Transition Town Reading

The following is an update to a previous posting http://ergobalance.blogspot.co.uk/2012/02/achilles-heel-of-algal-biofuels-peak.html If anything, the situation might be worse that I had concluded then, but the issue of phosphate rock reserves is more complex than I had deduced. So, this article is as written before, but with a few more numbers worked through, to account for “real” phosphate rock, rather than my initial model of it being pure fluorapatite [Ca₅(PO₄)₃F (calcium fluorophosphate)]. The references are as appended to a full article on this subject that will appear in the next issue of the journal, Science Progress http://www.ingentaconnect.com/content/0036-8504

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 produce². If a peak in worldwide production of rock phosphate will occur within the next few decades, this will restrict the amount of food that the world will be able to produce in the future, against a rising number of mouths to feed. Additionally, there is a consensus of analytical opinion that we are also close to the peak in world oil production.

One proposed solution to the latter problem is to substitute oil-based fuels by biofuels, although this matter 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 in 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 (high compression ratio) engine to recover more of its energy in terms of tank to wheels miles, otherwise it could deliver only about 70% of the energy contained petrol, or diesel, weight for weight.

In order to obviate the competition between fuel and food crops, it has been proposed to grow algae from which to make biodiesel²⁷. Some strains of algae²⁸ can produce 50% of their weight of oil, which may be 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 hectare²⁹ is thought possible from algae, grown in ponds of equivalent area. Since the ponds can, in principle, be placed anywhere, there is no compromise over arable land, unlike fuel/food crops. Some algae grow well on salt-water too which avoids diverting increasingly precious freshwater from our normal uses for it, as opposed to the case for land-based crops which require enormous quantities of freshwater.

Diesel engines are more efficient²⁷ by about 40%, in terms of tank to wheels miles, than petrol-fuelled spark-ignition engines, and so, in the spirit of energy efficiency, we shall assume that all vehicles are converted to run on diesel. This means that a total of around 40 million tonnes/year of diesel would need to be substituted for. To produce an equivalent amount of algal biodiesel, and assuming a yield of 40 tonnes/hectare (the lower end of the 40─90 t/ha range²⁹), the algae ponds would require a total area of 10,000 km². Ideally, the algae plants could be integrated with fossil fuelled power plants, to absorb CO₂ from smokestacks by photosynthesis, driven only by the flux of natural sunlight. However, for the 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.

Two different methods are now used to estimate how much phosphate would be needed to grow this amount of algae: (1) to fuel the UK and (2) to fuel the world:(1) An analysis of dried Chlorella [http://en.wikipedia.org/wiki/Chlorella} is taken as illustrative, 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 PO₄^3- is 95, while that of P is 31).Hence this much algae would contain: 80 million x 0.0274 = 2.19 million tonnes of phosphate. By initially assuming the chemical composition of the rock to be that of fluorapatite, Ca₅(PO₄)₃F, FW 504, we can conclude that this amount of PO₄^3- is contained in 3.87 million tonnes of it. However, actual mined rock phosphate is a more impure material than this, and that normally used for fertilizer production is reckoned to contain 29─34% P₂O₅ (to be compared with 42.3% as may be deduced from the chemical formula of pure fluorapatite, above). Following the calculations so far for the quantity of PO₄^3- involved, and by using the ratio of FW for 0.5 P₂O₅/PO₄^3- (71/95), we may conclude that there are (71/95) x 2.19 million = 1.64 million tonnes of P₂O₅ contained in this amount of PO₄^3-. 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”, yielding a conversion factor of 1.34 up from the value reckoned for pure fluorapatite. We may use the latter in the remaining calculations.

World Case: The world produces and consumes 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.

Assuming that 50% of it is water, we would require twice the deduced mass of algae = 5.76 x 10⁹ tonnes of it, which contains: 5.76 x 10⁹ x 0.0274 = 158 million tonnes of phosphate. As before, by 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, we obtain a requirement of 374 million tonnes of actual mined rock phosphate.

(2) To provide an independent estimate of these figures, we may note that growth of this algae is efficient in a medium containing a concentration of 0.03─0.06% phosphorus. To avoid being alarmist, we may 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 we now 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 (assuming a density of 1t/m³) 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 PO₄^3- taken-up by the algae (2.19 million tonnes), as deduced above. This corresponds to 4.87 million tonnes of Ca₅(PO₄)₃F, and if the 1.34 “impurity factor” is applied, to 6.53 million tonnes of rock phosphate.

