Wednesday, May 30, 2007

Economic Dependence on Oil Growth will be a Disaster.

Supplies of oil are limited and finite. This at least is the view of a geologist. An economist, however, does not often see things in the same way and it is generally assumed that the relative forces of supply and demand for resources depend only on their price. Hiccups in oil supply, for example during the actions of the OPEC group of nations in the early 1970's, were indeed economically driven, and the price of crude oil was artificially hiked-up; it had nothing to do per se with how much of it was left in the ground. Now, we can expect to see oil prices rise inexorably, as the sweet, light crude production has peaked and the remaining heavy, sour (high sulphur) oil will prove more difficult to process and refine into gasoline. Indeed, it is more likely that diesel will be used increasingly as a fuel, necessitating the adaptation of vehicles to diesel engines in which to burn it, rather than the spark-ignition engines in which gasoline (petrol) is burned.

It is an apparent contradiction, however, that even though it is known that oil supplies will run-short and become more expensive, economies of nations are planned as though production will continue to grow, and that the oil that underpins economic expansion will not become outrageously expensive. George Monbiot has written a salient article in the Guardian (Tuesday May 29th), in which he refers to a UK government white paper on "energy" which speaks about new taxes, new markets, new incentives and new research, almost creating the impression that all is in hand and under control. However, in another part of the document is the bald fact that "66% of UK oil demand is derived from demand for transport fuels which is expected to increase modestly over the medium term." This rather begs the question that if it is necessary to implement all those "new" measures, how could our use of fuel increase?

There are plans to build another 2,500 miles of new trunk-roads and to double our airline capacity by 2030 (and more veiled allusions to triple the number of people flying around our skies by 2050). This surely is complete nonsense, as conventional oil supplies will be reduced to a trickle by then, so what are we going to put into all these planes by way of fuel, and in any case what about cutting our CO2 emissions in order to stall global warming, which is another pledge we hear from the government. The truth seems to be pretty clear. Inexorable growth is not an option. If we could extract crude oil from the ground maintaining current rates, we would have run out of this conventional resource in about 30 years (i.e. 2037), since there are about one trillion (1,000 billion) barrels of it left and we get through just over 30 billion barrels of it each year as a world sum total.

Clearly oil-production is not such a straightforward matter, and as a well depletes it gets harder to pump the oil out of it, so production will fall inevitably according to the "bell-shaped" Hubbert Peak type curve. Indeed, the harder you squeeze a well, using enhanced recovery methods, the quicker it becomes exhausted and so the fall in crude oil production is likely to be rather a steep plummet. The most probable outcome is that within 10 - 15 years the amount of world-crude coming onto the market will be significantly attenuated, maybe to just a half of current levels. How adequately that deficit might be augmented using unconventional oil (from coal-liquefaction, tar-sands, oil-shales etc.) is anybody's guess, but obviously the cost of the commodity overall must soar.

It is debatable just how much oil can be drawn out from the Earth, and estimates as to how much there is down there and what proportion of it can be brought-up vary considerably. I imagine we simply won't know until the fateful day comes and we may be either pleasantly or sorely surprised. Either way, now is the time to plan for the "Oil Dearth" Era. The stuff is going to run-short; even if it won't quite run-out for decades, the present jamboree of oil will prove a short-lived benefit. How beneficial is debatable too, since if the world does hit a wall of rapid depletion we can kiss our lifestyle goodbye. We might then rue the dawn of its discovery, realising we would have been better-off without it. However, what is necessary is a class-act. We all need to think about how we might survive in a new-age when we can no longer rely on plentiful, cheap oil. If I am right that we may have 10 - 15 years of significant conventional oil production (probably augmented by natural gas liquids, condensates, tar-sands and coal-liquefaction), that may be enough time to implementing a strategy of gearing-down in terms of our energy use.

Inexorable growth is not an option, but relocalising economies, and using less might be. However, applying the brakes (simply through a sudden loss of energy) to mighty and ambitiously expanding economies like China (expected to match the US in oil consumption by 2020), India and the US itself, would prove an extremely painful jolt to the relatively smooth ride we have come to take for granted.

Related Reading.
George Monbiot, "Our blind faith in oil growth could bring the economy crashing down." The Guardian, Tuesday May 29, 2006.

Monday, May 28, 2007

Prague, Hippos and Communism.

I have just returned from a week spent in Prague, enjoying the beauty and culture of that city and also meeting new colleagues and doing some research into biodiesel production and indeed potential wildlife conservation involving the zoo there. I have mixed feelings about zoos, but for some species, the creature would be extinct where it not for the efforts of them, and it seems that the hippopotamus (a creature of interest to me) if not already on the "endangered" list is certainly at risk. The problem for the hippo is that it has rather large teeth, made of ivory, and so if elephants are now protected from "tusk-hunters", hippos are not and have become a welcome substitute among poachers who will similarly machine-gun them to death in order to extract ivory from them.

I feel the enfeeblement of man in this way, needing to resort to fire-arms to kill such an utterly magnificent animal, without which a human would stand no chance against at all! Weighing-in at around 3 tonnes, an adult male hippopotamus, armed with incisor teeth as spears up to half a metre long, held in a head that itself weighs around half-a-ton, would prove a formidable adversary, and not too surprisingly they have no natural predators! They can trot comfortably at around 9 miles per hour and while estimates vary about their top-speed, it is claimed they can reach 30 miles per hour over short bursts. Since this is well beyond the velocity of humans, it would be foolish to either challenge one to a road-race or to get in the way of a hippo intent on getting back to the cool comfort of a river. Even crocodiles stand little chance against the hippopotamus, which can bite an adult "croc" in two! I have written a series of children's stories about a young hippo and the impact of the changing global environment on his perception of hippo-life, which I am currently in the process of marketing.

Prague zoo is a wonderful place to observe hippos, with two adults, a male called Slavek and his female partner Maruska ("Maria", in English), who last year gave birth to the product of their happy union in the form of a baby boy called Tomik ("Thomas" or "Tom" as he is known). Tom shares the same birthday as me, April 21 st, and at about 13 months old I estimate (assuming a barrel-form, and the mathematically described volume of a cylinder: pi x radius^2 x length) he must weigh about 400 kilograms. A big boy indeed. He is also a marvellous swimmer - submerging and then bobbing joyously above the surface, and doing seemingly choreographed aquatic side-motions - head held proudly above the water; alternately jumping over his parents backs - possibly dispelling the myth that hippos are unable to swim. I have seen them all swimming and so from this first-hand experience I know that they can! Tom is pretty cute, I have to say!

