Friday, April 28, 2006

"Peak Oil" has just Arrived.

At $75 a barrel, the age of cheap oil is over, and its consequences are about to unfold upon us all. So hang on to your seats! I wrote about "Peak Oil" in an earlier posting so entitled, explaining the analysis by the pre-eminent petroleum geologist M. King Hubbert which indicated that the peak in production from an oil-field should occur about forty years after the peak in discovery of new wells. Despite Hubbert's detractors at the time, his prediction proved spot-on (to within a year) for U.S. oil production in the late 1960's. If Peak Oil is applicable to other fields, e.g. in Saudi, where the peak in discovery occurred in the early 1970's, we must be approaching "Peak Oil" production any time now, especially with more efficient drilling and extraction technologies introduced in the last decade or so, and I have spoken to some in the oil industry who are of the opinion that it is already with us.
Once the peak is past - the half-way point at which according to Hubbert about half the oil originally present is left in the field - production then falls with a consequent rise in the price of oil, and hence the cost of everything that depends on it, either as a raw manufacturing material or as a fuel, or both, i.e. everything we rely upon, including food, most of which is grown using chemical fertilizers made from gas or oil. World "Peak Gas" is expected to come later, probably between 2050 and 2100, depending on how fast we use it up.
In a recent interview on Radio 4, the U.K. Chancellor of the Exchequer, Gordon Brown has spoken of a "moral duty" to fight climate change (echoing the urgent words of the Archbishop of Canterbury), meaning that we should burn less carbon-based fuel, especially oil and gas, to limit global CO2 emissions. This, along with the plain limit in quantity of a unique and precious resource that is available, would auger on the side of cutting back our profligate use of it. However, if we are sliding over the peak and onto the downward span where production falls and oil becomes more expensive, an economic driver might be expected to apply a brake on the rising demand and even to send it into reverse. Mr Brown has opposed calls for higher taxes to be imposed on fuels since he feels that overall economic needs must be balanced against environmental requirements, and he has warned that global economic stability could be compromised by rising fuel costs.
Mr Brown explained that the record high of $75 a barrel could be attributed to the growing demand for oil to fire the developing economies of China and India. He stressed further that it is the poorest nations who will suffer from the effects of climate change, and that individuals have a personal responsibility toward them. Mr Brown believes that the correct course is to freeze fuel duty in an effort to restrain oil prices into check. Meanwhile, motorists were warned to brace themselves for petrol costs of £5 a gallon in the U.K., but the AA (Automobile Association, not Alcoholics Anonymous) has urged them not to panic-buy fuel as this will make the problem of supply even worse. The £5 gallon is a predicted consequence of oil process hitting the $100 a barrel threshold; however, it would bring in an additional £8 billion to the treasury from the North Sea oil revenues alone. Since oil prices have roughly trebled during the past three years, establishing both stability and sustainablilty of supply is superlative; yet the resource is not sustainable.
The aviation industry is not exempt from the fall-out of rising fuel costs and British Airways have recently increased the fuel surcharge for long-haul flights by £10 to £60 per passenger. The hiked-up prices can be put down to fears over security in the supply of fuel, ranging from the impact of hurricanes on the oil fields off the eastern coast of the United States (e.g. the Gulf of Mexico, which has lost 300,000 barrels worth from the market) to political issues in the Middle East including a reduced supply from Iran if there is military action imposed upon this nation by the West.
If a supply crisis were to occur, petrol rationing and the use of military convoys to distribute fuel would be imposed. In other words, "The Army" would be put in charge of the whole fuel distribution network of garage forcourts, petrol tankers, oil-refinaries and oil-tankers. Mr Brown has asked the G-7 countries to unite in finding a solution to the volatility in oil prices by stabilising supplies of oil and to develop alternative sources of energy. Ironically, he also urged a boost in oil production which surely will drag the world more rapidly down the down-side of Hubbert's Peak and is a short-term solution at best, if it is a solution at all.
On first reading, a call on the World Bank to invest in developing a financial framework (whatever that means in truth?) so that developing countries - mainly China, India and Brazil - might provide for their (rising!) energy demands using low carbon emitting sources sounds like a good idea, but we come back once more to a sheer density of energy production which is probably impossible to meet by renewables, at least on the enormity of the scale required. The whole show is simply unsustainable, and the G-7 nations should put their heads together to revamp global society into a less energy consuming and sustainable means: this would be a serious commitment both to global CO2 emissions and surviving beyond "Peak Oil".

Wednesday, April 26, 2006

Chernobyl Shows a Green Light for Nuclear.

Unthinkable though it would have been 20 years ago, the lights have changed from red to amber and look set to turn green for nuclear power mainly because, catastrophic as the Chernobyl event in 1986 undoubtedly was, there has been no serious nuclear incident since then, despite a prediction made at the time that we could expect a calamity on an equivalent scale roughly every 10 years. This, and more decisively the desperate thinking about how we are to provide for our future energy in the light of "Peak Oil" shortages of cheap petroleum fuel, and an increasing lack of political certainties in those countries where our fuel originates (Iraq, Iran and Saudi) have passed the buck back to "nuclear" which is perceived as the more certain and most cost effective option, against a potentially shaky and expensive fossil fuel market.
Personally, I don't understand an argument that smacks to me of short-term economics. As I have explained in previous postings of this blog, even setting aside for a moment all the nuclear industry's less charming and well documented characteristics - loads of nuclear waste to dispose of securely in the long-term, including an "olympic sized swimming pool" of plutonium and uranium mix dissolved in concentrated nitric acid "found" unexpectedly at Sellafield that had poured from a fractured pipe for nine months without arousing suspicion, and is so radioactive that no one dare go anywhere near it to clean it up (so I guess it will just sit there in perpetuity); threats of terrorism; that another such Chernobyl incident could happen especially in more maverick regions of the world, and maybe we've just been lucky since Chernobyl etc. (that nothing else has "gone-up" since then) - uranium is a finite resource which will be used-up within 40-60 years, depending on the quality of the ore we are finally left with to mine, mill, process and fabricate into nuclear fuel. If the world were to go "all-out" for nuclear, we would use it all up in about 10 years or less!
The alternative is to "burn" the 99% majority isotope of uranium (uranium-238) by converting it into plutonium (239) in fast breeder reactors, a route that the French who produce nearly 80% of their nation's electricity from nuclear power plan to take in the longer term. Fast breeders have not been popular, mainly because they are perceived as less safe to operate than conventional fission reactors which "burn" the minority isotope (uranium-235), which constitutes only 0.7% of natural uranium and normally requires enrichment (using a centrifuge or gaseous diffusion) to 3.5% of uranium-235 in the nuclear fuel, unless "heavy water" rather than ordinary "light water", as comes from the tap, is used as the coolant and moderator.
Among the worrying aspects of breeder reactors are the necessity to handle plutonium which is highly toxic and that they use liquid sodium metal (which explodes on contact with water and ignites in air) as the moderator and coolant since unlike the nuclei (protons) in ordinary ("light") water, the sodium nuclei provide a poor moderator material and so do not slow down (moderate) the flux of "fast neutrons" that is required to "breed" plutonium (239) from uranium-238.
All a terrorist would need to wreak great terror and the consequent evacuation of a city such as London is a few grams of plutonium and a hand-grenade - he wouldn't need the 8 kilograms of plutonium required to make an atom bomb - a small "dirty bomb" would do just fine as a means for eliciting terror. Even the U.K. government's own Sustainable Development Committee has weighed it in the balance and found "nuclear" wanting on several counts (see my previous posting "No to Nuclear!").
Despite all of this clean and unequivocal evidence, and with the visceral thrust of Chernobyl comfortingly blunted by time, nuclear is back on the agenda as part of the energy portfolio that the U.K. government has in mind. As I have pointed out before, our emphasis must be on energy saving - less cars, more thermally efficient buildings, sea power (wave and tidal stream), micro-generation (even Her Majesty the Queen, with whom I celebrated a joint birthday on 21 April, has had a couple of hydroelectric turbines installed in the River Thames, below Windsor Castle), getting the majority of cars off the road by living in sustainable small (20,000 population) communities and so forth. This would relinquish probably 60% of the nation's annual energy demand in total and 90% of its reliance on oil - the fuel of wars and all kinds of human tragedy. Whether we like it or not, if we believe that burning oil causes global warming or not, we are shortly to be forced into a "low carbon lifestyle" by Peak Oil, who's wedge we are already seeing the thin end of, in the alarming price of oil which hit $75 a barrel a few days ago.
There are excuses being made for this, but frankly we need to be aware that oil is a precious and limited resource not to be squandered. There is nothing I can think of that isn't provided by oil either as a fuel or a chemical feedstock or both (including the fabrication of the keyboard I am typing this text on), and once it is gone it is gone for good. Certainly there is money to be made, and there are those lining their pockets by selling oil and cars, but it is future generations that will bear the cross of such foolish and selfish short term thinking. "We all need an SUV - 4x4"; well no we don't unless we live on a farm with limited transport access, but not just to take the kids to school. Transportation is the most immediate excess that humankind can tackle; forget about nuclear.

