Biorock

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Example of accretion : Aragonite deposit in a water pipe (" Karlsbader Sprudelstein)"

Biorock is the name for a process developed by Wolf Hilbertz for the electrolytic separation of minerals dissolved in seawater on 3D metal grids with the aim of creating a substructure for artificial coral reefs .

history

The Biorock technology was developed by Wolf Hilbertz in the 1970s in search of alternative building materials. In the graduation house in Bad Salzuflen he discovered a solid deposit. After his interest was piqued, he experimented with sea water. In 1974 he submerged a wire rack in salt water and applied a DC voltage. The next morning a thin, white layer of aragonite and brucite had already accumulated on the wire frame.

technology

Racks made of structural steel and metal mesh with the desired shape are sunk into seawater, through which a weak direct current flows. The electrolysis splits the seawater into its chemical components hydrogen and oxygen . The steel construction forms the negative pole and thus the cathode . Due to electrochemical processes, a solid crust is formed on it from the salts aragonite (calcium carbonate) and brucite (magnesium hydroxide) dissolved in seawater . The crystallized material on the steel is whitish to gray in color. The building material grows over the entire surface at a rate of one to three centimeters per year. The size and shape of the steel structures do not affect the process as long as there is enough direct current flowing. The strength of the future building material can be determined by varying the current strength. With a high current strength , more soft brucite is deposited on the steel and the process is accelerated. If the current is low, the process takes longer and the hard aragonite is predominantly deposited.

The Biorock process requires significantly less energy than, for example, the particularly energy-intensive production of a component from concrete, since a ton of building material can be produced with just 1000 kilowatt hours .

Application for creating artificial reefs

Among other things, Wolf Hilbertz was also inspired by corals and their growth. Together with the biochemist and coral researcher Tom Goreau , he used the Biorock technology to ensure the continued existence of many reefs severely damaged by coral bleaching in Jamaica , the Seychelles , off the Maldives island of Ihuru, in Panama and in Bali . Among other things, artificial coral reefs were created there. Up to 2008 there were Biorock projects in over 15 countries, including Thailand , Indonesia , Papua New Guinea and Mexico .

In 1997 and 2002 attempts were made to create an artificial island in the Saya de Malha sea ​​area in the Indian Ocean using the Biorock technique .

If you place broken, living corals on the steel structures, they will grow firmly and spread out on the solid ground. This is because the polyps in the corals use a large part of their energy to extract calcium and magnesium ions from the seawater. With the mineral accretion on the steel, people save them the energy expenditure to create a solid surface themselves. As a result, they grow four times as fast as under natural circumstances.

Biorock structures have great potential as breakwater because they get stronger with age. If the structure is damaged by storms and high waves or by a collision with a ship, it will largely repair itself with the help of mineral accretion.

With the help of technology, it has been possible to stabilize a severely eroded stretch of beach on Grand Turk Island ; instead of erosion, material is now accumulating here. As with other practical examples, both the seabed in the area of ​​the support grids and the latter itself were quickly colonized by marine organisms that enlarge the surface. Part of the effect is also due to the energy distribution of the wave impact due to the grid structure itself through which a flow can flow. The success was clearly demonstrable after just a few months. The costs of the process are far below those of conventional security structures.

literature

  • Solar-generated building material from seawater as a sink for carbon , Ambio 1992.
  • TF Goreau, NI Goreau, TJ Goreau: Coral and Coral Reefs , in Biology of the Seas, 1991, Spektrum Akad. Verl., ISBN 3-89330-753-2 .
  • Electrodeposition of Minerals in Sea Water: Experiments and Applications , in: IEEE Journal on Oceanic Engineering, Vol. OE-4, No. 3, pp. 94-113, 1979.
  • Solar-generated construction material from sea water to mitigate global warming , in: Building Research & Information, Volume 19 (4), July 4, 1991, pp. 242-255.

Individual evidence

  1. ↑ a b Biorock Bali: Korallen unter Strom , brandeins.de , 2016
  2. ↑ Olaf Kanter: Arche Saya , Mare No. 34 [1]
  3. ↑ PDF of the Saya de Malha Expedition 2002, rev. 1
  4. ↑ Thomas JF Goreau & Paulus Prong (2017): Biorock Electric Reefs Grow Back Severely Eroded Beaches in Months. Journal of Marine Science and Engineering 5: 48. doi: 10.3390 / jmse5040048

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