燃やす
alternative
background
bio
biofuel
biological
biomass
brown
closeup
compressed
domestic
eco
ecologic
ecological
ecology
economy
energy
environment
fire
fireplace
firewood
fuel
green
heap
heat
mass
material
money
natural
nature
organic
pellet
pellets
pile
pine
power
pressed
recycling
renewable
roll
sawdust
season
solid
stove
timber
top
view
winter
wood
wooden