In reply to Jed Rothwell's message of Fri, 05 Jan 2007 15:35:28 -0500: Hi, [snip] >Robin van Spaandonk wrote: > >>Reverse osmosis may superficially appear cheaper than distillation, >>but in fact >>it isn't if one uses one's brains. When coal is burned, 1/3 of the energy goes >>into producing electricity, and 2/3 goes up the chimney. Then part of that 1/3 >>is used for reverse osmosis. > >Yes, but RO is more efficient. That is, it takes far less energy per >gram of freshwater. Overall, it takes 4 to 30 times less than the >best mult-stage flash (MSF) distillation process.
My point is that using the waste heat is always going to be more efficient overall than using valuable electricity, even if the process itself is less efficient. You need to look at the big picture, and not stare yourself blind on a detail. >See the refs in my >book, chapter 8. MSF does produce purer water, as noted. > >The large-scale Saudi plants are all hybrids, that produce both >electricity and water, very efficiently. This is exactly what I mean. See http://www.water-technology.net/projects/shuaiba/ . Regards, Robin van Spaandonk http://users.bigpond.net.au/rvanspaa/ Competition provides the motivation, Cooperation provides the means.
