3 ms·

Well, if we use a "normal" (non solar) plant, using this as a base comparison: https://www.lenntech.com/applications/emergency-seawater-desalination-units.htm

by jaclaz 7y ago

Well, if we use a "normal" (non solar) plant, using this as a base comparison: https://www.lenntech.com/applications/emergency-seawater-desalination-units.htm https://www.lenntech.com/applications/emergency-seawater-des... it's 15 KW for 2000 lt/hour, assuming the efficiency scales linearly (I strongly doubt it does), a 40 lt/hour that would be 300 W (which I don't believe), it is more likely to be in the (not very accurate measure) "around 1 kW" range, which in laymans terms should mean some 6 or 7 sqm of solar panels, possibly a little bit more. About the cost, you can buy today commercial systems (only the desalination part) in the US$ 5,000 range: https://www.echotecwatermakers.com/beach_house_desalination_systems.htm https://www.echotecwatermakers.com/beach_house_desalination_... The smallest model has 5.4 A @230V which seems just in line with what we calculated above, around 1 kW. If we assume that the cost of the needed solar plant (the additional part needed to supply the desalination plant) would be around 500 US$ or less, the price to beat is 5,500 US$, but considering that added solar power surface produces power that might be used, I would say that a more reasonable cost would be below US$ 4,000, which is still a lot.

abdullahkhalids 7y ago
Thanks for the detailed answer again. Clearly, there exists a business opportunity to innovate on these systems, make them cheaper and sell them in my new city. Both the systems you link to are reverse osmosis systems which require electric power to run the pumps etc. Solar radiation -> electric power is only 20% efficient. My understanding is that membrane distillation tech uses hot water (60 degrees in OP link), which can run on solar thermal systems + small amount of PV. Solar radiation -> thermal energy of water can be 80%+ efficient, so the price of the whole system might come down significantly from the $5000.
- jaclaz 7y ago
  Yep, but it was a comparison aimed to the real world and costs, not abstract efficiency. Given that you need for both 5-10 square meters of surface exposed to the sun and assuming (and it is not necessarily given) that solutions "A" and "B" have the same "current" (maintenance, spares, consumables) costs, I don't care if solution "A" is more efficient than solution "B", I only care if solution "A" costs less than "B". If it does, then it should cost much less, as solution "B" might have a tangible advantage (once you have purified enough water the solar energy can be used for other uses). Now, be nice, check the actual Solar Spring Gmbh site /the spin-off of the Fraunhofer Institute for Solar Energy Systems mentioned in the wikipedia article ), and see how - strangely enough - they build/sell both "A" and "B" solutions: https://solarspring.de/en/products-and-services/#pg-356-2 https://solarspring.de/en/products-and-services/#pg-356-2 https://solarspring.de/en/solar-purification/ https://solarspring.de/en/solar-purification/ In any case high efficiency - usually - means more sophistication, added components, and what not, so rarely exists a solution that is more efficient AND costs less.

by jaclaz 7y ago

abdullahkhalids 7y ago

Thanks for the detailed answer again. Clearly, there exists a business opportunity to innovate on these systems, make them cheaper and sell them in my new city. Both the systems you link to are reverse osmosis systems which require electric power to run the pumps etc. Solar radiation -> electric power is only 20% efficient. My understanding is that membrane distillation tech uses hot water (60 degrees in OP link), which can run on solar thermal systems + small amount of PV. Solar radiation -> thermal energy of water can be 80%+ efficient, so the price of the whole system might come down significantly from the $5000.

jaclaz 7y ago
Yep, but it was a comparison aimed to the real world and costs, not abstract efficiency. Given that you need for both 5-10 square meters of surface exposed to the sun and assuming (and it is not necessarily given) that solutions "A" and "B" have the same "current" (maintenance, spares, consumables) costs, I don't care if solution "A" is more efficient than solution "B", I only care if solution "A" costs less than "B". If it does, then it should cost much less, as solution "B" might have a tangible advantage (once you have purified enough water the solar energy can be used for other uses). Now, be nice, check the actual Solar Spring Gmbh site /the spin-off of the Fraunhofer Institute for Solar Energy Systems mentioned in the wikipedia article ), and see how - strangely enough - they build/sell both "A" and "B" solutions: https://solarspring.de/en/products-and-services/#pg-356-2 https://solarspring.de/en/products-and-services/#pg-356-2 https://solarspring.de/en/solar-purification/ https://solarspring.de/en/solar-purification/ In any case high efficiency - usually - means more sophistication, added components, and what not, so rarely exists a solution that is more efficient AND costs less.