background
black
black gold
blue
branch
carbon dioxide
carbon structure
coal
coal pile
combustible
combustion
composition
contamination
dark
dirty
dusty
ecology
ecosystem
element
energy
energy storage
exploitation
factory
flake
fossil
fuel
geology
green
grill
hard
hard coal
heat
heat and power plant
heat source
industrial
industry
leaf
mine
miner
mineral
mining
oxygen
pile
plant
pollution
potential
power
production
purity
raw material
rock
solid
solid fuel
splintered
stone
stove
texture
tree
tuxedo
unclean
underground
vivid
wealth
young