Tuesday, December 27, 2005

So, what is the Alternative?

I would love to think that we will shortly discover some form of limitless energy, and thereby get around all our problems of globe warming CO2 emissions, security of fuel supply - of cheap fuel at that, to preserve our economic advantage, and the whole caboodle. I would also like to think that "Peak Oil" is at best a myth, or at least that it is a long way off, as the Oil Industry would have us believe. I neither think nor believe any of these things, but even those that do might ponder for a moment the question "what would be the alternative" if we were suddenly to find ourselves in the U.K. without (cheap) oil and gas, purely as an intellectual exercise.
"Nuclear Power", I can imagine some of you saying. Well, yes, there is some argument for it, but as I have pointed out in previous articles, nuclear could only provide 18% of our total "energy", even if it were to provide 100% of our "electricity", and there are issues of availability and supply, ignoring all the nasty nuclear waste that nobody has any idea what to do with yet, and what a horrible mess it would be if any of the uranium fuel ended up in a "dirty bomb" etc. etc. "Coal", others will argue, and it's a fair point. We do have plenty of coal. It's a bit rough on The Environment, and some viewers' quality of life would be impacted upon by the vista of dirty collieries and slag heaps - although the latter can be greened-over, mindful of the Aberfan Disaster - but you can't have it both ways. If we want more coal, the landscape will inevitably be scarred by its extraction. Indeed, we could probably dig up enough coal to supply practically all of our electricity and to heat most of our premises both commercial and domestic, if we re-tooled our systems for that purpose. However, even allowing this potentially reassuring solution, clearly coal is not generally a mobile source, and the remaining issue is transportation. Agreed, we could re-introduce steam trains and transport a goodly amount on their backs, but what about road transport - cars, vans and lorries, which carry more freight, in terms of both human and commercial cargo, than anything else does. Even trains run on diesel now.
I guess we could, in principle at least, adapt all these vehicles to run on gas, but gas supply is potentially a problem as we are running out of North Sea gas, and the U.K. is now a net energy importer, and we will need to import our gas increasingly from more politically maverick regions of the world such as Russia, which contains by far the world's greatest deposits of natural gas, mainly in the gas fields of Western Siberia. As I posed at the outset, it is both gas and oil that we are seeking to find an alternative for. "Run them all on hydrogen", others will propose. But, as I have also shown in this series of articles, hydrogen is totally impractical, since it is actually made from natural gas, and we could not realistically generate the phenomenal quantities of it required to substitute for oil if the current numbers of vehicles are to be maintained, by electrolysis - and the car industry would like even more of them.
In reality, there is no means to substitute for all the oil currently consumed. I won't say "which 'we' consume" since I deliberately don't own a car - I walk if my journey is anywhere within three miles, otherwise I use public transport, or if it's raining, say. And that seems to be the key. We can simply get around most of our problems of fuel supply by reducing or eliminating where possible the demands we place upon it. If we base those demands upon the requirements of a local economy and community, 90% of any actual"shortage" can be immediately avoided. However, any move toward such localisation beyond seductive lip-service will be deftly resisted by the oil companies and their sisters in the car industry, who will bend the ear of government to serve their will.
The Dahli Lhama thinks that all the problems of the world could be resolved through peace and understanding between people. I suspect he's right, but then he's not out to make a buck!

Wednesday, December 21, 2005

We Can't Live Without Fossil Fuels - CO2 or not!

