2004.)

The loss of energy from solar thermal storage is low but has been estimated by Sargent and Lundy as .9%.

Finally, the loss of energy in the very long distance transmission has to be taken into account, e.g., from Egypt to NW Europe.  This could be 15% of gross output.

Some of these numbers are uncertain but when combined they indicate that the total energy loss might be 35% of the meagre gross output, meaning that a net delivered amount well under 10 W/m might reach users in winter.  If so plant capable of delivering 1000 MW in winter would need 100+ million square metres of collection area.  At the estimated SEGS cost of $800/m (i.e., per square metre, not per kW)) the plant would cost $80 billion. (Trainer 2008

More confident data on trough performance in winter would be desirable here, but troughs would not seem to be viable.  (Heydon’s account comes to a similar conclusion.)  Note that the vision of abundant winter supply to Europe via troughs would involve harvesting radiation at about 55 degrees from the vertical.

Dollar costs.

Sargent and Lundy (2003) put the capital cost of solar thermal plant at $(US)4,589/kW ($(A6,556) for the “near term future” (including heat storage, which reduces required generator capacity and cost, by enabling the generation rate to be levelled out.)  NREL say the 2003 equivalent price of the SEGS plant is $(US)7,700.  These figures are to be compared with $(A)3,700 million for coal plant plus fuel (early 2000s price) over plant lifetime.  These figures are for peak outputs and the average output from a coal plant is c. .8 of peak whereas for a solar thermal plant it is around .25 of peak capacity (in the best locations).  Thus capital cost per gross kW delivered on average (as distinct from peak) from solar thermal plant would be over 7.5 times as great as for coal including fuel.  (See Trainer, 2007, Chapter 3.)  Transmission lines from the Sahara to Europe under the Mediterranean Sea would probably add more than 33% of generating plant capital costs. (Czisch, 2001, 2004) indicating a multiple of 10.  Note that these figures are not for plant large enough to deliver well in winter and for SEGS VI this factor might multiply by a further 2.5.  Note also that dish costs are at presently much higher than trough costs.

Again future materials, energy and construction costs are likely to be far higher than at present so these figures are not very meaningful guides to future viability.

Water pre-heating.

A solar thermal plant near Sydney, NSW, some 34 degrees south, has been constructed to pre-heat water for a coal-fired power station. ( Mills, Le Lievre and Morrison, 2000.) This is sometimes taken to show that solar thermal systems are viable in the mid latitudes.  However this system delivers heat at about half the temperature required in coal-fired power stations, and therefore does not have to concentrate solar radiation intensely. The absorber is about 1 metre wide and therefore reflectors can be wide with little curvature.  Thus the capital cost is quite low.  These features indicate that this plant is not a good guide to the effectiveness or cost of solar thermal plant at this latitude that would generate electricity without augmenting fossil fuel power generation.  In a world that did not exceed safe greenhouse limits there could be few if any fossil fuel plants. Also the performance of the system falls markedly in winter as the above discussion would lead one to expect.

Dishes.

Dishes collect more energy in winter because they can be pointed directly at the sun, but there are two significant drawbacks.  Their dollar costs are reported as being 2 – 4.5 times those of troughs (Sandia, undated), although costs will surely fall considerably with further development and mass production.

The data I have been able to access indicates somewhat surprisingly low but useful winter output from dish–Stirling devices.  Some US dishes seem to have an average 24 hour flow equivalent of around 20 – 30 W/m (Davenport, 2008.)  An output plot for the Mod dish-Stirling device shows that the January average flow (averaged over 24 hours) was c. 18 W/m, and for December, 22 W/m.  Commonly published power curves show that at 700W/m output falls to around half peak output.

However this is not very relevant to our problem.  If solar thermal systems are to provide electricity 24 hours a day, and also to solve the general intermittency problem set by other renewables, then heat must be stored.  This means that the efficiencies will be much lower than those represented in the literature on dishes, which almost entirely deals with the direct generation of electricity via dish-Stirling systems. Dishes are not well suited to large scale heat collection.

Trough systems transfer heat long distances to the power block mostly through the absorber pipes, which are heated as they collect radiation (nevertheless 4% is lost, according to Sargent and Lundy, 2003).  With a dish system this would not be so and either very long pipe distances would have to be insulated and would still lose much heat energy or many small generators would have to be located close to groups of dishes. (The equivalent of a 1000 MW plant in winter would involve tens of thousands of big dishes; below.)  For these reasons the European and US dish developers I have contacted regard the use of dishes to collect heat as not being viable. (Personal communications.)

Kenaff’s pioneering work at White Cliffs, Australia on dish-steam generation (without storage) achieved 9.1% annual solar to electricity efficiency.  The ANU Big Dish has a 13.9% efficiency, which it is expected can rise to 19% in future.  (Note that this is  a measure at a point in time under ideal conditions, not a measure of recorded annual average performance; which would be considerably lower, e.g., because of dust build up, warm up delay after cloud, etc. and winter performance.)  I do not have figures on the winter performance of either system.  If we assume 5 kWh/m/d radiation, the White Cliffs 15% loss of heat between collector and engine room, the 19% heat to electricity generation efficiency Lovegrove expects, and an 8% energy cost for pumping (the trough figure), then output might correspond to a gross 31 W/m 24 hour average flow.   However this assumes 1000/m radiation and in winter radiation barely rises above 700 W/m, which for dish-Stirling generators cuts output in half. Again Kenaff’s evidence is that steam generation is significantly affected by lower DNI. (See Trainer 2008 for more detail.)  Very important is the fact that the White Cliffs system involved only 14 rather small dishes and thus a very short distance for heat to be moved to the engine room, and the Big Dish is a single unit close to its steam generator. For the equivalent of a 1000 MW plant very long distances would be involved (or many small power blocks.).  Thus it is not possible with this information to estimate a winter average net output after heat storage, but it would seem likely to be well below 30 W/m.

The heat storage strategy using dishes which looks most viable is that being developed by the ANU group, involving the use of ammonia dissociation as a means of heat storage (Lovegrove et al, 2004).  Perhaps its main advantage is that no insulation is required, so heat would not be lost from the storage pipes or tanks.  (The energy is stored chemically, in the splitting of ammonia into hydrogen and nitrogen.)  This system is being built into a commercial plant at Wyhalla, South Australia.   It is estimated that half the energy entering the dish might be available for generating after storage by this means. (Wizard Power personal communications.)