Tuesday, April 25, 2006

Chernobyl (26th April 2006); 20 Years On.

In the early hours of the morning 20 years ago tomorrow (1:23:04) an ill-conceived experiment was embarked upon, the outcome of which would change the course of history. I have documented the details in my previous posting "Chernobyl (26th April 1986)" but in summary, a conspiracy of events and circumstances resulted in an unexpected surge in the power of the Unit 4 reactor at the Chernobyl nuclear power station which caused a steam explosion from the water in the primary cooling circuit of sufficient force to rupture the containment pipes, throw the 1,000 tonne concrete lid from the top of the reactor (it now sits to the side of it, sinking into the ground by a few inches every year), and blow the roof off the building. I was working in Russia at the time, and remember the whole incident and its aftermath very well. I also recall that my Russian colleagues got most of their information about what precisely had happened from their colleagues in the West, such was the influence of Soviet secrecy at the time, which delayed immediate action on the scale necessary to deal with such a calamitous incident, and it is the opinion of some that this contributed spectacularly to the demise of the Soviet Union.
The reactor core was thus exposed to air, and at the high temperature it had been heated to by the power surge, the graphite moderator ignited and sent a plume of radioactive smoke over the western U.S.S.R., western Europe and as far as the western United States - right across the Atlantic Ocean. This was a severe disaster whose detritus ended up in pretty well everybody's back yard. "NIMBY" is not an applicable strategy for nuclear issues, it is everybody's problem.
It is estimated that about 60% of the radioactive fallout landed on Belarus (then an area of the U.S.S.R. called Byelorussia) and the Ukraine (where the nuclear power plant, and the heavily contaminated town of Pripiat are; the city of Chernobyl itself lying some distance away), and around 200,000 people were evacuated within a few days from these regions.
To mark the burden suffered by his country, Ukraine Prime Minister Yuriy Yekhanurov has pledged 20 million hryvnia (about $4 million) in this, the world's most catastrophic nuclear accident. The money is intended to be spent on awards for those involved in dealing directly with the outcome of the disaster, of whom 50 died shortly afterwards. 1,000 cars are to be provided for those invalided by its aftermath. Two new health centres are to be built and pensions increased for those who responded actively in averting the disaster from becoming even worse than it was, or for their families as many of these true heroes no longer survive. In view of the sheer scale of the disaster, its widespread radioactive contamination, and images of horror and babies born with disfiguring cancers and other infirmities of radiation exposure, it is easy to imagine that a wasteland has been left of apocalyptic "Mad Max" movie proportions. However, this would be a naive and misguided image. Although a massive resettlement of people was acted out rapidly (within 5 days), many, mostly older, people came "home" again soon after, though none dare to live in the heart of the so called "Dead Zone" which is a six-mile exclusion zone too radioactive for humans to inhabit.
For plants and animals, the situation is quite different, since the absence of human activities has allowed flora and fauna to flourish. That anything even approximately good might emerge from a catastrophe of such proportions flies in the face of conventional wisdom about the risks of nuclear power. The picture becomes dephased by the defocussing estimates of the true human tragedy wreaked upon a neighbouring population of whom 5 million were exposed to elevated levels of radiation. According to U.N. estimates, around 4,000 cancer deaths are expected as a consequence of Chernobyl; however, a recent report by Greenpeace suggests that the true figure is nearer 100,000. There are estimates that 500,000 have already died in the wake of the disaster, but this remains unsubstantiated. Undoubtedly, cancer is not the sole health problem that Chernobyl caused, and there are more widespread effects of social disintegration, partly from the displacement of a large population, the collapse of the Soviet Union, and the consequent disruption of communities and families; loss of livelihoods and a sense of foreboding dispondency and gloom which leads to harmful lifestyle changes (cigarettes and vodka).
There is the sense of living with both a stigma and a time-bomb: that "Chernobyl" will "get you", or your children eventually: a sentiment reinforced by elevated incidences of thyroid and other cancers, leukemia and other diseases, particularly in the young. The witnessing of a weakening of the future generation convinces that there is no integral future - and forges a psychological break in cultural tradition and our innate belief in the order of human lineage. That we should die before our children; not the other way round.
That flora and fauna are thriving appears as an anomaly which requires explanation. Sergey Franchuk, a guide and local expert who has worked in the area since 1982 believes that the radiation has purified the soil by some inexplicable means. Most likely it is the removal of 135,000 people from an area about twice than of Luxemburg that is the driver of fertility. Those who still live and work in the 18 mile exclusion zone do so in highly localised areas, where the radiation levels are sufficiently low to permit them to, and so the region has become a natural wilderness where, largely in the absence of humans, animal and plant life is left to flourish undisturbed. An essential difference between animals and humans is the relative longevity of the latter species. Hence animals may live-out healthy lives of normal and shorter duration than a human life-span without developing cancer; humans on the other hand are more likely to get cancer in later life. Animals are more likely to be killed by predators before they reach a ripe old age - even in terms of ages noted for animals protected in captivity.
There is talk of opening the region as a a nature reserve, but it would make sense for any tourists to prepare for their visit according to the standard radioactive dress code - not quite the self contained radiation suit, but boots, gloves and sealed clothing to minimize possible contamination. Other estimates suggest that the area will be dangerous for at least 100 years, and there is no doubt that farms even as far away as Wales remain contaminated and will do for decades. In Northern Ireland, Scotland, Wales and the west of England 81,000 square kilometers of land was contaminated to a level above 4,000 Bequerels per square metre, which is blamed for increased rates of thyroid cancer in children; most notably a 12 fold increase in Cumbria which received most of the fallout from the Chernobyl plume.
One should not be mislead into a false sense of security about Chernobyl or about nuclear power plants generally.

Saturday, April 22, 2006

"Biohydrogen - a Preposterous Idea": Letter published in "New Scientist".