World Case: To meet the requirements of the entire world would demand the substitution by algae fuel of 2.88 x 10⁹ tonnes of crude oil, and an installation to produce this amount would occupy an area of 2.88 x 10⁹/40 t/ha = 7.20 x 10⁷ ha of land.

7.2 x 10⁷ ha x (10⁴ m²/ha) = 7.2 x 10¹¹ m² and at a depth of 0.3 m the ponds would occupy a volume = 2.16 x 10¹¹ m³. Assuming a density of 1 tonne = 1 m³, and a concentration of PO₄^3- = 0.092%, we need:

2.16 x 10¹¹ x 0.092/100 = 1.99 x 10⁸ tonnes of PO₄^3-, i.e. 199 million tonnes. This corresponds to 352 million tonnes of Ca₅(PO₄)₃F, or (x1.34) 472 million tonnes of actual mined rock phosphate.

This is also in acceptable 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.

Rock phosphate production¹⁰ in 2011 amounted to 191 million tonnes, against which must be compared the 472 million tonnes we have estimated would be needed to grow sufficient algae to fuel the world with algal biodiesel. Since food production is already being thought compromised by rock phosphate resource depletion, finding such a significant additional quantity is probably impossible. Currently, the U.S. produces less than 30 million tonnes of rock phosphate annually, but would require 104 million tonnes of the material to produce 22% of the world’s total algal diesel, in accord with its current “share” of world petroleum-based fuel. 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. In principle, phosphate could be recycled from one batch of algae to the next, but how exactly this might be done remains a matter of some deliberation, e.g. the algae could be dried and burned³⁰, and the phosphate extracted from the resulting “ash”, or the algae could be converted to methane in a biodigester^31,32, releasing phosphate and other nutrients in the process. Clearly there are engineering and energy costs attendant to any and all such schemes and none has been adopted as yet.

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 study³³ 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 for fuel, and those for food, even if not directly in terms of land, for the fertilizers that both depend upon. There is a dissonance in that apparently clean, renewable sources of biofuels, in reality depend on inputs of a mined and finite reserve, which not only is growing more scarce, but its recovery leaves radioactive waste as a legacy (phosphogypsum)¹⁸. In principle, at least, recycling phosphorus from one batch to the next, in algae production, might be done more readily than for land-based crops. Along with the higher relative areal yields that are possible with algae, this might alleviate the rising demand for phosphate rock.

The above, however, illustrates the complex and interconnected nature of, indeed Nature, which as 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)²⁷. Thus, the days of a society based around personalized transport powered by liquid hydrocarbon fuels are numbered. We must reconsider too our methods of farming², to reduce inputs of fertilisers, pesticides and fuel. Freshwater supplies are also at issue², in the complex transition to a more localised age that uses its resources much more efficiently.

References.

(2) Rhodes, C.J. (2012), Sci. Prog. 95, 203.

(27) Rhodes, C.J. (2008) Sci. Prog., 91, 317.

(28) Rhodes, C.J. (2009) Sci. Prog., 92, 39.

(29) Rhodes, C.J. (2012) Making Fuel from Algae: Identifying Fact Amid Fiction, in Gordon, R. and Seckbach, J. Eds. The Science of Algal Fuels: Phycology, Geology, Biophotonics, Genomics and Nanotechnology. Dordrecht, Springer, p177.

(30) Knoshaug, E.P. and Darzins, A. (2011) Chem. Engin. Prog., March, 37.

(31) Sialve, B. et al. (2009) Biotech. Adv. 27, 409.

(32) Heaven, S. et. al. (2011) Biotech. Adv., 29, 164.

(33) Clarens, A.F. et al. (2010) Environ. Sci. Technol., 44, 1813.

The title is a condensate of the latest rendition from Nigel Lawson, who served Margaret Thatcher’s government, both as Secretary of State for Energy and Chancellor of the Exchequer. In a recent interview, published by the Daily Mail (http://www.dailymail.co.uk/debate/article-2244822/Thought-running-fossil-fuels-New-technology-means-Britain-U-S-tap-undreamed-reserves-gas-oil.html), Lord Lawson makes various assertions, each of which invite some consideration and question. At bold face, his conclusions confound the difference between a resource and a reserve. Furthermore, they ignore the fact that it is not the quantity available, but the rate at which it may be recovered – and this not only as a technical but economic reality (this is the “reserve”) – which is the determinant of whether and when oil or gas will “peak”.