The designers cannot predict performance confidently at this stage (personal communications), and understandably will not make the technical information they do have available.  It would seem from above that if Big Dish efficiency can be raised to 19% then after storage at 70% efficiency, then can overall efficiency of 1.3.% could be achieved.  Gross winter output in Central Australia then might correspond to the region of 28 W/m continuous 24 hour flow. (At present Big Dish efficiency the figure would be 19.8 W/m/.)

Several factors would reduce this gross figure, including the effect of warm up delays after the passage of cloud, operating energy costs, energy embodied in the construction of the dish and the long trans mission lines (“emergy”), energy losses in those lines, and especially the embodied energy cost of the ammonia processing plant (including the reactors in the dishes which dissociate the ammonia, and the one in the power block that recombines it.).  The emergy implications of the ammonia processing plant are difficult to assess, and could be problematic.  The attempt sketched in Trainer 2008 suggests supply from a 1000 MW plant, taking the most favourable of the estimates for storage volume received (17 litres per kg of ammonia, and 4 MJ/kg), might require some 2,800 km of one metre diameter gas pipe, the intended containment vessel.

Also a concern is the fact that big dishes (Whyalla will use 500 square metre dishes) involve disproportionately higher materials and energy costs for structures, foundations and drive equipment, in view of the higher wind stresses they will have to cope with.  An uncertain estimate based on the materials in the ANU Big Dish indicates an embodied energy cost three times that of troughs, i.e., in the region of 13% of plant lifetime output.  (Trainer 2008.)  However the developers believe other advantages of big dishes outweigh these factors, although I do not know whether this is only a dollar cost calculation or one focused on embodied energy costs.  There is a high probability that in future the cost of materials and construction will be far higher than they are now.

These figures suggest that a solar thermal ammonia storage system will be capable of low but significant/useful net output in winter. From above, net energy delivered to distant users would seem likely to correspond to around 20+ W/m of collection area (not  plant area including space between dishes). However it is not clear that the very large numbers that would be required could be afforded.  On the above estimates a plant capable of delivering 1000 MW in winter might have to include up to 50,000 big dishes each of 400 square metres.  These would probably have to be spread over an 11+km x 11+ km area.   Just to connect the dishes to the power block would probably require some 2,800 km of pipe, although it would not have to be insulated.  This seems to be about the length needed for storage above, but easily overlooked is the need for the same length of pipe to carry the recombined ammonia back to the dishes from the power block. Having many small plants rather than one big 1000 MW plant would not alter the overall ratio of pipe length per kW output.  The total 5,600 km of steel pipe capable of taking 15mPa pressure might weigh 280,000 tonnes and have an embodied energy cost of 11.2 PJ.  This is around 45% of the annual output of a 1000 MW power station (assuming .8 capacity), so the embodied energy cost of the pipe alone might add 2.2% of lifetime output to the total embodied energy cost figure.

Also of concern is the fact that if net delivered output corresponded to a say 25 W/m flow in winter, then it would take 46 metres of dish collection area to sustain one person at the Australian average electricity consumption rate, meaning that the ANU Big Dish would provide for only 8+ people.

Direct hydrogen production.

It is possible to produce hydrogen by splitting water at high temperature, around 800 degrees, and a practical application of solar thermal to this strategy is being discussed. (Taylor, Davenport and T-Raissi, 2008 )  A theoretical 40% solar to hydrogen efficiency is thought to be achievable. If this becomes viable it would probably be the best option, although it would involve the usual problems in large scale handling of hydrogen. These include pipe embrittlement, leaks, and the very low energy density meaning either very large storage volumes and/or high compression. Especially problematic are the energy losses in long distance transport.  Bossell estimates that to pipe hydrogen from North Africa to Western Europe could require more than half the energy despatched from Africa. Ideal solar thermal sites are a long way from demand.

A system designed to deliver 1000 MW after storage would need a 1000 MW hydrogen-fuelled power station in addition to the dish system which generated the 1000 MW supply of hydrogen to run it, indicating high capital and embodied costs.  The efficiencies of the various steps (e.g., .4 for hydrogen production, .8 for handling/transport, .4 for fuel cell generation) suggest an overall gross solar to wheels/use efficiency of 13%, from which the embodied and operating costs of materials-expensive hydrogen handling plant would have to be deducted.  It is therefore not clear that this path would be more viable than the others considered above.

The intermittency problem.

The heat storage capacity of solar thermal systems overcomes some of the intermittency problems that trouble wind and PV systems, such as the occurrence of night time.  The standard provision will be 12 hour storage enabling continuous 24 hour electricity delivery.  However examination of climate data reveals that even at the best sites sequences of 4 or more days without sunshine are not unusual.  The best US sites often have 2 runs of 4 consecutive days of cloud in a winter month. (Davenport, 2008)

If 1000 MW(e) output was to be provided for four cloudy day from stored heat, some 290,000MWh of heat would have to be stored. Storage cost has been estimated at $(A)10/kWh(th) meaning that the required storage plant would cost more than $8 billion, or around twice the cost of a coal-fired plant plus fuel.  However this refers to trough technology and it is likely that for the ammonia process costs would be higher.

Again we would be faced with the prospect of very high capital costs for a large amount of plant that would not be used most of the time, and would still be insufficient occasionally.  There would also be the question of whether there would be enough solar radiation in winter to meet daily demand and also recharge a large storage sufficiently to cope with the next run off 4 cloudy days.

The climate evidence given in Trainer 2008 seems to show that solar thermal systems even at the best locations would suffer a significant intermittency problem, despite their capacity to store energy.

Another problem is that if solar thermal plants are to help buffer the intermittency of inputs from other renewable sources then a major cost saving often claimed for solar thermal systems would not be available.  The ability to store heat from peak mid day collection and generate with it at a much lower constant rate, perhaps .2 of peak capacity, means that much smaller and cheaper generators can be used, perhaps one fifth of the capacity that would be needed to use heat energy at the mid day rate of collection. The power block can make up around half of a solar thermal system’s cost so the saving in capital costs, energy costs and operations and management is considerable.  However if the solar thermal component of a renewable supply system must at times plug gaps left by variable wind and sun, then there will be times when it must meet almost all demand and so its individual stations must often be cable of generating at much greater than average rate.

