[permaculture] Infeasible power fantasies (Was: Energy-Energy Policy-Bioregional Design-The Sustainability of Biofuels.US.FL)

Robyn Francis erda at nor.com.au
Sat Jun 16 02:31:22 EDT 2007




On 16/6/07 1:02 PM, "jedd" <jedd at progsoc.org> wrote:

> On Sat, 16 Jun 2007, Robyn Francis wrote:
>> Solar Voltaics are only one means of solar power generation. Many of the
>> new solar thermal systems actually peak at 2am so the issue and some store
>> heat to generate energy for several days. The only issue then is backup for
>> extended cloudy wet periods.
> 
>  Hi Robyn,
> 
>  Are these the things that look like a black corrugated iron roof,
>  and that get stupidly hot in even the mildest heat .. ?  I've seen
>  these, and am expect I'll head down that path for my own hot
>  water system.  Do you have some pointers to manufacturer or retail
>  pages of the 2am-peak style systems that you're referring to?

Jedd, you need to think beyond the isolated individual household systems. At
that scale currently solar voltaics are pretty-much all that's on offer.
However there's a lot of innovation happening with solar thermal systems and
most of these operate on a larger scale to power from 20 up to 200,000
households. Many of these employ parabolic reflectors. Some store heat
overnight using various liquids.

Some of these could be installed on flat rooftops in innercity areas and
industrial estates or even over roofed carparks. Other prototypes have been
set up on farmland with no disturbance to livestock free-range grazing
underneath.

You might like to check out
http://en.wikipedia.org/wiki/Solar_thermal_energy just to see how a few
solarthermal power generation systems work. I've seen other
systems/variations in documentaries and various science & technology
articles.

There's also the solarthermal power station being built in Western NSW with
a big glasshouse covering hectares of land. The hot air accumulating under
the glass feeds convectively through a huge tower in the centre driving a
turbine. This system also is expected to peak daily at 2-3pm.

Ciao
Robyn





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