The Museum of Communism is also well worth a visit. Now, I have been told various things about that particular regime, but not having experienced it myself I keep an open mind. My colleagues in (now) Russia, Armenia, Slovakia, Poland, Bulgaria, Romania and the Czech Republic all have their own stories, for example the heavy guarding of the borders, e.g. between Slovakia and Austria, which was lined evenly by machine-gun turrets spaced 100 metres apart. Anybody entering this "forbidden zone" would be shot, and the guy who did this would probably get a promotion, or even a Communist flat (apartment) , though this would be in an area such as Petrozelka, which a Slovak friend described to me looking over it from the castle in Bratislava as "this is our Bronx". I used to live in Liverpool and I can envisage similarities with some of the more deprived areas there too. The Museum of Communism appears to me to give a very well balanced and unbiased view of the regime itself, its consequences and the human toll in totality... I am glad that I didn't live under it, I have to say. In its favour was a highly advanced education system, and belief in university-level knowledge that I once shared, rather than a totalitarian university system as now pervades in the UK, and in some shabby examples has "Professors" (that's "Full Professor", in the US) with no published work in the subject in which they are supposed to be entitled to "profess"!

In the Museum is one startling statistic, to the effect that when the Communism "fell" and industry accordingly declined, life-expectancy in the Czech Republic increased by an average of 5 years! I mention this now is the context of inevitable industrial decline in the Western world, following the "Oil Dearth" era that is imminent. However, our own life-expectancy will depend on whether we can provide sufficient food and basic energy (electricity and heat) requirements to keep our population fuelled and thriving.

Related Reading.

Friday, May 25, 2007

Energy from Space-Based, Solar-Lasers.

There are two new studies ongoing with the aim to investigate the feasibility of generating solar energy from solar panels borne by satellites. I can see the reasoning here: at the top of the atmosphere, the amount of the Sun's radiation falling onto the Earth amounts to about 1,400 W/m^2 (Watts per square meter); however, the air-molecules absorb various wavelengths of light and so at any point at ground level, the intensity of radiation is attenuated. In northern Europe a reasonable estimate is around 150 W/m^2, somewhere quite sunny it is about 350 W/m^2 and in the Sahara Desert the energy is not far short of 1,000 W/m^2. Hence, out in space the full complement of the Sun's power might be harvested.

In this particular concept being explored, a network of orbiting satellites would serve as energy transducers, capturing the abundance of energy from the Sun and sending it down to Earth in the form of a laser or microwave beam. (Mmmm... I wonder what the Health and Safety people would have to say about that?) . The original notion originated in the mind of Peter Glaser, a scientist working at Arthur D. Little in Cambridge, Massachusetts in the late 1960's. No one is in any doubt that there are difficulties and drawbacks attending this particular type of technology, which smacks of "Star-wars", and it is debatable just what the real economic benefit would be in practice.

The challenges of Space Solar Power (SSP) are various, but while concluding that the launching costs were too high, NASA (in 1995) decided to take a fresh look at the technology, possibly to attract financial and public support for its future activities. Since then interest in SP has accumulated, and a special study group at the National Research Council (NRC) has singled out several technological advances, which might be worth following-up on: (a) improvements in the efficiency of solar panels and the fabrication of light-weight panels, (b) progress in wireless transmission on Earth, notably in Japan and Canada, (c) robotics, deemed essential to run such an SSP assembly, has demonstrated significant improvements in terms of manipulators, machine vision systems, hand-eye coordination, task-planning and reasoning.

The panel concluded that significant breakthroughs are necessary before SSP technologies could produce energy in a cost-competitive way compared with Earth-based power generation. The final success of generating power on Earth from satellites depends "critically on 'dramatic reductions' in the cost of transportation from Earth to geosynchronous orbit (i.e. the altitude at which the orbiting period of the satellite is the same as that of a point on the Earth's surface, meaning that from an Earth-bound perspective, the satellite stays in the same place at all times... you wouldn't want it drifting off would you?!"). It further concluded the need for ground-based demonstrations of point-to-point wireless power transmission, and also the 'desirability' of ground-to-space and space-to-ground demonstrations... i.e. potential "Star-Wars" weapons.

We shall see, and I would rule nothing out as the world clutches ever more desperately at means to avoid drowning in the "Oil Dearth" era.

Related Reading.
"Bright Future for Solar Power Satellites," by Leonard David.

Wednesday, May 23, 2007

Antarctic Ocean a Blocked Sink for CO2?

The Southern (Antarctic) Ocean is thought to account for 15% of the total global "carbon sink" into which CO2 is drained from the atmosphere, but recent evidence is that it is being "blocked" by climate change, meaning that CO2 will increasingly accumulate in the atmosphere and possibly exacerbate global warming. It is a subtle feedback mechanism, since normally the oceans store CO2 in their deep waters, but as the atmospheric circulation (winds) increases over the Antarctic, the ocean water mixes more, and shuffles the deep, cold reservoir of CO2 toward the surface, where it can out-gas to the atmosphere. If this in turn leads to more warming and stronger winds, more of the deep waters will be churned upward in a symbiotic acceleration of effects that increasingly weaken the efficiency of the sink, and push-up both CO2 levels and temperature if CO2 really is the key to the Earth system's thermostat.

The effect had been predicted by climate scientists, and is thought at least partly to be included in climate models, though to what extent is debatable. The alarm-bell sounding now is that this is happening a good 40 years before its predicted time. Now this might be simply a feature of the enormously complex and interconnected nature of a truly "complex" system, in the mathematical sense of "complexity" where operating components can no longer be perceived in isolation from one another and conspire actively to bring about certain outcomes that might not be predicted by the reductionist logic that is standard to science. It is nonetheless worrying since it either indicates that the Earth systems are breaking down or that our simulations of reality may not be able to forewarn us of imminent catastrophes.

