Ocean Thermal Energy Conversion demo progresses

The U.S. Department of Energy (DOE) has awarded a cooperative agreement contract to Lockheed Martin to demonstrate a pipe fabrication approach using modern composite technology and manufacturing methods at both prototype and pilot plant scales. Lockheed Martin has contracted Owens Corning to provide its XStrand high strength glass fibre reinforcements for use in the large diameter cold water pipe that will be required to reach ocean depths of thousands of feet.

Ocean Thermal Energy Conversion (OTEC) generates electricity by exploiting the temperature difference between warm surface water and deep cold water. The temperature difference is used to drive a Rankine cycle operating with a low boiling point fluid. Warm surface water passes through a heat exchanger, vaporizing the fluid, which drives a turbine generator, producing electricity. The process is free of global warming emissions and does not require any external fuel source.

Dennis Cooper, OTEC program manager for Lockheed Martin said OTEC holds the promise of providing clean, base load electricity to energy markets that today rely almost exclusively on fossil fuels. He said, ‘It's conceivable, for example, that OTEC could enable Hawaii to achieve energy independence within a generation. Our independent research and development work to date has shown OTEC to be technically feasible. The next step is to demonstrate it on a commercial scale and the DOE contract will help accelerate our progress toward that goal.’

Since the ocean's temperature difference is relatively small, large volumes of sea water must be moved to generate commercial levels of power. The fabrication and installation of large diameter cold water piping represents one of the largest technical challenges to the successful installation and operation of an offshore OTEC system.

'This is another exciting application of composite technology in renewable energy, said Marcio Sandri, Americas vice president and managing director for the Owens Corning Composite Solutions Business. ‘Composite materials already enable cost effective fabrication of blades for wind turbines. With high strength glass fibre reinforcements enabling the continuous production of tough, corrosion resistant large diameter pipe at sea directly from a floating platform, OTEC can become another viable method for obtaining energy from renewable sources.’

Under terms of the $1.2 million DOE cooperative agreement, Lockheed Martin will demonstrate a cold water pipe fabrication approach using modern fibreglass technology and innovative composite manufacturing methods. Fabrication work will be performed at Lockheed Martin's Advanced Technology Centre in Sunnyvale, California. West Virginia University's Constructed Facilities Centre is also supporting the project.

To support the project’s early development work, Owens Corning performed fatigue and corrosion testing at its Science and Technology Center in Granville, Ohio, as well as provided quantities of XStrand high performance reinforcements and small composite components for aggressive performance testing. The company also worked closely with Lockheed Martin engineers to develop three special fabric designs for the project.

‘OTEC will be an eye opening demonstration of the potential of composite materials, added Sandri. ‘Manufacturing large diameter pipe directly from a floating platform will expand the definition of on-site fabrication, which is already a familiar practice for composites. The power and caustic effects of ocean water are also well known and make this a great application for the strength and corrosion resistance of composites.

‘This project is in illustration of our commitment to working with customers to develop new applications. The world desperately needs a diversified portfolio of renewable energy and the composites industry can help make that possible by working together on development projects like this one.’