Stupid question alert: Supposing that you can develop an effective solar/wind/renewable power type of desalination. How do you deal with the effluent? Can you sell the salt? Or do you just let it pollute the sea?
That is a very big question and not stupid. If you take in the ocean as a whole it will do nothing, but on a local level unless you pump it into major currents that is a big impact. There are though very serious effluent problems though. Salt is the least. You would also raise concentrations of all sorts industrial pollutants and that you will have to deal with safely.
wili:
But that is a very energy intensive affair, and energy is not something we will have lots of going forward, especially if we ever get serious on actually cutting back on ff use.
We have to get off of ff. the sooner the better. As for present day water sources. Major river systems of the world get most of their water from glaciers. Those are going, going, gone. With weather systems changing places like the US west will turn into a Sahara. Move them? where? East? doubling the pop of eastern states will turn that area into a desert. Then where do you go? Also where do you replace the food production lost? Right now the US west is keeping production going by replacing surface water with underground water. That is disappearing. OK you can conserve.
Most water is actually used in agriculture and industry. Somehow in order to keep those 2 areas working you have to find a new source of water because most of the old sources are disappearing fast.
For energy it has been stated that if you use the non food producing areas of the midwest US into solar farms you can generate all the energy needs of North America. So generating energy is not the problem. The problem is we have to start rethinking of the way we have always done things. The end result is we take for granted of what we have around us. Very little R&D has actually gone into desalination because of the idea that it was always costlier then putting a pipe into a local river.
Another point of energy. Do you have any idea how much energy and water is needed for the lithium battery that is in most of our batteries? If the totals where compared, I would be shocked if it would take more energy to run a desalination plant for a million people then it would be to keep those same people provided with lithium batteries. The issue is not costs, is not energy, it comes down to what is more important.
We also have as a western world always thought of getting things done by brute force. And now because you can get proprietary compensation for your invention, costlier, more energy inefficient and environmentally damaging ways of getting a job done all in the name of greed.
Unless you want to see the US west turn into a depopulated Sahara dessert, which climatologist are saying will happen because of AGW and changes to weather patterns, desalinization is the only option you have to save it because there is no fresh water source option left. It also is easier to make the changes now before everything does turn to desert and you lose your top soil, then wait until everything has turned into desert then try and rehabilitate it.
My belief is that it can be done and at an affordable and environmentally sustainable way, the question is are we going to continue to buy into the notion that it can not be done because it has never been done before until it is too late to find a solution.