There would also be a problem regarding the need for solar thermal plant to rapidly ramp up to high levels of output, in order to meet most of the demand when sun and wind energies fall suddenly.  Thermal generators can’t be brought up to full output quickly.

It is sometimes assumed that solar thermal systems will enable the gaps left b y other renewable sources to be smoothed out, by use of solar thermal heat storage capacity.    For this to be plausible storage capacity would have to be extremely large.  The following figures seem to show that this proposal is not viable.

If the solar thermal system was to average .3 of total electricity supply yet  had the storage capacity to meet total electricity demand through 4 calm and cloudy days, then its storage capacity would have to be 24 times as great as for 12 hour storage.  In addition its collecting capacity would have to be considerably greater then that required for average output, in order to accumulate such a reserve.

This evidence seems to mean that there is no chance that the capacity of solar thermal systems to store energy could overcome the problem of gaps left by combining the output from the other renewable energy sources, as some have hoped.

Solar thermal conclusions?

The climate data seems to show that despite their storage capacity solar thermal systems would suffer a significant intermittency problem and in winter would either need storage capacity for four or more cloudy day sequences once or twice each winter month, or would need back up from some other sources.  This means they could not be expected to buffer the intermittency of other components in a fully renewable system.

It seems that troughs suffer a big drop in output in winter, that dish-steam systems cannot operate well enough on stored heat and that hydrogen generating systems are too handicapped by the usual difficulties associated with hydrogen.  The prospects for satisfactory winter supply of electricity from solar thermal systems therefore seem to depend on whether or not the dish-ammonia system will be viable on a large scale, and capable of overcoming intermittency problems.  The unsatisfactory information available suggests that they will be significant contributors but are not likely to make possible reliable winter electricty supply at a tolerable cost, that they will suffer a significant intermittency problem, and that they cannot be a solution to the integration problems left by other renewables.

The dumping and additivity problems (for technosolar in general)

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 consider 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 x (total demand). So even if the non-renewable components in the system can 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 dramatic effect on the system’s average capacity measured in terms of energy actually used. (Storing as hydrogen and regenerating via fuel cells might yield no net electrical energy when system operating and embodied energy costs are deducted from the perhaps 25% of energy available after conversion, storage and retrieval.)

Stern’s Fig. 9.4 shows that this dumping problem has not been taken into account. Total demand is divided into components reflecting averaged or annual contributions with no consideration of what would happen when some or all are performing at their peak capacity rather than at average capacity.

The variability between summer and winter would more or less double the magnitude of this problem for solar sources, given that in good solar regions winter insolation is about half the summer value. (The multiple is greater in the lower latitudes.) Thus a PV system designed to meet 30% of demand in winter might meet 60% of it in summer. The effect would be offset to some extent by the fact that winds tend to be higher in winter. However with daily variability the effects compound rather than compensate; i.e., at night when there is no solar input winds tend to be lower.

Renewables are not additive

Renewable energy sources are usually thought of as additive, that is, as if building X GW of wind capacity and X GW of PV capacity would give us 2X GW of generating capacity. However on calm nights these two sources would give us no generating capacity at all. Thus they are best thought of as sources which at times can be alternated with or substituted for coal fired power, but not as sources which can always be added to each other. (Stern’s Fig. 9.4 reveals that the various components are being thought of as additive.) This means that we might have three or more very expensive systems each capable of more or less meeting demand while the others sit idle, and in addition we must retain a coal or nuclear system capable of meeting most or all demand when most or all the renewables are down.

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Questions that arise: (from a recent email to me by Ted)

1. How viable is storing heat from dishes? My European contact says not worth it. There would be long distance piping from tens of thousands of big dishes for a 1000MW power station, and thus large heat loss. With troughs heat moves through heated absorbers most of the way.

2. Where can we get performance data, for the different ST types, for every day of the year, along with solar radiation data for the sites in question?

3. What is the embodied energy cost of the ST types; Lenzen and Dey say 4% for troughs, but my attempts to check this are unsatisfactory, and it seems that for dishes the cost would be much higher (Derived from big dish materials inventory.)

4. Analysis is required of climate data for Eastern Sahara, SW US, and Central Australia, especially actual daily pattern of radiation (ideally pattern of hourly radiation every day.)

Another issue that require resolution concerns the angle between sun and reflector (the ‘cos‘ problem). With dishes this is no problem ever because you can point them at the sun anytime, so  I have tried (in the above) to deal with dishes mainly, because if that’s problematic then towers and troughs are out…because they do have an intractable cos problem, especially severe in winter even in the best regions. Troughs it seems just can’t do it, as performance goes down to 20%- of summer output in winter in the US good sites. Towers (CR) are of course good for storage, but I’m assuming their cos problem is serious. It would be great to get some actual data on their year round performance. I have found it fiendishly difficult to get such data out of anyone; they seem not to want to make it public, and this makes evaluation of claims very difficult.

Another problem is that if heat loss is 1% over a 12 hr period, which is what Sargent and Lundy seem to say, then over a 4 day period this is 8%, so would have to be added to other factors detracting from overall ER and dollar cost situation. BOM is where to go for climate data (in Australia) and I have put some time into this. I could get more detailed information than I have but what I have indicates that there is a problem with sequences of cloudy days in winter, even in Central Australia. US seems much worse. Can’t get much confident data on North Africa, which is what ST electricity for Europe would depend on. Note a problem is time taken for systems to come back up to output after “transients”; i.e., passage of cloud. Can be significant I believe, and thus average radiation per day could be misleading; if this is made up of a lot of passing cloud and sun you might not total much time on full output.

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If anyone can help Ted source relevant information on the above (or if you have insider information, email him), I’m sure he’d greatly appreciate it.

Climate Denial Crock

In a recent post, I directed readers to a couple of excellent information websites, which are designed explicitly to answer/rebutt all of the common ‘arguments’ (for want of a better word) that are recycled by climate change pseudo-sceptics. Those two websites, Global Warming Debate and Skeptical Science, along with other excellent anti-denial sites like Deltoid and Greenfyre’s (which deal with the day-to-day lunacy that crops up in the newspapers and blogosphere), serve this ongoing need very well. But they do require one to take the time to read a lot of stuff, and let’s face it, there is such a morass of reading material thrust at us each and every day, that it can be easy to ’switch off’.

