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Effects of biofuels revealed

5 February 2013, by Harriet Jarlett

Concern is growing about finding alternatives to fossil fuels, but the negative impact of one of these – biofuels – may be greater than we first thought, say scientists.

Willow coppice

Researchers show, using a computer model, that the natural chemicals released through growing biomass plants could be dangerous to crops and humans.

Biofuels are seen as a suitable alternative to oil and coal in the bid to reduce carbon dioxide and mitigate global warming. Because of this, four years ago the EU set aggressive targets to replace ten per cent of transport fuel with biofuels by 2020. Yet these new findings suggest the health and agricultural costs could outweigh any benefits to the climate.

Professor Nick Hewitt, from the Lancaster Environment Centre who led the research, says, 'At present there's 215 million hectares of land being cultivated across Europe and using previous estimates we show that you would actually need to plant one third of that with biofuels to meet the target.' Land used to grow commercial crops over biomass would still be at risk from a product of biofuel production – ozone.

Using the model, the scientists populated their digital Europe with fast-growing trees used in biofuel production, such as poplar and willow. But when these trees are grown, chemicals such as isoprene are released. When these compounds combine in the atmosphere they form ozone – a key component of smog and a cause of crop losses. By growing enough crops to reach the targets the scientists found up to 39 per cent more isoprenes were released, and in turn ozone levels rose.

'We didn't have preconceived notions about what we might find, although we anticipated that increasing the amount of poplar would increase the amount of isoprene and ozone,' Hewitt says. 'But we had no idea of the impact we saw on human health and crop yields.'

Ozone poisoning can amount to nearly £3 billion in losses in wheat alone. Yet with plans to increase biofuel production, a further £1 billion of crop losses could be added to this.

'We had no idea of the impact we saw on human health and crop yields'
Prof Nick Hewitt - Lancaster Environment Centre

Ozone can cause severe respiratory problems. The World Health Organisation (WHO) currently believes that 22,000 people in Europe die per year due to ozone, but by planting enough poplar and willow to reach the EU target there could be over 1300 more deaths each year.

In order to generate enough land on which to digitally plant enough biofuel to reach the EU target, the scientists had to include countries outside of the EU, specifically the Ukraine. 'It is unrealistic to expect to plant that much only in the EU countries, since it would be more than half the available agricultural land,' explained Hewitt.

Even with the inclusion of these countries, by converting a third of the land to biofuel production it would mean a third less land being used to grow food . This loss was deemed a necessary forfeit, particularly since food consumption in Europe is expected to remain fairly stable until 2020.

'Deciding whether biofuels are good or bad is difficult, because they're probably beneficial from a climate point of view as they reduce CO2 in the atmosphere,' concludes Hewitt. 'But they can be a bad thing from an air quality point of view as they raise ozone levels. How you balance these though is a political decision.'


Ashworth, K., Wild, O., and C.N. Hewitt. 2013. Impacts of biofuel cultivation on mortality and crop yields. Nature Climate Change doi: 10.1038/nclimate1788.


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Your comments

So grow something else - not just poplar and willow!

Susan Linkletter, Canada
Thursday, 7 February 2013 - 17:35

This article fails to correctly identify the biofuel source category which is biofuel crops, and so it tarnishes a very very important biofuel process. Biofuels made from agricultural and forestry waste, and even MSW do not present the risks alleged in this article. There are vast undeveloped sources of these types of biofuel feedstocks that pollute our air and water by being ignored, and they should be high on the agenda... ot food or crop source feedstocks.
Lets be clear on what biofuel sources talked about and avoid being alarmist about all....

John Christie, Kelowna, British Columbia
Thursday, 7 February 2013 - 19:01

Biofuels are snake oil. There is no way but nuclear way. Why it's so hard to grasp? The problem is already solved, but Greens go on driving the world into environmental disaster.

praos, Croatia
Friday, 8 February 2013 - 01:02

1,300 people per year is about half the number of people killed on UK roads every year.

Do deciduous trees release the same quantities of isoprene?

Simon Bates, UK
Monday, 11 February 2013 - 08:53

Deciduous trees release volatile organic compounds, which include isoprenes.

Both poplar and willow are just examples of short rotation coppice, the type of biomass which was studied in this paper.

Harriet Jarlett, Swindon
Monday, 11 February 2013 - 14:45

If you're interested in the effects on air quality of different kinds of tree, Professor Hewitt's group produced a fascinating report on the subject a few years ago that's well worth a look. You can download it as a PDF here. Basically it depends a lot on the species of tree. For example, they found that Scots pine, common alder, larch, Norway maple, field maple, ash and silver birch remove the most pollutants without emitting too many new ones, whereas oak, poplar and willow can have more detrimental effects on air quality downwind so more care is needed when planting them.

Tom Marshall, Planet Earth Online
Tuesday, 12 February 2013 - 10:30

Having just written a piece for publication based on this item I now realise it does not make sense. Planet Earth should be an accurate resource reflecting accurately the research that it presents. In this case it has singularly failed to do so and is extremely confusing and misleading. Please ensure that the lead researchers approve what you write about their research, otherwise you will bring your resource and NERC research into disrepute.

Sue Everett, Somerset
Monday, 25 March 2013 - 13:52

Hello Sue,

It's hard to respond in specific terms since you don't say what in particular you think doesn't make sense and is misleading. Our articles generally are checked for factual accuracy by the authors of the paper; in this case two of them looked over it and were presumably satisfied it didn't misrepresent the findings.

Tom Marshall, Planet Earth Online
Monday, 25 March 2013 - 16:35

this is very useful for someone who needs
some help for their Investigatory project

shane ann, philippines
Wednesday, 28 August 2013 - 02:24