I submitted a letter to the magazine "New scientist", based on my previous posting "Biohydrogen - a Preposterous Idea" (which it is) and that was published in the 8 April issue. I referred to this blog ( for details of how I arrived at this conclusion. The text is the following:

Peter Abrahams (Letters, 11 March) raises the question of how much water would be required to produce hydrogen fuel by farming algae, in response to the 25 February articles "The parched planet" (p 32) and "Green gold" (p 37). While I do not have the figures to answer this question, I have made a calculation on hydrogen production by bio-fermentation, which might prove illustrative. To replace the 54 million tonnes (and rising) of petroleum fuel currently used annually in the U.K. would require 1.78 x 10*11 cubic metres of H2. To produce this amount would need a total volume of 152 cubic kilometers of fermentation vessels, which is rather more than the entire reserve of freshwater available in the U.K. (148 km*3), assuming we had no other need for it. To grow the sugar crop for fermentation would require around 520,000 km*2 of land, which is more than twice the entire area of the U.K. mainland (most of which, of course, is not arable). The waste, mainly butyric acid (essence of sweat) and acetic acid (raw vinegar) produced would amount to around 400 million tonnes, or more than sufficient to fill Lake Windermere...and that is every year, in perpetuity. The details of these and other calculations on meeting future fuel requirements by renewables, nuclear etc are available at:, which your readers might find interesting.

The Three Degrees (...or the inevitability of global warming).

No matter what we do now, the global temperature will continue to rise. Even if Mr Blair manages to convince the rest of the world to join his gang and sign-up to a global consensus on stabilising greenhouse gas emissions, the world is likely to experience a temperature increase of 3 degrees Centigrade, according to the U.K. government's Chief Scientific Advisor, Professor Sir David King. He warned that even if such international agreement could be met - unlikely, given the U.S.'s refusal to so comply, on the grounds that to do so would "ruin the U.S. economy" as George Bush put it, and India and China's need to increase their economies in order to tackle the poverty of their combined and rising population of 2.5 billion people - at 550 parts per million of CO2, this would cause a temperature rise in excess of the 2 degrees C that the U.K. government seeks, in accord with the limits set by the European Union.
3 degrees C might not sound like much, but the consequences of such a temperature rise are forecast to be profound. For instance, it is estimated that there would be a fall in cereal production of 400 million tonnes, placing around 400 million people at risk of hunger; further stress on already dwindling supplies of fresh water would pose between 1.2 billion and 3 billion people in danger of water shortages. The effect of a 3 deg. C rise would compromise the various ecosystems of the earth, such as natural forests, few of which could adapt to the stress thus imposed upon them, and it is likely that half of nature reserves would no longer be worthwhile and one fifth of coastal wetlands would be lost to flooding.
In Professor King's view, it is unlikely that Mr Blair will manage to obtain unanimous global consensus (and practical action beyond the usual lip-service, if even that I would venture!); however, this doesn't mean we should do nothing and be bludgeoned into an attitude of apathy and despondency where we shrug our shoulders hopelessly and carry on with our business as usual. We are going to have to cut our use of fuel in any case, once the supply becomes too expensive to squander - I note this morning that the price of oil has reached $75 a barrel, and probably "Peak Oil" is already with us. So, we'd better all hang-on to our seats in the repercussions of this fact.
It is interesting though that the U.K. looks almost certainly set to miss its own target to cut CO2 emissions by 20% from 1990 levels by the year 2010 (which is only three and a half years away). I remember that when that target was set, 2010 seemed a comfortingly distant date - now it is almost with us. So, we are not setting too good an example if Mr Blair expects other nations to rally to our cause, especially developing nations like India, China and those in Latin America, all with rather more pressing agendas of their own. In the face of poverty, rhetoric about CO2 emissions must seem a nebulous luxury. At one stage the U.K. appeared to be doing well, having indeed cut its CO2 discharges into the atmosphere, but this was a red herring and had nothing to do with cuts in energy use or gains in energy efficiency, but was simply the result of switching over to cheap natural gas as a fuel for power stations, from more expensive coal, since gas is a more energy-rich fuel and produces less CO2 than coal does per unit of electricity generated. Ironically, economics now looks set to reverse this trend.
The U.K. is now a net importer of gas, and will henceforth rely on imports of gas from elsewhere, with unpredictable vagaries in its supply. (However, as a Post Script in this see-saw saga, the government has just announced its intention to build new gas-fired power plants - I wonder whether ultimately they will in fact become coal-fired?). Gas prices (and electricity prices too, since much of the U.K.'s electricity is made from burning gas) are about to increase sharply, and the government - at last! - is now called for "energy efficiency". In consequence of both forces - economic and of supply worries - it appears that we will switch, at least partly, back to coal, and this will increase the nation's CO2 emissions, unless we cut electricity production dramatically, which we won't!
In order to hit our 20% CO2 reduction target by 2010, we need to make personal changes, inasmuch as reducing use of gas/electricity in the home, at work (for those of us who are self-employed and have an office at home it is the same difference), and cutting-out unnecessary journeys. As I have commented before, by changing our society to a more "localised" level of operation, we could cut-out 90% of transportation immediately, which would eliminate 90% of 26% of the nation's total energy bill or 23%, all of which is derived from burning liquid petroleum fuel - oil! - and so our CO2 emissions would be well within the limits set for them.
The sad fact is that it matters not one iota what the U.K. does, and even if we alone do by some means meet the target set for us by our elected leadership, the good work will literally be swamped-out by the rising levels of CO2 from China, India and the recalcitrant "U.S. of A", all of them acting on economic grounds. Ultimately, all nations will be forced to cut their emissions from transportation as we head downwards on the roller-coaster of Peak Oil; an inexorable perspective heralded from the relatively comfortable flat fulcrum of "Hubbert's Peak", where we appear to be just now. We will continue to burn gas directly as a fuel to make electricity, while it remains available as a stable supply at an acceptable cost. Then we will burn coal, and lots of it.
Interestingly in the U.K., either to put a literal seal on the coal industry or in an act of spite, or both, many of the coal mines were filled with concrete. This was an economic decision, since Margaret Thatcher's government believed we would never again need our (then) uneconomic coal industry - riddled with militancy and strikes - since we were rich in gas and oil and could buy coal cheaper from Germany and Eastern Europe than mine it ourselves. Now the tables may be turned, and the current government will need to blast away the concrete as a first stage to revamp the extraction of a fuel we need once again to produce on our own shores.
It doesn't look too good regarding CO2 emissions, however, but I suspect such considerations will take an economic back-seat in the U.K. as they seem to have done in those other countries which bear more than half the world's population.

Wednesday, April 19, 2006

Coal and Dust.

