Friday, June 30, 2006
Canada's Oil Sands are not "Endless Oil".
It must be borne in mind that the Oil Sands do not contain "oil", as such, and are best described by the synonym, "Tar Sands", since they contain bitumen ("Tar") which has to "cracked" in order to decompose it into oil. This requires heating the material to several hundreds of degrees centigrade, and is therefore an energy intensive process in its own right. A rule of thumb is that it "takes one barrel of oil to produce one barrel of oil", which errs on the side of pessimism since the figure is nearer "two barrels to produce three more". Nonetheless, in terms of EROEI (Energy Returned on Energy Invested), this is not great, at 1.5 (3:2), and it is thought that 3 is the limit below which extraction of an energy resource is not worth the effort or expenditure of existing resources (See previous posting "You Need Energy to get Energy - Time is Running Out.").
Therefore, there lies a fundamental issue of what fuel might be used to empower any putative oil-sands programme. There is insufficient natural gas in Canada to support such an enterprise on top of the nation's other dependences on it. Bitumen itself can be used as a fuel (rather like coal), but that doesn't really square with acknowledgement of the Kyoto treaty. Nor, necessarily does burning any of the oil that is extracted, but this is a separate issue, and working within any set limits on CO2 emissions will rely upon the sum of natural and imported crude oil and its products, along with what may be garnered from the oil sands themselves. It seems that for any practical, long-term production of "tar-oil", investment in new nuclear facilities will be necessary to generate energy at-source for the projects. However, there is no chance that "Peak Oil" will be thus averted.
Analysis of a short-term crash programme indicates that a production level of 3.6 million barrels/day might be attained by 2018, and a long-term such programme could yield about 5 million barrels/day by 2030 (in 2005, 1.1 million barrels per day were produced). These figures may be compared with the monolithic world daily oil consumption of almost 90 million barrels, and rising - a staggering deficit, even at best. It is likely that the quantities of oil produced from Canada's sands will do no more than compensate for the declining output of oil in Canada and the North Sea, during these projected periods. Today, with the exception of ultra-deep off-shore fields, 54 of the world's 65 oil producing countries are already over the peak in their production and are in a state of irrevocable decline.
Whatever course we decide upon it must involve breaking our dependence on oil - otherwise it will break us!
Wednesday, June 28, 2006
Bulgaria Closes Nuclear Reactors.
Bulgaria is set to close two more reactors at its Kozloduy nuclear power station. Since Kozloduy generates 40% of Bulgaria's electricity, and supplants around 80% of the growing power shortfalls in its neighbouring southern European states, in terms of its exports, the future looks dim. The European Union has been attempting to coerce the closure of Kozloduy for a number of years, on grounds of fear for its safety. The move will be seen as a strong commitment to Bulgaria's accession to the EU, which it is due to join in the next wave of "enlargement" in 2007 (i.e. next year). Nonetheless, what exactly will be done to supplement the abrupt disengagement of such a large proportion of Balkan electricity remains a "black-hole", which senior officials are staring into, but no illumination escapes from it.
Bulgaria's electricity production will drop in 2007, until a second nuclear plant is built - expected in 2012 (the year of the "London Olympics") - and is anticipated to cover 60% of South East Europe's electricity imports. A new 670 MW coal-fired power plant (Maritsa Iztok 1) is being constructed by the American company AES, and is expected to be up and running by 2010 - 2011, which, if on schedule, will take the edge of Bulgaria's export limitations. It looks like a frugal three or four years, though, at best.
To bridge the gap meanwhile, Bulgaria intends to rely on a hydroelectric power installation (Tsanikov Kamuk) and a gas-fired plant in the capital, Sofia. Together, some 210 MW capacity will be thus secured. Reactors 1 and 2 were closed at Kozloduy some years ago, and so the planned closure of the remaining two (reactors 3 and 4) of the "old" design (440 MW each) leaves two more modern reactors running with an output of 1000 MW each. Mardik Papazyan, who is the executive director of the National Electric Company (NEC) has said that if one of the two remaining Kozloduy reactors should fail to operate, electricity could be imported from Romania and Serbia. It is interesting, however, that these are two of the southern European nations who currently depend on Bulgarian electricity exports, and so it is difficult to see how they might do this, especially while trying to meet their own rising demand for electricity.
At longer odds, Bulgaria is placing bets on the construction of a new 2000 MW nuclear power plant at Belene.The seriousness of the situation is voiced plainly by Papazyan who is quoted as saying, "without Belene, we cannot guarantee that Bulgaria will not need to import electricity after 2013-2015" (and this is after the initial "new" plant is built in 2012). He also confirmed that with Belene, 60% of Bulgaria's power exports could still be met, and that the plant could be built in six years time: the main contractor for it will be selected by early August.
The Maritsa Iztok 1 coal-fired power plant is the biggest single foreign investment so far made in Bulgaria, and is one of the largest greenfield initiatives in South east Europe. The plant will be situated near the town of Gulubovo in south eastern Bulgaria (for geographical comparison, Kozloduy is located in the north of the country, near to the border with Romania.). The base load operation will serve to provide electricity for Bulgaria and South East Europe, including Serbia. A "clean-combustion" technology will be employed, and 12% of the investment is to provide desulphurisation plants. The coal-fired plant Maritsa Iztok 3 also looks set for a windfall, as the Italian company Enel is considering making an investment of over 500 million Euro's to build an additional 900 MW unit to supplement the 840 MW plant that is there currently.
The whole issue of energy control in Bulgaria is one of potential political power, since whoever owns and operates either the nuclear Belene or the "clean-coal" fired Maritsa Iztok (whichever comes first, and probably the latter) will have the considerable advantage of a carte-blanc to trade electricity all over the southern European region. However the cards fall, there will be some lean years to be negotiated, immediately following the loss of output from the closed reactors 3 and 4 at Kozloduy.
For an update regarding this story, please see later article: "Bulgarian Reactors are Not of Chernobyl Design", posted February 29th, 2008.
Monday, June 26, 2006
Antarctic Ocean key to Global CO2 levels.
As the study's corresponding author, Irina Marinov, put it: "Cold water that wells up regularly from the depths of the Southern Ocean spreads out on the ocean's surface along both sides of this dividing line, and we have found that the water performs two very different functions depending on which side of the line it flows toward. While the water north of the line generally spreads nutrients throughout the world's oceans, the second, southward-flowing stream soaks up carbon dioxide, a greenhouse gas, from the air. Such a sharply defined difference in function has surprised us. It could mean that a change to one side of the cycle might not affect the other as much as we once suspected."