In a utopian world, all our energy needs might be met by renewables. It is the green dream of a world in which wind/wave/solar/ hydroelectric/geothermal are the primary energy sources, and are used to turn turbines to make plentiful electricity for all, while leaving "The Environment" untainted. Even if we could find utopia in the U.K.'s pleasant land, currently the green dream would only supply 18% of the energy that the nation uses overall. Placed in context, the most favourable rallying cry, that 40% of the U.K.'s energy might be provided from renewables by 2050, appears a little limp, since it may be seen that even this most favourable scenario would only provide 40% of 18% = 7.2% of our total energy requirements, once the significance is appreciated that by the word "energy" it is "electricity" that is actually meant, but it sounds far more progressive to call it energy.
The current proportion of electricity generated from renewables is miniscule, at around 1%, i.e. perhaps 0.2% of total energy. The figure of 9% often quoted as being the proportion of electricity produced as "primary electricity" is highly misleading, since it includes electricity generated using nuclear power - rather, "uranium" should be listed separately as a primary fuel, reserving the term "primary electricity" for that produced from hydroelectric/wind/wave/solar/geothermal sources, i.e. those which are truly primary, and are renewable. Nuclear, as I have commented in previous articles in this series, is unsustainable (because it uses up uranium, of which there is only a limited supply), potentially dangerous and of limited benefit at best, neither securing security of supply nor significantly eliminating the U.K.'s own burden upon world CO2 greenhouse gas emissions.
If we "do the math" as they say across the pond, i.e. work a book keeping exercise, the figures find that 22% of total electricity is provided from nuclear sources, ignoring the Sun whose contribution to artificial energy production is negligible, standing trivially apart from the miracle of photosynthesis. As I have noted, even generating 40% of electricity from renewables by 2050 would only represent 7.2% of the energy we use in total, while oil and gas will still furnish the lion's share, together providing 78% of the total. As I stated at the outset, we are considering a perfect world where electricity is in limitless supply, and is provided from renewable sources. In such a world, why wouldn't we simply provide practically all our energy requirements by electrical means? Wind energy is more complex than at first appears. It is not simply a case of inaugurating 1 GW of wind capacity to replace 1 GW of fossil fuel or nuclear (ground based) power. The reason for this boils down to the fact that the amount of energy that may be extracted depends on the dimensions of the turbine blade and on the speed of the wind. Thus a blade that is too small might extract very little energy until the wind speed had reached, say 40 mph, and since the wind speed varies and is often significantly less than this, the turbine would not accumulate sufficient time at high power output to achieve a reasonable annual energy output.
A larger blade might begin to harvest wind energy at only a few mph, drawing a maximum power at, say 15 mph, but would need to be geared down, perhaps by the time the wind speed reached 25 mph to limit mechanical stress upon the turbine.
Experience in both Germany and Denmark - a country which produces 20% of its electricity from wind power (i.e. about the same as the U.K. does from nuclear) - is that 20% or less of full capacity is expected over a period of a year. This "capacity factor" as it is known, is simply the wind turbine's actual energy output over the year divided by the energy that would be obtained if it were run at full capacity over the same period (i.e. an upper limit of 0.2, which we now assume). A crude calculation indicates that if we were to try and replace around 62 GW of current energy demand by wind power, this would require 62/0.2 = 310 GW of full wind turbine capacity. But this large number still only refers to the 18% of total "energy" that comes from electricity. If we take the calculation to the limit of supplying all energy in the form of electricity, in order to eliminate the use of coal/oil/gas/nuclear generated energy, we would need about another 80% of the total which comes to 276 GW as derived from these greenhouse gas generating source (and building nuclear power plants, mining and milling their uranium fuel etc. also produces CO2, despite the rhetoric of the pro-nuclear lobby, the government and it's Chief Scientific Advisor), this steps up to a massive 310 + (276/0.2) = 1690 GW to be generated from wind energy.
The technology improves as turbines get bigger, but even using turbines rated at 0.5 MW full capacity, we would need to produce 3,380,000 of them, which would be a staggering endeavour. In addition, a vast network of hydrogen - an energy storage medium, which requires primary fuels to produce it, including electricity as in the present utopian scenario - storage devices, fuel cells for vehicles as we are going the whole hog of 100% reduction in carbon emissions here, would be necessary. Graham Sinden at the Oxford University Environmental Change Institute has estimated that a mix of 43% wind, 52% wave and 5 % tidal stream power could reliably produce the equivalent of 8 GW worth of coal, oil or gas power (out of about 344 GW worth of these total fuels burned), which is not a lot. If drastic reductions in emissions of greenhouse gases, in the range of 80 - 90% (still requiring 3 million or so wind turbines) of the current level is required by 2023, we really are in trouble, as there is no real means to replace the huge qauntities of fossil fuels that we currently use.
The only scenario which could succeed in making any significant impact is to focus on energy saving strategies, e.g. buildings designed perhaps along the lines of the "40% House" being researched by Dr Brenda Boardman's group in the Oxford University Environmental Change Institute, and further advances of it where heat from appliances, body heat etc. would fulfil most of its space heating requirements. The "Zed Bed" and "Passivhaus" concepts are also most interesting, and there are web pages available for them which are worth purusing for more detail. The Passivhaus is a continuously ventilated unit, which draws warm air into it via pipes that are heated geothermally by being buried in the soil, thus avoiding the veltilation problems that might arise from an "ultra"- insulated building and since the incoming air is to some extent warmed (to 5 degrees C, even in winter), along with efficient insulation, relatively modest additional heating is needed. However, the construction and engineering efforts required to substitute sufficient such buildings on time (i.e. before the climatic effect of CO2 is expected by some experts to be irreparable, 2030 perhaps) are truly daunting, and would meanwhile be producing CO2 until their final fabrications were complete. This point was reinforced by Professor James Wouduysen recently, in his statement: "It will take 1,000 years at current rates for our current housing stock to be replaced". He then suggested that houses could be constructed as part built kit homes, exported from China, which could be assembled in the U.K. and transported to their final site of location. This might require relocating some people to other parts of the country, but he argues that 280,000 computer designed, insulated units a year could be provided for the U.K. market by this means, which in many ways resembles car mass production.
However, the aspect of having more energy efficient buildings does not tackle the issues/problems of transportation, and its fuel requirements which remain enormous even allowing for improved efficiency methods - i.e. more miles per tank of fuel, using fuel cells etc. ultimately, and meanwhile using more efficient combustion engines, while the hydrogen powered utopia was being implemented. This leads to my final point, that we also need to reduce our dependence on transportation by living in "local" communities based on local economies, which supply smaller populations from local farms, and therefore cut down generally on more global transportation necessities. In our localised communities, we would also want fewer cars, and less foreign holidays too, once the general concept had been assimilated that we can't continue as we are. I'm afraid this is the best I can offer, which gives me no comfort either, but I can see no quick fix to our greenhouse gas emissions, as implementing all of this will take decades, if it happens at all. Meanwhile we will continue to pump out CO2 into the atmosphere.

