Sunday, February 26, 2012

The Thorium Age Waits in the Wings.

There is much written to the effect that thorium might prove a more viable nuclear fuel, and an energy industry based upon it, than the current uranium-based process which serves to provide both energy and weapons - including "depleted uranium" for armaments and missiles. There are different ways in which energy might be extracted from thorium, one of which is the accelerator-driven system (ADS). Such accelerators need massive amounts of electricity to run them, as all particle accelerators do, but these are required to produce a beam of protons of such intensity that until 10 years ago the prevailing technology meant that it could not have been done. As noted below, an alternative means to use thorium as a fuel is in a liquid fluoride reactor (LFR), also termed a molten salt reactor, which avoids the use of solid oxide nuclear fuels. Indeed, China has made the decision to develop an LFR-based thorium-power programme, to be active by 2020.

Rather like nuclear fusion, the working ADS technology is some way off, and may never happen, although Professor Egil Lillestol of Bergen University in Norway is pushing that the world should use thorium in such ADS reactors. Using thorium as a nuclear fuel is a laudable idea, as is amply demonstrated in the blog "Energy from Thorium" ( to which there is a link on this blog (above left). However, the European Union has pulled the plug on funding for the thorium ADS programme, which was directed by Professor Carlo Rubbia, the Nobel Prizewinner, who has now abandoned his efforts to press forward the programme, and instead concentrated on solar energy, which was another of his activities. Rubbia had appointed Lillestol as leader of the CERN physics division over two decades ago, in 1989, who believes that the cause is not lost.

Thorium has many advantages, not the least being its greater abundance than uranium. It is often quoted that there is three times as much thorium as there is uranium. Uranium is around 2 - 3 parts per million in abundance in most soils, and this proportion rises especially where phosphate rocks are present, to anywhere between 50 and 1000 ppm. This is still only in the range 0.005% - 0.1% and so even the best soils are not obvious places to look for uranium. However, somewhere around 6 ppm as an average for thorium in the Earth's crust is a reasonable estimate. There are thorium mineral deposits that contain up to 12% of the element, located at the following tonnages in Turkey (380,000), Australia (300,000), India (290,000), Canada and the US combined (260,000)... and Norway (170,000), perhaps explaining part of Lillestol's enthusiasm for thorium based nuclear power. Indeed, Norway is very well endowed with natural fuel resources, including gas, oil, coal, and it would appear, thorium.

An alternative technology to the ADS is the "Liquid Fluoride Reactor" (LFR), which is described and discussed in considerable detail on the blog, and reading this has convinced me that the LFR may provide the best means to achieve our future nuclear energy programme. Thorium exists naturally as thorium-232, which is not of itself a viable nuclear fuel. However, by absorption of relatively low energy "slow" neutrons, it is converted to protactinium 233, which must be removed from the reactor (otherwise it absorbs another neutron and becomes protactinium 234) and allowed to decay over about 28 days to uranium 233, which is fissile, and can be returned to the reactor as a fuel, and to breed more uranium 233 from thorium. The "breeding" cycle can be kicked-off using plutonium say, to provide the initial supply of neutrons, and indeed the LFR would be a useful way of disposing of weapons grade plutonium and uranium from the world's stockpiles while converting it into useful energy.

The LFR makes in-situ reprocessing possible, much more easily than is the case for solid-fuel based reactors. I believe there have been two working LFR's to date, and if implemented, the technology would avoid using uranium-plutonium fast breeder reactors, which need high energy "fast" neutrons to convert uranium 238 which is not fissile to plutonium 239 which is. The LFR is inherently safer and does not require liquid sodium as a coolant, while it also avoids the risk of plutonium getting into the hands of terrorists. It is worth noting that while uranium 235 and plutonium 239 could be shielded to avoid detection as a "bomb in a suitcase", uranium 233 could not, because it is always contaminated with uranium 232, which is a strong gamma-ray emitter, and is far less easily concealed.

It has been claimed that thorium produces "250 times more energy per unit of weight" than uranium. Now this isn't simply a "logs versus coal on the fire" kind of argument, but presumably refers to the fact that while essentially all the thorium can be used as a fuel, the uranium must be enriched in uranium 235, the rest being "thrown away" and hence wasted as "depleted" uranium 238 (unless it is bred into plutonium). If both the thorium and uranium were used to breed uranium 233 or plutonium 239, then presumably their relative "heat output" weight for weight should be about the same as final fission fuels? If this is wrong, will someone please explain this to me as I should be interested to know?

