Barking up a new tree for renewable energy sources

Alternative energy sources, such as solar power, tidal power and wind power, are often derided by critics as expensive, impractical or even (in the case of wind turbines) damaging to the environment. But there is another little-discussed alternative which can be used both as a fuel and to provide electricity.

It is widely available, easily renewable and carbon-neutral. And unlike wind and solar power, it provides energy on demand rather than intermittent energy dependent on the weather.
This revolutionary material is wood. Banish from your mind the thought of a homely log fire. Often referred to as biomass – because it is a combustible product of biological origin – wood fuel these days comes in the form of dried pellets, 15mm long and 6mm in diameter.

Pellets provide twice as much energy as wet wood – 1kg of wood pellets provides as much heat as a 1 kilowatt electric fire running for five hours. They are burned in specially adapted boilers that can be used both in ordinary homes and in large buildings to fuel central heating systems.

Widely used in Germany, Austria and Scandinavia, wood pellets have been slow to find a market in the UK. But what exactly is so good about wood? “It’s a renewable fuel, because obviously you can plant more trees,” says Laura Yates, a climate campaigner at Greenpeace. “And it’s effectively carbon-neutral, because trees and plants suck up carbon dioxide when they grow and then emit that same amount of carbon dioxide when they’re burnt.”

There are downsides. Wood’s energy density is about two-thirds that of coal, and half that of oil; you need more wood to get the same amount of energy.

Guardian