Only about half (I worked it out at 40% since 1950, in the posting "Carbon in the Atmosphere") of the CO2 that is released into the atmosphere actually stays there - the rest is absorbed into carbon sinks. A good proportion of CO2 is absorbed by plants (including the phytoplankton of the oceans), thought to be about 50:50 into land and marine based flora. Some of it is simply dissolved into the oceans and over time it is taken-up into plant and animal life, ultimately becoming mineralised as calcium carbonate, in the form of sedimentary deposits. CO2 is also absorbed directly from the atmosphere in the weathering of silicate rocks, which are thus converted into silicon dioxide and calcium carbonate. The CO2 that is not absorbed by some particular sink therefore accumulates in the atmosphere.

It was believed that ocean sinks would maintain pace with increasing levels of CO2 emitted from human activities, absorbing a comparable and consistent proportion of this greenhouse gas. It was expected that the sink-system might eventually break down but not before around 2050. Data from 11 sampling stations were noted in the Southern Ocean and from another 40 stations across the globe, which allowed the determination of how much CO2 was being absorbed by each according sink, and to compare their various efficiencies in performing this task. According to researcher Corinne LeQuere, "Ever since observations started in 1981, we see that the sinks have not increased. They have remained the same as they were 24 years ago, even thought the emissions have risen by 40%." This does appear significant, but is there a delay (a lag) behind CO2 emission and absorption? Are we pouring CO2 into the sky at such a rate that it will take some time before Nature activats her sinks (maybe by increasing the available quantity of phytoplankton) to absorb this (in geological terms) "abrupt"aberration in skyward CO2 levels?

Two factors have been cited as being culpable in the cause of this effect. Firstly the increased churning of the ocean waters by winds, as already noted, and secondly the increased warming of the Antarctic region as more solar radiation can get through the widening hole in the thinning ozone layer, which is particularly marked in the polar regions. This is thought to cause localised warming. The ocean surface becomes saturated with CO2 by the up-draught of CO2-laden waters from the depths, and so cannot take-up more of it from the air.

One further consequence is that these near-surface waters become more acidic, with a detrimental effect on marine organisms such as coral. Phytoplankton also do not tolerate unusually acidic environments well, and this important sink too may decline, in a similar fashion to the "clearing" rainforests. If our activities are not only raising CO2 levels directly in the atmosphere but blocking-up the sinks to remove it as well, we are surely in a condition of CO2-forcing... with unknown but probably not benign consequences.

Related Reading.
"Polar Ocean 'soaking up less CO2'," by Paul Rincon.

Monday, May 21, 2007

Comparative Solar Power.

When statistics are quoted, it is often helpful to know the various measurements and assumptions behind them, especially in relation to environmental matters, and particularly solar energy. I have just encountered a statistic that photovoltaic (PV) cells covering an area of desert 10 miles by 15 miles could generate 20,000 MW (megawatts) of electricity. That is 20 GW, or about half the amount of electricity that is normally generated in the UK. In metric units, this is 16 kilometers x 24 km = 384 square kilometers (km^2).

Since 1 km^2 = 10^6 m^2, we may deduce that the useful solar power amounts to: 20,000 x 10^6 W/384 x 10^6 m^2 = 52.1 W/m^2. If the solar irradiance is 350 W, that means the cells are working at an efficiency of 52.1/350 x 100 = 14.9% (15%).

Now the same article quotes that a similarly PV-stacked area of 100 miles by 100 miles could provide enough electricity to run the whole of the US. So this is 160 km x 160 km = 25,600 km^2. Simple division indicates that the total electricity generated in the US is 25,600/384 x 20 GW = 1,333 GW, which is rather in excess of the 425 GW that I understood it to be. Indeed, to provide 425 GW of electricity under "desert" conditions would take:

425 x 10^9/52.1 (W/m^2) = 8.16 x 10^9 m^2 = 8,160 km^2 or a square with sides (8,160)^1/2 = 90.3 km.

I will estimate the amount of electricity that could be generated under UK sunlight from 25,600 km^2 of solar panels. Here an average of 150 W/m^2 is reasonable, and assuming an efficiency of 10% (which is a fair value for working solar cells - there are more efficient research-stage cells that are reckoned at 30% but they are not available yet), we have 15 W/m^2 of usable light for PV generation.

Hence, 25,600 x 10^6 m^2 x 15 = 384 x 10^9 W. Now this is only 10.7% less than the 425 GW US national electricity consumption, and indeed the discrepancy can be taken-up by (a) 166 W/m^2 (cf. 150 W/m^2) or (b) an efficiency of 11.1% (cf. 10%), so we are close either way. My main point is that obviously the 10 mile x 15 mile "desert" PV estimate does not apply to the same conditions that the 10o mile x 100 mile "US total" figure was estimated from, which must refer to less sunny climes!

As a matter of interest, let's consider how much silicon would be required to provide this much PV using prevailing technology. If the thickness of the silicon is 180 microns (which is the lower end of the 180 350 micron range quoted in wikipedia for solar cells), that is .18 mm = 180 x 10^-6 m.

Therefore the volume of silicon = 25,600 x 10^6 m^2 x 180 x 10^-6 m = 4.6 x 10^6 m^3 (cubic metres). Silicon has a density of 2.2 tonnes/m^3 and so this amounts to 4.6 x 10^6 x 2.2 = 10.1 million tonnes of silicon.

In the entire world, there is just 30,000 tonnes of pure silicon produced annually, and so it would take 10.1 x 10^6/30,000 = 337 years to produce enough of it to turn the US over to solar in total! Even that little patch in the desert intended to provide 20 GW of PV needs 384 x 10^6 x 180 x 10^-6 x 2.2 = 152,064 tonnes of silicon, which would require 152,064/30,000 = 5 years worth of the entire world supply of pure silicon to install it. I am not being flippant here, but trying to show that there is a limit on resources and that many more silicon manufacturing plants will be needed if the world is to move over to PV seriously.

In a previous posting "Slim Chance for Solar Energy" I estimated that to make all the world's electricity from PV would require an approximate one hundred times the silicon production capacity that exists now, in order to provide this raw material with which to match current electricity generation. Thin-film cells and dye (Gratzel) cells would require different and far less resources to fabricate them, but can they be brought on-line soon enough to make a difference either in terms of depleting natural gas reserves (much electricity is made from gas, certainly in Europe) or in trying to avert our contribution to global warming? It is all a moot point.