As a way of adding diversity to your climate and energy education, I’ve already pointed to some useful multimedia sources for understanding more about fast reactor nuclear power. This post is to alert you to a similar non-textual resource which tackles the recycled pseudo-sceptical arguments head-on. It’s called ‘Climate Denial Crock of the Week‘, produced by Peter Sinclair (aka ‘greenman3610′).

This is an expanding series of ‘documentary’ videos posted on YouTube, underpinned by excellent production values, and narrated with a dash of humour to keep the material interesting. Each weekly ’smashing of the crockery’ lasts about 5 to 10 minutes, so it’s not a huge time committment to follow this, week in, week out. It’s definitely worth the bandwidth — Sinclair manages to pack a whole lot of useful and accurate information into each video. All in all, it’s a really superb resource and I applaud his ongoing effort.

So far, the following 13 episodes have been posted (listed below in so particular order — you can watch them in any sequence) — the blurbs after the title are by the producer:

Solar Schmolar — A favorite hobby horse of Climate Denialists is that there is some kind of invisible, undetectable influence from the sun that is responsible for the unequivocal warming of the last century. Let’s put that crock under a microscope and see where the cracks are.

Ice Area and Volume –Denialists continually try to confuse the issue of northern polar ice caps. Here are the facts from the National Snow and Ice Data Center.

Party like it’s 1998 – One of the enduring classics of denialism, “Global warming stopped in 1998″, is of course, nonsense. Here’s why.

It’s Cold. So there’s no Climate Change – ”I looked outside, and it was snowing, therefore, there is no climate change.” If that’s what passes for rational thought in your social group, you owe it to yourself to watch this edition of Climate Denial Crock of the Week.

The Scoop on Southern Polar Ice — Don’t back down from the watercooler wars. Climate Denial Crock of the Week shoots down the brainless, Rush Limbaugh factoids of global climate denial. Keep coming back each week for more real science on climate change, and send me your suggestions for climate crocks to crush.

Mars Attacks! – It seems to be agreed among deniers, that there is a warming happening on other planets in the solar system. And not just one or two planets. It is considered climate denier gospel that all the other planets are warming, and that this is proof that some kind of solar activity is warming the whole system. Let’s look at the evidence.

The ‘Temp leads Carbon” Crock –Find out what a straw man argument is, and how the most spectacular cherry pick in the history of scientific argument is just part of a day’s work for the professional deniers.

All Wet on Sea Level Rise – Sea level rise will be one of the most destructive effects of climate change, so naturally, Deniers have something grossly in error to say about it. We’ll look, as always, at the source documents.

The Medieval Warming Crock – The so called Medieval Warming Period is an article of faith among deniers. But what does the “Supreme Court of Science” say?

The Great Petition Fraud — We’ve all heard about the “Petitions” of “Scientists” who disagree with Climate Science. This sordid little episode in the history of climate denial points up once again the fundamental dishonesty of the climate denial industry.

I Love the ’70s!! – Everyone has a favorite decade, and for Climate deniers, that decade has got to be, the 70s. Yes, the decade of disco, kung fu, and watergate Because in the 70’s, Deniers will tell you, All climate scientists believed an ice age was coming. Those crazy climate scientists! Why can’t they make up their minds? But is that really true? Maybe a little historical perspective is in order.

That 1500 Year Thing — Climate Deniers S. Fred Singer and Dennis Avery make their living by confusing and obfuscating the science of climate change. Their latest book, “Unstoppable Global Warming every 1500 Years”, is a compendium of vintage as well as cutting edge climate crocks. Let’s find out who they are and how they are bamboozling their audience.

The “Urban Heat Island” Crock — Could the scientists at NASA, the National academy of science, the American Meteorological Society, and every professional scientific organization on the planet really have been so silly as to miss something this obvious?

Enjoy the Channel, and make sure you subscribe to the feed, so that you’ll always remember to get your weekly dose of climate crockery! I’ll also keep this post’s title listing updated as new vids are added.

A cooling story involving ozone, the sun and the sea

A note from the author Erl Happ, who is a Western Australian wine maker from Margaret River.  We can learn a lot about the behaviour of the Sun/ Earth system via an examination of historical temperature data. This little essay illustrates that point. It was first published at the blog I share with Carl Wolk at http://climatechange1.wordpress.com/

All data is presented as a 12 month moving average centered on the seventh month. Data sourced from: Kalnay, E. and Coauthors, 1996: The NCEP/NCAR Reanalysis 40-year Project. Bull. Amer. Meteor. Soc., 77, 437-471. at:

http://www.cdc.noaa.gov/cgi-bin/data/timeseries/timeseries1.pl

Figure 1 Response of lower stratosphere to ocean warming

When the tropical sea heats up evaporation is enhanced. Convection tends to carry moisture high up into the tropical atmosphere and some overshoots the tropopause into the stratosphere where it encounters ozone.

Ozone is soluble in water. In the commercial manufacture of ozone the air that is to carry the ozone is cooled to minus 80°C so as to dry it out and make it possible for that air to convey the ozone to the point of application, for example the empty wine barrel to be sanitized.

Ozone is a strong absorber of both UVB from the sun (or we would get more sunburn and more cancer) and also long wave radiation from the earth. The ozone molecule swiftly transfers the extra energy gained to the surrounding air and the temperature of that air increases. If however the ozone content of the air diminishes there is less heat imparted to the air and its temperature falls. So air that contains ozone can fall in temperature from two sources. The first is a reduction in radiation. The second is a reduction in ozone content.

Figure 1 demonstrates that increased evaporation in the tropics is accompanied by a fall in the temperature of the air in the lower stratosphere at 70hPa. This fall in the temperature of the air at 70hPa relates directly to the magnitude of the increase in sea surface temperature. The fall in temperature in the stratosphere at 70hPa is due to loss of ozone into water solution.

How far into the stratosphere does this effect extend?