It has long been recognised that the (Antarctic) Southern Ocean influences the planet overall in a number of different ways. However, only two years ago the Princeton team discovered that the world's ocean nutrient distribution depended on the circulation pattern in the Southern Ocean, but did not realise then that the pattern also affected carbon dioxide levels. The real advance made by these workers is that they have been able to draw a distinct line between the two effects, regarding nutrients and CO2.
At the Antarctic sea-air interface, CO2 dissolves in the water, which is then drawn down deep into the ocean depths by the particular circulation pattern there. The team suggest that focus should be shifted from the Atlantic to the Antarctic in reference to CO2 uptake and regulation. They speculate that their research may have implications for future "iron fertilisation" studies, where the growth of certain microorganisms is stimulated by iron, which consequently take-up more CO2, as an antidote to human-induced (CO2) greenhouse gas emissions. When the organisms die, they fall to the ocean floor, taking down the CO2 that they have absorbed with them, so lowering its concentration in the surface waters and allowing more atmospheric CO2 to be absorbed.
There is one caveat, however: namely that these conclusions are based on computer models, which necessarily have limitations according to the precise nature of the algorithm that is employed to do the calculations. In conclusion, this interesting finding reveals yet another element of the complex interplay between the various global components that will altogether conspire to bring about the outcome of the "Global Climate Change Experiment" that we are each and all of us involved in, whether we like it or not!
Friday, June 23, 2006
Under an agreement between the state-controlled Rosenergoatom consortium and the Sevmash shipyard, in the far north of Russia, which is used to build nuclear submarines and is where this new facility will be constructed, the first electricity will be provided from the mobile power station in 2010, to supply electricity for the Sevmash naval facility. The cost is expected to be in the region of £183 million ($336 million) for the first unit, of which up to six are anticipated in total. From an engineering viewpoint, the project is fascinating. The structures will supply heat and electricity to far flung corners of Russia's far east and northern regions, which lie well above the Arctic Circle, and where it is consequently very difficult, expensive and unreliable to ship coal and oil. Once the technology is proven, Russia plans to sell the floating structures to other nations, in particular India and China. The structures are planned to have a service lifetime of 40 years. They will need a "crew" of around 70 souls, and could provide enough energy to power a "medium sized town." The initial power station will be moored in the White Sea, off the coast of the town of Severodvinsk in Russia's northern Archangel region.
I live in the village of Caversham, which borders the river Thames on the north side, with the medium sized town of Reading to the south of it. Perhaps we might see such an installation floating up-river from London, having traversed the North Sea, to provide local energy here, in the likely uncertain times forthcoming. However, I doubt that local environmentalists would be any more keen on the idea than are other environmental groups, who are now warning that these "floaters" could sink in stormy weather and that they could become a target for terrorists. A report from Bellona Foundation, an independent Norwegian research group, has accused the floating power station of being "a threat to the Arctic, the world's oceans, and the whole concept of non-proliferation".
Russia presently generates around 17% of its electricity from 31 nuclear reactors housed among 10 different sites, and President Vladimir Putin has said that he wants to increase this figure to 25%. It is interesting that all the major nuclear nations including the U.S., U.K., France and Russia are set to expand their nuclear programmes. This is not necessarily only in the interests of providing nuclear power. Yesterday's newspapers all bore a headline close to a picture of Gordon Brown, the U.K. Chancellor of the Exchequer (who may well become the next Prime Minister, if Tony Blair steps down before the next election), alluding to his statement this week that Britain should hold on to its "independent nuclear deterrent". This is in reference to the fact that the Trident weapons delivery system, supported adamantly by Margaret Thatcher in the early 1980's, is due to be mothballed by around 2025. In order to maintain that "deterrent", work needs to be started pretty soon on whatever the "new" ("Trident Mark II") programme will be, to have it up and running, having sorted out any teething troubles - there are bound to be some - within 2 decades.
The warheads will require a nuclear explosive, irrespective of the means by which they are to be delivered to potential targets, and this is most likely to be in the form of plutonium. Hence, fast-breeder reactors might be employed in the "new generation" of nuclear reactors that coincidentally are also needed within about 2 decades, to make the available uranium fuel reserve go further by converting it into plutonium, which could also serve a secondary purpose of being loaded into warheads.
There is a lesson from history, that the U.K. atomic power programme was not really instigated to produce "electricity too cheap to meter", but to provide plutonium for atom bombs, thus securing our position in the world nuclear order in the aftermath of WWII. If there is ever a world consensus that we do need nuclear power, an alternative fuel to uranium could be introduced, namely thorium. Although far more of this is available as a nuclear fuel once "bred" into uranium-233 (see previous posting, "Thorium instead of Uranium?"), it is far less effective in terms of plutonium production: rather more being a good way of disposing of plutonium and other "nasty" actinides. Hence I envisage the uranium-plutonium based approach remaining popular for the forseeable future.
Wednesday, June 21, 2006
Solar Energy Production and World Resources.
It is not only silicon that is in the minds of researchers into photovoltaics. Silicon at least as a raw material should be found in sufficient quantities for whatever uses humankind might envisage. Around 25% of the earth's crust consists of silicon, albeit mostly in the form of "clay" and other aluminosilicate materials. For silicon production, it is silicon dioxide (SiO2) that is needed, mainly as mined in the form of sand. This is "silica sand", as formed from the weathering of silicate rocks, as part of the natural CO2 cycle, where silicate in contact with CO2 and water is eroded into silica, and calcium carbonate, an inorganic and geologically sequestered form of CO2. Desert "sand" is often misunderstood to be the kind of (silica) sand that one finds on beaches, whereas it is in fact dried earth (clay). A simple way to tell the two kinds apart is to spit into the palm of your hand, add a small quantity of the "sand" and then rub it: if it is clay, it will turn into brown mud, whereas if it is silica, not much will happen beyond the material becoming damp and clumping together. Thus, as the Sahara Desert advances because of lack of rainfall, more sand appears, but really it is just the earth turning into dust.
It seems likely that there is sufficient silica in total to extract from it all the silicon we are likely to need in any foreseeable period. Other imponderable events are more likely to hit us before we run out of sand. But if it is not just silicon devices that are being considered, what other materials are, and how much of each is there thought to be as a world resource? I have looked into the following elements (metals and semimetals) that might find a place in future solar technology (photovoltaics, rather than roof-based water heating systems).
Cadmium. There are 6 million tonnes of cadmium, of which world production amounts to 16,000 tonnes.
Selenium. Reckoned at 80,000 tonnes worldwide, and currently extracted at a rate of 200 - 300 tonnes per year.
Arsenic. There is somewhere over 1 million tonnes of arsenic wordwide, of which 54,000 tonnes is produced annually. This is predominantly in the form of arsenic sulphur compounds, although another 11 million tonnes is thought to occur along with copper and gold ores.
Gallium. Also reckoned at a global resource of 1 million tonnes, and extracted at a rate of only 61 tonnes per year.
