The link below has info for 2008-09 that indicates the breakdown for power generation is:
thermal 82%
hydro 15%
nuclear 2%
other 1%
Reasonable to assume that the thermal is predominatly coal.
Projections are for ongoing growth of generation from coal. Productivity (which depends on god safety) will continue to drive IDL growth IMO - as per BRR talk the other day - thanks for that link by the way.
http://www.j-fep.co.jp/consul/2009e/231.pdf