Student - September 21, 2006

Trees with a plug socket

In theory, enough energy can be generated from a tree to supply an entire household – not by burning its wood, but by tapping its sap, and then applying a new process to convert the sap’s components almost directly into hydrogen or electricity. Wageningen researchers are working on a technology that could set the energy world on its head.

The process exists thanks to the bacteria that Wageningen researchers discovered not so long ago in sewage sludge, explains Professor Cees Buisman from the sub-department of Environmental Technology. Buisman was one of the speakers at the Wereldlezing (series of lectures in Hotel de Wereld) organised by the alumni association KLV on 15 September. The theme of the lecture was bio-based energy sources.

‘These bacteria convert molecules present in large numbers in nature into hydrogen and give off electrons in the process,’ says Buisman. ‘Six AIOs are currently working on biofuel cells in which we are applying this principle. One AIO is working on an even more extreme project, in which we are studying whether we can directly tap the sap streams from trees and other plants and use it as fuel. Buisman expects that this will not harm the trees, although it will slow their growth. ‘If the project proves to be successful, we will try to get some EU funding for it,' says Buisman, adding that it is not easy to raise money for such a daring project.

Nonetheless, Buisman’s alternative green energy source could be in great demand some day. The other green energy sources currently being pursued by the EU such as biodiesel made from coleseed have limited potential, according to Christoph Tönjes, energy specialist at Clingendael Institute. Tönjes was the second speaker invited by the KLV. ‘To replace all the diesel we use with biodiesel made from coleseed, we would need more than the entire agricultural area of the Netherlands,’ says Tönjes. ‘We could certainly satisfy part of our energy needs by producing in other countries, but even this has its limitations. We also need land to produce food.’ This is why Tönjes believes the solution to the energy problem should not be sought primarily in new energy sources, but in energy savings.

It became clear during the lecture that there is surprisingly little interest in technology to save energy, compared to the enthusiasm expressed for technology to produce alternative energy. As an example, Buisman reported that ‘Windmills supply one to two per cent of our energy needs. That isn’t very much, yet the government has invested a considerable amount of money in wind energy. In contrast, six per cent of the energy produced in coal-fired power stations is not used. The stations operate in the middle of the night when there is little demand for energy. Operating at night enables them to handle the sudden surge in demand for electricity that occurs in the morning.’

A system to store this wasted electricity would make a bigger difference than all that expensive wind energy. ‘And yet it’s not being pursued,’ says Buisman. ‘I wonder why.