Global Warming is Nonsense - According to the "Daily Mail."

The Daily Mail, having recently published an interview with Nigel Lawson, which attempts to convince its sentient readership that Peak Oil is nonsense http://www.dailymail.co.uk/debate/article-2244822/Thought-running-fossil-fuels-New-technology-means-Britain-U-S-tap-undreamed-reserves-gas-oil.html is now embarked on a mission to alert us to the news that Global Warming is yet another myth http://www.dailymail.co.uk/news/article-2294560/The-great-green-1-The-hard-proof-finally-shows-global-warming-forecasts-costing-billions-WRONG-along.html. I published a rebuttal to the DM's Peak Oil coverage, in which I emphasised that it is not a matter entirely of how large the reserve (let alone resource!) might be, that will determine the instance and timing of a production peak - of oil, gas, coal or indeed any other finite commodity - http://oilprice.com/Energy/Crude-Oil/Peak-Oil-is-Nonsense-...-Because-Theres-Enough-Gas-to-Last-250-Years.html, but rather the rate at which the material can be extracted, according to prevailing physical, geological, economic and technical determinants.

I concluded the article with the line "He's obviously forgotten about climate change", but whatever Lord Lawson's recollections are, the Daily Mail is compelled to the view that anthropogenically-driven global warming is a phantom. Having done some basic sums on the subject, with a German colleague Alexander Koewius http://www.koewius.de/Website/Climate_Change.html, which show that rising levels of greenhouse gases in the atmosphere, particularly CO2,  are expected to elevate the mean global temperature considerably, I find such assertions less than convincing. Rather as resources are all too frequently confused with reserves, to make a case that there is plenty of "oil" to be had, but which in any case say nothing about actually getting it out of the ground - i.e. reserves are static reckonings, while production is a dynamic process - any apparent "flatness" of the recent climate temperature record (if it is real http://liberalconspiracy.org/2013/01/10/global-warming-is-not-at-a-standstill-despite-ignorant-claims-in-uk-press/ http://www.guardian.co.uk/environment/2013/mar/27/climate-change-model-global-warming) ignores the difference between trend and variation. A lovely illustration of this is of a man walking a dog on a beach. If you watch the dog, he meanders all over the place (variation), but in fact is heading in a define direction, according to his master's wishes (trend) http://www.skepticalscience.com/trend_and_variation.html. As the elements prevail upon us over the longer term, trend is climate, while weather is variation.

Through the latter link http://www.skepticalscience.com/trend_and_variation.html is a video clip which shows that straight lines can be "fitted" which imply an absence of warming over different periods, and yet the overall trend is to a higher mean global temperature. If indeed it were to prove the case that the Earth has stopped warming, then the question arises of "where is the excess thermal energy going?" It has been suggested that some of this is being stored in the deep oceans https://www2.ucar.edu/atmosnews/news/5364/deep-oceans-can-mask-global-warming-decade-long-periods, and if this is so, when it resurfaces, we are likely to be in deep trouble indeed, through the forcing of complex and interwoven mechanisms of the Earth System. i.e. We are likely be hotter, (wetter or dryer, depending on location and sea-level proximity), and hungrier than we thought. Will the variations oscillate with greater amplitude, or run out of control?... we simply will not know the outcome of this, the greatest geo-engineering experiment in human history, until it is concluded, but the consequences of burning all the carbon we can get our hands on are unlikely to be favourable http://math.350.org/.

Wind for Hydrogen - An Update.

This is an update of some numbers from an older posting http://ergobalance.blogspot.co.uk/2007/10/ulf-bossel-platinum-and-hydrogen.html in light of the larger commercial wind turbines that are now available http://ergobalance.blogspot.co.uk/2012/01/shaky-foundations-for-offshore-wind.html. There is some improvement in the overall figures, but the task of switching from oil to hydrogen remains stupendous.

