ScienceDaily (Nov. 2, 2009) — Generating energy on a large scale by mixing salt and fresh water is both technically possible and practical. The worldwide potential for this clean form of energy — ‘blue energy’ or ‘blue electricity’ — is enormous. However, it will be necessary to work actively on several essential technological developments and to invest heavily in large-scale trials.

Blue Energy tide turbine diagram

On 3 November, Jan Post is presenting his research during his doctorate dissertation on this subject from Wageningen University.

The principle of generating electricity by mixing salt and fresh water, taking advantage of the difference in charge that results, has been known for more than 100 years. It was first tested in practice in a laboratory in the 1950s. There are two methods for generating blue energy: pressure-retarded osmosis and reverse electrodialysis.

Post, in his research, has focused mainly on the latter because it is the more attractive method of generating energy from sea and river water. With his research into the practical applicability, techniques and preconditions for large-scale energy generation from salinity gradients, he was the first to demonstrate that very high yields are possible. In the laboratory, it is possible to recover more than 80% of the energy from salinity gradients; the technical feasibility would be 60-70% and the economic feasibility a little lower than that.

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