What can I do with a degree in renewable energy?

You could run for Vice President and eventually invent the internet.

It depends on exactly what the degree teaches you, but green energy is in higher and higher demand, and the field is on the verge of exploding. I'd say it's an excellent degree to get as far as job opportunities after graduation.

there is no such thing as renewable energy

sounds like a very wanky degree to me.
You can probably get a job working for a coal fired power plant.

Memeorize "Would you like fries with that?"