However, allowing that the LFR in-situ reprocessing is a far easier and less dangerous procedure, the simple sums are that contained in 248 million tonnes of natural uranium, available as a reserve, are 1.79 million tonnes of uranium 235 + 246.2 million tonnes of uranium 238. Hence by enrichment 35 million tonnes (Mt) of uranium containing 3.2% uranium 235 (from the original 0.71%) are obtained. This "enriched fraction" would contain 1.12 Mt of (235) + 33.88 Mt of (238), leaving in the other "depleted" fraction 248 - 35 Mt = 213 Mt of the original 248 Mt, and containing 0.67 Mt (235) + 212.3 Mt (238). Thus we have accessed 1.79 - 0.67 = 1.12 Mt of (235) = 1.12/224 = 4.52 x 10*-3 or 0.452% of the original total uranium. Thus on a relative basis thorium (assuming 100% of it can be used) is 100/0.452 = 221 times as good weight for weight, which is close to the figure claimed, and a small variation in enrichment to a slightly higher level as is sometimes done probably would get us to an advantage factor of 250!

Plutonium is a by-product of normal operation of a uranium-fuelled fission reactor. 95 to 97% of the fuel in the reactor is uranium 238. Some of this uranium is converted to plutonium 239 and plutonium 241 - usually about 1000 kg forms after a year of operation. At the end of the cycle (a year to 2 years, typically), very little uranium 235 is left and about 30% of the power produced by the reactor actually comes from plutonium. Hence a degree of "breeding" happens intrinsically and so the practical advantage of uranium raises its head from 1/250 (accepting that figure) to 1/192, which still weighs enormously in favour of thorium!

As a rough estimate, 1.4 million tonnes of thorium (about one third the world uranium claimed, which is enough to last another 50 years as a fission fuel) would keep us going for about 200/3 x 50 = 3,333 years. Even if we were to produce all the world's electricity from nuclear that is currently produced using fossil fuels (which would certainly cut our CO2 emissions), we would be O.K. for 3,333/4 = 833 years. More thorium would doubtless be found if it were looked for, and so the basic raw material is not at issue. Being more abundant in most deposits than uranium, its extraction would place less pressure on other fossil fuel resources used for mining and extracting it. Indeed, thorium-electricity could be piped in for that purpose.

It all sounds great: however, the infrastructure would be huge to switch over entirely to thorium, as it would to switch to anything else including hydrogen and biofuels. It is this that is the huge mountain of resistance there will be to all kinds of new technology. My belief is that through cuts in energy use following post peak oil (and peak gas), we may be able to produce liquid fuels from coal, possibly using electricity produced from thorium, Thorium produces less of a nuclear waste problem finally, since fewer actinides result from the thorium fuel cycle than that from uranium. Renewables should be implemented wherever possible too, in the final energy mix that will be the fulcrum on which the survival of human civilization is poised.

Thursday, February 23, 2012

Thorium Nuclear Power – A Lesson From Norway.

Norway holds a resource of 170,000 tonnes of thorium, which amounts to 15% of the world’s total of 1.2 million tonnes. There is far more thorium than that within the earth’s crust all told, averaging 8 ppm compared with around 2.8 ppm for uranium, but the above figures refer to richer ores, most commonly monazite sand which contains up to 12% of thorium. There is some opinion that thorium nuclear power might be a better environmental/energy-strategy for Norway than relying on carbon-capture which many consider to be uneconomic. However, the matter of thorium reactors is not straightforward. Professor Egil Lillestol of Bergen University has been pushing thorium for some years now, and thinks that Norway should set the trend in building a prototype accelerator-driven reactor in which a massive particle accelerator converts thorium-232 to uranium-233 by irradiating it with slow (spallation) neutrons generated by the impact of a 1.6 GeV proton beam on a lead target. The conversion is not direct, and involves the initial formation of thorium-233, which decays rapidly to protactinium-233, and then to uranium-233 over a period of about a month. Hence presumably reprocessing is involved in the final stage, since if the protactinium-233 is left in the reactor it will be at least partly converted to protactinium-234, which is not a useful fissile material.