Related Reading. ("U.S. Department of Energy - Energy Efficiency and Renewable Energy Solar Energy Technologies Program").

Friday, May 18, 2007

An Assessment of Biofuels.

Biofuels are enthusiastically being sought as an alternative to petroleum-based fuels, in consequence both of a desire to break the dependence of the West on imported crude oil from politically unpredictable regions of the world, and also to counter the simple fact that the world is entering the "Oil Dearth" era, as I have dubbed the time at hand post Peak Oil. In principle too is the added benefit that as a crop grows, it absorbs and fixes CO2 from the atmosphere, and so in an ideal world, the biofuel would be carbon neutral, having obtained all its carbon from this source, merely recycling it in the sense that an equivalent amount of CO2 as is produced when the fuel is burned is absorbed into the next year's crop.

The world, as we are well aware, is not ideal, and there are carbon costs incurred throughout the entire process, from the initial planting of the seeds, addition of synthetic oil and gas-based fertilizers, the final cutting of the crop, the processing of it, the production of the fuel by transesterification (biodiesel) or fermentation (bioethanol), and the final extraction or distillation of the fuel itself ready to be put into "petrol tanks". It is indeed a hotly debated topic just how energy intensive biofuel production is, and much angst pertains over the EROEI for ethanol production for which figures in the range 0.7 to 1.3 have been deduced. Thus for each barrel of oil worth of energy expended in producing bioethanol, 0.7 or 1.3 barrels of ethanol are obtained as a return on the investment: anything below an EROEI of 1 is a loss and above it a profit can be declared.

I have also shown in various postings that it would be impossible to grow enough fuel crops to quench our current thirst for liquid petroleum fuels using biofuels instead, even if we were to stop growing food altogether. There does come the inevitable conflict between growing crops to feed people and animals or cars and planes, as the amount of arable land is relatively quite limited to do so. Nevertheless, the adaptation of the biofuels strategy to break-down and ferment cellulose/cellulosic materials into ethanol or the production of biodiesel by high-yielding algae does offer sufficient promise that I remain hopeful about still being able to produce significant amounts of fuel in the future, albeit through technologies that are as yet unproven on the large scale. Coal-liquefaction is a tried and tested method for making hydrocarbon fuel on a large scale, but we would need to build around 30 combined cycle plants in the UK to produce the equivalent of one third of currently used petroleum fuel, while producing most of the UK's electricity simultaneously.

Since we will begin to run short of gasoline type fuels within a decade, as the sweet (low sulphur) light crude oil will have mostly been exhausted by then, this is the timescale that any alternative technologies need to be installed against, meaning that we need to get cracking. My own view is that either in terms of physical shortages of fuel or their cost, we will never again see the equal of the present energy jamboree, meaning a substantial fall in transportation and a fragmentation of industrialised societies into small communities which I have termed "pods", containing say 10,000 - 20,000 people. If we run out of energy, then forget about nanotechnology and focus on breeding horses and planting fields instead.

Notwithstanding these reservations, let's look at some potential sources of biofuel. Brazil uses sugarcane as the feedstock for an industry that produces 4 billion US gallons per year of ethanol, which covers 40% of the country's fuel requirements. In contrast, the US produces a comparable 3.4 billion gallons of ethanol from corn, but which amounts to somewhat less than 2% of the fuel used altogether by the huge fleet of cars needed to get around in this far more dispersed nation. Europe ranks third in ethanol production, but achieves it using mainly sugar beets, wheat and barley as the "sugar crop". It is interesting that if Brazil meets its plans to expand the arable area used to grow sugar cane from 5.3 million hectares to 8 million hectares, it would become self-sufficient in automotive fuel within only a few years while maintaining its production of sugar and exports of sugar and ethanol. Presently about half the Brazilian sugar cane is used to make fuel and the other half for sugar.

There are two essential criteria for elucidating the relative merits of growing particular crops for biofuel production, namely the fuel yield per hectare/acre and the energy yield of the biofuels. [I would issue a caveat here, e.g. while ethanol has only 70% of the energy that gasoline does, on the basis of the relative heat of combustion of the two fuels, it can be burned more efficiently in specially adapted engines, and so the output power of the fuels is comparable]. For ethanol, the best yields per hectare are 1785 gallons from sugar beets in France and 1655 gallons per hectare from sugar cane in Brazil. In the US, corn yields close to 885 gallons/hectare or about half that from beet and cane crops.

The king of biodiesel is palm oil which may be produced in a yield of 1270 gallons per hectare. Coconut oil comes next at 575 gallons/hectare, and rapeseed at 255 gallons/hectare. However, as I mentioned earlier, as supplies of conventional crude oil fall short, there will be an economic competition between crops for fuel or crops for food, and there is only so much land upon which all of them can be grown. In the line of fire then comes forest land, which increasingly is being cleared to grow palm plantations in Indonesia and Malaysia, and in Brazil to grow more sugar cane to match that expansion to 8 million hectares of land for the purpose, that I referred to. For sure, there will be environmental costs to be paid, even if a compromise can be struck between food production and biofuel production. But until the cellulosic and algae technologies are brought on-line (if they ever are), we will be embroiled in the greatest battle ever - over resources and prices, with casualties on all sides; perhaps this is the real WWIII.

Related Reading.
"People and Fuel Compete for Land,"
The article is based on Lester R. Brown's new book "Plan B 2.0: Rescuing a Planet Under Stress and a Civilization in Trouble," Chapter 2, "Beyond the Oil Peak", published by W.W.Norton, New York, 2006.

Wednesday, May 16, 2007

Photosynthesis and Peak Oil.

The realm of plant-life on Earth, including the vast lawns of phytoplankton that lie in the first 50 - 100 metre depths of the oceans, in places, exists through photosynthesis. By definition, this is a process in which light from the Sun is harvested by chlorophyll (the green colouring matter in plants) which absorbs wavelengths in the range 400 - 700 nm (nanometres), a spectroscopic region known often as the PAR (photosynthetically active region). This accounts for around 47% of the total energy from the Sun, another 2% being from ultraviolet (U.V.) wavelengths, and the remainder mostly infra-red (heat). The initial light excitation events have quantum yields of close to 100%, but there are so called "dark reactions" too, and the energy losses in the various biochemical steps involved in using light energy to "fix" CO2 into carbohydrate and thence other components of life such as proteins and lipids accumulates to an efficiency often quoted as 6% of the total solar irradiance being converted usefully to biomass.

