Charter Street plant on UW-Madison campus does burn coal, but it's a pretty small plant, and this energy mainly goes to steam and hot water on the UW-Madison campus. It's a very small plant - about 10 MW (MegaWatt = 1 million Watts). MGE's Blount Street station burns coal and natural gas with a peak output of 190 MW, which is also pretty small. Blount St. is scheduled to go natural gas-only in 2011. The newish West Campus Cogen facility burns gas only and produces 150 MW at peak. It doesn't operate much in the spring and fall - it usually only fires up for the summer-afternoon air-conditioning spikes and other peak-load events. I toured the West Campus Cogen back in March - it was down then and hadn't run since the beginning of January, because there wasn't enough demand to run it. Almost all natural gas plants are peakers - they don't run 24/7.
The bulk of MGE's power (other than what they buy from other utilities) comes from the Columbia coal plant in Portage. This plant is 1,000 MW, which is baseload generation that runs most of the time.http://www.mge.com/about/powerplants/
The proposed biomass conversion at Charter Street will increase campus train volume by 5-10x versus coal. The current plan includes several new sidings for the trains and an automated mechanical dumper system to make things as efficient as possible, but it's still going to mean more trains.