In 2004, 6,000 people died in China as a result of coal mining accidents, which has added another black mark to the Chinese coal mining industry. Burning coal is furthermore a major source of arsenic poisoning in rural communities. China is both the world's largest producer and consumer of coal, and its production has increased year on year for the past 25 years to an annual output of almost 1.7 billion tonnes. While in the U.S. only a small fraction of coal is consumed domestically, perhaps 1%, in China over 50% of the energy for urban households is supplied by burning coal in stoves and small coal fired boilers. 75% of China's primary energy is produced from coal, in contrast say to the U.K. which uses less than 20%, but around 40% natural gas and 32% petroleum (including 26% used for transportation; most of the other 6% for industry) instead. The loss of 6,000 lives in a single year has prompted the Chinese government to announce the closure of 7,000 coal mines across the entire country; however, these are the smallest mines and so coal production should be overall little affected. Nonetheless, since it is the small mines that are less well regulated and operate with less stringently imposed safety rules, a significant improvement to the industry's safety record is to be expected.
At a ratio of 6,000 deaths/1.7 billion tonnes of coal, which amounts to a fatality rate of four deaths per million tonnes of coal produced, China has the worst safety record in the world. By means of comparison, the United States produces one billion tonnes of coal per year, which is an output similar to that of China, but at a death toll of 50 miners, giving a fatality rate of 0.04 per million tonnes of coal, or over a hundred times better, as a simple statistic, which it is not to those directly involved or to their families. The consequences of China's industrialisation programme, fuelled as it is by coal, are unpleasant but predictable. Air-borne pollution and smogs blight major cities, which is a problem compounded by the rising number of cars and other road vehicles. As a result, there are unprecedented levels of pulmonary (lung) disease.
However, even more rural regions such as Guizhou Province are far from immune to the effects of burning coal, where over 3,000 of its population are documented to be suffering from severe arsenic poisoning. The principal cause of this epidemic is thought to be the consumption of chili peppers that have been dried over fires fuelled by coal containing up to 35,000 parts per million (i.e. 3.5%!) of arsenic, from which they absorb an average of 500 parts per million of their own weight of arsenic. This is not the sole problem, since more than 10 million people in Guizhou Province are showing symptoms of fluorosis: an accumulation of excess fluoride in the teeth and bones. The excess fluoride arises from eating corn that has been dried over burning briquettes fabricated from coal containing high levels of fluoride bound with clay that also has a high fluoride content. A double-whammy.
The practice of burning coal in poorly ventilated homes produces high ambient levels of PAH (Polycyclic Aromatic Hydrocarbons), which are known carcinogens (cancer causing agents) and are believed to contribute to the elevated incidence of esophageal and lung cancers in parts of China. I note, however, that the Chinese tend to be heavy smokers, and it is perhaps the combined burden of these two sources of PAH that causes the problem. Incidences of mercury and selenium poisoning have also been attributed to the domestic burning of coal that is contaminated by these elements.
While this is an essentially localised "dust" problem, I find my thinking being led onto one that is not: namely, the long-range transport of mineral dust, principally from North Africa (meaning the Sahara Desert and regions north of there), into the global atmosphere. Measurements made at sampling stations over the Earth indicate that atmospheric dust can be considered as an almost homogeneous component of the atmosphere, something like a trace gas.
Soil dust is a main provider of airborne particles ubiquitously to the atmosphere, as attested to by the sighting of dust-plumes, which are one of the most prominent and commonly visible features imaged by satellites. It is thought that dust may play a fundamental role in many biogeochemical processes, though the details remain as yet speculative. Dust particles that are transported over large distances usually have a mean particle diameter of less than 10 microns (one micron is one thousandth of a millimeter, hence 10 microns is one hundredth of a millimeter. For comparison, a human hair is on average 70 microns thick). Larger particles tend to settle-out of the atmosphere before they can travel very far.
Particles of less than 2.5 microns in size have been established by the Environmental Protection Agency (EPA) as constituting a human health hazard, because they are small enough to be inhaled into the deep lung. Since dust particles from North Africa can be detected as far away as Florida, concerns have been raised regarding its potential health hazard, although clearly this kind of dust has been with humankind throughout the course of our evolution, and it is the truly anthropogenic aerosols that are a greater cause for concern, e.g. that from combustion processes, including running motorised vehicles, and sulphate particles which arise at least partly through human activities, though they are mostly an entirely natural phenomenon.
It might be argued that because of climate change and the increased desertification of central regions of Africa, e.g. the inexorable advance of the Sahara Desert that I have noted in previous postings, the atmospheric dust load is increasing and so there is a potential health issue thus connected with climate change. It is further plausible that there may be an interplay, in which increasing dust generation through global warming induced climate change participates in a feedback loop where the mobilised dust causes "climate-forcing", e.g. to cool the earth's surface by reflecting sunlight away from the earth and back into space.
In truth, these are all complex issues that cannot realistically be addressed in isolation of one another. The global experiment that we are all part of will need to run its full course before we may perceive a valid answer to any of our currently vexed questions. As the English writer Sir Osbert Sitwell put it: "But what is dust, save time's most lethal weapon...?"

Sunday, April 16, 2006

Zeolites - "The Magic Rock".

"La Roca magica", so printed a Cuban newspaper, in applaud of one of its country's greatest mineral resources - Zeolites. The first zeolite was identified in 1756 (marking this year as its 250th anniversary) by the Swedish mineralogist (Baron) Friedrich Axel Cronstedt, who observed that on heating the stones he had gathered in a blow-pipe flame, they danced about in a froth of hot liquid and steam, appearing as if the stones themselves were boiling. He thus coined the name "zeolite" which from Greek derivation means "stones that boil". The phenomenon he observed provides a vital clue to an essential property of zeolites, which is their ability to absorb a substantial proportion - perhaps half their own volume, depending on the type of zeolite - of water, and indeed of other liquids. Zeolites are aluminosilicates whose essential structure consists of a negatively charged "honeycomb-like" framework, containing (micro)pores of molecular dimensions, normally less than 13 Angstrom units (1.3 nanometres) in diameter. The pores contain sufficient (positively charged) cations to neutralise the framework electric charge, but these are loosely bound and may be exchanged with other cations from solutions placed in contact with the zeolite.
This combination of features confers particular properties upon zeolites and from which unfold a wealth of applications for them. I have already noted the use of natural zeolites (clinoptilolite) in absorbing radioactive caesium (134 and 137) and strontium (90) from the waters used in running nuclear power plants (see my previous posting: "The Stones that Boil - Radioactive Waste Management"). Indeed, it is estimated that the world level industry based on zeolites is worth around $2 trillion (i.e. $2,000 billion) annually. 4 million tonnes of natural zeolites are mined annually, of which 2.5 million tonnes are shipped to China, mainly to make concrete to supply a burgeoning construction industry as the country undergoes an unprecedented phase of industrialisation. There are 48 different types of zeolite known to occur naturally, while another 150 or so have been artificially synthesised. Synthetic zeolites can be engineered with a selectivity to perform specific tasks, and they are in any case of a more homogeneous composition than their naturally occurring counterparts. A good example of a tailored zeolite is H-ZSM-5. It is designated "H" because it is the hydrogen (proton) exchanged form that is referred to, "ZSM" because these are the initial letters of the surnames of the three scientists who created the framework material, and "5" because it was the fifth attempt that worked, attesting to the often serendipitous nature of zeolite synthesis: the previous four batches were presumably consigned to the Mobil waste disposal enterprise.
H-ZSM-5 was introduced by Mobil in 1978 to catalyse the "methanol to gasoline" (MTG) process, in which it cracked methanol (an organic compound with just one carbon atom) into hydrocarbon mixtures (generally of compounds containing 6 to 9 carbon atoms) which are suitable for combustion in internal combustion engines. H-ZSM-5 is also used on a large scale for the selective production of para-xylene, which is oxidised to terephthalic acid and then esterified with glycols to make "polyesters" for the clothing industry.
For environmental applications, it is preferable to use a natural zeolite which can be mined (ideally locally to minimise transportation requirements) and used with the minimum of processing: just crushing the raw material into a powder may be all that is needed. Natural zeolites are produced by the forces of volcanism, and are often associated with mountain ranges, e.g. the Caucasus and the Balkans, while there are also deposits found in the Himalayas and in Switzerland. Essentially, the force of molten magma, which pushes up mountains can escape through a volcanic vent and the ash/glass that is produced may turn (crystallize) into a zeolite by contact and reaction with alkaline lake or ground-waters. I have a nice slide showing a zeolite deposit in New Mexico, which shows a layer of brown tuffacious rock ("tuff") - compressed ash - lying above a layer of pure white zeolite into which it has been converted by contact with alkaline groundwater over a period of up to 50,000 years.
As noted the applications of zeolites are manifest, of which the following list is merely indicative:

*Cation exchange: radioactive decontamination, e.g. removal of Sr and Cs from "dump waters" of nuclear power stations; industrial "water softeners", to prevent lime-scale blocking up cooling pipes in manufacturing facilities; removal of heavy metals from the environment, e.g. lead, zinc, copper, mercury, cadmium.

*Use of zeolites as a "builder" in detergents, to remove and encapsulate Ca2+ and Mg2+ cations which make water "hard", rather than polyphosphates which cause algal bloom in lakes and rivers.

