[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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