air

burning

carbon

chimney

cloud

coal

condensation

contemporary

danger

day

dioxide

dirty

dust

electricity

energy

environment

factory

fog

fossil

fuel

fumes

gas

generating

generation

generator

global

gray

industry

natural

overcast

pipe

plant

pollution

power

powerhouse

refinery

silhouette

sky

smoke

stack

station

steam

supply

technology

tower

toxic

warming