*Anion absorption. Environmental contamination by toxic anions may also be removed, by reaction with heavy metal cations previously exchanged into the zeolite, e.g.:
Ag+ - zeolite + Na+ I- --> Na+ - zeolite + AgI (precipated). In this example, a silver exchanged zeolite can be used for removing radioactive iodine (iodide ions) in the form of insoluble AgI, which is both formed and contained within the zeolite pores. When it is saturated, the material may be removed for disposal.
The principle may be adapted for the management of other toxic anions: e.g. cyanide, arsenic (both arsenite and arsenate), chromate, molybdate and others.

*Molecular sieves: small pore zeolites selectively absorb small polar molecules, e.g. water, and so zeolite "molecular sieves" are highly efficient drying agents for removing traces of water from other solvents.

*Hydrocarbon sieving: linear n-alkanes (needed for detergent manufacture) can be separated from branched alkanes, since the former pass more slowly through a column packed with zeolite 5A in consequence of their preferential absorption within the zeolite pores, which results in a more tortuous passage through the material. Millions of tonnes of n-alkanes are produced annually by this method.

*H+ exchanged zeolites (e.g. H-ZSM-5) are used as solid acid catalysts, e.g. for "cracking" in the petrochemical industry.

*Medical applications: Hemosorb and KwikKlot are commercial products based on zeolites which when applied to wounds (in accidents or surgery) are said to cause an "instant" cessation of bleeding. Also used in kidney dialysis machines, to absorb ammonia from blood and prevent it from building up (a job that healthy kidneys normally do).

*Agriculture: for supplying K+ and NH4+ to plants from soils that have been enriched with zeolites exchanged specifically with these cations. It is suggested that such "zeoponics", as the strategy is called, might be used to grow food on long space missions, e.g. if we ever send "a man to Mars".

*Separation of gases: there are commercial units that can provide oxygen of 95% purity for use in hospitals or for patients e.g. suffering from emphysema and other forms of Obstructive Pulmonary Disease (OPD), by separating it from air. Nitrogen (80% of air) is preferentially absorbed over oxygen because of its much larger molecular electric quadrupole moment, and so enables oxygen to separate from air almost in a state of purity.

*Use in more efficient heating systems. Essentially, the adsorbed water can be driven out of a zeolite by heat, but when the water is readsorbed, heat is given out. The principle can be incorporated into a heat-pump system which uses more of the available energy for actual heating, most of which would otherwise be wasted.

*Desulphurisation of diesel: Ni2+ exchanged zeolites have been demonstrated to absorb sulphur compounds from diesel in accord with an aim to reduce "acid-rain" emissions from transportation.

*Reduction in NOx emissions from vehicles, using zeolite-loaded "catalytic converters".

*Use of natural "tuff" as a light-weight building material, since the rock is soft enough to be cut with a hand saw and durable in fairly dry climates, or it can be fabricated into light-weight cements, e.g. in China which consumes 2.5 million tonnes of zeolite per annum for this purpose.

Zeolites are also effective in remediation strategies, e.g. around 500,000 tonnes of zeolites were used in the clean-up after the nuclear power plant disaster at Chernobyl [see my previous listing: "Chernobyl (26th April 1986)."], which involved monopolising virtually every zeolite production facility in the entire former U.S.S.R. Zeolites were fed to cattle in an effort to keep the radioactive ions out of the milk, and were baked into bread and into biscuits (cookies) for children similarly in an effort to minimise radioactive contamination in humans. Zeolites were also used (albeit on a smaller scale since the problem was far more contained) at "Three Mile Island" a decade or so before Chernobyl. Contaminated, e.g. Brown Field land may be rendered fit for building and even for agriculture by treating the soil with sufficient quantities of zeolites.

Clearly, the uses of zeolites are manifest, and offer unique environmental benefits. I am not a native Spanish speaker, but "La Roca Magica" seems to say it all. I recall that synonyms for "Magica" (the adjective form of "Magico") include "Estupenda" and "Maravillosa". Who could disagree?!

[Based on an invited lecture given by Professor Chris Rhodes at Kingston University, London, on March 15th, 2006].

Thursday, April 13, 2006

You Need Energy to get Energy - Time is Running Out.

In order to judge the viability of an energy source, it is necessary to run a full balance sheet on it, which includes the full energy costs of discovery, extraction, processing and supply, including any infrastructure that needs to be emplaced if it does not already exist for these tasks. The viability of the source is then the sum of the above, subtracted from the total energy contained by that source. As in any book-keeping exercise (or business plan, for that matter), if the net difference is significantly in the black the proposition is probably viable, or otherwise a non-starter, and not to be bothered with. As we teeter on the edge of Hubbert's Peak - the peak in oil production - beyond which extractable resources will become more limited in supply and hence inexorably more expensive, we need to know just how much oil, gas, coal and uranium the world might grasp, ignoring the unattainable resources that lie beyond its fingertips, requiring so much energy to extract that it is simply not worth the effort, and might even shift the net energy profit into the red.
A good example is the resource available in the "oil sands" of Canada, which do not actually contain oil but bitumen. I have heard it said apocryphally that to extract one barrel of oil from such "tar sands" uses the energy equivalent of one barrel of oil. It is not quite that bad, since only two barrels worth are required to extract three barrels of oil from the bitumen ("tar"), which must be processed in a fairly energy intensive manner to yield "oil". If the supply/demand ratio falls far enough, this may yet become a worthwhile option, but it is sobering to note that older, conventional oil reserves can provide 20 times the energy expended in its extraction, and newer ones about 8 times - still a pretty good deal. If Peak Oil is already with us, "Peak Gas" is not scheduled to arrive until around 2100, and we hear that there are 300 years worth of coal left. Of course, these figures refer to current rates of use, and if we substitute these other fuels for oil, there will be a shift forward in their "Peak Production".
So goes an argument based on simple common sense. It is actually worse than this, however, because it is the best, the richest veins of coal or uranium for that matter, as I have commented previously, that will be extracted first. Of course it will: on level economic grounds, clearly the energy used in the extraction and processing costs money (the debit side of the balance sheet) to be offset against the credit side of providing a rich (high energy) fuel primary source. As the best is used up, so increasingly poorer coal and uranium must be dug, and this ultimately to the point when it is no longer viable to do so, and the net energy that may be obtained from the material is exceeded by that demanded for its extraction.
Even if we were armed with full "projections" in our energy business plan, and we knew the timing of the production peaks, and then their production "tails" matched against extractive energy costs, the ball nevertheless rolls down in the same direction. Once resources are used they cannot be restored - ever - and this is the brutal truth of Hubbert's analysis. Although in a common sense overview this is obvious, we still seem surprised in our dawning acknowledgement of the fact of the situation.
If this is the case for non-renewable primary energy sources, then we might find a brighter future for "renewables" which by definition are inexhaustible and will not peak, then tail-off and finally run out. I am all in favour of renewables in principle, but (e.g. my previous postings on Wind, Biohydrogen, Biofuels) I do not believe we can compensate for the loss of the concentrated forms of fuel we have come to rely on by these far more dispersed forms of energy. Whatever course we chart, there is no alternative initial step to devising strategies to use less energy in the first place, particularly in terms of transportation, which uses 54 million tonnes of the total 67 million tonnes of oil (equivalent) consumed annually in the U.K. alone; 12 million tonnes of that being burned by the aviation industry (this will have to stop!). I estimate that by localising our society into smaller communities of say up to 20,000 population (simply on the basis that this number could live in an area of about two miles square and could get around mostly without cars) supplied mainly by local farms, we could cut our use of transport fuel by 90%. This would put us down for only about 5 million tonnes of fuel annually, from the 54 million we presently use, which is an enormous saving.
It is estimated by the Oxford Environmental Change Institute that about 50% of space heat for buildings could be saved through more thermally efficient materials and design. CHP energy schemes are more efficient than separate large scale heat and power production, and if applied locally further losses by national distribution systems (e.g. the "national grid" for electricity distribution) are avoided. Even on a national level, it would be more to the point to burn natural gas directly to provide heat (which delivers up to 90% of the energy contained in the primary fuel), rather than first converting the gas to electricity and using that as a heat source (which recovers only about 35% of the fuel's energy overall).
Having made these demand savings, we are then asking far less from renewables, which may, in a combination of localised (CHP, micro-hydroelectric, wind) production methods, along with larger scale production, e.g. sea-power (wave power; stream power turbines, which probably would still need a grid network as they are impractical on a small scale), provide a significant proportion of what we finally discover we actually need. But so far there is no all-out commitment to any such intention, not even at the level of coherent government policy on the production and use of energy. If we are at the peak of oil production, with the other fuel peaks to follow suite, surely it makes sense to use some of the resources that we still have available to us in a serious effort to investigate the possibilities that renewables might provide, rather than continuing to burn oil profligately until we hit a wall of resource depletion, which will furnish an impassable barrier to achieving the sustainable future use of our resources which really is the only way forward.

