"do traditional desalination techniques require more energy than boiling the equivalent amount of water?"
No, far less, because the end product is condensed liquid water (not vapor). When* the desalination method is distillation (evaporating + re-condensing), the heat used to evaporate water is released again when the steam is condensed, and can be recovered and reused. E.g. [1]. The real-world figure wikipedia cites is about 90 MJ/m^3, compared to about 2,250 MJ/m^3 for boiling water at STP [2]. The theoretical limit from thermodynamics -- the minimum energy needed to separate salt and water -- is about 3 MJ/m^3 for seawater [3] (or [4-5]).
*(as opposed to methods like reverse osmosis [6], which is forcing water through a filter with atom-sized holes -- no boiling involved)
No, far less, because the end product is condensed liquid water (not vapor). When* the desalination method is distillation (evaporating + re-condensing), the heat used to evaporate water is released again when the steam is condensed, and can be recovered and reused. E.g. [1]. The real-world figure wikipedia cites is about 90 MJ/m^3, compared to about 2,250 MJ/m^3 for boiling water at STP [2]. The theoretical limit from thermodynamics -- the minimum energy needed to separate salt and water -- is about 3 MJ/m^3 for seawater [3] (or [4-5]).
*(as opposed to methods like reverse osmosis [6], which is forcing water through a filter with atom-sized holes -- no boiling involved)
[1] http://en.wikipedia.org/wiki/Multi-stage_flash_distillation
[2] http://en.wikipedia.org/wiki/Enthalpy_of_vaporization#Other_...
[3] http://http://www.sandia.gov/water/docs/MillerSAND2003_0800....
[4] http://en.wikipedia.org/wiki/Enthalpy_change_of_solution
[5] http://en.wikipedia.org/wiki/Seawater
[6] http://en.wikipedia.org/wiki/Reverse_osmosis