At the outset, we should note that hydrogen does not occur free in nature but must be freed from other elements, such as oxygen in water, with which it is naturally combined, and the separation of elements requires other forms of energy. Almost all the hydrogen used currently in the world - principally as a chemical feedstock e.g. for oil refining and making artificial fertilizers - is made by steam-reforming natural gas, and there is a CO2 budget that must be costed-in, hence hydrogen from this source is not clean but contributes to CO2 emissions. Furthermore, it consumes natural gas, and so there is a further demand placed on another resource, in accord with the indisputable fact that it takes resources to extract resources. Ideally therefore, that hydrogen should be produced by e.g. water electrolysis using electricity made from renewable sources.

Some while ago, Ulf Bossel pointed out http://www.fuelcellforum.com/reports/E21.pdf there are losses at each stage in the chain of production, storage and distribution for hydrogen. There is obviously a loss of 50 - 60% incurred when the material is oxidised in a fuel cell, but in its favour is the fact that an efficiency of even 40 - 50% is substantially above the Carnot-cycle limit (Thermodynamics again) of around 35% for a typical internal combustion engine. The losses may be summarised as follows: 90% efficiency for rectifying alternating current to DC to run the electrolyzer; 75% overall efficiency (ideal) for the electrolyzer itself; and then the storage of the bulky hydrogen gas either as a highly compressed gas, which takes about 20% of the energy content of the hydrogen to compress it (or as a cryogenic liquid, which takes 30 - 40% to produce); 10% for distribution and say 50% efficiency for the fuel cell itself, which amounts to about a 25% efficiency overall.

There are electrolyzer units http://www.nrel.gov/docs/fy04osti/36705.pdfthat can produce high pressure hydrogen and if each gas-station were to make its own hydrogen by electrolysis, much of the distribution losses (probably 30%) might be avoided. A report has been published by a firm of independent analysts in Germany which is critical of some of Bossel's figures http://mpfc.de/pdf/LBSTonBossel.pdfespecially in regard to storage and transmission, particularly across large distances say from sunny north Africa (if the hydrogen were produced using PV technology which would be much more efficient there) by pipeline to Europe. However, an in-situ arrangement as I allude to would surely get around that, presuming we could make enough renewable electricity, or if there were a grid of electrons (rather than of hydrogen) including north African PV, European wind-power, North Sea wave energy and so on, such power might be supplied to run local electrolysis equipment, which would avoid actual hydrogen transmission. But if Bossel is right, why not use these electrons in a more direct manner?

On a tit-for tat basis, we can make the following calculation:

The heat of combustion of hydrogen is -285 kJ/mol, and so 1 kg of hydrogen = 1000 g/2 g/mol x -285 kJ= -142,500 kJ = 1.425 x 10^8 J.

We get through 82 million tonnes of oil altogether annually in the UK and we use 60 million tonnes of that for fuel. The energy content of oil is rated at 42 GJ/tonne and so that 60 million tonnes "contains" 60 x 10^6 x 42 x 10^9 Joules = 2.52 x 10^18 J of energy.

Hydrogen can be produced at a pressure of up to 10,000 psi by electrolysis at a rate of 60.5 kW/kg of H2. Hence the equivalent H2 to match that amount of oil is:

2.52 x 10^18 J/1.425 x 10^8 J/kg = 1.768 x 10^10 kg H2. Bossel has used the conversion factor of 1.5, i.e. that H2 can be used with 1.5 times the recoverable energy efficiency of gasoline. Since gasoline gives an approximately 14% well-to-wheel efficiency that would make about 21% overall for hydrogen, which seems a bit low and I would think that say 59% for the electrolysis system x 90% for rectification x 50% for the fuel cell = 26.6% is more like it.