Saturday, December 03, 2005

Die Off.

The ownership of the largest deposits of oil, notably in the former U.S.S.R., e.g. Siberia and Kazakhstan and the Caspian region generally, in addition to the fields in the Middle East, will likely determine the future balance of world power. "The New World Order" as it is sometimes referred to. It is interesting that it is scientists from the former U.S.S.R. who throng highly among the ranks of "Hubbert detractors" - those who do not believe in an imminent "peak oil" scenario. There appears to be a conflict of opinion, and probably of interest too, between Western and Soviet oil experts, which revolves around different viewpoints as to the origin of petroleum. The western belief is, as we were all taught at school, that petroleum is a result of "cooking" plant and animal remains over millennia, and proof of its origin thus is taken to be the presence of the same type of organic molecules (porphyrins etc.) as are found in living plants and animals.
Soviet thinking, which goes back at least as far as the great Russian chemist Medeleyev (who invented the Periodic Table of the chemical Elements), is that petroleum is formed in the deep earth by geochemical processes - Mendeleyev thought by the action of water on iron carbides. The explanation for the presence of porphyrins etc. is that they are simply dissolved from higher strata by petroleum moving upward from the depths, and acting as an organic solvent. The essential difference between these schools of thinking is that, if the Russians are right, oil can be considered a limitless resource, while the western view readily accords with an imminent peak oil; i.e. a finite supply of oil. The Russians, however, are sufficiently convinced after more than 50 years of intensive research that their theory is correct and they have made enormous investments in developing "deep drilling" techniques (2 km and more down) with which to reach the petroleum deposits formed deep underground.
Either the Russians will secure their position more strongly in the new world order, or affordable oil will eventually run out - for everybody. This is particularly alarming in the context of world population. In 1900, there were less than 2 billion people on the planet (up from about 1 billion in 1800); now the figure is 6.4 billion, and the exponential curve in population growth that these numbers can be plotted upon is an exact parallel with that for oil production. Without the vast quantities of chemical fertilizers, which are made from oil and gas, we could not grow enough food to feed the rising population, nor even the current number, nor far less than that. Some predict that a "die off" will follow peak oil production, and that the world population will fall from 6.4 billion to perhaps as few as 500 million (the death of almost 5 billion people, or about 92% of the number now alive).
An analogy can be drawn with the growth of bacteria, which, so long as there is sufficient food available, follows a "sigmoid curve". There is an initial growth in population which multiplies rapidly (the rising upper of the sigmoid), and then levels off abruptly when the food supply becomes restricted relative to the new, far larger population. Then they begin to eat each other instead, and the number of bacteria remaining alive plummets.
It is hardly a comforting prospect.

