4 ms·

So for one person you'd need $2000 worth of solar panels, 16 square meters of panel. One person. It seems like you've supported my point, not refuted it. But

by zzalpha 11y ago

So for one person you'd need $2000 worth of solar panels, 16 square meters of panel. One person. It seems like you've supported my point, not refuted it. But I appreciate your analysis, even if I dispute your conclusion! Thanks!

msandford 11y ago
It's kind of like the Tesla, which people think is amazing. For $90k you could also buy a $60k car and $30k worth of gasoline up-front and tada! you can now refuel it for free or almost free (it takes a little energy to pump the gas out of the underground storage tank and into your car's gas tank).
kragen 11y ago
Does US$2000 per person for the energy to solve the potable water problem for 30 years seem like a lot to you? Compared to the cost of other survival necessities (housing, food, sanitation, heating, cooling — http://resiliencemaps.org/ http://resiliencemaps.org/) it's quite reasonable. 16 m² is also pretty small compared to the space customarily used for housing. However, I made an error! It turns out I left out the coefficient of performance in my calculations. So it's actually 105 watts, 8 m², and about US$1000: You have: (8 liters / day) * (41 kJ / mol) / (18 g / mol) * (1 g / cc) You want: W * 210.90535 / 0.0047414634 You have: (8 liters / day) * (41 kJ / mol) / (18 g / mol) * (1 g / cc) / 2 You want: W * 105.45267 / 0.0094829268 You have: (8 liters / day) * (41 kJ / mol) / (18 g / mol) * (1 g / cc) / 2 / (13 W / m^2) You want: m^2 * 8.1117442 / 0.12327805 My guess of US$1000 for 8 m² is based on my guess that 8 m² is about 8000 watts of solar constant, and at 16% efficiency that's 1280 peak watts, and people quote PV modules as below US$1/watt, which I assume is a peak watt. The actual price right now is about US$0.55/watt, depending on where you are, so a more precise estimate is actually US$700: You have: 8000 watts * 16% * $ 0.55/watt You want: Definition: 704 US$ My friend who's getting those 13 W/m² has her panels in England, though. So that's kind of a worst-case number. You'd need a fraction of that (like, say, 20% or so) in an equatorial desert. If PV modules return to their previous price trend (they were dropping fairly smoothly by 36% per year in 2010-2013, but have been nearly plateaued since hitting grid parity in much of the world in 2013 and therefore having a hard time with capacity keeping up with demand) then they'd drop by another factor of 4. The Credit Suisse doc posted earlier today to HN https://doc.research-and-analytics.csfb.com/docView?sourceid=em&document_id=x691349&serialid=L3f%2bdcbQOUfpFcJ2bz9CDEuCoQT2wz09vthmZKbV4oU%3d https://doc.research-and-analytics.csfb.com/docView?sourceid... about how we are now in a "solar manufacturing oversupply" situation suggests that something like that might actually happen. Like what happened to DRAM prices in 1996 after the price-fixing cartel collapsed and they went from $40 a meg to $10 a meg almost overnight.

by zzalpha 11y ago

msandford 11y ago

It's kind of like the Tesla, which people think is amazing. For $90k you could also buy a $60k car and $30k worth of gasoline up-front and tada! you can now refuel it for free or almost free (it takes a little energy to pump the gas out of the underground storage tank and into your car's gas tank).

kragen 11y ago

Does US$2000 per person for the energy to solve the potable water problem for 30 years seem like a lot to you? Compared to the cost of other survival necessities (housing, food, sanitation, heating, cooling — http://resiliencemaps.org/ http://resiliencemaps.org/) it's quite reasonable. 16 m² is also pretty small compared to the space customarily used for housing. However, I made an error! It turns out I left out the coefficient of performance in my calculations. So it's actually 105 watts, 8 m², and about US$1000: You have: (8 liters / day) * (41 kJ / mol) / (18 g / mol) * (1 g / cc) You want: W * 210.90535 / 0.0047414634 You have: (8 liters / day) * (41 kJ / mol) / (18 g / mol) * (1 g / cc) / 2 You want: W * 105.45267 / 0.0094829268 You have: (8 liters / day) * (41 kJ / mol) / (18 g / mol) * (1 g / cc) / 2 / (13 W / m^2) You want: m^2 * 8.1117442 / 0.12327805 My guess of US$1000 for 8 m² is based on my guess that 8 m² is about 8000 watts of solar constant, and at 16% efficiency that's 1280 peak watts, and people quote PV modules as below US$1/watt, which I assume is a peak watt. The actual price right now is about US$0.55/watt, depending on where you are, so a more precise estimate is actually US$700: You have: 8000 watts * 16% * $ 0.55/watt You want: Definition: 704 US$ My friend who's getting those 13 W/m² has her panels in England, though. So that's kind of a worst-case number. You'd need a fraction of that (like, say, 20% or so) in an equatorial desert. If PV modules return to their previous price trend (they were dropping fairly smoothly by 36% per year in 2010-2013, but have been nearly plateaued since hitting grid parity in much of the world in 2013 and therefore having a hard time with capacity keeping up with demand) then they'd drop by another factor of 4. The Credit Suisse doc posted earlier today to HN https://doc.research-and-analytics.csfb.com/docView?sourceid=em&document_id=x691349&serialid=L3f%2bdcbQOUfpFcJ2bz9CDEuCoQT2wz09vthmZKbV4oU%3d https://doc.research-and-analytics.csfb.com/docView?sourceid... about how we are now in a "solar manufacturing oversupply" situation suggests that something like that might actually happen. Like what happened to DRAM prices in 1996 after the price-fixing cartel collapsed and they went from $40 a meg to $10 a meg almost overnight.