It may well turn out that thorium is the better nuclear fuel as compared with uranium, since it offers the advantages that: (1) it is present in around 3 times the abundance of uranium on Earth, overall, (2) it can be bred into the fissile nuclear fuel uranium-233, (3) far less plutonium and other transuranic elements are produced than is the case from uranium fuel, (4) the thorium fuel cycle might be used to consume plutonium, thus reducing the nuclear stockpile while converting it into useful electrical energy.

However, it is a very big accelerator that will be needed to do the job, and the estimated costs for the project are about 500 million Euros. There are various advantages cited for this type of reactor, including the claim that it can be stopped easily if things get out of hand, and that it produces less long-lived nuclear waste than the uranium-fuelled fission reactors that are currently in common use. However, there are a whole host of scientific and engineering challenges that need to be overcome, and even identified in the first place because nobody has ever built one of these reactors, and hence the plans are still only on the drawing board.

As I have already stressed, it is a very big accelerator that will be needed if the project has any chance of success, so big in fact that there are none with sufficient power anywhere in the world. Some of the suggestions include using molten lead as the coolant for the system, but the reactor would run at a temperature above 700 degrees C. when the material becomes corrosive. A number of countries (including the US, Russia, the UK, France and Japan) have entrenched firm investments in uranium based reactors, and will use them for as long as they can. There are sizeable quantities of uranium on the world market, although the price has recently soared. Nonetheless, there is likely to be resistance to the research and development of a brand-new technology based on thorium, in view of huge costs that will effectively be borne by the Norwegian taxpayer if they go it alone down this unlit path.

The immediate future doesn’t look optimistic for thorium, certainly with the untested accelerator-driven reactors, and yet two thorium reactors have been operated, which were of the far simpler molten-salt reactor kind. Thus it might prove more expedient to invest in this at least tried technology, which could extend the useful lifetime of nuclear power by hundreds of years. The reason is that converting thorium-232 to uranium-233 is a form of “breeder” technology meaning that practically 100% of the thorium can be processed ultimately into nuclear fuel, rather than just the 0.7% uranium-235 isotope that exists in naturally occurring uranium, and which requires enrichment before it can be used. Indeed, the 99+% of uranium-238 can be converted into plutonium-239 and this used in fuel-rods, but there are many negative connotations attached to plutonium, which is almost the “p-word” for the nuclear industry: i.e. unmentionable, certainly in the tabloid press. There are serious issues of terrorism – dirty bombs at the very least, if not an out and out A-bomb detonation involving plutonium. The word alone would swathe a city and the world with fear. Uranium-233 made from thorium is harder to conceal than plutonium, since it is always contaminated with uranium-232, a strong gamma-ray emitter, and accordingly quite easily detected “in a suitcase” than plutonium which is principally an alpha-particle emitter and far more readily hidden.

There is no doubt that we will see a rise in nuclear power and for a number of reasons – cutting CO2 emissions, and securing energy supplies. Most of current thinking is based around using uranium as the fuel to drive it, but thorium could prove a very useful supplement and might power a new generation of reactors when we are short of uranium and do need to “breed” fuel if it proves uneconomic to mine poor quality uranium ores. I maintain my reservations about how long other resources, e.g. oil and gas will last, with which to mine and process either uranium or thorium, but if the latter appears viable in the longer run, I suggest that molten salt (liquid fluoride) reactors would be a better approach than the far more complex (and as yet untested) accelerator-driven systems.

The latter are reminiscent in scale to the putative nuclear-fusion reactors, said to mimic processes in stars, e.g. the sun, of which a working model is not expected for at least another 60 years. No one should forget that we need to make our energy provisions against a backdrop of 10 – 20 years at best, as oil and then gas begin to run short (the “Oil Dearth Era”). We do not want to back a loser now, as it is a one-off bet with the future of civilization resting on the outcome of this particular race.

Related Reading. There is also a link at the top left hand corner of this blog.

Wednesday, February 15, 2012

The Achilles' Heel of Algal Biofuels - Peak Phosphate.

The depletion of world rock phosphate reserves will restrict the amount of food that can be grown across the world, a situation that can only be compounded by the production of biofuels, including the potential large-scale generation of diesel from algae. The world population has risen to its present number of 7 billion in consequence of cheap fertilizers, pesticides and energy sources, particularly oil. Almost all modern farming has been engineered to depend on phosphate fertilizers, and those made from natural gas, e.g. ammonium nitrate, and on oil to run tractors etc. and to distribute the final produce. A peak in worldwide production of rock phosphate is expected by 2030, which lends fears over how much food the world will be able to grow in the future, against a rising number of mouths to feed [1]. Consensus of analytical opinion is that we are close to the peak in world oil production too.

