alt Hacker NewsSure you can burn them, doesn't mean you're accomplishing anything from a thermodynamic point of view.
Metric to look at is EROI - Energy Return on Investment. How much energy do you put into growing these crops to get a unit of energy out?
Corn ethanol in the US is stupid because it's a 1.6:1 return at best, often a 1:1. To get a unit of energy out of corn ethanol, you need to put almost a unit in. And that's economic inputs, we know the sunshine is free. Sugarcane is a bit better, but you can only grow it in the tropics.
For reference, solar tends to be something like 4:1 - 10:1, wind is 10:1 +/- onshore or offshore, fracked oil tends to be down around 5:1-8:1, and a saudi well is (or at least used to be) 40:1.
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You are looking it from the wrong angle the way I see it.
First there are significant quantities of oils grown used in cooking and discarded, in an often environmentally damaging way.
Reclaiming and burning these adds value to a waste product.
What is the EROI on batteries surely under 1.
These oils can provide energy storage and transmission in applications where electricity is ill suited, jet engines (coconut oil is especially suitable for this) and shipping come to mind.
EROI is also why we really need to get off of fossil fuels long before we actually literally run out (i.e. now would be great)
As a resource reaches depletion, there are two forces acting on EROI: 1) the increased cost of each unit of energy input, and 2) the reduced yield from that energy input.
The EROI curve bends negative faster than you think by looking at history.
> Sugarcane is a bit better, but you can only grow it in the tropics.
Not for long! Or rather, the range of the tropics are moving, so that won't be the thing holding us back if that's the route we wanna take.
Once you have a sustainable process, these last holdout areas like dredging (where you can't use batteries or wires) can have relatively terrible EROI as long as they're a small minority of the economy. All aviation and shipping combined is about 6% of final energy, and with major redesigns for shipping it could be as low as 4%. So you'd trade a much better EROI for 96% of the economy for a terrible one that only affects 4%.