However, let's consider the generating capacity the whole enterprise would need. To make 1.768 x 10^10 kg of H2 over a year, i.e. 8760 hours, would require:

1.768 x 10^10 kg x 60.5 x 10^3 (W/kg H2)/8760 = 122.1 GW. But this figure is mitigated according to the efficiency with which hydrogen may be used. If Bossel is right, this becomes 81.4 GW or let's call it a factor of two (which seems more reasonable), making it 61.0 GW.

Either way, we would need a colossal installation of renewables, e.g. 5 MW wind-turbines, with a rated capacity of 5 MW - but an actual output of say 30% if placed offshore, which amounts to 1.5 MW per unit. Hence we would need 61 GW/1.5 MW = 40,667 of them. Probably these could be accommodated in the North Sea in a 202 x 202 square of turbines, and at an average spacing of "ten rotor diameters", i.e.  1.23 km,we are talking about an area of 247 kilometers squared (= 61,113 km^2), which doesn't sound too bad, albeit that the weather in the North Sea is some of the roughest in the world, and so maintenance might prove a problem. If the turbines were placed around the coast of the U.K. mainland (assumed to be 2,500 km in length), at a mutual separation of 1.23 km, 2,033 turbines could be so accommodated in a single strand, and to contain all of them, a band would be created, 40,667/2,033 = 20 turbines deep. Assuming that same 1.23 km separation, this would be 25 km (15 miles) wide. So, how quickly might this farm of 40,000+ wind turbines be created? The question really is one of "how long is a piece of string?" but assuming that one turbine could be fabricated and installed every day, the process would take at least 111 years, and probably far longer, in reality.

As an alternative, around 60 new nuclear reactors could be installed to make the electricity for hydrogen, and on top of the new generation required to replace the decommissioned current 31 reactors, actually equal in output to about 14 1 GW reactors, and so it would be necessary to quadruple this capacity by which means to install a "Hydrogen Economy" in the UK. I have been told that hydrogen could be made more efficiently using the thermal power from a nuclear reactor to run the iodine-sulphur cycle, rather than by electrolyzing water (50% compared to 35%) , but the installation capacity needed remains huge. If Bossel is right and electrons can be used with three times the efficiency than will be recovered (hydrogen actually re-generates electrons in the fuel cell, to turn wheels, in a chemically-fuelled electric car) by turning them into hydrogen, the installation capacity immediately falls to 20 new nuclear power stations, or about 13,555 turbines, which is still enormous but appears more achievable.

I am not ruling out hydrogen altogether but simply making the point that when oil supplies begin to wane, it is not a simple matter of switching from oil to hydrogen, but a new and vast infrastructure must be implemented first, to both produce and use hydrogen. The question looms: is it worth it, or might there not be better ways to deal with our impending transportation problems, such as relocalising society to use less transport? Even those who are profound advocates of the "Hydrogen Economy" need to address the problem that the PEM (Proton Exchange Membrane) cell relies on an electrode consisting partly of platinum (about 50 - 100 g worth), which is a metal so rare than only 200 tonnes of new platinum are produced each year, and well below the current and growing demand for it.

Admittedly, the 40% of world platinum that is presently put into catalytic converters could be fabricated into PEM cells, were the putative conversion from oil-power to H2-power to be made, but this is only sufficient to put around: 200 tonnes x 1000 kg/tonne x 1000 g/kg x 0.4/50 g/cell = 1.6 million new "vehicles" on the road each year, out of a world total of about 1,000 million. Hence over a period of 15 years we could replace just 2.4% of the current number. Thus, unless more platinum is recovered on a huge scale (from sources as yet unknown to geology), or some alternative fuel cell technology is brought to a commercial level of development on some similarly immediate timescale, the enterprise looks set to fall at the last fence, in this, the last race that humankind will ever have to place bets on.

Governments Must Work Together to Mitigate a Peak Oil Scenario.

