I'm actually in the process of finishing my first dedicated workshop right now. I live in Minnesota, so heating was definately a concern. My other concern was cost. If I did gas heat, I'd have to run gas lines. I didn't want the danger of fire in a woodshop, and kerosene is too messy. I also didn't want to have to deal with constantly refilling a propane bottle. So, that left me with electric.
After a ton of research, I settled on the Solar Comfort by SunCloud. I've included a link.
http://www.suncloud.com/research.shtml
It uses 4 R-40 375Watt Lightbulbs to heat a special panel inside the unit. After the panel get's to 120 degrees, that fan kicks in and starts circulating the air in the room.
I don't have my ceiling in my shop yet, and you loose about 70% of your heat thru your ceiling, but so far, the coldest day we have yet had is about 25 degrees and the Solar Comfort kept the room (132 sq ft, 10' 8" x 11' 8") at about 40 degrees. Once I get the ceiling up (should be tonight or tomorrow) the unit should keep the heat at about 65 degrees. The unit is capable of heating 500-800 sq ft (depending upon insulation) and costs approximately $1 per day to run if running all of the time (ie. never turns off). I've had it running for almost a month now, so i'll know for sure when I get my next electric bill.
I did talk to a few people who own these units, and one of them told me that her house used to cost about $400 to heat in the winter using gas. She bought 2 sun clouds, and her monthly bill is now $90. Sounded good to me. I may just buy a few of these for my house if it works that well in my garage!
At any rate, I wanted to share this with you, as it is an awesome little furnace.
Take care,
Wade