Wednesday, April 12, 2006

Methane Gas Hydrates - Vast Energy Resource or Ecological Disaster Awaiting?

A vast and untapped resource of fuel? A contributor to global climate change? A submarine hazard, and potential trigger of tsunami's? A cause of catastrophic species extinction: an ELE; Extinction of Life Event? All of these are possible scenarios for methane gas hydrates. Methane hydrate is formed when methane gas and water are brought together under suitable conditions of low temperature and elevated pressure, such that an "ice" type structure is formed containing methane molecules in considerable quantity. It is thought that vast quantities of methane hydrate exist on the ocean beds and in the sediments of the sea floors and in permafrost, and some speculate that it might be possible to harvest the material to provide a massive reserve of methane as a fuel. Gas hydrates are among the class of materials known as "clathrates", in which guest molecules occupy cavities (pores) within a host structure. The whole field is part of what is known as "guest-host" chemistry. In a fully saturated methane-hydrate, the material holds 164 times its own volume of methane gas, but packed tightly within its confines. The hydrate provides, therefore, an effective storage unit for methane.
The temperature at which methane-hydrate is stable depends on the prevailing pressure. For example, at zero degrees C, it is stable under a pressure of about 30 atmospheres, whereas at 25 deg. C, nearer 500 atmospheres is needed to maintain its integrity. The occlusion of additional gases within the ice structure tends to add stability, whereas the presence of salts (e.g. NaCl, as from sea water) requires higher stabilising pressures. Appropriate conditions of temperature/ pressure exist on Earth in the upper 2000 metres of sediments in two regions: (i) in permafrost at high latitudes in polar regions where the surface temperatures are very low (below freezing), and (ii) submarine continental slopes and rises, where not only is the water cold (around freezing), but the pressures are high (greater than 30 atmospheres). Thus, in polar regions, methane-hydrate is found where temperatures are cold enough for onshore and offshore permafrost to be present. In offshore sediments, methane-hydrate is found at water depths of 300 - 500m, according to the prevailing bottom-water temperature. There are reported cases where "chunks" of methane-hydrate break-loose from the sea bottom and rise to the surface, depressurizing and warming, where they "fizz" from the release of methane as they decompose to the gas/water state.
There are manifold and widely disputed estimates of exactly how much methane-hydrate there is. However, a figure of 10*16 cubic metres (m*3) of methane gas occluded within the entire global deposits of this material is probably a reasonable estimate. One estimate (Dobrynin et al., in "Long-Term Energy Resources," Pitman, Boston, 1981, pp. 727-729) puts the total at nearly 10*19 m*3, but this is the only one of such magnitude. Notwithstanding, the quantities of methane-hydrate are vast, and in view of this, it is thought that it might provide a potentially significant energy source, probably at least four times the entire reserve of fossil fuels (gas, oil, coal) known (estimated). As "Peak Oil" bares its teeth, the possibility appears increasingly attractive. However, the actual extraction of methane from this source is beset by a number of difficulties: e.g. low permeability of sediments, which restrict the actual flow of methane; lack of sustained interest from the oil/gas industry (though this may well change, vide supra, according to rising pressures of demand upon the existing limited resource); current limited gas-industry infrastructure at methane-hydrate locations; and the fact that no good field example has yet been demonstrated of the successful production of methane from its gas-hydrate. All these considerations score on the negative side as far as methane-hydrate becoming a serious fuel source is concerned.
Methane is a greenhouse gas and is often cited as having a global warming potential around 20 times that of an equivalent quantity of CO2, released into the atmosphere. I am slightly at odds with this argument which seems to downplay the effect of methane, since the model assumes the release of equal volumes of methane and CO2 simultaneously, and then integrates the influence over twenty years (by which time about four-fifths of the methane will have been removed by oxidation in the Troposphere). In my view, a more realistic model is one of "steady release" of both methane and CO2, in which case the global warming potential is equal to the "instantaneous radiative forcing constant", which is nearer 110, not 20; i.e. the global warming potential of methane is a lot worse than it is given credit for!
It seems clear that in a warming world (for whatever reason), methane will be released in increasing quantities, e.g. from warming permafrost, thus augmenting global warming. Disturbances on the sea bed may also cause the decomposition of methane-hydrate. It is known that drilling into methane hydrate poses a hazard to oil prospecting operations, and it is also thought that decomposition of methane hydrate with an eruption of methane could trigger a tsunami. More catastrophically, it is believed by some that world-scale eruptions of methane from these "ice" deposits can have triggered climate-change (global warming) on a cataclysmic level, most notably the Permian-Triassic (P-T or PT) extinction event, sometimes informally called the Great Dying, which was an extinction event that occurred approximately 252 million years ago, forming the boundary between the Permian and Triassic geologic periods. It was the Earth's most severe extinction event, with about 90 percent of all marine species and 70 percent of terrestrial vertebrate species going extinct.
For some time after the event, fungal species were the dominant form of terrestrial life, and perhaps this is where the planet is ultimately heading once more...

Saturday, April 08, 2006

Oily Fish?

