There are some environmental advocates who oppose using wood chips for energy. 

This YouTube video includes the following description: "Forests are also one of our best defenses against global warming, absorbing vast amounts of carbon pollution out of the air. But power companies are increasingly proposing to burn whole trees for energy. Trees are not a "carbon neutral" fuel source. Just like coal, when trees are burned in power plants, the carbon they have accumulated over long periods of time is released into the atmosphere. Unlike coal, however, trees will continue to absorb carbon if left alone. So burning forests for energy not only emits a lot of carbon, but also degrades our carbon sinks. This video shows what happens to the balance of carbon between and forest and the atmosphere when we burn forests to produce energy instead of leaving them standing to continue to absorb and store carbon. Burning forests for electricity is dirty and destructive!" 

It is shared by the Natural Resources Defence Council.