blue
business
chemical
chemistry
chimney
color
distillery
energy
engineering
environment
equipment
factory
fuel
gas
gasoline
global
heavy
high
industrial
industry
iron
manufacture
manufacturing
metal
oil
petrochemical
petrol
petroleum
pipes
plant
pollute
pollution
power
process
production
refinery
resource
silo
sky
smoke
station
steam
steel
structure
sunset
supply
technology
tower
warming
work