Figure 2. Response of stratosphere to humidification and solar activity

Figure 2 shows that the fall/rise in the temperature of the air at 70hPa also occurs at 50hPa and 30hPa. This shows that the stratosphere is fairly well mixed, and relatively speedily so, despite the more sluggish convection (than in the troposphere) due to the temperature increase with elevation.

If the temperature of the air in the stratosphere falls as the surface warms (due to the evaporation humidifying the stratosphere) we would expect the temperature of the stratosphere to warm as the surface cools. That indeed is what has happened since 1998. I show the increase in stratospheric temperature with arrows. The increase is due to more ozone in the stratosphere as the tropical ocean has gradually cooled.

Now I want to draw the readers attention to what is going on at 10hPa when the surface warms. After 1978 when the sun became very active and tropical sea surface temperature jumped we can trace the episodic fall in temperature all the way from 70hPa to 10hPa. The paradox is that the micro-structure involves cooling during specific El Nino warming events but the macro-structure shows a general increase in 10hPa temperature due to a secular increase in ozone due to the impact of enhanced ionizing radiation on oxygen. If we examine the data closely we see that prior to 1978 a rise in 70 hPa temperature (due to enhanced ozone as the tropical sea surface episodically cools) is accompanied by a fall in 10hPa temperature due to diminished solar activity (less ionizing short wave radiation). This observation links the sun with surface temperature change.

If the macro-structure at 10hPa shows the impact of ionizing radiation on oxygen we can see from the curve that this particular macro warming event that began in 1978 is not yet over. We have some way to go before 10hPa temperature returns to the 1948 level.

Let’s move right along to an examination of temperature change in the atmosphere since 1948.

Figure 3 Temperature change in the lower troposphere

Figure 3 shows that in general the lower levels in the atmosphere have definitely warmed. Whatever the cause of this warming, and the analysis above suggests that it is entirely due to the sun, the atmosphere above 400 hPa is not storing warmth. Its temperature has not increased at all. Below 700hPa temperatures took off in 1978 and have not yet returned to base level. Above 700 hPa temperatures have returned to base level on many occasions, most recently in the year 2000. Why have temperatures below 700hpa not returned to base? I suggest that it is because these levels are too close to the great earthly store of warmth, the ocean.

In passing we note that the largest increase in temperature is not at the surface but at 850hPa (1 km) where water vapour condenses to form cloud. This is not a ‘greenhouse effect’ but is due to release of latent heat of condensation. The tropics tend to be heat saturated so more energy goes straight into evaporation. Water is the Earth’s refrigerant gas and the troposphere is the engine that drives the refrigeration mechanism.

Figure 4 Temperature change in the upper troposphere

Figure 4 shows the pattern of heating in the upper troposphere. Again we note the lack of any long term increase in temperature. At all levels the temperature has returned to base. However, between 200hPa and 100hpa the period of increased solar activity that is evident in 10hPa temperature in figure 2 manifests as a strong and sustained increase in temperature between the onset in 1978 and demise about 2006.

Those who have followed my discussions with Leif Svalgaard will know that he steadfastly maintains that 200hPa temperature simply reflects surface temperature and that the level of ozone in the troposphere below the tropopause (100hPa) is too slight to produce a thermal response to UVB. He is plainly incorrect. The surface is warmer today than in 1948 but 200hPa temperature is back to 1948 levels. Look again I say?

Above 500hPa the temperature of the air is below freezing point and clouds exist as micro crystalline ice with highly absorptive (infrared) and reflective (visible spectrum) properties. In the period of warming between 1978 and 1999 the ratio of ice cloud to droplet cloud changed because, while humidity fell continuously at all levels evaporation in the tropics and convection kept up the moisture supply to the upper troposphere and, as we have seen, the stratosphere. In this regime ice cloud becomes an ever more important constituent of the Earths armoury against solar radiation. When the temperature of the upper troposphere warms ice cloud evaporates and more sunlight gets to the ocean surface. This is the atmospheric dynamic that drives ENSO.

Take home messages:

1. There is a natural cycle that drives the concentration of ozone in the stratosphere. This is shown by the cooling at 70hPa as the tropical sea warms.
2. The influence of the sun is seen in the micro-structure and the macro-structure of temperature at all levels of the atmosphere above the 200hPa pressure level between 20°N and 20°S.
3. The atmosphere does not store warmth. Above 700hPa it has returned to base temperature after each warming episode between 1948 and 2008. It is the sea that stores warmth.
4. The rate of warming at 850hPa (1 km) is a good measure of the increased energy that the Earth receives from the sun over the course of time. It is here that the temperature has increased most since 1978. Temperature at 850hPa will only return to base when the tropical oceans themselves return to base temperature. This return seems to be in process but rest assured that warming and cooling events will continue to provide a secure topic for everyday conversation.
5. Cooling of the stratosphere is not due to greenhouse gas warming of the troposphere. There is no temperature change in the lower troposphere except very close to the warmer ocean. Cooling of the stratosphere is due to ozone loss associated with surface warming.
6. Ozone loss in the stratosphere is a natural consequence of sea surface warming.

Have you comprehended the argument? Here is a test.

Explain why 10hPa and 100hPa temperatures are in sync under high solar activity and out of sync at low solar activity as seen in figure 5 below.

Figure 5 Temperature change at 10hPa and 100hPa

Satellites Confirm Half-Century of West Antarctic Warming

The Antarctic Peninsula juts into the Southern Ocean, reaching farther north than any other part of the continent. The southernmost reach of global warming was believed to be limited to this narrow strip of land, while the rest of the continent was presumed to be cooling or stable.

Not so, according to a new analysis involving NASA data. In fact, the study has confirmed a trend suspected by some climate scientists.

“Everyone knows it has been warming on the Antarctic Peninsula, where there are lots of weather stations collecting data,” said Eric Steig, a climate researcher at the University of Washington in Seattle, and lead author of the study. “Our analysis told us that it is also warming in West Antarctica.”

Figure at right: Red represents areas where temperatures have increased the most during the last 50 years, particularly in West Antarctica, while dark blue represents areas with a lesser degree of warming. Temperature changes are measured in degrees Celsius. Credit: NASA/GSFC Scientific Visualization Studio > Print resolution image

The finding is the result of a novel combination of historical temperature data from ground-based weather stations and more recent data from satellites. Steig and colleagues used data from each record to fill in gaps in the other and to reconstruct a 50-year history of surface temperatures across Antarctica.

