net energy is the amount of energy required to make more energy (or energy returned on energy invested–EROEI).
in other words,
net energy = energy out – energy in
where “energy out” is energy gained and “energy in” is energy invested. For instance, at the tar sands, net energy = 2 barrels out – 1 barrel in = 1 barrel (thanks, luis, for the sharp eyes)
the post-carbon institute says it’s the most important but least understood term.
when energy companies say there are billions of gallons of oil IN the tar sands, they’re not telling the whole truth.
a hundred years ago, we got a hundred barrels out for every barrel of energy in. cheap oil.
but today, in the tar sands, we get two barrels out for every barrel of energy in. no more cheap oil. it costs a lot more to get energy. this has not only economic costs, but environmental and social costs, too. and it’s more than just oil, it’s everything. unless we choose otherwise.
so, understanding ‘net energy’ is key to understanding our future, to knowing where we’re going. but ignorance is bliss, right until we fall off the tower…