3 ms·

I tried smell testing it too. For glass, we find 70 tonnes for a 1 MW capacity unit [1]. Using slightly more normal 20 year lifetime, and I'll re-use 25% capaci

I tried smell testing it too. For glass, we find 70 tonnes for a 1 MW capacity unit [1]. Using slightly more normal 20 year lifetime, and I'll re-use 25% capacity factor (which is about the avg in the USA), this comes out to 1597 tonnes/TWh of glass, compared to 2700 on the plot I showed. Running some sensitivity analysis shows that if you use 15% capacity factor, then you get 2662, basically the number given. Capacity factor is very location dependent so I guess the answer for solar resources is also highly location dependent. For instance if you're choosing between nuclear and solar in Boston, these numbers are pretty reasonable. In Arizona, there might be a factor of 2-3 improvement in solar's resource usage. In any case, best-case solar uses vastly more raw materials from Mother Earth than all-case nuclear. Also, solar is usually first built where it will make the most money, so early fleet capacity factors are likely to be biased high. They will decrease as people build solar in less sunny places. [1] https://www.irena.org/-/media/Files/IRENA/Agency/Publication/2017/Jun/IRENA_Leveraging_for_Solar_PV_2017.pdf https://www.irena.org/-/media/Files/IRENA/Agency/Publication...

epistasis 6y ago
Your original graph is heartily contradicted by the IRNEA numbers. I used glass as a baseline because the bad QBER numbers had it as a small component, but it has become the dominant component in these builds. The original table (vs. IRENA): 2.9x (vs. 0.8x) as much steel as glass 1.4x (vs. 0.67x) as much concrete as glass 0.62x (vs. 0.55x) as much "other" as glass Panels have 25 year warranties, assuming they will be replaced before the warranty ends doesn't seem very realistic. Choosing the worst-case-for-solar deployment of Boston isn't a good comparison metric either. So all in all, the numbers that you have linked here show that solar, in its heaviest form deployed in an open field, is within a factor of 5 compared to nuclear on the weight per amount of energy over a lifetime. And various nuclear designs easily vary by a factor of 5. SMRs, the only hope for nuclear going forward, have been avoided for a long time because it was thought they would be less efficient on a W/kg scale. So nuclear's future designs will take more mass per kilogram. In contrast, solar is decreasing its weight and efficiency all the time, and there is no shortage of sites for solar, so we will see solar's Wh/kg decrease as the technology develops. This is all a meaningless metric, but even if it did have some sort of meaning, it's not much of a win for nuclear.

epistasis 6y ago

Your original graph is heartily contradicted by the IRNEA numbers. I used glass as a baseline because the bad QBER numbers had it as a small component, but it has become the dominant component in these builds. The original table (vs. IRENA): 2.9x (vs. 0.8x) as much steel as glass 1.4x (vs. 0.67x) as much concrete as glass 0.62x (vs. 0.55x) as much "other" as glass Panels have 25 year warranties, assuming they will be replaced before the warranty ends doesn't seem very realistic. Choosing the worst-case-for-solar deployment of Boston isn't a good comparison metric either. So all in all, the numbers that you have linked here show that solar, in its heaviest form deployed in an open field, is within a factor of 5 compared to nuclear on the weight per amount of energy over a lifetime. And various nuclear designs easily vary by a factor of 5. SMRs, the only hope for nuclear going forward, have been avoided for a long time because it was thought they would be less efficient on a W/kg scale. So nuclear's future designs will take more mass per kilogram. In contrast, solar is decreasing its weight and efficiency all the time, and there is no shortage of sites for solar, so we will see solar's Wh/kg decrease as the technology develops. This is all a meaningless metric, but even if it did have some sort of meaning, it's not much of a win for nuclear.