Over the years, climate research in northern latitudes led researchers to believe that the Arctic is where impacts of global climate change would be seen first. Less certain is how climate is affecting Antarctica where inland temperatures are known to plunge to -112°F, and ground-based weather stations have been sparse.

It’s this sparse data collection — from ground-stations on the Antarctic Peninsula and previous reports that much of East Antarctica has experienced cooling since 1978 — that led the International Panel on Climate Change to conclude in its most recent report that Antarctica is the one continent where we have failed to detect human-caused temperature changes.

With funding from the National Science Foundation’s Office of Polar Programs, Steig and colleagues set out to reconstruct Antarctica’s recent past. Ground-based stations have recorded temperatures since 1957, but most of those readings come from the peninsula and areas on the edges of the continent. But at the same time, scientists such as study co-author Joey Comiso of NASA’s Goddard Space Flight Center in Greenbelt, Md., have been gathering measurements from a series of Advanced Very High Resolution Radiometer (AVHRR) instruments deployed on satellites since 1981.

To construct the new 50-year temperature record, the team applied a statistical technique to estimate temperatures missing from ground-based observations. They calculated the relationship between overlapping satellite and ground-station measurements over the past 26 years. Next, they applied that correlation to ground measurements from 1957 to 1981 and calculated what the satellites would have observed.

The new analysis shows that Antarctic surface temperatures increased an average of 0.22°F (0.12°C) per decade between 1957 and 2006. That’s a rise of more than 1°F (0.5°C) in the last half century. West Antarctica warmed at a higher rate, rising 0.31°F (0.17°C) per decade. The results, published Jan. 22 in Nature, confirm earlier findings based on limited weather station data and ice cores.

While some areas of East Antarctica have been cooling in recent decades, the longer 50-year trend depicts that, on average, temperatures are rising across the continent.

Figure at right:The northern section of the Larsen B ice shelf, a large floating ice mass on the eastern side of the Antarctic Peninsula, shattered and separated from the continent on March 5, 2002, and represents a major impact that climate warming can have on the region. Credit: NASA Earth Observatory.

West Antarctica is particularly vulnerable to climate changes because its ice sheet is grounded below sea level and surrounded by floating ice shelves. If the West Antarctic ice sheet completely melted, global sea level would rise by 16 to 20 feet (5 to 6 meters).

To identify causes of the warming, the team turned to Drew Shindell of NASA’s Goddard Institute for Space Studies in New York, who has used computer models to identify mechanisms driving Antarctica’s enigmatic temperature trends.

Previously, researchers focused on Antarctic ozone depletion, which influences large-scale atmospheric fluctuations around the continent — most notably, the Southern Annular Mode, which speeds up wind flow to isolate and cool the continent.

Shindell compared Steig’s temperature data with results from a computer model that can simulate the response of the atmospheric system to changes in land surface, ice cover, sea surface temperatures, and atmospheric composition. He found the ozone-influenced Southern Annular Mode is not necessarily the primary influence on Antarctic climate. Instead, it appears that smaller-scale, regional changes in wind circulation are bringing warmer air and more moisture-laden storms to West Antarctica.

“We still believe ozone depletion can increase wind speeds around Antarctica, further isolating the interior,” Shindell said. “But it’s clear now that it’s not such a dominant influence on temperature trends.”

Reference

Steig, E.J., D.P. Schneider, S.D. Rutherford, M.E. Mann, J.C. Comiso, and D.T. Shindell, 2009: Warming of the Antarctic ice-sheet surface since the 1957 International Geophysical Year. Nature, 457, 459-462, doi:10.1038/nature07669.

Hansen to Obama Pt III – Fast nuclear reactors are integral

Nuclear energy? Pah! Too dangerous (risk of meltdown or weapons proliferation), too expensive, too slow to come on line, insufficient uranium reserves to power more than a small fraction of the world’s energy demand, blah di blah blah blah blah. There is certainly plenty of opposition out there to nuclear energy in any way, shape or form. Nuclear is bad news, it’s a distraction, it’s a carry over from the cold war, it’s old school thinking. And so on.

Well, the above is what the majority of environmentalists and pacifists would tell you. And there is some very solid reason for scepticism about the widespread use of nuclear power, especially Generation II nuclear fission reactors (I suggest we keep the ones we’ve got, but don’t bother with any more of them). But in the brave new world of the Sustainability Emergency (climate crisis + energy crisis + water crisis + mineral crisis + biodiversity crisis, etc.), we simply haven’t got time or scope for such hard-line negativity. We need every solution we can lay our hands on — and more for good measure.

Hansen is willing to talk about nuclear energy. I am too – given chronic intermittency issues with large-scale renewables and the need for plenty of extra energy to fix huge looming problems with hanging together a sophisticated civilisation on a habitable planet, it’s got to be in the mix. Indeed, in the long run, it, in the form of fusion power, could well be the only form of energy that matters to humanity (if we manage to get through the post-industrial crunch, that is). There are plenty of tantilising prospects for safe, effective, long-term baseload power from 4th+ generation nuclear fission power. But for now, there is just nowhere near enough action ($$ and willpower) on the R&D and roll out front.

Hansen explains this in part III. He also goes into more detail on this issue in his earlier Trip Report, which I also quote below…

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Tell Barack Obama the Truth – The Whole Truth (Part III of IV)

Dr James E. Hansen

Nuclear Power. Some discussion about nuclear power is needed. Fourth generation nuclear power has the potential to provide safe base-load electric power with negligible CO2 emissions.

There is about a million times more energy available in the nucleus, compared with the chemical energy of molecules exploited in fossil fuel burning. In today’s nuclear (fission) reactors neutrons cause a nucleus to fission, releasing energy as well as additional neutrons that sustain the reaction. The additional neutrons are ‘born’ with a great deal of energy and are called ‘fast’ neutrons. Further reactions are more likely if these neutrons are slowed by collisions with non-absorbing materials, thus becoming ‘thermal’ or slow neutrons.