The detailed process of photosynthesis is very complicated, but it may be represented in summary by the following chemical equation:

CO2 + H2O ---> [CH2O] + O2

It takes an average of eight photons of light to "fix" each molecule of CO2, and assuming a mean energy of 217.4 kilojoules per mole (kJ/mol) for each photon, and a mean enthalpy (heat) of combustion for a CH2O unit of 467 kJ/mol (obtained as one sixth of the heat of combustion of glucose, C6H12O6, an hexamer of CH2O = 2801 kJ/mol), we may deduce that the process has an efficiency of:

(467 x 100)/(8 x 217.4) = 27%. So we might expect an overall photosynthetic efficiency of 47% x 27% = 12.7% as an absolute maximum. [Obviously the photon energies vary within the range 400 - 700 nm, they are not all absorbed with equal efficiency, but this is a rough upper limit, i.e. it won't get better than this!].

In reality, there is an energy required for translocation and respiration that amounts to about 33% of the total and in a forest, say, the presence of a tree "canopy" limits the available light to about 80%, so we might expect nearer to 12.7% x 67% x 80% = 6.8%, which is the commonly quoted mean. In reality this varies enormously, and sugar-cane turns over at around 8% whereas some plants may be as low as 0.1%, while for most crop plants, 1 -2 % is typical. Nonetheless, I am going to use the 6% value now.

Biomass Production Reckoned in Terms of Sugar.
To form one molecule of sugar (glucose) by photosynthesis requires locking-in 2801 kJ/mol worth of energy, according to the process:

6CO2 + 6H2O ---> C6H12O6 + 6O2. It is clear that the combustion of glucose involves the reverse of this process, and hence we may deduce the amount of energy for the forward step as being the negative of the heat of combustion, i.e. 2801 kJ/mol.

If we assume that our crop will be grown somewhere sunny, a mean solar irradiance of 5 kWh/m^2/day is reasonable. It is often quoted that the Sun's energy falling on earth amounts to 1,400 W/m2, but this is only true at the top of the atmosphere, and directly overhead. Below this, the absorption of radiation by the molecules of atmospheric gases attenuates the solar flux, and so the "solar constant" of 1.4 kW/m2 is geared-down to about 1000 W/m2.

The mean irradiance of a point on the Earth's surface depends on both the attenuation, the latitude and the cosine of the angle (theta) between the sun's ray and an imaginary "normal" drawn out from the surface point. Hence to get the average amount of sunlight falling on the surface, noting that at any instant half of it is in darkness, we need to integrate cosine theta over the surface of a hemisphere (i.e. between 0 and 180 degrees which comes out as 1) which multiplied by pi x r^2 gives just pi x r^2 or half the two-dimensional area of the hemispherical surface (i.e. 2 x pi x r^2. The surface area of a full sphere is 4 x pi x r^2). The integration allows for the fact that while cos theta = 1 at theta = 0, it is 0 at theta = 90 degrees. Put another way, while the irradiance is at a maximum when the sun is directly overhead (theta = 0), it is practically zero at the horizon (theta = 90 degrees). The integral of cosine theta = sine theta which amounts to 1 as taken between the limits of 1 and 0.

The upshot is that the average irradiance over the year is one fourth of the solar constant (roughly since this varies by a few percent over the duration of the annual orbital cycle of the Earth around the Sun) or about 350 W/m^2; i.e. 8.4 kWh/m^2/day. As noted, the value depends on latitude and is close to 5 kWh/day near to the equator or in the tropics, but about half that (it is reckoned at 100 W/m^2 or 2.4 kWh/m^2/day in northern Europe, e.g. the UK).
However, let's assume sunny climes in the following but note we need to probably double the figures for northern Europe.

If we assume 5 kWh/m^2/day, or a mean 208 W/m^2 then 6% of that gives an irradiance of 208 x 0.06 = 12.5 W/m2 = 12.5 (J/s.m2). Over a year, this amounts to 3,600 s/hr x 8760hr/yr x 12.5 (J/s.m2)= 3.94 x 10^8 kJ/m2.

Over an area of one hectare = 10,000 m^2, we have 3.94 x 10^5 x 10,000 = 3.94 x 10^9 kJ/ha, which is enough to form:

3.94 x 10^9/2801 (kJ/mol) = 1.4 x 10^6 moles of C6H12O6. Since the molecular mass of glucose is 180, this equals: 1.41 x 10^6 x 180 = 2.53 x 10^8 g = 2.53 x 10^5 kg = 2.53 x 10^2 tonnes, or 253 tonnes per hectare. So, in principle, if cellulose-digesting/fermenting technology can be implemented in time, we could make an awful lot of fuel; let's assume half of that matter is cellulose (at least, cellulosic) and the fermentation efficiency happens with a typical 60%, giving around half the fermentable weight of ethanol , and so that would give us 253 x 0.5 x 0.6 x 0.5 = 75.9 tonnes of ethanol per hectare which is significant. It is particularly significant in that it is the chaff, the crop refuse that would be fermented meaning that no special crop need be planted in competition with food production, and in the oil-dearth era at hand, we will need to grow as much of our own food as possible, rather than flying it in from far flung regions of the world!

Biodiesel produced from Algae.
As I wrote about in the posting, "Biofuel from Algae - Salvation from Peak-oil?", there is the possibility to produce biodiesel from algae farmed in ponds (or special flowing-systems with extensive pipe-networks) on a scale that is very large indeed compared with the yield of fuels that might be extracted from fuel-crops, e.g. soya. The technology is yet to be implemented on the large scale, and the quoted yields, though optimistically impressive, are arrived at by scaling-up the results from much smaller situations. For example, the wikipedia entry ( quotes a yield of biodiesel of between 5,000 and 20,000 gallons (US) per acre, which is the equivalent of 42 and 170 tonnes of it per hectare. In my previous posting on the subject, I quoted another study which indicated a yield of 125 tonnes of biodiesel per hectare, and I shall use this as a reasonable average among estimates.

