The Royal Society of Chemistry, Europe's biggest stinks association, has weighed into the biofuel debate. RSC chief Dr Richard Pike, in a statement issued today, criticised current and near-future alternative fuel technologies and characterised carbon offsetting schemes as "bogus".

"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 the hard-hitting brainbox, a chartered engineer and chartered scientist.

Dr Pike's remarks appeared to have been stimulated by the fuss arising from biz kingpin Richard Branson's recent flight test of a 747 partly running on fuel made from coconuts.

"Flying on biofuel is a milestone," says the RCS statement, "but it must not become a millstone." Pike apparently sees the quest for biofuels as a wild goose chase through a minefield amid dangerous waters, up a creek without a paddle towards a plan you wouldn't touch with a bargepole.

Ahem. The good doctor went on to say that biofuel was a very inefficient way of using land to turn sunlight into portable energy. He said that solar power devices used to generate hydrogen by electrolysis would give you 20 times as many joules per acre.

Pike admitted that such technology would be "more expensive and complex" than "low-cost, low-yield" biofuels competing with food production and rainforests for fertile land. But he said that a hydrogen-fuelled transport system, as well as using sunlight and space relatively efficiently, would be able to draw on other kinds of low-carbon power.

"If the issues of hydrogen and electricity storage can be resolved," he said, "this would expand the flexibility of applying other energy sources, such as wind, tidal, geo-thermal, hydro-electric and nuclear, to the transportation sector."

The doc isn't wedded to hydrogen, however, saying that the true "Holy Grail" for future transport fuel would be artificial photosynthesis, in which water and CO 2 would be combined to produce energy-dense fuel. Pike speaks of driving this using "the sun's energy and new catalysts in a land-efficient way" - but American boffins have said that you could power such fuel factories using any kind of energy you fancied.

Despite being a former oil and gas exec, Pike had little time for the various kinds of synthetic fossil-derived transport fuels currently being tested. These are sometimes seen as a possible alternative to juice made from expensive and increasingly insecure crude oil imports. Under these plans, liquid fuel would instead be made out of coal or natural gas - relatively cheap and securely available, at least for some Western countries.

"Coal-to-liquid (CTL) and gas-to-liquid (GTL) options are also being promoted," says Dr Pike, but "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."

The RCS boss rounded off his remarks with harsh words on companies buying carbon credits to achieve green credentials.

"The majority of carbon-offsetting schemes are bogus," he said bluntly, "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."

So there you have it - greenbacks can't make you green. There ain't no such thing as a carbon neutral organisation - according to the RCS, anyway. And the official opinion of the biggest alliance of chemistry boffins in Europe has to carry some weight in this area at least, whatever you think of hydrogen cars and photosynthetic fuel grails. ®