All nuclear plants in the United States today are Light Water Reactors (LWRs), using ordinary water (as opposed to ‘heavy water’) to slow the neutrons and cool the reactor. Uranium is the fuel in all of these power plants. One basic problem with this approach is that more than 99% of the uranium fuel ends up ‘unburned’ (not fissioned). In addition to ‘throwing away’ most of the potential energy, the long-lived nuclear wastes (plutonium, americium, curium, etc.) require geologic isolation in repositories such as Yucca Mountain.

There are two compelling alternatives to address these issues, both of which will be needed in the future. The first is to build reactors that keep the neutrons ‘fast’ during the fission reactions. These fast reactors can completely burn the uranium. Moreover, they can burn existing long-lived nuclear waste, producing a small volume of waste with half-life of only sever decades, thus largely solving the nuclear waste problem. The other compelling alternative is to use thorium as the fuel in thermal reactors. Thorium can be used in ways that practically eliminate buildup of long-lived nuclear waste.

The United States chose the LWR development path in the 1950s for civilian nuclear power because research and development had already been done by the Navy, and it thus presented the shortest time-to-market of reactor concepts then under consideration. Little emphasis was given to the issues of nuclear waste. The situation today is very different. If nuclear energy is to be used widely to replace coal, in the United States and/or the developing world, issues of waste, safety, and proliferation become paramount.

Nuclear power plants being built today, or in advanced stages of planning, in the United States, Europe, China and other places, are just improved LWRs. They have simplified operations and added safety features, but they are still fundamentally the same type, produce copious nuclear waste, and continue to be costly. It seems likely that they will only permit nuclear power to continue to play a role comparable to that which it plays now.

Both fast and thorium reactors were discussed at our 3 November workshop. The Integral Fast Reactor (IFR) concept was developed at the Argonne National Laboratory and it has been built and tested at the Idaho National Laboratory. IFR keeps neutrons “fast” by using liquid sodium metal as a coolant instead of water. It also makes fuel processing easier by using a metallic solid fuel form. IFR can burn existing nuclear waste, making electrical power in the process. All fuel reprocessing is done within the reactor facility (hence the name “integral”) and many enhanced safety features are included and have been tested, such as the ability to shutdown safely under even severe accident scenarios.

The Liquid-Fluoride Thorium Reactor (LFTR) is a thorium reactor concept that uses a chemically-stable fluoride salt for the medium in which nuclear reactions take place. This fuel form yields flexibility of operation and eliminates the need to fabricate fuel elements. This feature solves most concerns that have prevented thorium from being used in solid fueled reactors. The fluid fuel in LFTR is also easy to process and to separate useful fission products, both stable and radioactive. LFTR also has the potential to destroy existing nuclear waste, albeit with less efficiency than in a fast reactor such as IFR.

Both IFR and LFTR operate at low pressure and high temperatures, unlike today’s LWR’s. Operation at low pressures alleviates much of the accident risk with LWR. Higher temperatures enable more of the reactor heat to be converted to electricity (40% in IFR, 50% in LFTR vs 35% in LWR). Both IFR and LFTR have the potential to be air-cooled and to use waste heat for desalinating water.

Both IFR and LFTR are 100-300 times more fuel efficient than LWRs. In addition to solving the nuclear waste problem, they can operate for several centuries using only uranium and thorium that has already been mined. Thus they eliminate the criticism that mining for nuclear fuel will use fossil fuels and add to the greenhouse effect.

The Obama campaign, properly in my opinion, opposed the Yucca Mountain nuclear repository. Indeed, there is a far more effective way to use the $25 billion collected from utilities over the past 40 years to deal with waste disposal. This fund should be used to develop fast reactors that eat nuclear waste and thorium reactors to prevent the creation of new long-lived nuclear waste. By law the federal government must take responsibility for existing spent nuclear fuel, so inaction is not an option. Accelerated development of fast and thorium reactors will allow the US to fulfill its obligations to dispose of the nuclear waste, and open up a source of carbon-free energy that can last centuries, even millennia.

The common presumption that 4th generation nuclear power will not be ready until 2030 is based on assumption of ‘business-as-usual”. Given high priority, this technology could be ready for deployment in the 2015-2020 time frame, thus contributing to the phase-out of coal plants. Even if the United States finds that it can satisfy its electrical energy needs via efficiency and renewable energies, 4th generation nuclear power is probably essential for China and India to achieve clear skies with carbon-free power.

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MORE by Hansen on the same topic, with some extra details and a book recommendation for further reading…

Trip Report – Nuclear Power

On one of my trips I read a draft of “Prescription for the Planet” by Tom Blees, which I highly recommend. Let me note two of its topics that are especially relevant to global warming. Blees makes a powerful case for 4th generation nuclear power, the Integral Fast Reactor (IFR). IFR reactors (a.k.a. fast or breeder reactors) eliminate moderating materials used in thermal reactors, allowing the neutrons to move faster. More energetic splitting of nuclei releases more neutrons. Instead of using up less than 1% of the fissionable material in the ore, a fast reactor burns practically all of the uranium. Primary claimed advantages are:

a) The fuel is recycled on-site, incorporating radioactive elements into new fuel rods. The eventual ‘ashes’ are not usable as fuel or weapons. The radioactive half-life of the ashes is short, their radioactivity becoming less than that of naturally occurring ore within a few hundred years. The volume of this waste is relatively small and can be stored easily either on-site or off-site.

b) The IFR can burn the nuclear ‘waste’ of current thermal reactors. So we have a supply of fuel that is better than free – we have been struggling with what to do with that ‘waste’ for years. We have enough fuel for IFR reactors to last several centuries without further uranium mining. So the argument that nuclear power uses a lot of fossil fuels during uranium mining becomes moot.

c) IFR design can be practically failsafe, relying on physical properties of reactor components to shut down in even the most adverse situations, thus avoiding coolant problems of Chernobyl and Three Mile Island, as well as the earthquake problem. The terrorist threat can be minimized by building the reactor below grade and covering it with reinforced concrete and earth.

Wait a minute! If it’s that good, why aren’t we doing it? Well, according to Blees, it’s because, in 1994, just when we were ready to build a demonstration plant, the Clinton Administration cancelled the IFR program. Blees offers a partial explanation, noting that Clinton had used the phrase “You’re pro-nuclear!” to demonize rivals during his campaign, suggesting that Clinton had a debt to the anti-nuclear people. Hmm. The matter warrants further investigation and discussion. It’s not as if we didn’t know about global warming in 1994.