One proposed solution to the latter problem is to substitute oil-based fuels by biofuels, although this is not as straightforward as is often presented. In addition to the simple fact that growing fuel-crops must inevitably compete for limited arable land on which to grow food-crops, there are vital differences in the properties of biofuels, e.g. biodiesel and bioethanol, from conventional hydrocarbon fuels such as petrol and diesel, which will necessitate the adaptation of engine-designs to use them, for example in regard to viscosity at low temperatures, e.g. in planes flying in the frigidity of the troposphere. Raw ethanol needs to be burned in a specially adapted engine to recover more of its energy in terms of tank to wheels miles, otherwise it could deliver only about 70% of the "kick" of petrol, pound for pound.

In order to obviate the competition between fuel and food crops, it has been proposed to grow algae to make biodiesel from. Some strains of algae can produce 50% of their weight of oil, which is transesterified into biodiesel in the same way that plant oils are. Compared to e.g. rapeseed which might yield a tonne of biodiesel per hectare, or 8 tonnes from palm-oil, perhaps 40─90 tonnes per hectare is thought possible from algae [2], grown in ponds of equivalent area. Since the ponds can in principle be placed anywhere, there is no need to use arable land for them. Some algae grow well on salt-water too which avoids diverting increasingly precious freshwater from normal uses, as is the case for growing crops which require enormous quantities of freshwater.

The algae route sounds almost too good to be true. Having set-up these ponds, albeit on a large scale, i.e. they would need an area of 10,000 km2 (at 40 t/ha) to produce 40 million tonnes of diesel, which is enough to match the UK's transportation demand for fuel if all vehicles were run on diesel-engines [the latter are more efficient in terms of tank to wheels miles by about 40% than petrol-fuelled spark-ignition engines], one could ideally have them to absorb CO2 from smokestacks (thus simultaneously solving another little problem) by photosynthesis, driven only by the flux of natural sunlight. The premise is basically true; however, for algae to grow, vital nutrients are also required, as a simple elemental analysis of dried algae will confirm. Phosphorus, though present in under 1% of that total mass, is one such vital ingredient, without which algal growth is negligible. I have used two different methods of calculation to estimate how much phosphate would be needed to grow enough algae, first to fuel the UK and then to fuel the world:

(1) I have taken as illustrative the analysis of dried Chlorella [3], which contains 895 mg of elemental phosphorus per 100 g of algae.

UK Case: To make 40 million tonnes of diesel would require 80 million tonnes of algae (assuming that 50% of it is oil and this can be converted 100% to diesel).
The amount of "phosphate" in the algae is 0.895 x (95/31) = 2.74 %. (The Formula Weight, FW of PO43- is 95, while that of P is 31).

Hence that much algae would contain: 80 million x 0.0274 = 2.19 million tonnes of phosphate. Taking the chemical composition of the rock as fluorapatite, Ca5(PO4)3F, FW 504, we can conclude that this amount of "phosphate" is contained in 3.87 million tonnes of rock phosphate. In fact, rock phosphate is a more impure material than this, and the mineral usually used for fertilizer production is reckoned to contain 29─34% P2O5. From the ratio of FW for PO43-/0.5 P205 (95/71), we may deduce that there are (71/95) x 2.19 million = 1.64 million tonnes of P2O5 contained in the above amount of “phosphate”. Taking the range average of 31.5% for the mineral P concentration, reckoned as P2O5, this would accord with 5.20 million tonnes of actual “rock phosphate”, a conversion factor of 1.34.

World Case: The world gets through 30 billion barrels of oil a year, of which 70% is used for transportation (assumed). Since 1 tonne of oil is contained in 7.3 barrels, this equals 30 x 109/7.3 = 4.1 x 109 tonnes and 70% of that = 2.88 x 109 tonnes of oil for transportation.

So this would need twice that mass of algae = 5.76 x 109 tonnes of it, containing:
5.76 x 109 x 0.0274 = 158 million tonnes of phosphate. As before, taking the chemical composition of the material as fluorapatite, Ca5(PO4)3F, FW 504, this amount of "phosphate" is contained in 279 million tonnes. Applying the factor of 1.34 as arrived at above, to account for the typical degree of impurity in the mineral, this accords with 374 million tonnes of actual mined rock phosphate.

