AU2016101704A4 - A method for saving coral reefs from bleaching by cloud intensification - Google Patents

Abstract

Abstract: A device for iecting seawater droplets into the atmospheric boundary layer in order to reduce [he solar energy incident on the ocean surface thereby lowering the water temperature. The purpose of this invention is, by using it in the vicinity of coral reefs, to reduce or prevent coral leaching, 1 sea water droplet nozzle 2 Radar refleco 3 Battery 4 Filter 7 5 Computer 6 Solar cells 7 Pump 8 iniet water pipe 9 small fish access CotC) C ao ad

Description

2016101704 22 Sep 2016

Description

Coral reefs worldwide undergo bleaching when the water temperature becomes higher than their evolutionary tolerance. For example in Australia the Great Barrier Reef (GBR), in 2016 underwent excessive coral bleaching attributed to higher temperatures from a El Nino climate event exacerbated by climate change. When the water temperature is unusually high, particularly for extended periods, the symbiotic algae desert their coral host, leaving the coral to starve and perish. Reduced water quality due to urbanisation and agriculture, and increased ocean acidity from carbon emissions often prevent the coral from recovering. Bleaching events are expected to become more frequent, more extensive, and of longer duration in the future due to climate change. In order to save coral reefs the water temperature needs to be reduced when bleaching is imminent.

Small water drops, such as occur in white clouds, reflect sunlight and increase the albedo of the earth. If the cloud layer is thickened or the droplets are made more dense, there is an increase of the incoming solar energy reflected. The short wave solar energy reaching the sea surface is reduced. Salter et al. (2008) describe a system involving autonomous sailing vessels that will increase the water droplets in the atmospheric boundary layer over the entire globe for the purpose of lowering global average temperature. Jones (2011) teaches that the cost of mitigating greenhouse gas warming by this method could be economical. However in reef infested areas sailing ships are not an attractive approach. Lt James Cook, RN, while exploring in the GBR, ran aground in 1770 and many others have followed him. A novel approach to controlling the temperature of waters surrounding coral reefs is to deploy “Cooling Candles” fixed to the sea floor or to islands. The cooling candles are designed to create cloud forming nuclei into the lower atmosphere. They achieve this by emitting salt particles or very small droplets of seawater, which may become very small salt crystals by evaporation of the water. A proportion of these very small droplets or crystals will be carried aloft as described below. A network of candles can intensify cloud over the region and thereby lower the water temperature. There are a few regions of the sea where there is an extensive area of shallow water suitable for piles to be driven or jetted into the sea floor. The Great Barrier Reef in Australia is such a region, as are other coral reef systems.

The GBR lagoon has numerous islands. It is well known to glider pilots that darker regions of the earth create thermals which allow glider pilots to increase their height. It is a novel concept to locate the cooling candles adjacent to islands. The water droplets produced by the Cooling Candles will be carried away from the sea surface by the island induced thermals. Even in the absence of thermals, a proportion of the droplets will rise in the atmosphere due to turbulent and convective processes.

Salter, Sortino and Latham show for realistic values of droplet diameter, cloud thickness, and atmospheric conditions, that 30 W/mA2 of solar energy can be reflected before it reaches the sea. A 20 m deep column of sea water needs 83400 kJ/mA2 of energy to change temperature by 1 degree C.

The water of the GBR has a long retention time (some months). This is illustrated by observing drifters in a numerical model of the GBR flows, see Luick et al. 2007. Cooling of the water of the GBR by one degree at a rate of 30 W/A2 will take 32 days. This cooling is most needed in summer during El Nino years. The stations will be intelligently controlled (by automated computer system or remote control) such that they can be activated only when bleaching is imminent.

The Cooling Candle would be supported on the seafloor or island and only a thin tube of diameter about 300 mm supporting solar panels would be above the water surface having minimal impact on the visual amenity of the region. A number of these Cooling Candles would placed throughout the reef system but only used when there was a danger of bleaching. They will each contain a radar reflector to stop collisions with vessels. The permanently installed pile may incorporate small holes or 2016101704 22 Sep 2016 other artificial structure to provide a safe habitat for a small number of reef fish. The removable upper portion of the pier contains the mechanism to generate the droplets and can be removed for maintenance on shore.

While some of the technology developed by Salter et al (2008) is used in our invention, Salter et al (2008) invented a method to reflect a small amount of solar energy over a very large area for the purpose of cooling Earth's atmosphere. The present invention is designed to produce a large change in water temperature over a small region. Salter et al. (2008) were interested in mitigating climate change while the present invention is designed to save the GBR and other coral reefs from coral bleaching.

Description of invention.

The device for reducing the ocean surface water temperature consists of: 1. A device to extract energy from the currents, winds or solar radiation. 2 A battery to allow continuous operation during periods of low energy generation. 3 A high pressure seawater pump, or air pump to distribute droplets or dry salt particles. 4 A seawater filter. 5 A device for making droplets of micron diameter. 6 A computer controller with telemetry to enable remote or automated control. 7. Where natural processes are insufficient, a device to create initial uplift of the nuclei.

References S Salter, G Sortino and J Latham (2008), “Sea-Going Hard ware for the Cloud-Albedo Method of Reversing Global Warming” Philosophical Transactions of the Royal Society A, Vol. 366, No. 1882, 2008, pp. 3843-3862. doi:10.1098/rsta.2008.0136. ISF Jones (2011) “Engineering Strategies for Greenhouse Gas Mitigation”, Cambridge University Press, pp. 167. JL Luick, L Mason, T Hardy, MJ Furnas (2000) "Circulation in the Great Barrier Reef Lagoon using numerical tracers and in situ data" Continental Shelf Research, 27, 757.

Claims (5)

1. A method for saving coral reefs from bleaching by cloud intensification.

2. A method of reducing the near surface water temperature of the ocean where the water has a long retention time by cloud intensification.

3. A method of reducing the near surface water temperature of the ocean surrounding a coral reef where the water has a long retention time by cloud intensification.

4. The use of a device fixed to the seabed or foreshore which produces and expels potential nuclei (for example water droplets or salt particles) able to intensify clouds.

5. A device as in claim 4 powered by renewable energy (e.g. solar, wave, or current power) and located on islands to take advantage of thermal updrafts in delivering the nuclei.