Well it does depend on which method you are using.
There are a number of biomass powerstations that use organic waste which they bake to release gas. The gas is burned to generate electricity while after baking the organic material is sold as fertiliser. The best stations of this type are quite small, taking organic waste from the loclity and so reducing transport costs.
The biggest, most obvious, ones of these that I am aware of is just to the southwest of the M25/M4 junction.
But the burning wood pellets from the USA is, ecologically, very unsound. There was a documentary about it on the Beeb about 6 months ago.