The energy value of biodiesel is given as 35.7 MJ/litre, and at an average density of 0.84 kg/litre, this is 35.7/0.84 = 42.5 MJ/kg. On the basis of these figures, we can estimate the amount of useful radiation that is hitting the Earth per square metre. So, a yield of 125 tonnes/ha = 125 tonnes/10,000 m2 = 12.5 kg/m2, which is a quantity of biodiesel that contains:

12.5 kg x 42.5 MJ/kg = 531.25 MJ of energy = 531.25 x 10^6 J/(3600 x 8760 s) = 16.85 J/(s.m2) = 17 W/m^2.

If the irradiance is 208 W/m2, the photosynthetic efficiency amounts to: (16.85/208) x 100 = 8.1%, which is possible but on the high side of what is normally found for the plant kingdom. The upper estimate of 20,000 gallons/acre amounts to 9.2% (19.2 W/m^2), while the lower 5,000 gallons/acre translates to one quarter of this, i.e. 2.6% (5.4 W/m^2).

There are many problems associated with growing algae and making biodiesel from them as may be seen from the "oilgae" link (top left hand side of blog), but I think there are reasons to remain optimistic about cellulosic and algae based methods for producing biofuels in the oil-dearth era. I still don't believe that we can match current supply/demand for petroleum based fuel, but it won't be a lack of solar-energy that will let us down.

On a final note, it is interesting to compare the energy yields of different fuel materials. So, the heat of combustion of glucose (taken as representative of wood etc. type biomass) is 2801 kJ/mol x 1000/180 (g/mol) = 15,561 kJ/kg = 15.56 MJ/kg.

c.f. 42.5 MJ/kg for biodiesel as we have deduced above. This factor of 2.7 is very close to the ratio of calories obtained per unit mass of fats vs. sugars in the diet, quoted in attempts to help us to lose weight, emphasising the point that fuel is fuel and energy is energy, whether it is burned in mechanical or animal machines such as our own bodies!

Related Reading.
(2) Thomas L. Weyburn, "A Report on My Recent Investigations of Solar Energy Harvested by Photosynthesis in a Controlled Environment." (just google it!)

Monday, May 14, 2007

After the Oil Peak?

I have written extensively on the subject of Peak Oil as indeed have many others. This is not surprising perhaps in view of its significance, and the almost certain consequences of ignoring its eventuality, which some think will be the collapse of civilization as we know it. The worst case is the "Die-Off" prognosis, in which around half the world's population of 6.5 billion will be consumed through wars over resources and by starvation. This is unlikely to be an evenly proportional loss of life, as is indicated by the relative population increases across the world. For example, in the UK in 1900, the population was close to 40 million, and now it is 60 million. As a world total it was around 2 billion, and so there has been an overall more than tripling in numbers, mostly in the developing world. Hence, without a plan, it is there that the greatest losses will be suffered.

The growth in human population can be plotted on the same curve as that for the rise in oil production, and that is not surprising given that we depend on oil or gas (which are interrelated in their production) not only for fuel to drive transportation and to provide much space-heating too, but also as a chemical feedstock for industry, and there is practically nothing we use that does not depend on hydrocarbons in some way, including food. Even "natural materials" like wood are treated with chemical preservatives. At one time the main wood preservative was creosote, and made from coal tar, now it is a mixture of more exotic substances sythesised ultimately from oil. If we are close to the peak in conventional world oil production, beyond which it is thought the amount of oil recovered will begin to drop at a rate of 2 - 3% per year, then what? Is a Die-Off scenario leading to a post-apocalyptic Mad Max outcome inevitable?

I don't believe it is, but exactly what happens depends acutely on what we choose to do about the impending oil-crisis, now. There are many who think that this is just another scare because we have seen "oil-crises" before, notably in the early 1970's, when the OPEC cartel flexed its political muscles to drive up the price of crude oil. But it was merely a political matter - there was still plenty of oil in the ground to be recovered and OPEC could decide how far to open the valves from the wells of its giant fields. Now the constraints are not political but geological, and it will simply become impossible to pump enough oil out of the ground to match an inexorable thirst for it. Indeed, production of the "sweet" (low sulphur) light crude oil which is most readily refined into gasoline (petrol) and aviation fuel has already peaked, and henceforth we will rely increasingly on processing heavier kinds of oil and that produced by thermally cracking tar sands and shales which are all highly energy-intensive processes, and the latter especially demanding additionally in the resource of water required to run them.

Future historians may well record that it was a pity humankind did not act 30 years before the peak, probably when OPEC temporarily throttled-back its output of oil. There were many research projects inaugurated to find alternatives to oil, but they did not become large-scale enterprises, because cheap crude oil came back onto the market and quenched the incentive for them. Now the incentive is paramount. For example, food production depends on oil to run farm machinery etc., and on natural gas to manufacture chemical fertilisers to squeeze greater crop-yields from land that has become extremely depleted in organic matter. If we lack oil, we have no choice but to return to organic farming, ploughing manure from animals back into the ground to nourish the next year's harvest. Organic farming requires far more land to yield a given quantity of crop than chemically-driven modern intensive farming methods do, and so to keep a nation fed, there is little arable land left on which to grow crops for biofuels. New cellulose-fermenting technologies that turn waste into fuel then look increasingly attractive, but we need them on-line as soon as possible, not forgetting that all our implementations of alternative technologies must be done within about 10 years, by when oil supplies will have begun to fall significantly, and against a demand for oil that grows by around 3% each year.

Transportation is THE big problem. I retain considerable optimism that cellulose-based methods will prove useful and I like the idea of making biodiesel from algae, although that technology too has many problems that need to be ironed-out before it might be possible to do so. Implementing a "Hydrogen Economy" on the scale required to substitute for oil-driven (forgive the pun) transportation would demand a feat of engineering so great that it is probably prohibitive, as I have indicated in previous postings and so I think that given the limited time left to us, we would be better to seek our salvation elsewhere. There seems no doubt that we will be forced to curb transportation (especially personal transportation) considerably, perhaps by 80 - 90% within 15 years, and that inevitably means a considerable relocalisation of society into relatively small communities, supplied by local farms. If that sounds like a slide-back to the Stone Age, it is probably worth recalling that this is exactly how Cuba managed not only to survive the abrupt loss of oil and chemical fertilisers from Russia when the Soviet Union collapsed, but to become a thriving nation based on local-economics. In Cuba, local farms provide for local markets, and while there are still some food shortages in more populous places like the capital Havana, as an overall strategy it has worked.