Decline in output from the world's oil fields is averaging 5% per year http://aspousa.org/peak-oil-reference/peak-oil-data/oil-depletion/, with some speculation that we may have reached the global production limit for conventional crude oil http://www.skepticalscience.com/Climate-Policy-Peak-Oil_U-Washington.html. Once the loss in output overtakes what can be provided from unconventional sources, it can be said that we have passed the point of global "peak oil". The exact timing of this will be known only to posterity, but its circumstance is widely perceived as an unquenchable and imminent disaster of planetary proportions, and the "End Times" movement, hard-line Christian fundamentalists, mostly in the US, are rubbing their hands in anticipation of such "proof" that God really did tell us 2000 years ago that the Tribulation would befall us, in preparation for the second coming of Jesus Christ, who would ultimately transform the Earth into paradise. A cynic might say that since these are mostly people who live in a nation that consumes vastly more energy, and has more cars than anywhere else on earth, such acceptance is really an act of inertia, and they would rather die than change their lifestyles to anything less energy consuming.

Being essentially an optimist by nature, I am trying to avoid falling to apathy along the wayside, although it is extremely difficult not to see things in a gloomy perspective, especially living in a country that has pledged itself to additional debts of around $1.2 trillion (£750 billion) in the wake of the 2008 banking crisis, and which will take so long to pay-off that the point when (or if ever) the balance sheet comes back into the black is really anybody's guess. If it takes 30 years, one can only speculate as to the kind of world and society that will prevail then, and since I am a man of a certain age, in all probability I won't be part of it.

There are many scary scenarios to be had, and which are gratuitously foretold, but mostly these involve wars over resources, mainly oil and also water. The two are connected inextricably in the matrix of energy and production that forms the web of globalisation, with oil-powered pumps drawing water to bring desert into fecund crop-land and pasture. Thus if oil fails, so does the land, and much of the food production especially in the mid-western United States, once it is no longer possible to extract water, much of which is of fossil origin, drawn up from underground aquifers. These are not routinely refilled by rainwater, but are an essentially finite resource, laid-down millions of years ago http://ergobalance.blogspot.co.uk/2012/08/terminal-shortage-of-water-for-us.html.

It is not worth elaborating the conceivable plots of mayhem, including one I have heard of, where the governments are forced to bomb the inner cities to destroy the rapacious and desperate millions, before they become lawless and soulless roaming hoards, rather as in the 1956 novel "The Death of Grass http://ergobalance.blogspot.co.uk/2012/01/death-of-grass.html. Rather, to consider that there may be a solution, but only one, and that is for the governments of the world to unite in a voluntary and cooperative programme to reduce oil consumption by 3 million barrels/day (ca 3%) per year, in line with the predicted fall in oil production from the present to 2030 http://ergobalance.blogspot.co.uk/2012/03/can-solar-fuels-avert-imminent.html. Any other strategy - including business as usual - will be tough, unpleasant and disastrous, and must inevitably abrade society into conflict and all-out wars between regions and between nations. In a nutshell, oil-producing nations must agree to reduce their production by 3% per year and oil-importing nations to reduce their imports by an exactly matching amount. Production will fall and must be planned to fall, while consumers take-up the slack in supply, in the form of fuel rationing.

We need a clear strategy to gear-down our dependence on personalised transportation and on the carriage of essential goods such as food and water to the extent that should this mechanism fail, in Britain we have probably three days supply before the supermarket shelves are empty and the country begins to starve. To put it another way, a fall in oil provision by 3% per year means building more localised means that depend less on transport by that same figure, pro rata. Since the problem is a global one, the solution can only be found globally, and individual nations - under the leadership of their governments - must cooperate in creating an overall less fuel-dependent ideology and putting this into practice. Fuel rationing is key and a reconstruction of societies so that the means for shelter, work, food production, money and all else are not separated, but become part of the integrated hive of community.

The Petroleum Rollercoaster.

I wrote the following in a previous posting http://ergobalance.blogspot.co.uk/2012/03/can-solar-fuels-avert-imminent.html but there are a number of points of issue, which I shall now address. In particular, the aspect of the apparent rate of decline of oil production needs clarification, and indeed what exactly is meant by "oil".