For twenty years, I have heard that eating "oily fish" is good for you. Suddenly, its health benefits appear less certain. Four years ago, I attended the EUROFEDA conference in Cambridge on antioxidants (held at Churchill Hall; a college devoted to science and technology, and named in honour of Winston Churchill, who believed that it was new technology that would help to win the war, and then rebuild and advance the nation). The concluding remark of the chairman of this conference was that the term "antioxidants" should be reversed to the older "micronutrients", in accord with the concluding affirmation that even after forty years research, we know little about the dietary molecular properties of these materials but that on epidemiological grounds - e.g. the "Mediterranean diet" - they are "good for you". However, having been invited to lecture in Greece a few years back, I was thoroughly struck by the apparent level of contentment among the people I met and I wonder whether it is so much the diet and more so the less stressed prevailing human mental state in the Mediterranean countries which furnishes the greater health benefits.
Also according to epidemiological studies (medical statistics), Green Tea is believed to protect against both breast and prostate cancer; however, there is recent evidence that the role of the majorly effective polyphenolic compound EGCG is not that of a free radical scavenger (antioxidant) but that its cluster of OH groups enable it to bind to the cell surface and presumably alter the cell signaling mechanism in such a way that a cancer is avoided. Thus, while many "antioxidants" undoubtedly can intercept free radicals and ameliorate their influence in damaging proteins and DNA, their molecular complexity lends to them a further role at the level of molecular biology which is sufficient to prevent the progression from a simple molecular lesion to a cancer. Hence the word "micronutrient" may prove more global than "antioxidant". We have recently published a review (Chemico-Biological Interactions, 160 (2006) pages 1-40) of the role of free radicals, metals and antioxidants in the development and prevention of cancer.
So, what about the "oily fish"? Are they good or bad for you? A major review has been published by researchers at the University of East Anglia (UEA) on the subject, the balance of which suggests that oily fish are not necessarily all they have been cracked up to be. The topic was overviewed by The Independent recently (Friday 24 March). Sales of fish oil capsules provide a thriving industry, aimed at those who wish to obtain the health benefits, but can't stand the taste of the fish themselves. Interestingly, a study called DART-2 published in 2003 changed the overall view, since it concluded that in a study of over 3,000 men, there was a higher death rate from heart disease in those taking fish oil capsules. This reminds me, in fact, of a similar study named CARET (published in 1999? from memory), which aimed to investigate the anti-cancer properties of beta-carotene. The project was stopped after only nine months when a 20% increase in cancer rates was discovered among those taking the supplement compared with the control (i.e. those who weren't on it).
However, the UAE review, which includes 89 different studies of omega 3 fats (the key ingredient in fish oils) found no clear evidence that they are of any benefit at all in protecting against heart disease, strokes or cancer. The British Heart Foundation has speculated that these finding might be linked to mercury levels in fish, which was a suggestion made by the UEA authors. Mercury is highly toxic and accumulates in oily fish which live in waters contaminated with the metal and its compounds. There was a notable and extreme case which occurred in Japan in the early 1950's at the seaside fishing village of Minamata, on Kyusha Island, where the cats went mad from eating fish contaminated by dimethylmercury, a potent neurotoxin formed by biological methylation of mercury compounds which had been dumped into the sea water by industry. Humans too sustained considerable health problems, including death.
We are of course not speaking of anything on the scale of Minamata, but organomercury compounds like dimethylmercury may well show toxic effects, even at relatively low levels, and it is the general consensus that more research is needed on fish oils (and oily fish themselves, I presume, not just the synthetic oils in isolation?) to resolve the whole matter.
I shall await the results of this with a lively interest, but meanwhile try to even out the odds by eating a reasonably balanced diet!

Sunday, April 02, 2006

The Nuclear Age.

In the minds of many is set the view that the forces of nuclear power are so horrible that its activities should immediately be ended. Surely, we all stand before the images of Hiroshima and Nagasaki in a stunned and fearful contemplation. This is the clear and underpinning manifestation of our horror; and even if we have not witnessed atom bombs as agents of war in our own lifetimes (these images are now old), the media representations of the disaster at Chernobyl, and of the human burden which is its aftermath, fill us with dread. We are warned there are many potential "Chernobyls" awaiting us in a rotting nuclear legacy.
The U.K. is a small island-land, buffeted by the winds and tides; surely we might use this good-fortune to supply our energy from "wind-power", from "wave-power", since we also have sufficient economic resources to implement the technology this would require. Failing this, the U.K. remains sufficient in coal and can access oil and gas reserves; again because we can pay for it. So we, at least, could do without nuclear power, if we so decided. But, there is, as I have documented in this series of postings, a limit upon which we can place precisely what could be substituted by "renewables" for the colossal energy use that sustains modern society, and which must surely cease, in an alternative adoption of localised and communal societies. We might indeed "make it" if we chose our course carefully, growing our own food, insulating our houses and constructing them from more thermally efficient materials, and living in smaller communities of an estimated size of a mile or so square (hence containing just a few thousand people; i.e a village settlement), and moreover in this estimate thus shoving all the SUV's and most of the other unnecessary petroleum impelled vehicles off the road . We have in the U.K. enough coal, certainly for 200 years or so, and for the next decade or so we can probably buy-in enough hydrocarbon fuel; but we may need to fund an appropriate university to research into the"sequestration" of the consequent CO2 emissions (as Gordon Brown has promised in the recent budget) which will use-up anywhere up to 40% (no-one knows, so this is an average) of the energy produced in burning it in that particular "nappy changing" process!
Many countries have less choice, lacking both funds and natural resources. In the former Soviet state of Armenia, nuclear power is considered the lesser of evils in providing sustainable energy for the future. Armenia is in a precarious position: political instabilities - notably its conflict with Azerbaijan - prevent a reliable oil supply into the country; Lake Sevan has been severely drained for hydroelectric power, which has impacted on its ecology; the forests have been devastated - cut for firewood. Even some environmentalists in Armenia agree that the nuclear power plant is the only feasible means to fulfill this country'’s energy needs. Neighbouring countries are concerned, however, since the Armenian nuclear power plant, near the town of Metsamor, is located on an earthquake fault-line; the plant was closed in 1988, amid fears for its safety, when a large part of northern Armenia was devastated by an earthquake.
The main problem with running nuclear power plants (NPP'’s) is the interception and disposal of the nuclear waste that they generate. If, in the absence of alternatives, NPP'’s will continue to operate into the foreseeable future, it is vital to ensure they do so as safely as possible, and their radioactive waste must be contained securely.

A nuclear power plant will not explode like an atomic bomb, as many believe and fear. It was not a nuclear explosion that occurred at Chernobyl, but a conventional explosion caused by the development of enormous steam pressure in one of the reactors. Therefore, while the worst outcome will never be the cataclysm of Hiroshima or Nagasaki, it may cause the wholesale contamination of large areas, and potentially of their human and animal populations, by radioactive material (an accidental "dirty bomb"). Such catastrophes are extravagant events whose likelihood is minimised by adherence to correct operational practices and maintenance procedures for NPP'’s. Should such a terrible event occur, it is necessary to clean-up the radioactive detritus, having evacuated those populations most at risk; generally in near proximity of the event, or those at the mercy of adventitious weather-plumes which deposit the contamination more widely.
Radioactive material is an inherent feature of NPP's, since they use an initial radioactive fuel, which produces further radioactive products of its "burning". While radiation can be employed in humanly useful applications, some of which are mentioned later, it is highly toxic to humans: radiation can modify the constituent molecules of living cells - DNA is especially vulnerable, and is very dangerous when damaged, since later biological events in living cells can propagate mutations and cancers. This is principally why we fear radiation.
In an NPP, the nuclear fuel is contained in the form of "fuel-rods" which are in contact with cooling water. Some of the radioactive material is leached-out into this water, and must be removed prior to its drainage into the environment.