Indium. The reserve base (that's everything - economically minable ore and that which is uneconomic according to the present stock-markets) is around only 6,000 tonnes, of which 350 tonnes is extracted annually.
Nickel. Plenty of nickel, at 130 million tonnes worldwide.
Zinc. 1.8 billion tonnes overall - loads!
Copper. 1.6 billion tonnes as a world resource - loads too!
Interestingly, in the production of silicon by the reduction of SiO2 using carbon (high-grade charcoal), it is thought that around 1.5 tonnes of CO2 is produced per tonne of silicon that is manufactured. However, since generating 2,283 kWh of electricity produces 1 tonne of CO2, and 13 MWh (13,000 kWh) of electricity is required to maintain the temperature of 1,700 degrees C, in order to make the reaction (SiO2 + 2C --> Si + 2CO) go, that means another 13,000/2,283 = 5.7 tonnes of CO2 is released just to provide the electrical power, and hence 1.5 + 5.7 = 7.2 tonnes of CO2 are released overall to make each tonne of "solar silicon". However, even the 374 million tonnes of CO2 that would be produced if we could manufacture the 52 million tonnes of silicon, over a 20 year period, fades into the background of 24 billion tonnes of CO2 released in 2004, from all our fossil fuel combustions, being less than 0.1% of that per year.
Thin film devices that use gallium arsenide, and composites of indium, copper, selenium (and other chalcogenides) would undoubtedly reduce any potential strain on the extraction and ultimate availability of some of these materials (particularly indium and selenium). There is the further and as yet unsolved problem of energy storage. Storing hydrogen and transmitting it enmeshes a technology that is fraught with problems: low energy to weight ratio; embrittlement of metallic containment vessels and pipes, with leakages of hydrogen gas and ultimate wholesale fractures; energy losses in compression or liquefaction of hydrogen etc. etc. Therefore, since renewable electricity, e.g. from solar, can't be produced at a constant rate (the sun doesn't always shine - not at night! - the wind doesn't always blow, or not at a constant speed), there is the need to store it, and if we can't perform this task using hydrogen, we need some other means. The energy that we want supplied in the form of electricity is best stored in the form of electrons, and so some type of battery technology comes to mind. I note there is plenty of nickel and zinc and so zinc-nickel batteries might supply part of the solution, whereas nickel-cadmium (only 6 million tonnes of cadmium worldwide) batteries are of limited use, considering the stupendous number of them that we would need.
There are other ways of storing "energy", e.g. flywheels, pumping water "up" into reservoirs, as low-tech devices, and high-tech means such as confining electrons in superconducting storage rings, which would probably consume more electricity to run than it could hold: liquid helium to cool the superconducting magnets to provide the magnetic fields, power supplies etc. Indeed, all such energy storage systems, including hydrogen, incur large energy losses, both intrinsically and when that residual energy is used to generate electricity once again.
In principle solar might work very well on a local level. For example, an average "terrace" of 8 houses in this neighbourhood has a total roof area of around 800 m2. Taking the "British" sunshine level of 150 W/m2, and using solar panels at 10% efficiency, this could produce 800 m2 x 150 W/m2 x 0.1 = 12,000 W. i.e a generating capacity of 12 kW, and hence 12 kW x 8760 (hours/year) = 105,120 kWh. Dividing by the 8 households, that gives a little over 13,000 kWh, which is about half the total energy reckoned to be used by the average U.K. household for everything: electricity (3,500 kWh) plus space heating (20,000 - 25,000 kWh). Energy efficiency could cut this by about 50%, according to the Oxford Environmental Change Institute, and so we would be about spot-on, just from solar. I accept that there are issues of energy storage which we must meet if we are to use solar as our exclusive energy source. However, even if it could power our "terraced" dwellings during the day only, in combination with an efficient CHP (Combined Heating and Power) system for the terrace, we might be close to energy self-sufficiency, without needing a national grid system (which is also energy wasteful). Much of industrial power provision might be provided by some similar "localised" means, once again leaving-over the problem of profligate transportation use. However, using less cars, more sustainable living, with activities and food production being carried out locally, and using electrified tram-style systems on the scale of a town, say the size of Reading with its population of 150,000, to link together local "pods" as necessary, could work. Probably a "county-sized" grid system could be used to supply such "meso" infrastructure, drawing in electricity from off-shore wind farms and sea-power (wave and tidal stream) installations, and even for (ideally throium fuelled) nuclear power.
Cutting energy demand through such efficiency-driven strategies must be our first move in the future energy game.
Tuesday, June 20, 2006
Thorium - letter published in The Daily Telegraph (19-6-06).
Sir - Despite the reassuringly good record of Dounreay over 20 years, there remain grave fears about the overall safety features of fast breeder reactors.
The liquid sodium coolant is a perceived potential fire hazard and the containment of plutonium is a real public relations bugbear, for fear of radioactive contamination and that it might get into the hands of terrorists.
One alternative is to use thorium as the principal nuclear fuel, which can be bred into uranium-233 as the nuclear fuel using slow neutrons, thus avoiding the liquid sodium coolant, and has the following advantages.
First, plutonium and uranium could still be consumed in such a reactor, but without the need to manufacture yet more plutonium.
Second, while uranium-235 and plutonium-239 can be shielded to avoid detection "in a suitcase", to use that cliche', uranium-233 could not, because it is always contaminated with uranium-232, a strong gamma-ray emitter, which is far less easily concealed.
Prof Chris Rhodes, Reading, Berks
I shall see if there are any follow-ups to this. Interestingly, after posting my recent article about "Thorium", I was approached by a journalist wanting to write something on the subject (his boss had given him a 24 hour deadline!), so I gave him a few facts. He was lucky as I didn't get the message until about 7.00 P.M. on the Friday, having picked up my e.mail on my way "out" for the evening! He didn't get back to me so I hope he managed to write his piece O.K., and that I was of some help to him.
Monday, June 19, 2006
A Slim Chance for Solar Energy?
The solar radiation flux (sunlight intensity) at the top of the atmosphere is 1,400 W/m2, but some of this energy is absorbed by the atmosphere as the radiation passes through it. At the equator, at sea level, and at noon on a clear day, the solar flux reaching the earth is attenuated to 1,000 W/m2. If the performance of the solar cell were perfect (i.e. 100% conversion of radiation to electricity) an electrical output of 1,000 W/m2 (i.e. kW/m2) would be obtained. However, the actual output is nearer 100 W, i.e. 10% efficiency. Undoubtedly, the technology will improve, and there are fuel cells in research labs that can generate electricity with an efficiency of more than 30%, but 10% is a reasonable figure for a commercial solar cell at present, so we will work with this. In the U.K., however, an average value for the received solar flux is nearer 150 W/m2, which at 10% efficiency means 15 W/m2.