We must plan now, rather than remaining in denial that the onward march of progress is at all possible. The future can be an optimistic one, if we choose the simpler way. We will have this ultimately, whether we choose it or not, since it is the "default-setting" for a society with less energy at its disposal. That said, it is in our hands just how rough the transition is from now to then.

Related Reading.

Friday, May 11, 2007

Biofuels Take Another Knock.

I have written on the subject of various kinds of biofuels, and broadly concluded that even if we were to stop growing food in the U.K. we could at best match only somewhere between 16% and 50% of our current transportation fuel based on petroleum, depending on whether biodiesel or bioethanol is the substituting fuel. My figures are based the requirements for the U.K., but they broadly scale-up to similar conclusions for the U.S., in terms of the greater area of arable land available but the greater overall "national" fuel consumption. It amounts to the same for European countries in addition to the U.K., nonetheless, everybody seems to be going hell-for-leather for biofuels.

George Bush wants to free his country from the need for fuel imports from the Middle East especially, and probably from a less friendly South America too (notably Venezuela), although its supplies from Canada are likely to be fairly secure for the foreseeable future. The U.S. imports almost three quarters of its fuel from abroad, and consumes one quarter of the world's production. However, other nations are in a flux of rapid and massive development (China and India) and so the tug-of-war over the world's oil reserves is becoming a fraught and complex game with many more than a simple two sides pulling at them. In short every nation wants to be set free from demand on oil, for the simple reason it is running out, but how much time can biofuels really buy us? If the amount of them we can produce without starving, is a fraction of the energy equivalent currently supplied from petroleum, at best we have a shallow safety-net, that "might", and I use that word advisedly, make the bumpy ride down the oil-poor edge of Hubbert's Peak a little smoother. But there is no doubt we will end-up in a world with much less transportation fuel, even if wholesale coal liquefaction is done to make it, and on environmental grounds, e.g. climate change, this would seem unacceptable.

I have no doubt that many environmental concerns will take a back seat to attempts to maintain economic growth, and so I expect the U.S. will begin to produce synthetic hydrocarbons from coal, given their enormous reserves of it, some 30% of those known in the world; however, since much of this will be scraped from the Earth in open-cast pits, it is going to create quite a mess, and I'm sure too that Europe will not be too far behind in implementing the technology, and China and India are already considering large scale coal liquefaction projects. Now coal is an obviously dirty material, but what about biofuels - even if the amount we can feasibly make of them is limited, the technology is at least clean...or is it?

I am skeptical how much environmental good will be done by blending biofuels with petrol, in relatively low proportions (5 - 10% say), partly in terms of emissions and probably more impact will be made there as petrol begins to run out and we have less fuel to burn and pump CO2 into the atmosphere. However, America wants to double its biofuel production to 7% of the total within 18 months, while Europe aims more modestly for just under 6% by the end of the decade (slightly under 3 years). It is intended that the share of the market from biofuels will grow to 15% in the U.S. and around 10% in the EU. To encourage its own market the U.S. has imposed tough import tariffs on Brazilian-made ethanol but subsidises its own corn-ethanol. However the Brazilian product can be produced at a yield of around 6,000 liters per hectare and is the world's most efficient, whereas its corn-based equivalent is the least so.

There are fears that forested land will be cleared to grow fuel crops, as is happening in Asia, mainly in Indonesia and Malaysia, to produce palm-oil, diesel from which overall is ten times as polluting in terms of CO2 emissions than petroleum-based diesel. According to Friends of the Earth, 87% of deforestation that occurred in Malaysia between 1985 and 2000, was carried out to provide palm oil plantations. The U.K. government has said that a "significant proportion" of this country's biofuels will be imported, from places where they grow best, like Brazil and Indonesia, leaving both direct and indirect consequences of deforestation to follow. Economically, it is a difficult transitional period too, because the "second generation biofuels" made from cellulose are expected to come on stream perhaps in five years and so why would companies want to invest in massive biofuel production now, when these "first generation" plants would then have to be decommissioned? The second-generation approach sounds good, because it is intended to use household waste, sewage, chaff from food crops and so on, but the technology remains to be proven on the grand scale as is true of producing biodeisel from algae, which looks particularly promising.

In my opinion the jury is still out on how much biofuel can be produced altogether, and although I am optimistic about some of the putative technologies for doing so, I don't believe we can ever match the amount of petroleum-based fuel we now get through, and bearing in mind that the world supplies of oil are running out. In less than 20 years there will be practically no conventional oil left, and it is against this backdrop that all other considerations must be contrasted.

Related Reading.
(1) "Biofuels: The great green con", by Tim Webb.
(2) "A Lethal Solution," by George Monbiot.

Tuesday, May 08, 2007

U.N. say Climate Change can be Halted.

Experts from the United Nations have concluded that it is still possible to avert global warming and climate change, but the world needs to act immediately to do so. In a recent report, the UN Intergovernmental Panel on Climate Change (IPCC) has stated that a range of established and emerging technologies including renewables and nuclear power, along with carbon capture and sequestration are needed to reduce greenhouse gas emissions, particularly CO2, to a level where global warming would be stabilised. The refusal of the US to tackle the issue, and also the massive volumes of carbon expected to be emitted by developing nations such as China and India, are predicted to increase global temperatures by up to 6 degrees C during the next century.

The report asserts that renewable sources of energy could be increased to provide 35% of the world's electricity by 2030, up from the 18% it currently generates, and that nuclear could provide 18% by that same date, meaning a relatively marginal increase from 16% as now. It is worth pointing out however, that many of the existing nuclear power pants will need to be decommissioned and replaced by new before then. Biofuels are also promoted as offering the potential to cause significant reductions in emissions from transportation. However, as I have stressed in previous postings, it appears unlikely that the massive quantities of petroleum that the world currently gets through to run the global fleet of vehicles, including aircraft and ships, could be matched in kind by biofuels, unless new technology based on algae is successfully introduced to make biodiesel on a huge scale, otherwise there is insufficient arable land available to grow fuel-crops without severely compromising food production.