As an example where the former but not the latter criterion holds, we might say that it is technically feasible to mine minerals from the moon, and bring them back to earth, but in economic terms, the prospect is unrealistic. However, it is the inclusion of all known, proved, probable and theoretical, that is reckoned-up as a resource, not only ignoring technical and economic factors, but the uncertainty of whether the material is there to be had in the first place. A useful analogy for the relationship between the amount in the reserve, and how quickly it may be recovered, is that it is not the size of the tank but the size of the tap that matters.

No sensible person that I am aware of, is saying that oil or gas is going to “run out” any time soon. I give a talk entitled “What happens when the oil runs out?”, but I begin by explaining that this is not going to happen, and we will be producing oil for decades to come. That noted, continuing to produce oil at the present rate of 30 billion barrels every year is unlikely to be possible for very much longer. At some point, reckoned to be around now, conventional crude oil production will reach a maximum, and then fall relentlessly. It must – this is the nature of a finite reserve. In principle, so long as that “hole” in the output of crude oil can be filled from alternative, unconventional sources, all is well, but once the loss of conventional production exceeds the provision of the latter, the overall sum will pass into the negative; in other words, global oil production will have peaked.

Lawson begins with mention of the extraction of gas and oil from shale by hydraulic fracturing (frac’ing, for the purists, but more commonly designated as fracking). He is entirely correct that it is new technologies – horizontal drilling combined with fracking – that have brought the cost down sufficiently that exhuming gas and oil from such inaccessible reservoirs is now both practically and economically viable. In principle, shale gas can be recovered all over the world, although until an actual well is drilled, there remains speculation as to how much gas there is and indeed its quality; for example, from several shale wells in Poland, came a gas that was so heavily contaminated with nitrogen that it wouldn’t burn. It also contained high levels of hydrogen sulphide, and removing both these other gases to leave pure methane would be extremely costly. That noted, because production from shale wells, of either gas or oil, tends to decline quite rapidly, down to perhaps only 20% of the initial rate within 2 years, more wells must be drilled year on year, to maintain the overall output of a field, and this rate must be elevated to raise gas production, as is sought. Ultimately, the scheme must run up against material limits to the levels of financial investment, infrastructure, equipment and trained personnel that can be brought to bear in the effort.

As to how much shale gas the United States has, claimed in the media as sufficient to last for 100 years, detailed inspection of the available figures reveals this to relate to a resource – i.e. the most optimistic set of accounts – while the reserve (proved plus probable) is more like 20 years worth. Given the known reserves of shale oil, and the expected production from it over the next few years, it is difficult to see how the U.S. will overtake Saudi Arabia, to don once more its crown as the world’s greatest oil-producing nation, which would mean an output of about 11 million barrels a day, up from just under 6 mbd currently, by 2017. In the tally of “oil” is included other “liquids”, including biofuels, natural gas plant liquids and refinery gains, which compromise the truth, since they have different properties from crude oil – in particular, a lower energy density.

Unsurprisingly, oil shale gets a mention, for which it is claimed there is three times as much “oil” under the U.S. as has been used in the past 100 years. Yes, it’s that resource thing again. It is probably worth stressing that oil shale is not the same thing as shale oil. Shale oil (tight oil) is actual crude oil that if recovered, e.g. through horizontal drilling and fracking, can be refined in the normal way. However, oil shale does not contain oil as such, but a solid organic material called kerogen. To produce a material resembling crude oil requires large amounts of energy to heat the kerogen to above 300 degrees centigrade, in order to crack it into liquid form; the process also uses large amounts of freshwater, and churns-out an equal volume of contaminated, wastewater which must be dealt with responsibly.

There is, as yet, no commercial scale production of oil from “oil shale”, and there may never be, since it takes almost as much energy to get oil from it as will be delivered by the oil itself, i.e. pointless. The returns are better on “oil sands”, maybe 3 to 1, in energy terms – once the material has been “upgraded” to provide a liquid fuel – but here too, vast quantities of water are needed, and sufficient energy is required to extract the bitumen in the first place, that installing nuclear reactors in such locations is being considered seriously as a source of heat, currently generated by burning natural gas.

Lawson concludes, “Today, oil, gas and coal represent 80 per cent of the global energy mix. They will continue to dominate the world’s energy markets for decades to come. And within that picture, natural gas is going to offer the cheapest way to produce electricity: cheaper than nuclear energy and massively cheaper than renewables…”. He’s obviously forgotten about climate change.