This is of course during the day only. At night, the power output drops essentially to zero. In the early morning and late day, more of the sun's energy is absorbed by the atmosphere; clouds also reduce the power, and so the actual output is highly dependent on the weather conditions and hence the emphasis on finding ways to "store" the electricity produced by photovoltaic technology.
To get some rough numbers and a scale of what is required, let us consider generating capacities for the U.K., the U.S., China and the world as a whole, and hence the area of photovoltaic solar panels required to meet these outputs.
According to "The World Factbook (2003)", in that year the U.K. generated 360.9 billion kWh of electricity. Dividing by the number of hours in the year, this amounts to a generating capacity of 360.9 x 10*9 kWh/8760 h = 41.2 GW (41,200 MW). Hence, we would need:
41.2 x 10*9 W/ (15 W/m2) = 2.74 x 10*9 m2 of solar panel area to generate it. Since 1 square kilometer (km2) = 1 million m2, this amounts to 2,747 km2, which is only 1.2% of the total land area of the U.K. mainland (230,000 km2).
For the U.S., the total is 3.717 trillion kWh = 3.717 x 10*12 kWh/8760 h = 425 GW.
China generated 1.42 x 10*12 kWh/8760 = 162 GW.
And for the entire world, a grand total of 14.85 trillion kWh was generated, which translates to a generating capacity of 14.85 x 10*12/8760 = 1,695 GW.
The relative solar panel areas appear quite respectable. I leave the reader to work out the percentage of total area required for the U.S. and China, and confine myself to noting that for the whole world, 1,695 x 10*9 W/(15 W/m2) = 113,000 km2 is needed.
This is worked out on the basis of the U.K.'s sunshine and the area could be reduced considerably by placing the panels nearer to the equator, so probably, any solar-powered "local" electricity generating operation would be more efficient in the developing world, e.g. India, Africa, South America - China is more complex in terms of its climate.
Given that 30% of the surface of the Earth is land (i.e. not presently covered by sea - a value that might change if sea levels rise; although they appear to be falling in the Arctic for reasons no one understands), and assuming the planet to be a perfect sphere, we have a land area of:
0.3 x 4(pi) x r*2 = 0.3 x 4 x Pi x (6366)*2 = 153 x 10*6 km2.
This is a rough estimate made on the basis of a circumference of 40,000 km for the Earth, and hence a radius (r) of (40,000/pi)/2 = 6366 km.
Hence, we need "only" cover the earth to the extent of 113,000/153 x 10*6 = 0.07%, which doesn't sound much. Indeed, it corresponds to an area of about 300 kilometers by 380 kilometers, or 235 miles by 300 miles, which is almost exactly half that of the U.K. mainland. Not that I am suggesting we host the whole world's solar production capacity within these shores!
As noted, the sun only shines during the day, and we can expect a sizable output for, say, only 8 hours per day (on average: more in the summer, less in the winter). Therefore, some other means for providing our electrical power is necessary during the dark (night) period. Alternatively and in principle, we might have around three times the area of solar paneling ( 3 x 8 hours = 24 hours) to meet the total demand required, and store the extra in the form of an "energy carrier", either as electrons (batteries) or hydrogen.
If we need this energy in the form of electricity, then "electrons" stored in batteries would be the better bet, as getting electricity "back" from hydrogen via fuel cells would be overall less efficient.
How much silicon would be required to make the required swathe of solar panels? To estimate this, I shall assume that a silicon layer with a thickness of 200 microns (= 0.02 cm) is to be used (this is toward the "thin" end of the 180 - 350 micron range quoted in Wikipedia for solar cells).
The total required solar panel area of 113,000 km2 = 113,000 x 10*6 m2 = 113,000 x 10*6 x 10*4 cm2. This corresponds to a volume of 1.13 x 10*15 x 0.02 = 2.26 x 10*13 cm3 = 2.26 x 10*7 m3.
Assuming an average density of silicon of 2.3 tonnes/m3, this volume corresponds to:
2.26 x 10*7 m3 x 2.3 tonnes/m3 = 51.98 x 10*6 tonnes; i.e. about 52 million tonnes of pure silicon.
The manufacture of one tonne of silicon is reckoned to cause the release of 1.5 tonnes of carbon dioxide (Wikipedia). This, presumably, is reckoned on the basis of an overall mass balance as:
SiO2 (60) + C (12) --> Si (28) + CO2 (44).
From the ratio of molecular/atomic masses for CO2 and Si, 44/28, a value of 1.57 is obtained, in close agreement with the above estimate. However, since the reaction occurs at 1,700 degrees C, a considerable input of energy is required in the form of electricity to make the reaction "go", with an additional amount of CO2 being unleashed skyward. Indeed, it is estimated that 13 MWh of electricity is used to make one tonne of pure silicon. To make the 52 million tonnes of silicon required for our global solar programme would demand 6.76 x 10*11 kWh. We are not of course going to make it all in one year, and perhaps over twenty years would be more realistic. However, that still means making 2.6 million tonnes of silicon every year, a figure to be compared with the current 30,000 tonnes currently produced, and in factories that make up to 10,000 tonnes per year each (some are far smaller than this). Hence, for a start we need something like 100 times the number of silicon factories that we now have!
What about the power requirement for them? To arrive at a per annum estimate we divide the total 6.76 x 10*11 kWh by 20 years, which gives us 3.38 x 10*10 kWh, and is to be compared with the world total electricity production of 14.85 x 10*12 kWh.
Hence, for a twenty year silicon programme, we would need at this rate to increase the world's annual electricity production by just 0.23%.
Nonetheless, building the number of factories necessary to manufacture "pure" silicon on 100 times the scale of current production is simply breathtaking, especially given the difficulty of even meeting the existing demand. Taken with the acquisition of the silica "ore" and the production of charcoal at the necessary grade to make "solar grade silicon", along with the fabrication of the solar panels themselves, the whole enterprise would be a stupendous undertaking.
The message is clear that solar will never become a sole producer of the world's electricity, although it will become increasingly important for stand-alone applications, particularly in the developing world.
I am not anti-renewables - I emphasise this - not in the slightest way! However, as with my earlier calculations on wind-power and biofuels, I am pointing out the sheer scale and energy density of human demand on the planet, which is not readily supplanted by renewable sources of energy. My considerations here are only made over current electricity production. If we try to factor in how much provision, e.g. by solar, would be required to produce electrons or hydrogen to run the world's transport systems at their current and rising size, we could easily multiply the above estimates by a factor of three or four: i.e. Renewables offer us little comfort in the absence of energy efficiency, which must be our leading step forward; then we may be in with a slim chance.
