Bioetanols no pārtikas augiem, vēl viens viedoklis

"The debate about bio-fuels is getting scientists, economists, motor car designers and even political wiseacres like the aging Fidel Castro, hot under the collar. It is easy to use one line of argument to show that bio-fuels are the salvation of the future and no more difficult, using a different logic, to cast ethanol as a hopeless loser. It all depends on whether you choose energy efficiency, potential impact on food supplies, environmental concerns, farm subsidies or energy security as the king-pin of your case. With oil prices within spitting distance of $100 per barrel even the layman needs to understand the trade off between these choices. The recent acrimony about land clearing in the Uva for sugarcane planting adds urgency and relevance to the debate. This article will have a shot at presenting the case from different perspectives.
Producing ethanol
The most important liquid bio-fuel useable as a substitute for petroleum is ethanol (ethyl alcohol) whose more felicitous tinkle is in a glass – on the rocks or with a chaser. For this hallowed purpose, however, it must be free of harmful chemical companions, and matured in wooden barrels, preferably for several years. The mass produced stuff is more suited to the internal combustion engine than the gut. Ethanol is made by the fermentation of sugars followed by distillation and dehydration; at above 96% concentration (meaning 4% water) it is a substitute for petrol. Usually it is mixed with ordinary petrol (ethanol is not suitable for blending with diesel) to form a blended fuel – Brazil mandates 23% ethanol in gasoline, the US prefers 10%, and some US states are legislating a minimum 10% ethanol content; many European countries including Sweden and Germany have similar rules in place.
The blend runs smoothly in an ordinary petrol engine, no technical problem, though miles per gallon will fall a bit. The stuff can also be used straight, that is unblended (E100) but then the engine compression ratio has to be increased – or to say it non-technically, the blended stuff can go straight into your tank but if you want to use E100 then the engine has to be adjusted. Thereafter it won’t be happy with just ordinary petrol unless you adjust it back each time you change fuel.
There are a huge number of potential feedstocks for ethanol production but three are of practical significance, sugarcane, corn (maize, corn-on-the-cob, iringu in Sinhala) and cellulose. Cellulose means just about any old vegetable fibre, tree branches and woodchips, but switchgrass and poplar are attractive fast growers. Cane sugar can be fermented as quickly as you can say rum, and is the best; corn is a starch which must be first coaxed into a sugar and then allowed to ferment, hence consuming more energy in production. Turning cellulose into ethanol requires even more effort and is not yet an industrial scale mature process.
The energy debate
If one expends 100 units of energy in making ethanol from corn, the product will give you back less than 100 or up to 135 units of energy, depending on which research paper you believe. This energy balance, as it is called, for example 1.35 according to the best estimates, is not large. The point however is, that the 100 units of processing energy expended doesn’t need to come from oil based sources; process by-products (dried sludge), coal or firewood can employed. Some studies claim that only 17% of the energy used in production need come from oil based fuels. In this case even if the energy balance is a mere 1:1, meaning you get back only as much energy in the ethanol as you expend in making it, there is still the advantage that you cut oil consumption by 83% and in effect run your buses and limousines on process by-products, coal and firewood.
There is a group of scientists who go so far as to argue that it takes more energy to make ethanol than the final energy returned when you consider not just the final processing but also fertilizer, agricultural machinery and so on. Two American scientists David Pimentel and Taduez Patzek have championed this ethanol debunking argument. They claim that the energy balance is just 0.59 for corn and hence corn based ethanol is a non-starter. Most other scientists and U.S. Government studies have concluded otherwise, they say an energy balance of about 1.35 is achievable even with corn as feedstock.
The case for Brazil, where ethanol is made from sugarcane, is much stronger. The energy balance is above 2.0 since the initial feedstock is already a sugar, not a starch. As with corn, the residual pulp can be used for the process heat - the residue from corn and cane can also be used for animal feedstock. Conversely, the case for cellulose is weaker, since the energy balance with current technology is less than one, and in any case the technology is not industrially mature. Bear in mind that if reducing oil reliance, to save foreign currency (Lanka), or for strategic reasons (USA), is the main concern, then it doesn’t matter if more energy is expended in production then returned in the final product provided the raw materials are local.
The relative economics of ethanol versus petrol varies from country to country, and is affected by weather patterns and the wild swings in oil price. In Brazil, ethanol production costs have fluctuated between 40% and 65% of petroleum price (for equal amounts of usable final energy) over the last 10 years. Elsewhere in the world, however, the price advantage is probably with petroleum.
