Rachel Armstrong and Neil Spiller suggest that Venice's sinking foundations might be supported by an artificial reef grown using 'protocells' that precipitate limestone from sea water (Nature 467, 916–918; 2010). The technology already exists to grow structures rapidly from sea water, and this could be applied in Venice immediately.
'Biorock' electrolysis of sea water has been used for nearly 35 years in more than 20 countries to grow limestone structures of any size and shape in sea water and brackish water (W. Hilbertz IEEE J. Oceanic Eng. 4, 94–113; 1979).
Biorock products have a load-bearing strength of up to 80 newtons per square millimetre (80 megapascals), around three times higher than concrete made from ordinary Portland cement. Corals and oysters grow faster and survive environmental stress better on Biorock structures. These have helped to restore severely eroding beaches on atoll islands within just a few years (for example, see http://go.nature.com/buyqjk).
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