The best option for photovoltaic technology is through the development of thin-film technology, which uses perhaps 1/100th of the amount of semiconductor material, but the task is still monumental on the grand scale, while more localised applications are thus favoured. Other means to capture solar-energy are through roof-based water-heater systems, which use the heat from the Sun's rays to heat water - and of course, good old fashioned photosynthesis!
Friday, June 16, 2006
French - British Nuclear Deal Struck.
I have commented previously on the relative scarcity of uranium in terms of a viable fuel for nuclear fission, and which at current levels of usage worldwide will not last for more than about 50 years. I note that the Daily Telegraph yesterday published a letter extolling the virtues of fast breeder reactors, on the grounds that this way the uranium can be made to last far longer. This letter was supported by another one in today's Telegraph, but neither the author of this letter nor the editorial team have picked up on a notable error in the first case. However, there are often misunderstandings over such technical issues, in this case the estimate that 50 kilograms of uranium are sufficient to power a 1 GW fast breeder reactor for 40 years. As I explain below, the quantity is nearer 50 tonnes (not kilograms). The Telegraph have yet to print my letter on this matter, so I have copied it below, as it seems to me an issue rather central to the whole matter of nuclear power provision:
I think Paul Sutton (Letter, June 15) is being a little overoptimistic in his appraisal that just 50 kg of yellowcake would be sufficient to fuel a fast breeder reactor for 40 years. A closer estimate is 50 tonnes (not kilograms). Essentially, all the uranium (99.3% uranium-238) has to be converted ("bred") into plutonium in the fast breeder, rather than wasting it, and only using the 0.7% component, uranium-235 for fission as is usually done. 150 tonnes of yellowcake (mainly uranium oxide, U3O8) contains around 130 tonnes of uranium, which could (ignoring energy losses) fuel a fast breeder reactor for 130 years. Hence for a 40 year operational lifetime, 46 tonnes of yellowcake (call it 50 tonnes) would be required.
Despite the reassuringly good record of Dounreay over 20 years, there remain grave fears about the overall safety features of fast breeders: the liquid sodium coolant (used to avoid slowing down the fast neutrons needed to breed uranium-238 into plutonium-239) is a perceived potential fire hazard and the containment of plutonium, for fear of radioactive contamination and that it might get into the hands of terrorists, is a real public relations bugbear.
One alternative is to use thorium, which can be bred into uranium-233 as the nuclear fuel using slow neutrons, thus avoiding the liquid sodium coolant, and which has the following additional advantages. (1) Plutonium and uranium could still be consumed in such a reactor, but without the need to manufacture more plutonium. (2) While uranium-235 and plutonium-239 can be shielded to avoid detection "in a suitcase" to use that cliche, uranium-233 could not, because it is always contaminated with uranium-232, a strong gamma-ray emitter, which is far less easily concealed as a "bomb". These issues are discussed in detail at: ergobalance.blogspot.com, which your readers may find interesting.
My point is that there has been nothing explicit mentioned in the press as to whether the U.K.'s "new" reactors will be fast breeders or not. If not, the alternative fission reactors, implemented by around 2025, will have only 30 years worth of fuel left on the clock to run them. Is it worth the effort, given the enormous engineering effort and cost involved. Are they a stop-gap measure to keep the lights on in the country, while the potential of renewables is explored? I doubt it, since all discussion about our new generation of nuclear is presented as "the solution" to global warming by cutting CO2 emissions, with no reference to any time limit.
I am confused, and so is the general public, notwithstanding numerical faults in letters published in support of fast breeder reactors - an uncomfortable technology, in so many ways, albeit one potential means to make the uranium last for probably several hundred years, which might be a blessing or a curse depending on the show of hands into which it will ultimately find itself. In a poll conducted by The Sunday Telegraph, 47% of the sample were opposed to building new nuclear power stations, while 40% were in favour. Interestingly, 56% of men want nuclear, but only 26% of women share that view. It is encouraging that 79% of those surveyed had taken practical steps to reduce their own energy consumption, for example insulating the loft or fitting energy efficient light bulbs.
Politically, the nuclear issue remains a hot potato, with some Scottish Nationalist M.P.'s accusing Mr Blair of intending to dump radioactive waste in Scotland. Mr Blair insists that nuclear is essential to address the energy security needs of the country, stating that "we have to be prepared to take the decisions necessary to make sure that we don't end up in a situation where we are entirely dependent on foreign imports of gas."
Fair enough, but only 18% of our energy is provided in the form of electricity, which is the only form provided by nuclear in the U.K. so far, although other thermal processes, e.g. the sulphur - iodine cycle, to produce hydrogen are in principle possible. Only 20% of that 18% of total energy in the form of electricity is produced by nuclear. How does this get around the quantity of natural gas that is currently imported for electricity production, unless there is a second "new" generation of nuclear plants planned, to increase the share of nuclear in the electricity market? Additionally, much of the imported gas is burnt directly for space heating, and the new generation of nuclear plants will not substitute for this. We will surely still be dependent on imported gas for both electricity and direct heating, even with "new" nuclear. I remain confused.
Thursday, June 15, 2006
The Black Menace of Chinese Coal.
The air quality in Datong has deteriorated sufficiently that the city's air-monitors were on red alert, and desert dust and particulates forced the pollution index above 300, a level at which people are advised to remain indoors. 4 of China's 10 most polluted cities are in Shanxi province, including Datong. The air in Datong has been described as "(getting) very black" and even during the daytime, people have to drive with their lights on. The coal mining activities have damaged waterways and made the land barren in places, and due to the intensity of underground mining, thousands of hectares of land are at risk of sinking. Hundreds of villages are blackened with coal waste, roads are covered in coal tar, miners haul carts full of coal with their faces blackened by coal dust, and the air is thick with the sulphurous aroma of burning coal.
The incidence of respiratory diseases, including lung cancer, has soared in the past 20 years, but despite years of government intervention and mandate on the issue of atmospheric pollution, the problem has just got worse. Now the Chinese government has pledged its commitment to close the worst offenders, the factories and the most polluting coal mines - these are generally the smallest, and are also those with the most lamentable safety record: the death toll among Chinese coal miners amounts to around 6,000 per year, in comparison with the U.S. toll of about 50, to dig out a comparable amount of coal (just over one billion tonnes, annually). While this government plan sounds laudable, there is apparently no measure being discussed to curtail the Shanxi and Shaanxi regions' coal-fired power plants, and moreover there is a rapidly escalating programme to build more of them, to maintain pace with the soaring energy demand in this industrialised region. In part to provide Beijing with electricity, Shanxi province alone is expected to produce nearly as much coal as was mined last year in the U.K., Germany and Russia combined.
