Re: Cellulosic Ethanol

From: quasarstrider (quasarstrider_at_yahoo.com.br)
Date: 08/27/04 

Date: 27 Aug 2004 16:59:04 -0700

Robert <RB@..> wrote in message news:<qrqsi0t7kv32on82k7mvp1cr79rh9jla94@4ax.com>...
> On 26 Aug 2004 08:10:09 -0700, bri1600bv@hotmail.com (brianb) wrote:
>
> This argument has been put forward many times and knocked on the head.
> Sunlight is low entropy energy.
> It cannot be converted to useful forms very easily.

You sure could have fooled me. Most of this planet runs on sunlight.

> PV cells offer the best solution but they are energy costly to build.
> ..and as I pointed out, we will need 300,000 sq kms of them at least.

Solar thermal is more efficient and simpler for mainline power generation.
PV is only 15% efficient using current mass-production panels. The solar
thermal trough rankine cycle facilities are approximately 22% efficient:
http://www.consumerenergycenter.org/renewable/basics/solarthermal/thermal.html

Alternative solar thermal designs like the solar tower, which uses molten
salt for thermal storage, allow more continuous power generation:
http://www.solarpaces.org/SOLARTRES.HTM

There are also trough generators using thermal storage:
http://www.solarpaces.org/US_TROUGH.HTM

Solar PV will still be used where it makes sense. Low-maintenance,
low-power generation in innacessible places. Once their efficiency improves,
they may be used for mainline power generation as well.

I still think nuclear power is better for baseline power generation in most
places, but these technologies will have their share as well.

> Ethanol production will need even more land.
>
> If we want to burn wood directly, we will use up all the Earth's rainforests
> each year.
>
> Humans can certainly reduce their usage of oil and coal but that will only
> postpone the inevitable.

Forests are very inneficient in converting solar power. We can do better than
that.

Relevant Pages

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