> From: David Thatcher <davidt@xxxxxxxxxxxxxxxxxxx>
>
> On Thu, Apr 05, 2007 at 04:39:12PM +1000, Wayne Harridge wrote:
>
>> That's a good question, I wondered about that myself. Off the top of
>> my head I'd guess that used cooking oil would only fuel a very small
>> percentage of diesel vehicles on the road.
>> ...Wayne
>
> ...produces similar sorts of quantities of greenhouse gases too...
In theory, if you burn biofuels, you're putting carbon in the air
that plants took out of the air last year, rather than millions of
years ago, and that plants take back up from the air in the following
year.
In reality, it takes ten calories of petroleum to produce a single
calorie of grain these days, so unless you grow your own oilseed
without using petroleum, it does in fact consume petroleum to burn
biofuels.
In fact, David Pimentel (Cornel University) claims that commercially
made ethanol from corn actually consumes more energy in its
manufacture and distribution than it contains! So it's digging us
into the energy debt hole faster than simply burning the petroleum to
start with.
(Pimentel says biodiesel has a positive energy balance, but just
barely. He draws a lot of ire from people who are fans of sugar cane
or switchgrass or anything else, but if they had actually studied his
work, they'd see that he only makes claims for currently used methods
of production from commodity-sold, agri-business corn.)
:::: Jan Steinman, Communication Steward, EcoReality: http://
www.EcoReality.org ::::
:::: 160 Sharp Road, Salt Spring Island, BC V8K 2P6, Canada,
250.537.2024 ::::
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