Zeolites are naturally occurring minerals with a tremendous capacity to absorb environmental pollution, both from radioactive and other kinds of contamination; indeed, thousands of tonnes of zeolites were transported to Chernobyl during the resulting clean-up process; some of which were mined in Armenia. The word "zeolite" means "stones that boil", a feature which provides a clue to their abilities overall: the structures of zeolites comprise tiny holes, comparable to the size of individual molecules (micropores), into which actual molecules may be sorbed. In consequence, natural zeolites usually contain a large quantity of water which, when they are heated, erupts as a froth of hot liquid and steam, appearing as though the stones themselves are boiling. Their facility of molecular sorption confers to zeolites a number of important applications, for example: "catalytic cracking" in the petroleum industry; as drying agents (molecular-sieves) in chemical synthesis; in the separation of oxygen from nitrogen in the air; in ion-exchange. Of this (highly incomplete) list, "ion-exchange" is the accomplishment of zeolites most central to the issue of radioactive decontamination. The structure of a zeolite may be viewed as an essential porous framework, which carries an overall negative electrical charge; this is neutralised by the presence of positively charged ions (cations), e.g. H+, Na+, K+, Ca2+, Mg2+, and many more (some cations have one and others two units of positive charge, depending on their type of atom). In consequence of some delicate interplay between the charges in zeolites and the size of their micropores, a given zeolite will have a different affinity for different cations. We most often encounter this effect in "water softeners", some of which use zeolites, and so the calcium (Ca2+) and magnesium (Mg2+) cations that make water "hard" are absorbed into the zeolite, by displacing into the water those H+ or Na+ cations originally present (H+ and Na+ cations do not cause water hardness). The process is called "ion-exchange".
The cooling-water from nuclear power plants is contaminated with strontium (Sr2+) and caesium (Cs+) cations, which are radioactive, and hence are a cause for concern. These contaminants are present at low levels in relatively large volumes of water (8,000 tonnes per year are produced from the Armenian NPP). Clearly, this water cannot simply be "dumped" into rivers or drained into the ground, while acknowledging unnerving tales from less-enlightened days when precisely this was done. (It is probably a fair judgement, that all parties involved in the early years of nuclear power each had their own share of calamity).
It is uneconomic and impractical to simply boil-off the water to obtain the Cs+ and Sr2+ as a residue for further use or disposal. The ion-exchange capacity of zeolites comes into its own right here; in a collaborative project involving U.K. and Armenian scientists, the NPP cooling water is filtered through barrels loaded with a natural zeolite called clinoptilolite. Each barrel contains about "half-a-ton" of zeolite. Clinoptilolite is especially abundant in Armenia, and may be mined for this and other applications. In its natural condition, the zeolite is rich in Na+, Ca2+, Mg2+ and K+ cations, which are displaced by Sr2+ and Cs+ cations ("water-hardness" is not an issue here!). Ultimately, the displacement is complete, and the zeolite is saturated with radioactive cations, which are now in a fairly concentrated form. The zeolite is then removed, either for recovery of the Cs+ and Sr2+ in the form of chemical compounds, such as CsCl and SrCl2, or for long-term disposal, as discussed later. Fresh charges of zeolite are next introduced, and the entire process is repeated.
Clinoptilolite does not occur as a pure material, but needs to be purified from accompanying rock and clay. The crude mineral is known as "tuff". This is first crushed into a fine gravel, and then treated with dilute acids and alkalis, to release the zeolite in almost pure form. Experiments are underway to improve the efficiency of clinoptilolite in ion-exchange, and to increase its selectivity for Cs+ and Sr2+ cations. The aim is to make the whole process of cleaning NPP cooling water more effective, so that the output water contains the minimum possible levels of these cations. Such an improved zeolite would also need to be replaced less often, but this is not a major consideration given the overall costs involved.
The simplest way to monitor the speed of an ion-exchange process and its efficiency, is to compare, over time, the cations in the input solution with those in the output water. This does not, however, reveal the inner-workings of the zeolite. Sorption into the zeolite may be investigated using a variety of molecules as probes. To investigate the diffusion of the cations themselves, radioactive ions are often employed, e.g. 137Cs+ and 90Sr2+ cations may deliberately be added to an input solution and monitored by measuring their radioactive decay. This is a very sensitive method. Since the solvent (water) plays a major part in the whole process, it is also necessary to determine its diffusion, for which a similar approach, using radioactive water, might be helpful. Alternatively, more complex cations can be introduced, responsive to the pervasive "eye" of spectroscopy, which reveals their movement within the zeolite in association with the solvent. This system provides by far the greater insight.
Since zeolites are not fully transparent to light their contents remain largely invisible, unless they are squeezed artificially into very thin wafers; alternatively, a magnetic "eye" can be used. A magnetic field can penetrate large samples, even a human body in magnetic resonance imaging (MRI), used to scan for cancers and other diseases; therefore a small zeolite sample presents no obstacle. A selectively designed cation probe is introduced to the input water and allowed to be absorbed into the zeolite micropores. The entire sample is then placed in a strong magnetic field. Since the cation probe is a tiny molecular magnet, we could measure the magnetic strength of the collection of these magnets in the zeolite, which would be futile as it would only tell us what we knew already - i.e. how many probe molecules we had introduced. There is no need for disappointment, since a greatly sophisticated adaptation of the strategy is possible, based on the fact that the magnetic molecules are sensitised by the applied magnetic field to absorb very weak microwaves, which can also penetrate zeolites easily. Since the detail of the microwave absorption depends on how the cations and the solvent water molecules coexist and diffuse within the zeolite structure, the influence of the electrical charges in differently treated zeolites can be determined. Information is thereby provided, on the molecular level, about the relative efficiency of different zeolites in ion-exchange.
The aim of this work is to provide an immediate evaluation of batches of clinoptilolite, before they are introduced directly to clean the NPP cooling water output. This will help to minimise overall operational costs.

Disposal of nuclear waste.
One question stands-out from the many - what ultimately is to be done with thousands of tonnes of zeolites, heavily laden with concentrated radioactive material? Since there are beneficial uses for radiation, it may sometimes be advantageous to recover Cs+ and Sr2+ cations, by re-ion-exchanging the zeolite with Ca2+ cations. In the highly concentrated form of their compounds, e.g. CsCl and SrCl2, 137Cs+ and 90Sr2+ may be used to irradiate other materials for a variety of purposes: radiation kills bacteria, so food and medical supplies (bandages and surgical instruments) can be sterilised; radiation can be used in cancer-treatment; plastic materials with specific properties can be created with radiation; there are many such applications. Alternatively, and ultimately, radioactive material must be disposed-of. Clearly, this must be done carefully, with respect for the longer-term. In isolation, zeolites store radioactive cations very securely; they are also highly robust materials, and resist the effects of radiation so their integrity is preserved over many hundreds or thousands of years. In this respect alone, zeolites are far superior to ion-exchange resins, which sustain severe damage from radioactive cations, and can no longer contain them after even only a few years. The security may be further supplemented by melting the zeolite into glass "bricks", which are then stored.
It is essential to choose a final storage site well-away from groundwater, otherwise ion-exchange and erosion forces will slowly release the radioactive charge into the environment. One example is Yucca Mountain, in Nevada. Here, the storage channels are situated at least 200 metres both below the surface, and above the water-table; the annual rainfall is also very low. The channels are sealed in clay, and are further reinforced by rich veins of zeolites present at lower levels, to guard against the long-term leaching of radioactive material into the environment. It is intended to store the entire radioactive output of the U.S. nuclear industry over the next 100 years at Yucca Mountain; there it will remain for millennia. High-level nuclear waste from fuel reprocessing will also lie here. Other such sites will need to be found for other centuries and other countries; an on-going effort will be required, while nuclear power continues.

A nuclear future?
It is for politicians to decide on the future of nuclear power, and I am not a politician. In any event, it is clear that existing NPP'’s will continue to operate for decades to come; indeed, the former USSR has for some time considered that a realistic sustainable energy programme requires their proliferation; an opinion now shared by the U.K. government. Political decisions are driven by economic will and priority, and both the decommissioning of NPP'’s and their substitution by alternative technologies, will prove extremely costly (estimated at £85 billion in the U.K., alone). It is arguable that money is not the only cost involved, but that long-term radioactive pollution (including acts of terrorism) is the ultimately high price. These are all complicated issues, which are the responsibility of our politicians, but while they are debated, and weak nuclear empowered economies have little choice of alternatives, there will be nuclear power. It is my own hope that the present time reflects a temporary and interstitial period, pending the ultimate resolution of economic and social dilemmas. Meanwhile, science can offer some practical consolation, both in reducing future contamination from NPP'’s and in mitigating past legacies. We can at least try to "cleanse" the nuclear earth, and so minimise our own legacies to it.
There is a rider to all such considerations: namely that uranium is not an unlimited resource. The final day for nuclear power must surely be reached when its vital fuel has run-out, and this may occur in only 50 years, unless we go down the route of fast-breeder reactors which the French are focussed upon in the long-term and that strategy would eke-out the uranium [by "burning" the 99+% isotope of uranium (238) via its conversion into plutonium (239)] perhaps to several hundred years, but by flooding our planet with a mightily toxic material that terrorists would rub their hands with joy in handling it (though carefully!).