Petroleum coke

Petroleum coke is like a really dirty, black rock that is made from oil. You know how sometimes you get a tiny bit of a black stuff on your face when you rub your eyes? That's called soot, and petroleum coke is kind of like a whole bunch of that soot stuck together. People use petroleum coke to make things like fuel and electricity. But it's really bad for the environment because it releases a lot of pollution when it's burned. So, people are trying to find other ways to make fuel and electricity that don't use petroleum coke.