blue
business
chemical
chemistry
chimney
construction
dark
diesel
distillery
ecology
economy
energy
engineering
environment
environmental
equipment
factory
fuel
gas
gasoline
global
industrial
industry
manufacture
manufacturing
metal
night
oil
petrochemical
petrol
petroleum
pipe
pipeline
plant
pollution
power
production
refinery
sky
smoke
smokestack
stack
steam
steel
structure
supply
technology
tower
tube
warming