environmental
abstract
bicolor
cartoon
clean
concept
design
duotone
eco
energy
enhanced
factory
flat
flow
geothermal
geyser
graphics
gray
green
heat
hydro
illuminating
illustration
infographic
isolated
lava
metaphor
modern
nature
plants
pollution
power
pump
renewable
scene
smoke
solar
sources
station
steam
story
storytelling
system
technology
thermal
volcano
water
wind
yellow