| ▲ | dwedge 3 days ago |
| Paving deserts with black heat absorbers that are only 10-20% efficient in converting that energy to electricity could well end up affecting climate more than burning coal would |
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| ▲ | glenstein 3 days ago | parent | next [-] |
| 1% from a Dyson Sphere would be a better energy return than 100% efficiency from any conventional energy sorce. Similarly, 20% from solar is competitive with 60% from nuclear, 50% from coal, and is easily better than 100% from my neighbor Dan riding a bicycle powered electricity generator. You can't cite efficiency percentages in a vacuum to imply they are a better or worse than alternatives, because those aren't percentages of the same kinds of things, and they don't tell you about the economics, production in absolute terms or EROEI. |
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| ▲ | Ardon 3 days ago | parent [-] | | The solar panels would overheat (and lose efficiency), since ~80% of the solar energy hitting it is absorbed as (mostly) heat. Generating solar energy in deserts is often done with a mirror based heating system for this reason. | | |
| ▲ | glenstein 3 days ago | parent [-] | | Something like 98-99% installed solar capacity in the American southwest is traditional PV. Mirrors are there, and they're awesome, but PV dominates. PV are designed to account for heat and "less efficiency" means they risk performing at 17-18% instead of 20%. And it's actually generating more total energy at 18% because more total sunlight is hitting it, an advantage in desserts. | | |
| ▲ | Ardon 3 days ago | parent [-] | | Yeah that's true. I was thinking more long term though, deserts see much faster yearly degradation than places with more normal temps. (up to 2-3% compared to the standard 0.5-0.8%) That's just an economic factor rather than a blocker. PVs are cheap as right now, and could be even cheaper if they weren't tariffed. I wouldn't be surprised if PVs in the desert is nonetheless the right approach right now, and not concentrators. |
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| ▲ | downrightmike 3 days ago | parent | prev | next [-] |
| They're blue, and nothing about coal would be less impact. Coal starts with pulling down entire mountains to get to the coal. The whole process starts with environmental destruction and that's how it ends. The thermal mass of the panels is no where near significant. Especially compared to a run away greenhouse effect we know coal to cause. |
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| ▲ | easygenes 3 days ago | parent | prev [-] |
| Definitely not. At global scale, the offset effects of solar installations outweigh albedo effects on the order of about 30x. [0][1] [0] https://www.nature.com/articles/s43247-024-01619-w.pdf
[1] https://acs.figshare.com/articles/journal_contribution/Net_Radiative_Forcing_from_Widespread_Deployment_of_Photovoltaics/2871685
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| ▲ | dwedge 3 days ago | parent [-] | | It's about the localised effect of the heat generation https://www.westernsydney.edu.au/hie/stories/news_archive/so... | | |
| ▲ | easygenes 3 days ago | parent [-] | | I wouldn't give much credence to that report, as there is no demonstrated understanding of PV site installation management principles (e.g. bright ground treatment). They deliberately highlight a worst case scenario (covering 20%+ of the entire Sahara in unmanaged high density PV) and shove a quick note at the end saying that they modeled 5% and even without other mitigations that was fine. Their model also doesn't include the carbon offsets at all, so it's absolute worst case and entirely unrealistic. With proper site selection and albedo managed via density and bright ground treatment, you can expect net neutral local heat impact. |
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