[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.
> 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?





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
ICBM: 48.07100, 11.36820 http://www.ativel.com http://postbiota.org
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