One hundred feet below the Essex countryside lies the Secret Nuclear Bunker at Kelvdon Hatch, intended to house up to 600 military and civilian personnel – which may have included the Prime Minister – for 3 months, to coordinate the surviving population of London and its environs in the aftermath of a nuclear war. The bunker, in its entirety, is encased by a 10 foot thick wall, created by pouring continually some 40,000 tonnes of concrete, over a period of 7 months in 1951/52, working through the winter, and keeping the material warm by burning fires around the installation while the concrete set. The entrance to the bunker is concealed behind a very ordinary looking bungalow, and leads to a corridor 120 yards long, running into a hill. The corridor is truncated by a left, right-angle bend, intended that in the event of a nuclear blast, much of its energy would be dissipated before it could enter the main body of the bunker, which is closed-off by a pair of two-inch thick armoured-doors, each a tonne and a half in weight. A universal Faraday cage was installed to protect any electronic devices within the bunker from being taken-out by the high-energy electromagnetic pulse that always accompanies a nuclear detonation.

To allow 600 people to survive for 3 months, a supply of 24,000 gallons of water was preserved in underground tanks, along with enough food to feed that number during this time. At a daily dietary intake of 2,400 “calories” (kilocalories), a human body produces around 117 Watts of heat, and so, at full capacity, 70 kW of heat would need to be dissipated, for which an extensive cooling system was emplaced. The air supply into the bunker was drawn from the outside through a primary and secondary filtration system, and traces of dust not thus intercepted, were removed by a fine spray of water to avoid introducing any radioactive contamination. A facility was also installed with sufficient power that, in case of fire or other source of toxic release, all the air from the bunker could be extracted within 10 minutes. Since the whole is, in effect, a rather voluminous three-storey building, I imagine that to have been in there during such an operation would have been quite an experience.

Once the blast doors had been closed, that was it for the next 3 months. Some of the personnel were armed, and so anyone getting cabin fever and trying to escape would have been immediately shot, so as not to breach the security of the rest. The sanitation arrangements were interesting, since once the tanks from the latrines were full, the pumps would come into play, automatically discharging their contents to the surface in a powerful jet, possibly adding to the discomfort of anyone still surviving and unfortunate enough to get in the way of it!

In the anticipation that medical attention would be needed among the 600 throng, there was a sickbay, including a basic operating theatre, on the second floor, and also a supply of cardboard coffins, which stack flat. After about 3 days, a corpse begins to balloon with the gases of its incipient decomposition, and so the dead would be returned to the outside fairly rapidly. Since the living need sleep, there were dormitories – with the “hot bed” system intended – so that as one person went on shift, another would take his place in the warm bed, although with no lights on, this would be a noisy procedure and probably very little rest would be had by anybody.

The bunker is no longer “secret”, and is quite well signposted. It was decommissioned in 1992, and is now privately owned as a tourist attraction. Though never used for its purpose, the bunker was inaugurated entirely during the “cold war” period – such was Western fear of an all-out nuclear attack from “The Russians” – and is not a relic from WWII. Altogether, there were 12 bunkers of this kind built across the country, and connected by telephone cables set deep into the ground, so that communication could be maintained, even while the civilian population was being reduced by radiation sickness, starvation and marauding gangs, beyond those already killed instantly by the nuclear explosions.

There are many parallels that might be drawn between the mentality of the bunker, in anticipation of a nuclear attack by a foreign power, and the survival of humanity in the face of peak oil and ultimately climate change. Will a select few try to hide behind barriers, while the rest tear each other apart, fighting for what resources are left? In reality, there would have been nothing left for those in the nuclear bunker to come out to. The crops of the first year would have been destroyed by extreme cold and in the second year, there would have been little growth beneath the dust-filled skies of this nuclear winter. Much of the population would have been dead, and the land and infrastructure inhospitable to start anew. In reality, those “protected” few would have been condemned along with the huddled masses they sheltered from, once their carefully squirrelled resources had run dry.

The only course for humankind is to create a stable set of conditions, which such catastrophes cannot be part of; where our immediate security is not vulnerable to disruptions in exogenous global supply chains or threats from external forces. We, all of us, stand or fall together in the unfolding future – a choice of implementing the structures of local resilience over those of global dependency.The threat to human civilization is no longer of an external kind, but lies in our actions and behaviour – we cannot hide from ourselves.