Biofuel: milestone must not become a millstone
27 February 2008
Claims and counter-claims about biofuels, made in the race to acquire green credentials, risk confusing the general public, the chief executive of the Royal Society of Chemistry said today.
"And, where spin takes precedence over hard facts, the outcome is likely to be a spate of uncoordinated initiatives that have not been fully thought through," said Dr Richard Pike.
Dr Pike, a former oil industry senior executive, added: "Firstly, current biofuel sources convert only about one percent of sunlight into ethanol, or a range of bio-diesel or bio-kerosene, depending on whether the feedstock is sugar cane, vegetable oil or other types of biomass."
This compares with close to 20% for solar power devices that could be used to generate hydrogen by electrolysis.
He said that a key question for transportation was, therefore, whether or not society should go for essentially low-yield, low-cost technology for fuels that easily blend with their fossil-based equivalents, but with potential competition with regard to food-crops, and uncertainties over actual carbon-savings?
"Or, should we look more seriously at an alternative that requires around just one-twentieth of the land area, energy for energy, but is more expensive and complex, and places demands on innovative ways of storing hydrogen and electricity?"
The step beyond this, he said, was the 'Holy Grail' of using the sun's energy and new catalysts in a land-efficient way, to combine existing carbon dioxide in the atmosphere with water, to manufacture alcohols and other fuels in a process known as artificial photosynthesis. This would be particularly attractive for air transportation, and would be completely green.
"If the issues of hydrogen and electricity storage can be resolved, this would expand the flexibility of applying other energy sources, such as wind, tidal, geo-thermal, hydro-electric and nuclear, to the transportation sector.
"Although coal-to-liquid (CTL) and gas-to-liquid (GTL) options are also being promoted, these are based on fossil fuels and their manufacture is extremely energy intensive. Roughly, for every tonne of 'clean' fuel used by the consumer as diesel, another tonne of feedstock has been burnt at the production site, so that globally carbon dioxide emissions per litre of fuel at end-use are significantly more than with conventional fuels."
Future carbon capture and storage (CCS) at source will address, he said, only half this total. Furthermore, 'sulphur-free' at the exhaust pipe shifts responsibility for sulphur disposal to the producing country.
"The majority of carbon-offsetting schemes are bogus because the net carbon savings of tree-planting, or other designated renewable sources, do not take account of the full-life-cycle energy and carbon balances."
Flying on biofuel is a milestone, but the achievement should not conceal, Dr Pike added, the enormous advances in energy yields per unit area of land that must be made if it is to be sustainable.
"Furthermore, it may prove, instead, to be a millstone, if in the euphoria, we neglect the really sustainable routes that should be an inspiration for all scientists, young and old."
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