Even more curious is the assertion that Argonne scientists, distraught about the cancellation, were told they could not talk about it (why do I find this easy to believe?). Here too there is no explanation in depth, although Blees notes that the Secretary of Energy, Hazel O.Leary, was previously a lobbyist for fossil fuel companies (my gosh, is everybody in Washington an ex-lobbyist – alligators will go extinct!).

I have always been agnostic on nuclear power. I like to hope that, if our next President gives high priority to a low-loss national electric grid, renewables will be able to take over most of the power generation load4. Wind and solar-thermal are poised to become big players. IEA’s estimate that renewables will only grow from 1% to 2% (by 2030!) can be dismissed due to IEA’s incestuous relation with fossil industries – nevertheless, one must have healthy skepticism about whether renewables can take over completely. Maybe an understatement – I’m not certain.

Blees argues that it made no sense to terminate research and development of 4th generation nuclear power. Was it thought that nuclear technology would be eliminated from Earth, and thus the world would become a safer place?? Not very plausible – as Blees points out, several other countries are building or making plans to build fast reactors. By opting out of the technology, the U.S. loses the ability to influence IFR standards and controls, with no realistic hope of getting the rest of the world to eschew breeder reactors. Blees suggests, probably rightly, that this was a political calculation for domestic purposes, a case of dangerous self-deception.

Bottom line: I can’t seem to agree fully with either the anti-nukes or Blees. Some of the anti-nukes are friends, concerned about climate change, and clearly good people. Yet I suspect that their ‘success’ (in blocking nuclear R&D) is actually making things more dangerous for all of us and for the planet. It seems that, instead of knee-jerk reaction against anything nuclear, we need hard-headed evaluation of how to get rid of long-lived nuclear waste and minimize dangers of proliferation and nuclear accidents. Fourth generation nuclear power seems to have the potential to solve the waste problem and minimize the others. In any case, we should not have bailed out of research on fast reactors. (BTW, Blees points out that coal-fired power plants are exposing the population to more than 100 times more radioactive material than nuclear power plants – some of it spewed out the smokestacks, but much of it in slag heaps of coal ash. See http://www.inthesetimes.com/article/3614/dirty_smoke_signals/ re the effect of this waste on Native Americans in the Southwest, as well as ‘Burning the Future’, above, re the Appalachians.)

I don’t agree with Blees’ dismissal of the conclusion of most energy experts that there is no ‘silver bullet’; they argue that we need a mix of technologies. Blees sees a ‘depleted uranium bullet’ that could easily provide all of our needs for electrical energy for hundreds of years. His argument is fine for pointing out that existing nuclear material contains an enormous amount of energy (if we extract it all, rather than leaving >99% in a very long-lived waste heap), but I still think that we need a range of energy sources. Renewable energies and nuclear power are compatible: they both need, or benefit from, a low-loss grid, as it is more acceptable to site nuclear plants away from population centers, and nuclear energy provides base-load power, complementing intermittent renewables.

BTW, nuclear plants being proposed for construction now in the U.S. are 3rd generation (the ones in operation are mostly 2nd generation). The 3rd generation reactors are simplified (fewer valves, pumps and tanks), but they are still thermal pressurized reactors that require (multiple) emergency cooling systems. France is about to replace its aging 2nd generation reactors with the European Pressurized Reactor (EPR); a prototype is now being built in Finland. According to Blees, OECD ranks EPR as the cheapest electric energy source, cheaper than pulverized coal – that evaluation doubtless presumes use of a standard design, a la the French procedure for its 2nd generation reactors. The prototype in Finland, according to reports, is running behind schedule and over budget – that was also true in the prior generation, yet the eventual standard French reactors have been economical. Current efforts to start construction of 3rd generation nuclear plants in the U.S., so far, do not seem to have achieved a standard design or to have avoided project delays (partly due to public opposition) that drive up costs.

Blees argues that the 4th generation technology basically exists, that the design will be simplified, especially due to the absence of a need for emergency cooling systems. He foresees a standard modular construction of the reactor per se, smaller than earlier generations, which can be built at the factory, shipped to the site, and dropped in the prepared excavation. His cost estimates have this nuclear power yielding cheaper electricity than any of the competition. The system is designed to eliminate long-lived nuclear ‘waste’ and minimize proliferation dangers. There is enough fuel available without further uranium mining to handle electricity needs for several centuries, for whatever fraction of electricity needs cannot be covered by renewable energies. If these claims are anywhere close to being correct, we could phase out use of fossil fuels for electricity generation over the next few decades.

I do not have the expertise or insight to evaluate the cost and technology readiness estimates. The overwhelming impression that I get, reinforced by the ‘boron’ topic below, is that Blees is a great optimist. But we need some good ideas and optimism. The book contains a lot of interesting insights and tidbits, e.g., there is more energy available in the nuclear material spewn out as waste by coal plants than the amount of energy produced by the coal burning. The book will be available in about a month; see his web site www.prescriptionfortheplanet.com

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Well, that’s sure to stir the pot. But he’s got a point, hasn’t he? Part IV wraps this up, and closes with some strong statements about what we should and shouldn’t be willing to do.

Obamamania: How might it affect climate change?

I am not a political commentator – just an “average jo”! And if you would like to view a very funny YouTube clip form another Average Jo concerned about climate change go to http://au.youtube.com/watch?v=iWW8u5p-DVE

I have watched the media go crazy over Obama’s election – and I am deeply moved by USA’s vote for a man of coloured origin. Also a man about whom we really know so little, but one who seems to be smart and so right for our times. What will he really be able to deliver?

Obama has, throughout his campaign, talked about an 80% reduction in GHG emissions by 2050, a carbon cap and trade system, R&D for renewable energy, tax incentives for renewable energy, Green Jobs training …. all the things I want to hear for Australians too.

So into the global system of influence and politics now is a USA President (Elect) who sounds like he cares and “gets” it. If everything truly is connected – as we know it is (Just look at the finanical crisis if you need more evidence) – then this man’s very presence should make a shift.

The horse trading will go on – that is politics, but I continue to dare to hope that real change is near – and work for it too (nothing comes through hope alone!)

Josie