blue

cable

chimney

chp

cold

current

ecology

electric

electrical

electricity

energy

equipment

factory

frost

gate

green

greenhouseeffect

heat

heavy

hot

ice

industrial

industry

lamp

line

morning

nature

outdoors

pole

pollution

power

production

railway

sidetrack

siding

silo

sky

smoke

snow

sunshine

tall

tank

technology

track

voltage

water

watervapor

weather

winter

wire