"It has been estimated that the world's road transportation fleet will reach 2 billion by 2020, of which at least 50% will be cars. China’s and India’s automobile fleets are expected to grow at an annual rate of around 7 or 8%, while in the United States, it will be under 1% a year, and around 1 to 2% in Western Europe, but this depends tacitly on finding an expanding liquid fuel supply, and it is this which is at issue. Indeed, the International Energy Agency (IEA) has issued a report to the effect that a shortfall in oil production of 64 million barrels a day (mbd) can be expected by 2030, which represents a loss of 62% of the world supply of conventional crude oil, currently 84 mbd, assuming a demand by 2030 of 96 mbd, a figure significantly downgraded from prior estimates by the IEA of 120 - 130 mbd. At a mean decline rate of 2.9 mbd/year (-3.4%/year) this value accords closely with the prediction in a recent U.S. Army report that there will be a deficiency of 10 mbd by 2015, following a loss of any spare capacity for crude oil against demand for it by the end of this year (2012)."

In essence, the above is saying that, while demand mainly for cars, and hence liquid fuels to run them, is expected to double during the present decade, an enlarging hole in the production of conventional crude oil is expected to occur, against demand for it. However, in my expression of the situation, I have been rather louche with the term "oil". I am in good, or at least numerous, company in this respect, since the whole business of oil production has been obfuscated by reference, over the past decade or so, to "liquids". Back in 2005, production of total liquids did indeed amount to around 84 mbd, but since then, and up to the present, the proportion of that which is actual conventional crude oil (plus condensate, since the two are customarily reckoned together) has been around 72 mbd, although the production of liquids had "climbed" to 87 mbd in 2011.

Now, much of this increase in volume is due to an increasing amount of natural gas plant liquids (NGPL) being produced and included in the tally, in part as a side-product of shale gas production, through horizontal drilling and fracking. Overall, the procedure of combining NGPL and crude oil, in the same tally, seems a little disingenuous and rather misleading, since the two are not the same thing at all or even “close substitutes” in terms of what they can be used for. Globally, NGPL provides around 9 mbd, biofuels, coal-to-liquids and a very small amount of gas-to-liquids altogether provide another 2 mbd. Another 2 mbd is due to “refinery gain”, which is not real additional oil (or liquids) production, but measures the increase in volume of the total products obtained e.g. from cracking heavy oil. Indeed, it can be considered as a measure of the energy expended to “refine” crude oil http://www.energybulletin.net/stories/2012-07-08/how-changing-definition-oil-has-deceived-both-policymakers-and-public. But of actual crude oil, there has been no increase in production for about 8 years, which has led to the view that we may have hit the ceiling of world conventional crude oil production http://www.skepticalscience.com/Climate-Policy-Peak-Oil_U-Washington.html.

According to the U.S. Energy Information Administration (EIA), “the term ‘liquid fuels’ encompasses petroleum and petroleum products and close substitutes, including crude oil, lease condensate, natural gas plant liquids, biofuels, coal-to-liquids, gas-to-liquids and refinery processing gains.” Since the major gains in production have been in the form of NGPL, it is a matter of some importance to consider the exact properties of these materials in comparison with conventional crude oil, particularly in relation to providing liquid fuels. As the following data show http://www.spe.org/industry/docs/UnitConversion.pdf, a barrel of these liquids contains far less energy than a barrel of crude oil (6.12 GJ), natural gasoline (4.87 GJ), iso-butane (4.19 GJ), n-butane (4.56 GJ), propane (4.05 GJ), ethane (3.25 GJ) – data from original source converted from Btu to GJ. Moreover, they are far from being “close substitutes” for crude oil, in terms of their molecular and physical composition, and are mainly used for other purposes. The major single component of NGPL is ethane (42%), which is converted to ethylene mainly to make plastic from. Roughly 28% of NGPL is propane, which is mostly used to run small heating appliances, e.g. barbecues.

