Willow trees adapted for green energy
Willow trees, traditionally grown for wicker furniture and baskets, are now being viewed as an important source for energy and the environment. It has recently been discovered that willows cultivated for green energy can yield five times more biofuel if they are grown diagonally, compared with those grown naturally, i.e. skyward.
Previously, scientists were unable to explain why some willows produced more biofuel than others. British researchers, observing willows in the wild and in plantations around the United Kingdom, have identified the cause: a genetic trait, activated in some trees when they are at an angle, such as where they are blown sideways in windy conditions.
This effectively creates an excess of strengthening sugar molecules in the willows' stems, which attempt to straighten the plant upwards. These high-energy sugars are fermented into biofuels when the trees are harvested. The harvesting process currently used needs to be streamlined before it can rival the production of fossil fuels.
The study was led by Dr Nicholas Brereton and Dr Michael Ray, both from the Department of Life Sciences at Imperial College London, who worked with researchers at Rothamsted Research, and the University of the Highlands and Islands (UHI) Agronomy Institute at Orkney College. The study is published in the journal Biotechnology for Biofuels.
Dr Brereton said: 'We've known for some time that environmental stresses can cause trees to naturally develop a slightly modified "reaction wood" and that it can be easier to release sugars from this wood. This is an important breakthrough: our study now shows that natural genetic variations are responsible for these differences, and this could well be the key to unlocking the future for sustainable bioenergy from willow.'
In order to conduct their studies, a team of researchers used controlled laboratory conditions on a rooftop in central London. They cultivated willows at an angle of 45 degrees, and then looked for any genetic differences between these plants, and those growing naturally. They also looked for the same effect with willows growing in natural conditions on Orkney Island, off the northernmost coast of Scotland, where strong winds cause the trees to bend at severe angles.
Their measurements confirmed that the willows could release five times more sugar than identical trees grown in more sheltered conditions. Researchers say the the willow's capacity to make biofuels for motor vehicles, and for heating systems and industry, can in future be enhanced to make the tree a more productive and greener energy source.
The willow is cultivated widely across the United Kingdom. It requires less than a tenth of the fertiliser used for most cereal crops, and its shoots regrow quickly after they are harvested. Environmental groups also say that willow plantations are attractive to a variety of wildlife, having a positive impact on local biodiversity.
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Imperial College London
Biotechnology for Biofuels
Data Source Provider: Imperial College London
Document Reference: Based on information from Imperial College London
Subject Index: Biofuels; Scientific Research