(2) To provide an independent estimate of these figures, I note that growth of this algae is efficient in a medium containing a concentration of 0.03─0.06% phosphorus; since I am not trying to be alarmist, I shall use the lower part of the range, i.e 0.03% P. "Ponds" for growing algae vary in depth from 0.3─1.5 m, but I shall assume a depth of 0.3 m.

UK Case: assuming (vide supra) that producing 40 million tonnes of oil (assumed equal to the final amount of diesel, to simplify the illustration) would need a pond/tank area of 10,000 km2. 10,000 km2 = 1,000,000 ha and at a depth of 0.3 m, this amounts to a volume of: 1,000,000 x (1 x 104 m2/ha) x 0.3 m = 3 x 109 m3.

A concentration of 0.03 % P = 0.092% phosphate, and so each m3 (1 m3 weighs 1 tonne) of volume contains 0.092/100 = 9.2 x 10-4 tonnes (920 grams) of phosphate. Therefore, we need:

3 x 109 x 9.2 x 10-4 = 2.76 million tonnes of phosphate, which is in reasonable accord with the amount of phosphate taken-up by the algae (2.19 million tonnes), as deduced above. This corresponds to 4.87 million tonnes of Ca5(PO4)3F, or by applying the 1.34 “impurity factor” to 6.53 million tonnes of rock phosphate.

World Case: The whole world needs 2.88 x 109 tonnes of oil, which would occupy an area of 2.88 x 109/40 t/ha = 7.20 x 107 ha of land to produce it.

7.2 x 107 ha x (104 m2/ha) = 7.2 x 1011 m2 and at a pond depth of 0.3 m they would occupy a volume = 2.16 x 1011 m3. Assuming a density of 1 tonne = 1 m3, and a concentration of PO43- = 0.092%, we need:

2.16 x 1011 x 0.092/100 = 1.99 x 108 tonnes of phosphate, i.e. 199 million tonnes. This corresponds to 352 million tonnes of Ca5(PO4)3F, or 472 million tonnes of rock phosphate.

This is also in reasonable accord with the figure deduced from the mass of algae accepting that not all of the P would be withdrawn from solution during the algal growth.

Now, world rock phosphate production amounts to around 140 million tonnes (noting that we need 472 million tonnes to grow all the algae), and food production is already being thought compromised by rock phosphate resource depletion. The US produces less than 40 million tonnes of rock phosphate annually, but would require enough to produce around 25% of the world's total algal diesel, in accord with its current "share" of world petroleum-based fuel, or 118 million tonnes of rock phosphate. Hence, for the U.S., security of fuel supply could not be met by algae-to-diesel production using even all its indigenous rock phosphate output, and significant imports would still be needed. This is in addition to the amount of the mineral necessary to maintain agriculture.

The world total of rock phosphate has been reckoned at 8,000 million tonnes (Mt) and that in the U.S. at 2,850 Mt, using a Hubbert Linearization analysis [4]. The total world reserve, as expressed in terms of P2O5 content, is estimated to be in the range 3,600─8,000 Mt [5]. However, as is true of all resources, what matters is the rate at which it can be produced, and that once the peak is reached, what remains will be inexorably harder (of diminishing EROEI) to recover. The peak in world oil production will impact on the peak in phosphorus production, since rock phosphate, and all other mineral substances, is mined and recovered using machinery powered by liquid fuels that are refined from crude oil.

I remain optimistic over algal diesel, but clearly if it is to be implemented on a serious scale its phosphorus has to come from elsewhere than mineral rock phosphate. There are regions of the sea that are relatively high in phosphates and could in principle be concentrated to the desired amount to grow algae, especially as salinity is not necessarily a problem. Recycling phosphorus from manure and other kinds of plant and animal waste appears to be the only means to maintain agriculture at its present level beyond the peak for rock phosphate, and certainly if additionally, algae are to be produced in earnest. In principle too, the phosphorus content of the algal-waste left after the oil-extraction process could be recycled into growing the next batch of algae. These are all likely to be energy-intensive processes, however, requiring "fuel" of some kind, in their own right. A recent study [6] concluded that growing algae could become cost-effective if it is combined with environmental clean-up strategies, namely sewage wastewater treatment and reducing CO2 emissions from smokestacks of fossil-fuelled power stations or cement factories. This combination appears very attractive, since the impacts of releasing nitrogen and phosphorus into the environment and also those of greenhouse gases might be mitigated, while conserving precious N/P nutrient and simultaneously producing a material that can replace crude oil as a fuel feedstock.

