air
blue
chimney
city
clean
clouds
coal
commercial
condensation
construction
cooling
daytime
dioxide
dusk
ecology
electric
electrical
electricity
energy
engineering
environment
environmental
factory
fossil
fuel
gas
generator
global
industrial
industry
metal
plant
pollute
pollution
power
production
progress
resources
sky
smoke
stack
station
steam
technology
tower
turbine
vapor
warming
water
white