21世纪:生物燃料代替石油？

Enoch

[BBC 英文报道 1月14日]

http://news.bbc.co.uk/1/hi/sci/tech/7187361.stm



Biofuels 'are not a magic bullet'

Biofuels may play a role in curbing climate change, says Britain's Royal Society, but may create environmental problems unless implemented with care.

In a new report, the Society suggests current EU and UK policies are not guaranteed to reduce emissions.

It advocates more research into all aspects of biofuel production and use.

The report says the British government should use financial incentives to ensure companies adopt cutting-edge and carbon-efficient technologies.

"Biofuels could play an important role in cutting greenhouse gas emissions from transport, both in Britain and globally," said Professor John Pickett from Rothamsted Research, who chaired the Royal Society's study.

       
Nature has provided countless potential solutions in organisms as diverse as cows and microbes
Dianna Bowles, York University
"But it would be disastrous if biofuel production made further inroads into biological diversity and natural ecosystems.

"We must not create new environmental or social problems in our efforts to deal with climate change."

Variable savings

Biofuels - principally ethanol and diesel made from plants - are one of the few viable options for replacing the liquid fuels derived from petroleum that are used in transport, the source of about one quarter of the human race's greenhouse gas emissions.

Vehicles, and the infrastructure for delivering fuel through filling stations, can be modified at marginal cost - certainly compared with the price of a large-scale switch to hydrogen or electric vehicles, even if they were to prove technologically and economically worthwhile.

Hence the adoption by Europe and the US of policies to stimulate biofuel production and use.

But a number of recent scientific studies have shown that the carbon savings from using biofuels compared with petrol and diesel vary hugely, depending on what crop is grown and where, how it is harvested and processed, and other factors.

EU to reconsider biofuels
There are also concerns that widespread planting and use of biofuel crops would threaten natural ecosystems and raise food prices.

Policymakers are increasingly aware of such concerns. Before the Royal Society launched its report, European Environment Commissioner Stavros Dimas told the BBC that the EU had not foreseen all the issues thrown up by its target of providing 10% of Europe's transport fuel from plants.

Launching the Royal Society report, Professor Pickett noted that current EU and US policies did not mandate that biofuels should achieve any carbon saving.

The report said that the UK government's Renewable Transport Fuel Obligation (RTFO), which mandates that 5% of fuel sold on filling station forecourts by 2010 must come from renewable sources, suffers from the same flaw, though changes are being discussed in Whitehall.

As a result, the report concludes, these policies "will do more for economic development and energy security than combating climate change".

Next generation

On the UK policy front, the Society advocates:

    * extending carbon pricing to transport fuels
    * providing specific incentives for innovative approaches to fuels and vehicles
    * extending the RTFO to 2025

More generally, it says research into new biofuel technologies should be encouraged through financial incentives.

Of particular interest are ways of processing lignocellulose, the material which makes up the bulk of many plants and trees. Learning how to convert this easily and cheaply into ethanol or other biofuels would make refining much more efficient, and vastly expand the range of crops that could be used.

Biofuels: Next generation
"What we have to do is to undertake research and development in such a way that we can unlock the tremendous potential that nature has provided us with in terms of getting enzymes to degrade cellulose and make ethanol," said Professor Dianna Bowles from the University of York, another member of the Royal Society's study group.

"Nature has provided countless potential solutions in organisms as diverse as cows and microbes, and that offers tremendous hope."

But alongside this technology-focussed research, said Dr Jeremy Woods of Imperial College London, should go programmes aimed at measuring the true environmental and social impacts of different approaches.

He gave the example of African nations such as Tanzania, where various parties including the government, local entrepreneurs and multinational companies are exploring the potential of biofuel crops.

"Tanzania is quite likely to start indigenous biofuel production," he said, "and if they do it in a good way, they could improve food production and preserve biodiversity."

He suggested establishing some sort of certification scheme for biofuels, similar to ones already in existence for timber and fish, to show which are produced sustainably.

But, he said, there was a need to keep problems in perspective, particularly the idea that rainforest-destroying palm oil plantations were being established all over southeast Asia simply to provide biodiesel.

"Only about 0.7% of palm oil used in the EU is used for biofuel production," he said.