It is salutary that there remains a competition between growing crops (algae) for fuel and those for food, even if not directly in terms of land, for the fertilizers that both depend upon. This illustrates for me the complex and interconnected nature of, indeed Nature, and that like any stressed chain, will ultimately converge its forces onto the weakest link in the "it takes energy to extract energy" sequence. It seems quite clear that with food production already stressed, the production of (algal) biofuels will never be accomplished on a scale anywhere close to matching current world petroleum fuel use ( > 20 billion barrels/annum). Thus, the days of a society based around personalized transport powered by liquid hydrocarbon fuels are numbered. We must reconsider too our methods of farming, to reduce inputs of fertilisers, pesticides and fuel. Freshwater supplies are also at issue, in the complex transition to a more localised age that uses its resources much more efficiently.

There is a Hubbert-type analysis of human population growth which indicates that rather than rising to the putative "9 billion by 2050" scenario, it will instead peak around the year 2025 at 7.3 billion, and then fall [7]. It is probably significant too that that population growth curve fits very closely both with that for world phosphate production and another for world oil production [7]. It seems to me highly indicative that it is the decline in resources that will underpin our demise in numbers as is true of any species: from a colony of human beings growing on the Earth, to a colony of bacteria growing on agar nutrient in a Petri-dish.

Related Reading.
[2] “Making Fuel From Algae: Identifying fact Amid Fiction,” BY C.J.Rhodes, in Algal Fuels: Phycology, Geology, Biophotonics, Genomics and Nanotechnology, J.Seckbach (ed.), Springer, Dordrecht, in press.
[3] "Chlorella" - Wikipedia.
[6] “Environmental Life Cycle Comparison of Algae to Other Bioenergy Feedstocks,” By Andres F. Clarens, Eleazer P. Ressurreccion, Mark A. White and Lisa M. Colosi, Environ. Sci. Technol., 2010, 44, 1813.
[7] "Algae to Biofuel Conversion; Survival in the Oil Dearth Era," By C.J.Rhodes, Science Progress, 2009, Vol. 92, 39.

Sunday, February 12, 2012

Regenerative Agriculture: The Transition.

It is an illusion to think we can continue to use as much energy as we do now. No one can entirely rule-out that some extravagant technology will be forthcoming, e.g. solar power or nuclear fusion on the full-scale of 500 EJ/year as we get through now, but the particular issue of matching liquid fuels derived currently almost entirely from petroleum appears insurmountable. The "solution" is probably the collective of individual solutions, and that means adopting a completely different paradigm of human philosophy and intention. The most pressing demand is how to feed the population of the world, and how to adapt industrialised conurbations, with cities provided for entirely from external regions for their food and electricity. If oil is the most vulnerable element in the energy-mix as the life-blood of transportation, then we must aim to live with less transportation, and this includes the means and distribution implicit to modern food production.

I have spoken about regenerative agriculture and permaculture, in which most of the energy involved in running them is provided quite naturally by native soil fauna fed ultimately by photosynthesis, since the fuel for good soil derives from plants as the factories that supply carbon-rich nutrients and in a wonderful symbiosis, the living soil microbes, especially fungi can draw other nutrients and water from the soil to nourish the plants. The individual elements of life feed one another in a mutually dependent and beneficial manner.

While the two scenarios can be defined and envisaged rather clearly, the intermediate means for transition from industrial to regenerative agriculture is rather more nebulous, since it has not been done before, or at least not in the degree that necessity now demands. So how might we perform this revolution in the least painful way?

For a start, a decolinising and restructuring of present industrialised agriculture is necessary along with an appreciation and magnification of native and traditional food systems. Overall, a change in thinking and concept is required from conflict and limit to cooperation and abundance.

The scale of the transition may be compared with other milestone transitions throughout human history, such as the hunter-gatherers becoming farmers, and then modern industrial societies. It is the latter that are under threat and unsustainable, and a compromise devolution to a more localised collective of small communities (pods) is required, supplied by local farms and infrastructure with rail links between them for essential movement of goods and people. The maintenance of the Internet and electronic communications would seem desirable since ideas and knowledge can be transmitted from pod to pod and between countries and continents.