The consequences of burning the coal are felt well beyond the mining locality itself; sulphur dioxide pollution being a major problem, since Chinese coal is heavy in its sulphur content. In 2004, China released 22.5 million tonnes of "sulphur" (45 million tonnes of SO2) into the atmosphere, which is more than twice the amount emitted by the United States, and it is estimated that this figure increased to 52 million tonnes of SO2 in 2005. Around 30% of China is now drenched by acid rain, with the inevitable effect of acidification on crops, trees, rivers and lakes. The effects of such enormous levels of pollution by SO2 and ash are being felt in South Korea, Japan and beyond; countries which may well bear a legacy of respiratory disease as a consequence. In early April, a dense cloud of pollutants swept over northern China to Seoul and floated on over the Pacific, ultimately being detected by researchers in California, Oregon and Washington, who noticed specks of sulphur compounds, carbon (soot) and other byproducts of coal combustion, physically coating the surfaces of their pollution detectors. Pretty unambiguous evidence!
China is faced with some difficult choices. For the past two years, it has increased its coal production by around 14% annually. There is government intention to fit all coal-fired power stations with "sulphur filters" by 2010. The Japanese have offered assistance too, so worried are they about the effect of Chinese generated acid rain on Japan (though 1,000 miles east), and have agreed to lend Shanxi Province $125 million to help pay for desulphurisation equipment for large, coal-fired steel plants in the provincial capital, Taiyuan. Already, China uses more coal than the United States, the European Union and Japan, combined, Every week to 10 days, a new coal-fired power plant opens somewhere in China of sufficient capacity to provide electricity for all the homes in Dallas or San Diago.
Western companies could help China to control its emissions of CO2 and SO2, for instance by subsidising more energy efficient boiler systems. Some companies are involved in such schemes in other countries, but the scale of the emissions from China is tremendous. However, international climate experts remain loathe to admonish China without making an emphatic reference to the fact that China is nowhere near to a western lifestyle for the majority of its population, and that the average American still uses far more energy and releases 10 times more CO2 as a "carbon footprint" than the average Chinese. While China generates much more electricity from coal than the U.S., the latter's consumption of oil in the form of gasoline (petrol) drowns its Chinese equivalent. Given the rate of Chinese industrial growth, and the rise in the number of cars on its roads, it is unlikely that the current status quo will prevail in the future, when these two powerful nations will become embroiled in a struggle over oil, of whatever manner that may issue.
Monday, June 12, 2006
The prognosis is that beyond the maximum in oil production "Peak Oil", fuel and all other hydrocarbon based products will become increasingly expensive. This includes, in fact, everything that I can think of, and since pesticides and fertilisers are manufactured on a huge scale using oil or gas both as chemical feedstock and fuel, food production is heavily reliant on hydrocarbon resources, and so its price will initially rise, and its production level may ultimately become compromised. These are all complex issues, and before the ultimate "Armageddon" or "Mad Max" scenario of "post-Peak Oil" might occur (the Mad Max films represented a post-apocalyptic world in which the survivors would kill one another for a can of gasoline, such was its limited supply), we are likely to see price rises, potential panic on the stock markets, businesses and whole countries becoming bankrupt - in short a crash of 1929 proportions or worse. Most likely worse, since in all previous "oil-crisis" episodes, the cause was political; this time around, the precipitating factor will be the lack of the resource itself, as it becomes more costly in terms of energy to draw from the Earth. And there is no way around that - no more "gushers" certainly, and no more giant fields from which the black gold might be pumped in the quantity that the world and its population of around 6.5 billion has grown and fed upon.
For these and other reasons, principally concerns about global warming, alternative fuels are being sought, in an attempt to break our dependence on oil. A major alternative fuel is bioethanol, formed by fermenting sugar derived from plants such as sugar-beet and sugar cane, although other more highly yielding crops are under current investigation, and also from corn. Growing "corn" for bioethanol production immediately pits "food production" and "fuel production" at odds with one another. Moreover, there has been considerable speculation as to the viability of "bioethanol" as a fuel, in terms of the energy required to make it as accounted against that provided when it is burned, the details of which I shall consider in a forthcoming posting; however, it is obvious that turning arable land over to fuel production (either biethanol or biodiesel) leaves less available on which to grow food. In the U.K., we grow around just 70% of our own food while the remainder is imported. Growing "fuel-crops" limits this further, and while security of supply, i.e. becoming less dependent on foreign states to supply our fuel, is a commendable goal, even were we to turn all our arable land over to biofuel production, we could still achieve no more than a fraction of the vast quantities used for transportation. I calculated in a previous article "Biofuels - How Practical are They?" that such use of our arable land entirely for fuel production could only provide around 20% of what is actually used by the U.K.
In the U.S., bioethanol is big business, and around 15% of corn grown is, or is set to be, turned into "corn-ethanol". This is a large proportion of the food available to a nation which like the U.K. imports a large quantity of what is actually consumed, and potentially is central to security of supply in terms of food, should the politics of the world turn unusually maverick and food supply, like that of oil, become short. As the bioethanol business booms, there are sufficient putative bioethanol facilities planned in the U.S. to consume anywhere up to 40 % of its entire corn crop, which makes that unwelcome situation worse. It would be a supremely devastating combination of drivers: lack of oil, lack of imported food, and a shortage of home-grown corn turned into bioethanol, if all three cards were to show up in the same hand. Then the game would slip down the costly side of a Hubbert Peak on food provision..."Peak Food" would be with us.
Friday, June 09, 2006
A bad week for Nuclear!
Sellafield is located in the charming county of Cumbria, also known as the Lake District, where I have often been on walking holidays. The original "atomic station" was opened by Her Majesty the Queen in the mid 1950's, and in 1957 there was a serious fire which spread radioactive contamination widely. I recall as a "radiation worker" in the 1980's that we had to wear a "film badge" which consisted of a plastic wrist-band on which was a clear layer of plastic under which could be seen a small quantity of sodium iodide crystals. The principle was that exposure to radiation would liberate iodine which could be determined by titration against sodium thiosulphate, so providing a measure of the level of radiation exposure. One man who worked at Windscale in 1957 contracted cancer in later years and went after Sellafield (after the name was changed) for compensation. There was a television programme on the subject, and I recall him saying that on entering a particular room "[his] badge went black" (from the iodine), so the amount of radiation he received must have been enormous. I don't recall the outcome, but I believe that he died before the case could be brought to a conclusion, as often seems to happen in such cases of compensation claim, due to the long mechanical windings of the legal process.