Peak Oil.

The end of cheap oil is nigh. Although there is plenty left untapped, oil will become progressively more expensive to extract, with irrevocable consequences that impact profoundly on each and every aspect of human life. Even an increase in overall costs by 10% in transportation, imports and exports, processing and manufacture could jeopardise the world economy, and it is worse than that. There is almost no modern commodity that does not rely at some stage on oil or gas, and that includes food!, and it is thought in some quarters that a peak in oil production "peak oil" is either upon us already or at least by 2010.
If we try to save oil by using natural gas instead, "peak gas" will arrive sooner than by 2100 as is currently predicted. These dates refer to "world production" of oil and gas, and are misleading because the "peak" in production will vary from one gas or oil field to another. Precise dates are difficult to divine since no one knows for sure exactly how much of these fuels lie in reserve. Shell Oil got itself into trouble recently for somewhat overestimating the residual quantities of oil in the fields under their banner of exploration and extraction. Perhaps it was a simple mistake. I attended a conference in October on the provision of "U.K. Energy to 2050" (http://www.geolsoc.org/uk/template.cfm?name=PR60") where a spokesman for B.P. tried to convince the assembled delegation that there was plenty of oil left, and that for each additional one trillion barrels remaining, the "peak" in production would be shifted forward by about 33 years. Accordingly, if peak oil will strike in 2010, according to currently accepted reserves, another trillion barrels means the inevitable will not hit until 2043, and so on to 2076 and 2109. There is, however, no hard evidence for such additional aliquots of oil, and peak oil remains incontrovertible at some point. It is only a matter of "when?" not "if". Hence it makes sense to prepare for the eventuality by reducing demand on the resource; and yet demand increases inexorably, particularly in the developing world (notably China and India) who's citizens aspire toward a western lifestyle, which even the west can no longer afford.
The concept of "Peak Oil" originated in the mind of Dr M. King Hubbert, who published the fundaments of his ideas in a seminal paper in 1956. He arrived at the conclusion that there will be a lag of about 40 years between the peak in oil discovery and the peak in oil production: "peak oil". Hubbert's prediction was almost spot on for U.S. peak oil. The peak in oil discovery occurred in 1929 and peak oil in 1968; it's slightly premature arrival (by one year) being explained by more efficient extraction methods which were introduced during the latter part of that period. In the Middle East, peak discovery occurred in the early 1970's, so according to Hubbert, we might expect peak oil to occur there within a few years of 2010.
Such "Hubbert's Peak" analyses have not found universal favour. I mentioned that oil companies tend toward an optimistic view of how much oil actually remains in reserve to be extracted. Almost certainly, more advanced drilling methods have depleted the deposits more quickly than would have been the case using older technology. Accepting these and many other uncertainties, it is probably sensible to believe that peak oil is not so far away that we can ignore it. A Hubbert's peak is a "bell-shaped" curve: a plot of oil production versus time. There is a steady rise in production that follows discovery, which then peaks, and subsequently falls away. It is the letter portion of the curve that is dangerous, since it represents the failing of the oil jamboree, when the raw resource becomes progressively more expensive to obtain - this occurs once about half the original reserve is left. Since everything depends on oil, either as a raw manufacturing material, or as a production fuel, or both, the impact of peak oil on the world economy will be both profound and unpredictable.