In the 1970s, there were studies done that evaluated the massive inefficiency in energy requirements for food production. It was concluded that 10 Calories of energy are expended to bring 1 calorie of food onto the dinner plate. It has been stressed that essential agricultural production is to yield food and fibre - i.e. the essential elements of biomass. One might also add-in fuel as a product, if the consideration also includes fermentation of sugars form starch into ethanol, or hydrothermal production of liquid and gaseous fuels from biomass by heating it under pressure in the presence of water.

The impending stress of "climate change" is well acknowledged, e.g. sea-level rise and the spreading desertification of formerly green lands, but its impact on agriculture is rarely mentioned by climate-modellers. However, as a for-instance, it is speculated that the Colorado River basin could dry up. It's mighty dams would then look something like the pyramids of Egypt, maybe leaving future generations to speculate as to what their purpose was, and upon the nature of the civilization that created them. As climate zones shift, it is the variability of the weather that will have greater impact than ramping "mean temperatures" on the enormous investment made by humans in agriculture. The capital outlays required for new dams, irrigation supplies and the retraining of farmers will need to be contrasted with that for flood-defences in vulnerable locations (e.g. New Orleans and the east coast of England). Most likely both cannot be supported and it may prove expedient to simply let some regions "go to the sea".

Biodiversity is a natural means for evening-out the gains and losses of of living system. It is cooperative in the sense that pests are not encouraged as they are by growing single strains of crop, and that suitably matched plants help each other to grow - the holistic whole being more robust than the simple measure of its components. The term "global village" tends to signify an interconnected unity of trade or electronic communication, while aspects of cultural diversity and biodiversity seldom enter the line of thinking. However, it is a necessity to preserve and expand the traditional food and fibre production systems that are tried and tested and whose regenerative capabilities have been demonstrated over millennia. We may adapt to or readopt cultures that have been lost, as industrial civilization has supplanted them, and it is the latter that we must seek to break away from to arrive at a sustainable future, if we are to survive as a human species that is.

If "global village" means "global supermarket", the term lends acceptance to the concomitant rule of multinational corporations. If we restructure societies to become self-sustaining, rather than dependent on inputs and indeed outputs, as they are now, we also must abandon "limited liability" and the legal designation of "corporations" as "persons" with the same rights as individual citizens. Traditional food systems are storehouses both of biodiversity and cultural diversity. It is a pity that the seedbanks around the world contain no information about the culture, economy, details of cultivation methods, flavour or other human aspects of the crops and the food they produce. Including my own musings on the topic, most commentators on the post peak oil world refer to the need to localise food systems, such that small populations are provided for locally by means of community farms. However, establishing regenerative systems to grow food and fibre must include cities too, the design of which must be analysed in terms of the natural mechanisms that interweave them.

It is mostly not realised that the rural development or redevelopment urged by the industrialised nations for the developing world are precisely those they need to adopt themselves. E.F.Schumacher's "Buddhist Economics" which he describes in the bestselling "Small is Beautiful - A Study of Economics as if People mattered", applies equally to the industrialised world as it must of needs de-industrialise, and take lessons from simpler societies which consume far less per head of population. The example of Cuba may be taken as a benchmark for progress, as it has survived and indeed thrived through implementing a system of community gardens, in the abrupt absence of cheap and plentiful oil and fertilizers gifted from the Soviet Union when its regime collapsed in 1989.

We can mention too the Gaia hypothesis of James Lovelock, which has acted as an iconic beacon to the environmental movement, drawing-in a range of people dissatisfied with the industrial and materialistic way of life, and who seek alternative, more natural and or spiritually rewarding lifestyles, and with less detriment to the planet and life upon it. "Gaia" is holistic in nature and is based on ecology. Rather than an indstrialised "global village" it implies a "globe of villages". Food and fibre production is one of the most important features of the transition to a post-fossil fuel era, to which the establishment of regenerative food systems is essential.

Related Reading.
K.A.Dahlberg, "A Transition From Agriculture to Regenerative Food Systems," Futures, (1994), 26(2), 170-179.

Wednesday, February 01, 2012

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 postulated 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. Over the longer term, since the methane is oxidised to form carbon dioxide, the global warming effect is that of an increased burden of CO2. 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, which extinguished the life of up to 96% of all marine species and 70% of terrestrial vertebrae species. Because so much biodiversity was lost, the recovery of life on Earth took significantly longer than after any other extinction event, and hence it has been dubbed as the "mother of all mass extinctions."

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...