It would appear, however, that 49 years on parts of Cumbria are still affected by the radiation leaked from the Windscale fire, which peppered England and Wales with radioactive contamination, and left "hot-spots" over Cumbria. Although the incident pales by comparison with Chernobyl, it remains the west's worst nuclear accident, and was a greater threat to life than the partial melt down at Three Mile Island. In a relatively small upland area to the south east of the Windscale site, the vestiges of the 1957 incident contribute around 60% of the total caesium-137 that can be detected there; however, and interestingly, in the west of Cumbria it is caesium-137 from Chernobyl which remains dominant. In the east of the county, it is fallout from atmospheric nuclear tesing in the 1960's that is responsible for most of the caesium-137 now detected in the soil. Despite all of this, Cornwall notably is far more radioactive than is Cumbria, due to the high but natural level of radon which emanates from the granitic rock formed in the particular geology of that region.
Nuclear waste continues to be a thorny issue, as I suspect it will for some time, at least until pressures of other resources are such that we have too many other prevailing problems to bother about it too much any more. However, while we do continue to worry about it, security specialists have given a warning that the U.K. government is being a little tardy about securing our nuclear waste, which they claim, is vulnerable to terrorist attack, and the paper targets especially the liquid nuclear waste from the reprocessing operations at Sellafield. So, THORP is in the gunsights once again, it would seem. In addition to the uranium and plutonium "stored" at Sellafield, there is apparently about 40 times the amount of caesium-137 there as was released by Chernobyl. I guess that puts an element of scale on the matter, although the two things are not strictly comparable. Sellafield already has a no-fly zone overhead, and RAF fighters have instructions to "scramble" if an aircraft were to enter the zone. There are a score of other security measures emplaced, some introduced after the World trade Centre attack on 9/11 (2001), and the site is under armed guard, so I guess it is quite well protected in fact.
I have noted in previous postings my thoughts about exactly what language should be used to write an equivalent of "DANGER HIGH LEVEL NUCLEAR WASTE", so that that particular fact might instantly be recognised in say, 10,000 years from now, by when it is doubtful that modern English will be an understood language, except by scholars possibly. In 1993, the U.S. gathered a team of "experts": an anthropologist, an astronomer, an archeologist, an environmental designer, a linguist and a materials scientist, to decide upon the best design for the Waste Isolation Pilot Plant (WIPP) in New Mexico, a nuclear waste depository housed in a salt mine half a mile underground. The design was required to convey various messages, along the lines of: "this place was made by humans", "this place is repulsive and dangerous to us" and "this is a place of danger, the danger is to the body and can kill". The message was to be carried by various architectural artifacts, statues etc., with messages written in the current U.N. languages, leaving space for further tongues to be added as they developed, and current languages had been lost from memory.
The problem at Sellafield is on a smaller scale than this, and Ben Russell of Nirex (the U.K. company responsible for radioactive waste management) noted that in the 50's and 60's "...they really didn't know if the world would be around in the next generation, so passing on the information wasn't a priority. Now we have to concentrate on preserving our records for the next 10 generations and beyond."
Since any U.K. deep waste depository is not likely to be opened for another thirty years, I guess there is still time to find the right signs.
Wednesday, June 07, 2006
Thorium instead of Uranium?
Thorium is a naturally occuring element discovered in 1828 by the famous Swedish chemist Berzelius, who named it after Thor, the Norse god of thunder. It is found in soils at an average of 6 parts per million (ppm), and in most rocks. In higher concentrations, thorium occurs in several kinds of mineral, of which the most common is monazite which contains around 12% of it. Other than negligible amounts of a few highly radioactive isotopes, thorium occurs exclusively as thorium-232. The world total of economically extractable thorium is estimated at around 1.2 million tonnes, and Australia and India top the list with 300,000 and 290,000 tonnes of it respectively. Interestingly, Norway has 170,000 tonnes of thorium, which adds to the large energy reserves of this country in terms of gas, oil and coal. Perhaps Norway will be less hard hit by Peak Oil than will other nations, although given its largely northern location, should the Atlantic Conveyor slow down and cool the northern hemisphere, it will need to burn more fuel than more southern lands. For comparison, I note that the U.S.A. has 160,000 tonnes and Canada 100,000 tonnes of thorium.
Although thorium-232 is not fissile in itself, it can be converted to a fissile fuel in the form of uranium-233 via the absorption of slow neutrons. Hence as is the case for uranium-238, thorium-232 is "fertile" and may be bred into a nuclear fuel, which in the former case is plutonium-239. I am told that there is one essential contrast between the two elements thorium-233 and plutonium-239, namely that while the latter may be used as "weapons grade plutonium" in a nuclear weapon, uranium-233 is a far less effective nuclear explosive, and has not been therefore used as such.
Since 100% of the thorium fuel can be converted into nuclear fuel compared with only the 0.7% of natural uranium that is fissile uranium-235, which is enriched by centrifugation or gaseous diffusion of uranium hexafluoride, there is an obvious advantage. It might be argued that the rest of the 100% of uranium (238) can be converted to plutonium in a similarly effective manner, but this requires fast neutrons in a fast breeder reactor: a technology with many disadvantages, both in terms of handling the toxic plutonium, pyrophoric liquid sodium, or its even more reactive alloy with potassium, and that these kinds of reactors are less controlable and in a worst case scenario could go-off like a bomb! Thus, in avoiding the latter method, around 40 times as much energy might be extracted from thorium than from an equivalent quantity of uranium. Even on the basis of the "known" 1.2 million tonne resource of thorium, a simple sum indicates that it could provide 40 times the sustainability of current available uranium fission based nuclear power for: [1.2 million (tonnes of thorium)/3.5 million (tonnes of uranium)] x 40 x 50 years (i.e. the current estimate based on uranium) = ca. 700 years. Even if we made all our electricity from thorium, around a quarter of that would be possible, i.e. just short of two centuries worth, and so if governments are intent on nuclear expansion to get around global warming, thorium may well prove a better alternative to uranium.
I recommend to the interested reader an excellent blog that I have been referred to (http://thoriumenergy.blogspot.com/) which details the potential use of thorium as a nuclear fuel, and to which I have posted a link, above.
Having visited Prague recently, I was struck by the efficiency of their public transport system: trams and the metro. If sufficient electricity to power such systems might be provided from thorium, whatever is possible from water (hydro, tidal stream, wave), solar power and wind power, and they were employed generally in the world, we might just break the hold on us of our dependence on oil in the present enormous quantities required for transportation, at least on a localised level. Current levels of aviation would remain unsustainable, however.
Monday, June 05, 2006
Sussex Chemistry Saved!
The University of Sussex is my Alma Mater, where I studied for my B.Sc. and D.Phil. The latter is the same as a Ph.D, but along with Oxford University, and York too, I believe, Sussex has preserved that Oxford tradition of referring to their doctorates as D.Phil. Sussex also awarded me a higher doctorate in science (D.Sc.) three years ago, which was a rather transitional time for me as I had resigned from my post as university research professor in physical chemistry, deciding to move on and start up my own business. Luckily, in the form of my wife, I had someone to hold my hand and steer me through the various pitfalls that one inevitably encounters on becoming self-employed; like making your own tax arrangements, and having to go out to buy stationary rather than simply going off to the stock-cupboard as I was accustomed to!