Friday, December 02, 2005

"Energy" - not just "Electricity".

Implementing nuclear power on a grand scale will not secure an energy supply for the U.K., nor will it significantly reduce our CO2 greenhouse gas emissions. The reason is simple, but is seldom rendered explicitly, that only 18% of the total final energy consumption is provided by electricity. 78% (IEEE 430% more) of the U.K.'s energy is produced by burning natural gas and oil directly, and this burden would not be influenced at all by any amount of nuclear development. The maximum change that might be made - at least in principle - is the substitution of all fossil fuel (mostly coal and gas) fired power stations by nuclear. Exactly how monumental an undertaking this would be may be gauged from the fact that the current 22% of total electricity produced by nuclear is generated from 31 reactors, which are housed in 13 separate power stations. On this basis, to substitute for the 73% of electricity currently produced from coal and gas, using nuclear, would require building around 100 or so new reactors, and that is on top of the 30 new reactors that will be required in any case, to replace those existing reactors that will come to the end of their working lifetimes by the year 2025.
This clearly is a colossal undertaking which does not solve the major issues of "security of supply" or CO2 emissions in any significant degree. We will still need to import oil and gas from politically maverick regions, mainly Russia and the Middle east, and is the uranium fuel required for nuclear to be found on our doorstep? Hardly. Most of it comes over from Canada. What about renewables? It is thought that in the longer run (say, by 2050) around 40% of the U.K.'s electricity might be provided using wind/wave/hydroelectric/ solar power. A significant proportion of this would be produced by "microgeneration" devices, rather than a large scale "grid", though any excess electricity generated beyond the local demands of each "micro" community, could be fed into the central network. This still only addresses "electricity" as a final fuel, and the question of providing the greater bulk of "energy" persists.
In simple economic terms, on the level of an individual or a country, the degree of security depends on the gap between income and expenditure. More can be earned or less spent. As far as the U.K.'s energy earnings are concerned, the limit is in sight. We cannot realistically "earn" more fuel, and we may well have to endure a pay-cut. It is thus a matter of economy, and of economising. That we spend the precious resources of oil and gas only where it is essential to do so. This will involve schemes of energy efficiency, for example the "40% House" being researched by Dr Brenda Boardman's group in the Environmental Change Institute at Oxford University. Such advances in building design could make huge savings in energy use for "space heating" across both the domestic and commercial sectors (each of which accounts for around 30% of the national total energy demand). Transport, which uses another 26%, mainly in the form of oil, is another area where savings could be made, both through more efficient combustion engines (or fuel cells, if the costs can ever be made realistic), and simply by eliminating all unnecessary use of cars (especially the military style "road wagons" - 4x4's, SUV's, depending on which side of the Atlantic you are - that have more to do with symbolising status than any practical transportation issue) .
To a reasonable mind it all seems straightforward, but I suspect there are too many people making too much money to allow any attention more than lip-service to be paid, until it is too late and there is no longer any choice.

Feasible Fusion Power? - I doubt it!