The future of crude oil (and liquids) production has been given a more detailed consideration by Antonio Turiel http://www.resilience.org/stories/2013-02-05/the-twilight-of-petroleum and is most alarming in its conclusions. Using the graph for the forecast of "World oil supply by type in the New Policies Scenario" in the latest annual report of the International Energy Agency http://www.peakoil.net/headline-news/an-analysis-of-world-energy-outlook-2012-as-preparation-for-an-interview-with-science, Turiel has arrived at the following production levels in mbd for the year shown. I am using a slightly different presentation, which lists a running total under each heading, up to the final sum.

Year. Current crude. "New" projects. NGPL. Unconventional. Tight oil. Refinery gains.
2000        65.9                0                   73.8               74.9                0             76.9
2005        70.0                0                   79.7               82.0                0              83.9
2011        68.2                0                    80.2              83.2                84.4         86.2
2015        64.1              68.2                 82.6              86.8                89.3         91.7
2020        56.3              66.5                 82.1              88.0                91.1         94.0
2025        48.0              65.9                 82.1              89.2                93.3         95.8
2030        36.7              65.3                 82.1              90.9                94.6         97.6
2035        25.9              65.3                 83.2              93.3                97.0         100.0

Turiel makes many pertinent points, including the mismatch in properties and energy density between other liquids and crude oil. Most significantly, he stresses that it is misleading to use liquid volumes, rather that the energy content of the "liquids" (energy equivalents) would be a more meaningful measure of what is being produced, in terms of "oil equivalents". This takes the 2035 total down from 100.0 to 87.5 mbd.When the EROEI is applied, the figure for 2035 falls further to 79.7 mbd, indicating that we are "very close to the zenith of petroleum energy". When other considerations are made, as to the actual likelihood of production especially of the "new" projects, the 2035 energy equivalent is just short of 40 mbd.

However, it is actual crude oil that is at issue, and what rate of decline in its supply might be expected, since this represents the "hole" that must be filled from unconventional sources just to maintain our status quo. Obviously there will be fields with weaker or stronger production, but -5%/year appears to be the global average http://aspousa.org/peak-oil-reference/peak-oil-data/oil-depletion/. According to the data in the table, over the period 2005--2035, a fall in output from 70.0 mbd to 25.9 mbd implies a decline rate of only -2.1%/year. This is significantly lower than either the -5% global average, or the -3.4% that I had deduced crudely for total liquids, assumed as "oil", though the latter figure is in accord with analyses by both the German and U.S. military; the latter concluding that we can expect a shortfall of 10 mbd by 2015. It is of note that while the data are in the region of a -2%/year decline up to 2025, the rate does increase to around -5%/year over the subsequent decade, to 2035. I have used a simple division by year, rather than a compounded percentage decline, because the data seem to behave this way, and the discussion is illustrative. I note that a compounded -3.4%/annum decline from 2005 does agree quite well (24.8 mbd) with the observed 2035 value (25.9 mbd), though in all other cases it provides an appreciable underestimate of the amount of oil remaining.

Thus, the raw data in the table imply that in a little over 20 years time, we will only have about 38% of our current supply of conventional crude oil, or a shortfall of more than four Saudi Arabias to fill from other sources. This rises to nearer five Saudis, when the EROEI factor is included, to measure the difficulty of extracting oil post-peak, which is the top of the easy-oil rollercoaster ride that humanity is presently on. If the actual decline does maintain at nearer -5%/year, then, frightening though Turiel's conclusions are, they may underestimate the urgency and rake of the inevitable crash downwards. But before then, civilization will have either fallen, or re-adapted through localisation and by establishing resilient local communities. Yet, it is almost a matter of denial to ignore how little time we may have left to make the Transition.

The Achilles' Heel of Algal Biofuels - Peak Phosphate. - An Update.

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.