When I was a doctoral student at Sussex, the department could boast (if memory serves me well) seven Fellows of the Royal Society (FRS) and two Nobel Prize Winners (laureates), and it was indeed one of the top chemistry departments in the country. From what I gather, it has been run-down somewhat in terms of staff numbers, and there are plans to redress this matter by the recruitment of three new staff, according to Professor Geoff Cloke. I agree with Geoff that the entire episode and the attendant bad publicity internationally over the closure of such a world famous school of science - rated at Grade 5 in the last Research Exercise (RAE) - might well signal a watershed for the U.K. chemistry community, and perhaps the government will revise its university funding arrangements for science departments, which it must be agreed, are expensive to run, by their very nature - in terms of equipment and consumables. Having worked in a university which due to the nationally recognised problems in recruiting chemistry students, ran its chemistry department down (as have many others, as I mentioned above), I know what a distressing and demoralising experience this is, and I would not wish that upon Sussex or anywhere else for that matter.
If, in contrast, we do continue to destroy our academic science base, the prognosis for the nation is not good. As we are forced to confront the pressing issues of climate change, fuel supply, water provision and all those others that I have written about in these postings, we will need scientifically trained people in this country and in others, and it is about time the government waived its cash-only bums on seats university policy in order to facilitate some kind of decision over exactly how many, chemists, media studies graduates, psychologists and pharmacists we do in fact need. Otherwise, a "university degree" will just become a rubber stamp irrespective of what subject was actually studied, and the country will be full of "graduates" without the necessary knowledge that the world will demand in the future. We need a "plan", otherwise we won't succeed in circumventing the tragedy that market forces are apt to unfold on an undesigned stage.
Friday, June 02, 2006
Iran: Nuclear Fusion.
The "nuclear" issue in Iran is complex and looks set to precipitate military conflict. I sincerely hope that there will be no repetition of "Iraq", a war which was ostensibly fought over WMD's (Weapons of Mass Destruction) which were never found, or to topple a barbarous dictator, depending on who's words one was led to believe at its inception. It is interesting that Iran produces the world's third greatest volume of oil, following Saudi Arabia and Russia, and so is provided in that resource even more so than is Iraq. There are also large reserves of oil in Afghanistan; an interesting coincidence of that geological belt of the Earth. The story as I understand it is that there is consensus that Iran is enriching uranium in order to produce nuclear weapons, and the U.S. is telling them to stop it - or else. The Russians have offered to enrich uranium for Iran, but on Russian soil, which would preclude any action against the former.
There is a huge difference in the grade of enrichment required to produce uranium in a form suitable for fabrication nuclear fuel rods and that to make an atom bomb, or the warhead of a nuclear missile, however.
In the case of nuclear fuel, enrichment to only around 3.5% in uranium-235 is necessary. Indeed, natural uranium with its uranium-235 content of just 0.7% can be used if "heavy water" (deuterium oxide, D2O) is used as the coolant and moderator, rather than ordinary "light water" (H2O). However, to produce an atomic weapon, enrichment in uranium-235 to the level of up to 90% is the order of the day, and that is a more difficult process. However, the gas-diffusion or centrifugation apparatus that is used for the purpose of separating the two principal isotopes of uranium-235 and uranium-238 could simply be run for longer, and might well provide the means for making a nuclear device with military intent. Who it might be aimed at is another question. The Iranians claim that they are simply after providing nuclear power for electricity, exactly as the U.K., U.S., Russia and China are intent upon, and why shouldn't they do so as well? Indeed, the former three nations are urging their own nuclear weapons programmes along with a parallel expansion in their nuclear fuel industries.
I have commented before that the world's supply of uranium is a finite resource, which can only be eked out beyond about 50 years worth if fast breeder reactors are employed, which is a difficult technology and hence has not been widely adopted despite the intentions to do so in the 1970's. Instead the world relies mostly on fission powered reactors and hence the need to enrich the uranium fuel in the lighter isotope uranium-235 by gaseous separation of uranium hexafluoride, thus rendering available "depleted uranium" - uranium-238 - for use in tank armaments and warheads of military shells. Depleted uranium is a nasty material in that having torn its way through the side of a tank, and heated up to around 1,000 degrees centrigrade in the process, it then ignites into a fireball in contact with the oxygen inside the tank, and then it is "Goodnight Vienna"!.
Nuclear fusion, however, should not cause such angst. It is often incorrectly claimed that this would be a "clean" form of energy, but indeed the apparatus - the "magnetic bottle" required to confine the plasma of deuterium and tritium nuclei, plus a few electrons ionised from the atoms they originally come from - would become highly radioactive from the attendant neutron irradiation, and would form a high level (in terms of its radioactivity) nuclear waste with the well acknowledged conundrums associated with its disposal, exactly as we now face in providing a solution to the long term disposal of radioactive waste spewed-out by conventional fission powered nuclear reactors. The actual matter of "confinement" is the bugbear that has defeated scientists so far in attaining sutainable nuclear fusion, since there is an apparent tendency (I suspect due to entropy, although I am not entirely certain of this) for the plasma to "leak out" of the bottle, whence the fusion process breaks down.
It is necessary to heat the plasma to around 100 - 300 million degrees centigrade, in order to surpass the critical ignition temperature at which a deuterium nucleus will fuse with a tritium nucleus. Since both carry a positive charge, there is an inherent tendency for the two to repel one another, and this repulsive energy must be overcome; therefore the enormous temperature that is necessary for the process. There is moreover the issue of "fuel" here too. Tritium is a radioactive atom (the nucleus "triton" decays with a half-life of around 12 years) and so it does not exist on Earth in sufficient quantities to power a nuclear fission programme in Iran or anywhere else for that matter. It must be "Bred" from lithium using neutrons in an initial deuterium-tritium fusion stage, and ideally the entire process would become self-sustaining, with lithium fuel being consumed via its conversion to tritium, which then fuses with deuterium and releases more neutrons to breed more fuel. The lithium fuel would be partly employed in the form of a blanket around the reactor by way of increasing the overall tritium yield.
However, there is the opportunity of replacing the blanket of lithium by that other material, uranium, which could be "bred" into plutonium, arguably for nuclear weapons, and so I guess the Iranian proposal to introduce a nuclear fusion progamme could also be interpreted as a nuclear threat even if there is no such intention. However, I doubt the scheme is feasible, and the major political outcome is likely to be a struggle over a significant quantity of the world's oil, and all that may imply.