[ExI] Some thoughts on the ecopocalypse - the argument for domestic ground based solar.
Eugen Leitl
eugen at leitl.org
Fri Nov 27 13:24:50 UTC 2009
On Fri, Nov 27, 2009 at 12:42:38AM +0100, Anders Sandberg wrote:
> At a public lecture this summer the speaker before me proclaimed his
> green credentials by claiming that we must reduce carbon emissions by
> 80%. I instead argued that we ought to aim for a 150% reduction - we
> need large scale carbon negative activities. I proposed genetically
> modified afforestation. Ah, the sound of brains popping... :-)
The only advantage of trees is that they're autopoietic,
PV-driven air scrubbers which e.g. generate methanol from
captured CO2 could have an order of magnitude higher efficiency.
> Only good if you have a lot of solar around. Sweden and Britain are not
> known for their sunshine.
CIGS does quite well in diffuse daylight, so you can easily be a net
producer just from the PV area of your house surface.
http://www.nrel.gov/features/20091016_solar_decathlon.html
> I really recommend MacKay's "Sustainable Energy without the hot air"
> (full text at http://www.withouthotair.com/ ) It is a very good
> walkthrough of how to make estimates of energy needs and production,
> checking the realism of various claims and sketching possible energy
> scenarios. Not all perfect (his argument against my above afforestation
> plan is frankly stupid) but a very stimulating start for serious
> thinking (and lots of fun facts to throw at people).
His main fault that he considers thermal and electrical Joules the same,
which they are not. Thermal collectors are easily >80% efficient,
current residential PV <20%, not mentioning the price.
> The big question is economies of scale. For solar, MacKay points out
> that individual photovoltaic pannels are unlikly to become efficient
Au contraire, every building needs a roof and a facade. Integrated
approaches have very little or any incremental costs, and they can
provide net excess in cloudy, rainy weather. What would be nice
to see is a building that not only ROIs but also EROIs over lifetime.
> enough to be really effective in small scale. Solar farms look much
> better. Similarly, being able to store energy and distribute energy
Solar farms have the disadvantage is their output needs to be transformed
and transported, and sold by a monopolist. No wonder existing producers
want to go Desertec, and bypass sales by tapping tax-funded subsidies.
Pure genius, you might produce cheaper energy on your roof, but we don't
mind, since you've already paid us via taxes.
> efficiently seems to have great economies of scale, making the solar
> sheets inefficient compared to current systems.
>
> So what we want is a technology that has low thresholds to entry, can
> adapt itself fast due to competition, yet fits in with scale-ups. I
> wonder if pebble-bed reactors could do it?
Anders, have you missed peak uranium?
http://europe.theoildrum.com/node/5631
http://europe.theoildrum.com/node/5677
http://europe.theoildrum.com/node/5744
http://europe.theoildrum.com/node/5929
It doesn't look like novel reactor types will be there on time,
given that we need to roll out massive capacity by 2030 or 2040.
I think thin-film PV is the only technology up to the task.
--
Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org
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