I have an uninsulated garage. It's about 20X20 with 8 foot ceilings (almost flat roof) and lot's of air leaks.

i could run a natural gas line in there, or wire it to 220 (or use propane or kerosene) . What is the best choice for a safe heater that will enable me to work out there now and then this winter?

I don't need it toasty warm--Just warm enoough to take the chill off, and remove my gloves when i need to do finer work. This in in saint paul, mn. I should say i have asthma, so i wouldn't want anything that's very stinky.

what is the best and most economical option?

thanks in advance.