When I was about 10, I recall hearing that nuclear fusion power would become a reality "in about thirty years". The estimate has increased steadily since then, and now, thirty odd years on, we hear that fusion power will come on-stream "in about fifty years". So, what is the real likelihood of fusion based power stations coming to our aid in averting the imminent energy crisis? Getting two nuclei to fuse is not easy, since both carry a positive charge and hence their natural propensity is to repel one another. Therefore, a lot of energy is required to force them together so that they can fuse. To achieve this, suitable conditions of extremely high temperature, comparable to those found in stars, must be met. A specific temperature must be reached in order for particular nuclei to fuse with one another. This is termed the "critical ignition temperature", and is around 400 million degrees centigrade for two deuterium nuclei to fuse, while a more modest 45 million degrees is sufficient for a deuterium nucleus to fuse with a tritium nucleus. For this reason, it is deuterium-tritium fusion that is most sought after, since it should be most easily achieved and sustained.
One disadvantage of tritium is that it is radioactive and decays with a half-life of about 12 years; consequently, it exists naturally in any negligible amounts. However, tritium may be "bred" from lithium using neutrons produced in an initial deuterium-tritium fusion. Ideally, the process would become self-sustaining, with lithium fuel being burned via conversion to tritium, which then fuses with deuterium, releasing more neutrons. While not unlimited, there are sufficient known resources of lithium to fire a global fusion programme for about a thousand years. The supply would be effectively limitless if lithium could be extracted from the oceans.
In a working scenario, some of the energy produced by fusion would be required to maintain the high temperature of the fuel such that the fusion process becomes continuous. At the temperature of around 100 - 300 million degrees, the deuterium/lithium/tritium mixture will exist in the form of a plasma, in which are nuclei are naked (having lost their initial atomic electron clouds) and are hence exposed to fuse with one another. The neutron flux produced by the plasma is very high, and the overall breeding efficiency of lithium to tritium would be enhanced by surrounding the reactor with a blanket of lithium about three feet thick. The intense neutron flux will render the material used to construct the reactor highly radioactive, to the extent that it would not be feasible for operators to enter its vicinity for routine maintenance. The radioactive material will need to be disposed of similarly to the requirements for nuclear waste generated by nuclear fission, and hence fusion is not as "clean" as is often claimed. There is also the possibility that the lithium blanket around the reactor might be replaced by uranium, so effecting the option of breeding plutonium for use in nuclear weapons.
The main difficulty which bedevils maintaining a working fusion reactor which might be used to fire a power station is containing the plasma, a process usually referred to as "confinement". Essentially, the plasma is confined in a magnetic bottle, since its component charged nuclei and electrons tend to follow the field of magnetic force, which can be so arranged that the lines of force occupy a proscribed region and are thus centralised to a particular volume. However, the plasma is a "complex" system that readily becomes unstable and leaks away. Unlike a star, the plasma is highly rarefied (a low pressure gas), so that the proton-proton cycle that powers the sun could not be thus achieved on earth, as it is only the intensely high density of nuclei in the sun's core that allows the process to occur sustainably, and that the plasma is contained within its own gravitational mass, and isolated within the cold vacuum of space.
In June 2005, the EU, France, Japan, South Korea, China and the U.S. agreed to spend $12 billion to build an experimental fusion apparatus (called ITER) by 2014. It is planned that ITER will function as a research instrument for the following 20 years, and the knowledge gained will provide the basis for building a more advanced research machine. After another 30 years, if all goes well, the first commercial fusion powered electricity might come on-stream. The engineering requirements will be formidable, however, most likely confronting problems no one has thought of yet, and even according to the most favourable predictions of the experts, fusion power is still 60 years away, if it will arrive at all. Given that the energy crisis will hit hard long before then, I suggest we look to more immediate solutions, mainly in terms of energy efficiency, for which there is ample scope.

A Nuclear Future?

