Switchgrass

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davew
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Switchgrass

I've been reading more and more positive reports about cellulosic ethanol. It sounds promising, but this got me to thinking. They are talking about using a fairly energy intensive process to convert cellulose to sugar to alcohol and then shipping that alcohol to burn in cars. Thermodynamically speaking, wouldn't it be way more efficient to just burn your plant material in a power plant and run the cars off of the electricity produced?

reikiman
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Re: Switchgrass

It may be - I haven't looked up the figures but supposedly cellulosic ethanol is at least energy positive, unlike corn ethanol. And then in terms of boondoggles, there's fuel cells -- it takes electricity to extract hydrogen, so why not just ship electricity to EV's and skip the hydrogen step? Oh, wait, it doesn't let them put off the switch from oil engines.

Anyway.. there are a number of unintended consequences to this whole ethanol/biofuels thing. It sounded like a great idea when I first heard of it. But it involves choosing between food and fuel. Even if you grow the bio material in non-farming land -- e.g. jatropha is supposedly a great source for biodiesel, and jatropha can be grown on marginal land, so growing jatropha doesn't tie up land that would otherwise be growing food. But it still takes farmers to grow jatropha, so some farmers would switch from growing food to growing fuel.

It's a real curious situation.

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NickF23
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Re: Switchgrass

Yes it would be, but without an EV fleet and infrastructure the profit is in liquid fuels. Electricity currently isn't a replacement for liquid fuels, unless of course consumers would be happy to make the sacrafice of reduced convenience, range etc or governments create direct incentives to boost non polluting transportation.

Interestingly you can go one better still by generating syngas from the plant material for energy, electricity etc and sequestering most of the the carbon back into the soil, which also improves its fertility. see http://www.worldchanging.com/archives/004815.html thus the crop itself would be both energy productive and carbon negative.

spinningmagnets
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Re: Switchgrass

Its my understanding that growing oil-rich algae in the desert is showing some promise as a diesel alternative. Even if we all switched to e-bikes and public transportation, food and products are still shipped with trucks, and farms are the most productive using diesel equipment.

Fuel cell cars that use dry compressed hydrogen dont have much range, by adding a reformer to strip the H2 from methanol, you can have a 300 mi range, you can refill in two minutes from existing fuel pumps, and there is already an infrastructure in place that makes millions of barrels of methanol every year.

I think if ethanol really takes off, there won't be a problem developing a sugar-rich plant that can be grown in marginal soil.

If lithium batteries (or some other new type) become significantly cheaper in a larger format with a user-friendly smart-charger (along with higher fuel prices!) I believe more of the public will "settle" for an EV.

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