blue
building
carbon
chemical
chimney
climate
crude
diesel
distillate
ecology
emission
energy
engineering
environmental
factory
fuel
gasoline
heat
heavy
high
hydrocarbon
industrial
industry
iron
liquid
manufacture
metal
modern
natural
oil
petrol
pipeline
pollution
power
process
production
refinery
safety
sky
skyline
smoke
station
structure
supply
tank
technology
top
tube
white
work