One problem with conversion of agricultural feedstock to ethanol is scale. Even if all the corn in the US is turned into ethanol it will only yield 6 billion gallons per year, while the most optimistic future US cellulosic ethanol estimates envisage no more than 3 to 6 billion gallons per annum. Compare these numbers with current US gasoline consumption of about 150 billion gallons per annum.
Food or fuel
Castro went for Bush’s juggler for a different reason; his concern was about depriving billions of people of food, not energy balance economics. As someone said, just when everyone thought they were both dead, one physically the other politically, both sprang to life. The full report of his statement can be found on the web on Digital Granma International at (saite).
Surprisingly, Castro has evoked a chorus of support all the way from the Economist, Business Week and Foreign Affairs on the right, to scholarly and scientific writers, economists and the Marxist press.
The United States produces about 40% of the world’s corn and is the largest exporter - about 70% of world corn exports. If there is large scale conversion of corn to fuel, upsetting the global food trade, prices of all food will rise and shortages of staples will mean hunger for over one billion of the worlds poorest. Prices of all food will be pushed up because a shortage of corn will be reflected in price increases of all staples, wheat and rice included, and also because corn is a basic in many types of animal feed.
As Joel Wendland summarises (saite), Castro has strongly criticised the notion that people in developing countries should give up food production to put more fuel into automobile tanks in rich countries. Apart from food shortages Castro has pointed to serious water and land problems and warned against an ethanol dependant economy inextricably tied to rich country markets with little chance for diversification. Wendland says that he has even challenged one of Cuba's largest trading partners and closest friends, Brazil, for its growing role in ethanol production.
World food prices have escalated extraordinarily in nominal terms in 2007 – the IMF nominal food price index more than doubled in 2007 (real prices though are still only half their 1974 spike which also spiked Lanka’s coalition government!), and the nominal prices of wheat and corn are at an all time high. In the past prices shot up when there were shortages but not so this time though Australia has been hit by severe drought. Food prices are rising despite record global production of cereals! So what’s up?
One reason is a change of dietary habits, the second ethanol. The Chinese, Indians and indeed people elsewhere are getting richer and stuffing themselves with more meat and dairy products – it takes more than 8 lbs of grain to get a pound of beef into the curry pot, and about half as much for pork. The Chinese for example eat three times as much meat on average than they did pre Deng Xiao Ping. In the last two decades the world’s farmers have more than doubled the amount of cereal that they feed their animals. Human consumption of cereals has not increased much since 1980 despite population increase, but demand for meat has doubled in the developing world. The tragedy is that while many may be heaping their plates, about a third of the world’s population, the poorest city dwellers and landless rural people, go to the wall when food prices rise.
America now ties with Brazil as the world’s largest producer of ethanol, but the later uses sugarcane and does not take a plate of food away from the most hungry. The US on the other hand uses corn, and now uses more corn for making ethanol than it exports. What is worse is that American farmers and mega-companies are converting land used for growing other food crops to corn production to take advantage of huge government ethanol subsidies. Brazilian ethanol is greener (environmentally less damaging) and cheaper, but an import tariff of 54 US cents per gallon keeps it out – that is, the tariff effectively subsidises local ethanol. There are also a slew of direct subsidies to farmers. American agro-companies and big farmers are getting rich on obscene subsidies - corn, cotton, meat, and you name it. The resulting global price distortions are driving poor country farmers to the wall and led to the collapse of the WTO accords in the Doha Round.
The environmental argument
I have scoured the literature and ended up feeling that the environmental debate on ethanol is still inconclusive, so if you trust my judgement I suggest you too conclude that the jury is still out. The naysayers argue, rather convincingly, that the environmental benefit is limited since the amount of CO2 released during the production and use of ethanol is similar to that of gasoline. A blogger who uses the name Fray summarises the critical viewpoint briefly thus: "Bio-fuels will be an ecological disaster. If the price of crops increases, it will not be cattle farming land that will be used to produce these crops. Instead poor farmers will burn and chop down more forests to increase available land. In addition, much of the open land is unsuitable for large scale farming and using it will result in destruction of the top soil". In any case even if large amounts of forest land and pampas are given over to feedstock crops it will only make a small dent in meeting petroleum demand, so what’s the point of the environmental damage?
The pro-ethanol environmentalists put their case mostly in terms of the use of cellulose feedstock and the prospect of new technologies for this purpose emerging in the coming years. These include the use of microbes to extract fuel from straw and wood waste, ethanol from algae and the scatological joy of using good old excrement. I think we had better let the case rest at this before the odour of the debate gets fetid."

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