Nuclear power, now usually dubbed "nuclear" looks set to return to the fold, having been the black sheep of the family for a good three decades. Its protagonists claim that during the lifetime of a nuclear power plant (NPP), only around 20 - 40% of the CO2 generated by an equivalent typical gas fired plant is released, and so nuclear is a more environmentally benign supply of energy. This figure should be taken as representing the CO2 output during the whole lifetime of an NPP, which might be somewhere up to 100 years. The initial carbon debt incurred in constructing and fuelling an NPP takes about 10 years to be paid off. The aspect of fuel requires further consideration. Most NPP's use uranium as their fuel. As mined, uranium comes mainly in two kinds, uranium-235 and uranium-238. Only uranium-235 is "fissile", i.e. can be "burned" in a fission nuclear reactor. "Fissile" means that the atomic nucleus can split into two on absorbing a neutron with the release of a huge amount of energy. To envisage just how much energy is released, a million-fold factor is sometimes quoted, meaning that one gram of uranium-235 releases as much energy as burning one million grams, i.e. one tonne, of coal or oil - roughly, since their energy output is not exactly the same.
In most NPP's it is necessary to enrich the uranium fuel in uranium-235. This is done by depleting it in uranium-238 (which is non-fissile and hence useless as a fuel), which then provides "depleted uranium" on a large scale for use in armaments and explosive shells. It is not widely recognised that uranium is a finite resource just as oil and gas are. Estimates vary, but there are probably reserves containing about 3 million tonnes of uranium available to supply a current demand of around 68,000 tonnes annually. This suggests that the present number of NPP's could be run for another 40 years or so. But what then? Sir David King (the Government's Chief Scientific Advisor) is quoted as saying that since "global warming [is a] greater threat than terrorism", the use of nuclear should be expanded to supplant fossil fuel fired power stations and hence reduce the overall CO2 emissions attendant to power production. This is a view also recently espoused by no less than Professor James Lovelock, of Gaia fame, though Lovelock has never been entirely anti-nuclear. However, since the world generates around one sixth of its electricity from nuclear, if we could replace all the fossil fuelled plants by NPP's overnight, the forty year fuel enforced limit on fission powered NPP's would be reduced to about 7 years, and I have seen estimates as low as 3 - 4 years for this scenario. So, why are we still even talking about it?
There is one alternative, which still uses fission, but can burn the majority (99%) uranium-238, rather than the conventional reactor which is highly wasteful since it uses only <1% of natural uranium, in the form of uranium-235. A special reactor is needed to do this, which is called a "Fast Breeder". In a fast breeder, natural uranium is irradiated with neutrons, some of which are absorbed by uranium-238 nuclei and convert them to plutonium-239. Plutonium-239 is fissile and so can be used as a nuclear fuel. As the reactor runs, producing energy by the fission of plutonium-239, the uranium-238 present as an initial 80:20 mix of uranium:plutonium is conveted to more plutonium-239, hence the term "breeder" because the reactor "breeds" more fuel than it consumes. A blanket of uranium encases the reactor to absorb more of the available neutrons, and can be reprocessed to extract more plutonium fuel, making the overall breeding more efficient still. It is a "fast" breeder, because it is mostly highly energetic ("fast") neutrons that are absorbed by uranium-238.
Overall, the breeder technology is around 60 times more efficient in its use of uranium than a standard fission reactor is, and such an approach could extend the viable lifetime of nuclear to several hundred years, even allowing for the proliferation that King and Lovelock and others are promulgating. However, we would surely be replacing one form of pollution by another. If we cut back on CO2 emissions, which may be a good thing, although there are still some who remain unconvinced as to the link between anthopogenic CO2 production and global warming, further pressure is impressed upon our already heady dilemma of what to do with the existing burden of nuclear waste.
Unmentioned explicitly too in arguments favouring nuclear is the "P-word", "Plutonium", which would be manufactured on an unprecedented scale, presumably in politically dodgy regions of the planet, if it is a global effort that will be made, and ther is every reason to believe that terrorists or megalomaniacal governments could take advantage of the situation, either by getting hold of the material directly and fashioning it into dirty bombs, or by blowing-up the breeder reactor in-situ. Surely, more could be done in terms of energy efficiency and sustainable energy production, unless there is another agenda that requires plutonium for other purposes, such as a revamping of the nuclear weapons programme.

How to plug the Energy Gap to 2050.

It has been concluded that providing the U.K. with energy up to 2050 will require a suite of energy sources, including nuclear power. This inference is the outcome of a two day conference held in London in October 2005, which I attended. A subsequent report was written by John Loughead (Executive Director of the UK Energy Research Centre), of which an overview was presented to the Royal Society on November 10th. I will now give mention and some thoughts to the following points arising.

