In short, yes.
Green belt policy exists to protect land so that we do maintain a level of rural countryside across the UK. So it's rightfully much harder to obtain planning permission for land which has been designated as green belt. Harder... but not impossible. The green belt policy does allow for 'appropriate development' and each application is considered against criteria for this.
The map below shows the extent of green belt land in this area. If the CHP facility is to be built close enough to end users of the heat and power, it may have to be built on green belt land.