Biomass Baloney

I am not an expert on global warming...oops, strike that...climate change (apparently the globe hasn't actually warmed up that much in 20 years or more), but there was something on our local news the other night that caught my attention.  Apparently Drax Power Station near Selby, North Yorkshire is planning on being  biomass fuelled, instead of being coal fuelled.  Now this all sounds very ecologically friendly but the biomass material is made mainly from trees (from sustainable forests, so they say).  So for a huge power station burning fuel 24 hours a day, thousands of trees would have to be destroyed to fill up one 50,000 ton tanker with biomass pellets. Oh, did I mention that the biomass is shipped in from USA?  Is it just me or does this not make sense to you either?  The irony of it is that we used to have a good supply of coal from down the road in Doncaster.  I understand about Drax wanting to reduce their carbon footprint, whatever that actually means, but to destroy nature in the process just seems a bit strange to me.