The news source for Ocean Thermal Energy Conversion (OTEC)

 

  by Phil Kopiske 27 January 2002

References: SSP’s OTEC Review and Proposal for U.S. Navy, 1996
Product: 10 MW shore-based OTEC
Cost: $50,000,000 USD
Cost Year: 2002
Output 1: 10 MW electricity
Output 2: 3,000,000 gallons (85,000 m³) per day fresh water
Output 3: Cold nutrient-rich seawater for aquaculture and air conditioning
Input 1: 791 ft³/s surface seawater at 77 ºF in, 73 ºF out
              (22.4 m³/s, 25 ºC in, 22.8 ºC out)
Input 2: 484 ft³/s deep seawater at 40 ºF in, 51 ºF out
             (13.7 m³ /s, 4.4 ºC in, 10.6 ºC out)
Size: 100 ft x 80 ft x 40 ft (30.5 m wide, 24.4 m deep, 12.2m high)
Designer: J. Hilbert Anderson
Technology: Hybrid cycle 2 stage water vapor / propylene

Company: Sea Solar Power International
Address: 111 S. Calvert Street, Suite 2300, Baltimore, MD 21230
Phone: +1.410.547.1300
Web Site: http://www.seasolarpower.com

Sea Solar Power of York, Pennsylvania, has designed a floating 100 MW net plantship, a 130,000,000 gallon per day desalination version of that same plantship, and for technology demonstration purposes, a 10 MW shore based OTEC. This first abstract is a brief description of the 10 MW OTEC design, depicted to the right in an artist’s rendering. The drawing shows aquaculture ponds, and restaurant space on the ground level and rooftop.

In operation, warm seawater is drawn in through a slot in the concrete building’s surf side. It passes through a series of pressure drops, which deaerate the water. When the pressure finally gets low enough, the 80 degree F (27 ºC) water boils, giving off water vapor, which is then condensed into fresh drinking water. In the process of condensing, this low pressure steam is acting as a heat source to the second stage of the plant, because the water vapor condenser is also the propylene boiler, transforming liquid propylene into 76 degree F (24.4 ºC), 150 psi propylene vapor. Finally, this vapor is expanded through a turbine which drives an electrical generator, and then condensed with cold seawater brought up from the deep sea.

The deep cold water, now a few degrees warmer, is directed through an on shore aquaculture farm where its bounty of nitrogen is harvested. The water is then directed through an outfall pipe back into the deep ocean below the sunlit layers, where it sinks to equilibrium depth. The beauty of the cycle is that it can be designed to produce more fresh water and less power if the economic value of the water is greater than that of the power. The oxygen and carbon dioxide given off during warm water deaeration are injected into the cold water discharge upstream of the cold water pump suction, both as an energy saving measure and to increase the CO2 levels for aquaculture.

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