A green use for old Christmas trees
- 7th January 2011
- Comments (2)
As the festive period comes to a close, there will be hundreds of thousands of slightly tired-looking Christmas trees dotted around the country’s refuse collection points. While the majority of people feel a pang of guilt over this apparent waste, and many of the used trees are ‘recycled’ into chipped compost, scientists in the UK may have found a more effective use of the resource.
A special roasting process could see the masses of spruce and pine trees economically viable to be used as fuel in power stations instead of coal. The biomass products can be burned to produce a carbon-neutral form of energy, and in some power stations biomass is already used alongside processed coal dust. The problem is that due to the difficulty and expense of pulverising wood to a powder to burn alongside the coal dust, only small quantities can be used.
However, the New Scientist reports that Jenny Jones and colleagues at The University of Leeds are experimenting with a process called torrefaction to overcome this issue. Torrefaction is a roasting process where plant matter is heated in an air-free container, and is already used to produce biochar, a material used to improve soils and avoid the release of carbon dioxide that would normally result as plants decompose. The discovery that a different roasting recipe can make biomass suitable to burn alongside coal was made by Jones and her colleagues.
Furthermore, the roasting process allowed the biomass to retain some 75 per cent of its energy yield, and also made the resultant fuel hydrophobic, meaning it doesn’t absorb moisture – a distinct advantage in the storage of fuel for the future.
Comments (2)
Alastair White on 28th January 2011
Why is this desirable? Theoretically, surely, biochar is the ideal use since it kills two birds with one stone: sequestering carbon in the soil and improving fertility; whereas it’s unclear from this summary that burning the biomass would do anything more than eking the fossil fuel (coal) out with some renewable wood, and only to a limited extent since the roasting must use energy.
tony on 31st January 2011
fair enough – but but how much energy (fossil – non-fossil fuel) is used for the process – quite apart from the set up cost. Surely it is only viable as a central located plant to convert mega quantities of bio-mass waste.