Illustration courtesy ABS
The American Bureau of Shipping has just approved a new concept for renewable energy production for a commercial grid that converts the solar energy of tropic oceans into low-cost electricity. The new concept design utilizes a moored spar using ammonia in a closed-cylce process to produce electrical power and, unlike wind, tidal, or solar power, the system can deliver constant output 24 hours a day.
“This concept combines proven offshore principles with off-the-shelf power, technology and proprietary innovations, all assembled in a unique way,” says Ian Simpson, ABS Director of Offshore Technology and Business Development, Americas Division.
Developed by OTEC International (OTI) of Baltimore, Maryland, the concept converts liquid ammonia into gas in a heat exchanger using warm ocean surface water. The ammonia gas then drives turbines that turn generators to produce electricity which is then exported through a submarine power cable to a land-based utility company. The ammonia is condensed back into a liquid phase using cold ocean water pumped from 3,000 feet below the water’s surface and the process begins again. The process is based upon the well-established thermodynamic Rankine cycle.
“OTI has integrated the OTEC power block into a large floating vessel, in this case a spar, for an economically and environmentally-efficient means of converting solar energy from the tropical oceans into affordable electricity,” explains Barry Cole, OTI’s Executive Vice President and Director of Technology Development.
ABS has issued this first Approval in Principle for both the 25MW and 100MW designs and says OTI could be eligible for ABS’ class notation A1, Floating Offshore Installation (FOI) Spar, SFA(30).