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Title: Hydraulic tidal and wind power system sizing
Authors: Jones, Jack A.
Keywords: tidal energy
wind energy
hydraulic energy transfer
Issue Date: May-2012
Publisher: Pasadena, CA : Jet Propulsion Laboratory, National Aeronautics and Space Administration, 2012.
Series/Report no.: JPL Publication
Abstract: Tidal energy, offshore wind energy, and onshore wind energy can be converted to electricity at a central ground location by converting their respective energies into high-pressure hydraulic flows that are transmitted to a system of hydraulic enerators by high-pressure pipelines. The high-pressure flows are then efficiently converted to electricity by a central hydraulic power plant, and the low-pressure outlet flow is returned. All gears and submerged electronics are completely liminated (JPL/Caltech patents granted and pending). The Department of Energy (DOE) is presently supporting a project led by Sunlight Photonics to demonstrate a 15 kW tidal hydraulic power generation system in the laboratory. Sunlight Photonics will issue a separate report on this successful experimental phase. Another portion of this DOE project involves sizing and costing a 15 MW commercial tidal energy plant, which is the subject of this Final Report. For this task, Atlantis Resources Corporation’s demonstrated 18-m diameter tidal blades operate in a nominal 2.6 m/sec tidal flow to produce one MW per set of tidal blades. Fifteen blade units are submerged in a deep tidal area, such as Maine’s Western Passage. Each set of blades is attached to commercial off- the-shelf (COTS) Hagglund radial piston pumps, and all pumps are connected to a highpressure (20 MPa, 2900 psi) line that is 35 cm ID. High-pressure HEPG fluid is transported 500 meters to a parallel series of onshore, COTS axial piston hydraulic generators. HEPG is an environmentally-friendly, biodegradable, water-miscible fluid. The total cost of producing energy with this tidal power plant is estimated to be $0.15/kW-hr, which is between the cost of wind energy and solar energy. Hydraulic adaptations to Ocean Renewable Power Company’s (ORPC’s) cross-flow tidal turbines are also discussed. Costs to convert a submerged ORPC tidal system to a hydraulic device with onshore power generation are about 50 cents per watt, minus the cost of ORPC’s expensive submerged generators, which would be entirely removed. Although not originally planned, applications of Hydraulic Energy Transfer (HET) for wind energy have also been added to this report. For wind energy that is onshore or offshore, a gearless, high-efficiency, COTS, radial piston pump can replace each set of troublesome, topmounted gear-generators for conventional wind turbine systems. Environmentally friendly HEPG fluid is then pumped to a central system of easily serviceable ground generators, which consist of a parallel series of axial piston hydraulic generators. Total hydraulic/electrical efficiency of 81% is close to that of conventional wind turbines at fullrated wind speeds. Total HET efficiencies increase at slower speeds, however, while conventional wind turbine efficiencies decrease significantly. In addition, all troublesome gears are eliminated for HET wind and tidal energy systems
Appears in Collections:JPL TRS 1992+

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