<
https://cleantechnica.com/2024/02/02/energy-return-on-investment-rears-its-misshapen-head-again/>
"Over the past year or so, energy return on energy invested (EROEI) has shown
up multiple times for me as an attack on technologies that are now superior. A
nuclear shipping advocate tried to gotcha me with that for biofuels for
shipping. Others reasonably asked about it for biofuels in general. And there’s
a lot of disinformation floating around about fossil fuels vs renewables, being
spread by the fossil fuel industry.
It’s time for some disambiguation.
Let’s start with what EROEI is. Pretty simple, actually. It takes energy to get
energy into a form usable by us, whether that’s extracting and refining oil or
building a wind turbine. The ratio between the energy you get out versus the
energy you put in is the EROEI. And to be clear, it’s over the lifetime of the
production from the asset, whether it’s an oil well, a hydroelectric dam or a
wind turbine.
Agriculture makes energy in the form of calories which we consume. The
agricultural revolution 10,000 years ago resulted in a more positive EROEI than
hunting and gathering, so civilization arose. A positive EROEI is pretty good
for us. The Green Revolution doubled EROEI to about 4:1, so now we have a lot
more food for a lot less work. In fact, we make so much food these days that we
throw away a third of it globally, about 2.5 billion tons, something which is a
major climate headache because waste food ends up emitting a lot of methane
which is a lot worse for global warming than carbon dioxide.
It used to be that oil had really good EROEI, from 18-43:1. When it just
bubbles out of the ground, all you have to do is cap it. Conventional gas was
good as well, from 20-40:1. Stick a metal straw in the ground and cheap gas
came out. Coal has an EROEI in the 40s as well.
That’s a big reason why the Industrial Revolution occurred, because there was
an awful lot of cheap, easily extracted fossil fuels lying about the place.
What’s that? Cheap, easily extracted fossil fuels aren’t as readily available
as they once were? We’re using unconventional extraction techniques like shale
fracturing for oil and gas, and steam assisted gravity drainage (SAGD) for oil
sands crude. Those techniques use a lot more energy. What does that do to their
EROEI?"
Cheers,
*** Xanni ***
--
mailto:xanni@xanadu.net Andrew Pam
http://xanadu.com.au/ Chief Scientist, Xanadu
https://glasswings.com.au/ Partner, Glass Wings
https://sericyb.com.au/ Manager, Serious Cybernetics