Fossil fuels will provide the primary energy source for the next 50 years.

(1) Coal. It is thought that coal will likely remain fairly cheap, and so finding improved ways for using it as a clean fuel source is a priority. Nonetheless, there is no getting around the fact that burning coal produces CO2. Carbon capture and sequestration (pumping it underground or onto the ocean floor) might play some part in ameliorating the impact of coal use, but the technology has yet to be demonstrated on the full scale, and concerns remain about its long term safety (i.e. how confident can we be that the CO2 will stay put; or might it suddenly erupt, causing chaos to the climate), which will certainly delay its actual implementation.
In principle, coal might be "gasified", especially in seams which are not feasible to mine, to produce e.g. methane and hydrogen as fuels, but questions arise over issues of practicality and safety (e.g. a large emission of methane, with an instantaneous radiative forcing potential around 100x that of CO2, would not be good!).
(2) Oil. This is of prime importance to transportation. Hydrogen is sometimes spoken of as an "alternative fuel" but it is not a primary source rather an energy carrier, and has to be made using a primary fuel, often natural gas, or by the electrolysis of water which requires electricity generated using a primary source. Debate remains over just how much oil is available for exploitation, but it is expected that a peak in oil production "peak oil" will occur between now and 2050, and some believe that it will occur any time between now (2005, so we might be there already) and 2010 (which is not far off).
(3) Gas. Supplies of natural gas are extensive, and "peak gas" is not expected before 2050. There are concerns, however, that the U.K. is no longer a net exporter of gas, but will rely increasingly on imports of Liquified Natural Gas (LNG) from potentially politically complex and unpredictable regions such as Russia, hence security of supply is an issue.
(4) Nuclear. The matter of nuclear power has never been more contentious than it is now. It is argued that nuclear fission is a "mature technology", so we know what is involved, but the costs, in terms of new construction and the decommissioning of nuclear power plants (NPP) at the end of their working lifetimes, and of the disposal and long term storage of nuclear waste, are likely to be enormous. It is clear that all but one of the currently operating U.K. NPP's will need to be decommissioned by 2025, and probably replaced by new, since an alternative which provides 22% of the total U.K. electricity would be hard to implement in the short term (e.g. renewables). There are problems of supply of essential component parts, however, e.g. there are only two suppliers to be found worldwide who can supply the complex pressure vessels required by modern fission reactors.
(5) Renewables. Under the most favourable circumstances, it is thought that renewables might provide up to 40% of the U.K.'s electricity by 2050. Nonetheless, substantial investment and clear government policy is required to achieve the improved technology and its manufacture to bring, e.g. solar, wind, tidal, into economic parity with existing energy sources.
(6) Demand. This is a feature oft overlooked during discussions about energy provision, and yet it is surely key to addressing the considerable problems that face us. A simple rationing policy would prove instantly unpopular (a real vote-loser) since most of us wish to preserve our current (no pun intended) standard of living. We are, therefore, talking about "energy efficiency", of making the best use of what we have. The Oxford Environmental Change Institute are working on Ultra Insulated Houses (e.g. "The 40% House" project), which they think will ultimately evolve to the level where artificial heating is not required. Background and e.g. body heat, contained within improved building design, would be sufficient to provide a comfortable living environment. There are presumably issues of ventilation etc. to be addressed.
Even before this ideal is achieved, buildings generally could be so constructed to render huge reductions in the amount of energy required to heat them to the standards we expect. The same institute have concluded that the U.K. could provide up to 60% of its electricity through renewables, which does make me think that a judicious combination of efficiency and renewables could go a long way to "plug(ing) the energy gap to 2050", the title of this article. However, there is a vested infrastructure built around fossil fuels, both political and economic, which might put up some resistance to change. Clear government policies are mandatory on all these issues: we need guidance from our elected leadership as to which path we should follow as a collective nation.