Heating a basement

[maple1]

I'm not so sure 4.59 kerosene is more expensive than 0.13 electricity, btu per btu. I did some rough calcs here in the fall on 0.15 electric vs. oil at $1/litre, the electric was still 70% more expensive. For the OP, I'd max out on the insulation & air sealing, then try simple plug in electric space heaters. Or, figure out if all the output from the existing furnace can be directed/ducted down there - even with some minor ducting mods, if possible. It wouldn't take much of a blast from that to heat the basement space up.