Black grow room? Will it work?

Ok this might sound kinda dumb but would it be ok to line my grow area in black to keep heat in as I'm using the area to grow during winter months, grow room not build yet, I don't have to worry about electric as I have a wind turbine so I can have top lights, and side lights as well as any where else I might throw lights. My friend did one last year like this and he said it worked ok, I just wanted to now if it could cause any problems?

It won't cause problems, but you won't get any reflectivity. I'm not sure how lineing your room in black would help keep heat in any more or less than mylar, but it definitly won't hurt.

kinda dumb?

I just figured black traps heat and it would also help with light leaking around door

Black absorbs heat, it doesn't trap it any better any other material of the same thickness. The only thing it will do is make the room darker, which is the opposite of what you want. Go with mylar. Any light leaks around the door can be taken care of with some weatherstripping.

It would be much better to simply place an electric heater in there, you get the heat you need in a controllable manner, and the reflectivity you need... Besides, how were you planning on getting the black walls exposed to heat in the first place? is it a greenhouse type setup where there is lots of sun? If it is i guess you could put black 50g drums full of water to act as thermal batteries to help over-night temps a little... good luck either way