Energy efficiency is sensibly promoted too, and also quite blue-skies methods, such as putting a shield in space to screen-out sunlight are mentioned but are considered to be at best "speculative". Carbon offsetting appears strangely absent in the proposal, where for example a firm might be paid to plant trees to soak-up the CO2 emitted by its fleet of planes. Trading carbon credits between nations appears likely. The whole venture is estimated to cost about 1% of the world's GPD, which is perhaps a price well worth paying.

The main recommendations of the report can be summarised:

Lifestyle, which means cutting back on personal emissions (i.e. travelling less, and ideally not by air).

Energy supply: as noted, with a bigger share from renewables and nuclear.

Farming and Forestry: careful farming to retain carbon in the soil and minimise emissions of CO2 and methane too?

Industry: cut back emissions from highly polluting manufacturing plants.

High-tech means: the giant sun-shield and fertilizing the oceans to grow more phytoplankton to absorb CO2 from the atmosphere are thought to be unproven.

Related Reading.
IPCC Fourth Assessment Report.
The Independent, "Climate Change can be Halted", by Michael McCarthy.

Friday, May 04, 2007

Thermal Solar Power.

An array of 600 mirrors has been installed in a field outside Seville, in southern Spain, in an adaptation of the solar-furnace. I am familiar with the latter from working at the Paul Scherrer Institute in Switzerland, with a power output of just 40 kW, but when the bank of mirrors is positioned almost at 90 degrees to the horizontal, the immense energy can be felt instantly by anyone walking past it. The Spanish installation generates 11 MW, and focuses the Sun's rays onto a boiler (a network of pipes) positioned on top of a concrete tower 40 storeys high. Set in the midst of the Andalusian countryside, the thermal solar-power station must be quite an impressive sight, basking in the reflected sunlight.

It is indeed the first of its kind to operate commercially in Europe - i.e. it is not merely a research installation - and its operator, Solucar, announces proudly that it produces no greenhouse gases. True, as is that frequently cited advantage of nuclear power, but there is obviously a "carbon debt" to be paid-off, incurred in crushing rock to make the concrete and in the fabrication of the mirrors; however, the plant should run for years and certainly produce a lot less CO2 than a conventional gas or coal-fired station. This comparison has a further note, in terms of the relative generating capacity of the different technologies, namely that a standard electricity-generating station has an output of around 1 GW, i.e. 1,000 MW. Hence, the thermal solar-powered plant produces just about 1% of that. Put differently, it would take one hundred such installations for each gas or coal-fuelled plant it might be desired to replace by this sustainable technology.

As I have stressed over the putative hydrogen economy, the scale of engineering required to implement thermal solar-power on a comparative level with that which we currently enjoy from fossil-fuelled plants (and nuclear, especially in France where it produces 80% of the nation's electricity) would be truly collosal. The Spanish plant is undergoing a phase of development, and more fields are being cleared into which to install further banks of mirrors with the ultimate intention of providing enough electricity to meet the requirements of 600,000 people, which coincidentally is the population of Seville. In my opinion, we will need all the renewable energy we can lay our hands on, in order for human civilization to survive in the post-oil era that is at hand, but I think this technology will contribute a fairly minor component to the final energy mix, that I wrote about in the very first of these postings back in December 2005.

Who occupies centre stage in the new world order must follow the kind and amount of resources that each country ultimately has. In saying this, normally it is gas, oil, coal and uranium that is meant, and yet it might prove that an especially valuable and unlimited resource is available to the sun-kissed lands of the Mediterranean and Africa. If sufficient of thermal or photovoltaic generating capacity could be installed in sunnier regions, the electricity thus generated could be wired-off to the cloudier European climes. However, for any serious quantity of solar-power to be inaugurated, it is necessary to begin the process now, while we still have sufficient of our existing resources of oil and gas to do the job. In 10 years it may be too late to introduce any of the alternatives that are currently being speculated upon.

Related Reading.
"Power station harnesses Sun's rays," by David Shukman.

Wednesday, May 02, 2007

Putin Sanctions Nuclear Industry Reforms.

I have touched on this important development before, but it appears that Russia is set to become a major player in the world nuclear power game through the creation of Atomenergoprom, which President Putin has said: "will be a vertically integrated entity and unite the entire atomic technological cycle - from the production of uranium and nuclear fuel to the construction, operation and decommissioning of nuclear power plants." Now this is highly significant, since there is no counterpart anywhere in the world to this enterprise which would control all aspects of the Russian contribution to world nuclear power, presumably including providing enriched uranium to Europe and potentially (if they accede to this option) to Iran in order to break the threat of sanctions imposed by the UN.

This holding will enable Russia to beat its competitors on the world board of nuclear "Monopoly" and the initiation of the enterprise is expected to be complete by January 2008, in the form of a joint stock company owned wholly by the government. Russia has great strength in its natural resources, and has made determined efforts to consolidate and retain its gas and oil production and infrastructure within Russian control, even to the extent of sending some who would act against this aim to prison for significant terms. This appears to be a follow-on strategy to consolidate the share of nuclear resources, and in combination of all these sources of energy, Russia will indeed be a force to be reckoned with, in the shifting politics of the new world order, which must depend ultimately on who owns what and how much in terms of primary energy resources.

Fifty-five different unitary enterprises will be made corporate and subsumed into the holding by the 1st of December 2007, collectively including the means to mine uranium, process it, fabricate it into fuel-rods, build power plants and ultimately knock then down again at the end of their working life, including the final disposal of nuclear waste and radioactive components of decommissioned nuclear power stations. It is thought that isolated nuclear energy companies may well go to the wall against the competition from the international markets, for example large trans-national companies including French-German Areva and Siemens and the alliance between the US and Japan, Westinghouse-Toshiba.

The plan apparently does not include the creation of weapons-grade nuclear materials (HEU or plutonium), but as a force in the ongoing and undeniable economic war which has been described as the real (hidden) WWIII, mostly being fought over resources, it is a mighty launch indeed.

Related Reading.