This paper presents steady-state performance modeling and analysis of a novel wind powered system that concurrently exploits thermocline thermal energy through deep sea water extraction in conjunction with offshore wind energy for combined power and thermal energy production. A single offshore wind turbine rotor directly coupled to a large positive displacement pump is modeled to supply deep sea water at high pressure to a land-based plant, the latter consisting of a hydro-electric generator coupled to a heat exchanger. The steady-state power-wind speed characteristics for the system are derived from a numerical thermofluid model. The latter integrates the hydraulic characteristics of the wind turbine-pump combination and a numerical code to simulate the heat gained/lost by deep sea water as it flows through a pipeline to shore. The model was applied to a hypothetical megawatt-scale wind turbine installed at a deep offshore low wind site in the vicinity of the Central Mediterranean island of Malta. One year of wind speed and ambient measurements were used in conjunction with marine thermocline data to estimate the time series electricity and thermal energy yields. The total energy yield from the system was found to be significantly higher than that from a conventional offshore wind turbine generator (OWTG) that only produces electricity. It could be shown that at sites having less energetic wind behavior and high ambient temperatures as a result of a hotter climate, the cooling energy component that can be delivered from such a system is relatively high even at periods of low wind speeds.

References

1.
National Oceanic and Atmospheric Administration (NOAA), “
World Ocean Atlas
,”
2009
, NODC Live Access Server, accessed Dec. 2012. Available at: http://data.nodc.noaa.gov/las/getUI.do
2.
Diepeveen
,
N.
,
2009
, “
Design Considerations for a Wind-Powered Seawater Pump
,”
European Offshore Wind Conference Proceedings
, EWEA, Marseille, France. Available at: http://www.ewea.org
3.
Laguna
,
A. J.
,
2010
, “
Steady-State Performance of the Delft Offshore Turbine
,” M.Sc. thesis, Delft University of Technology, Delft, The Netherlands.
4.
Buhagiar
,
D.
,
2012
, “
Analysis of a Wind Turbine Driven Hydraulic Pumps
,” B. Eng. (Hons.) thesis, University of Malta, Msida, Malta.
5.
Risø National Laboratory,
1989
, “
European Offshore Wind Atlas
,” accessed Oct. 2012, www.windaltas.dk
6.
Jonkman
,
J.
,
Butterfield
,
S.
,
Musial
,
W.
, and
Scott
,
G.
,
2009
, “
Definition of a 5-MW Reference Wind Turbine for Offshore System Development
,” National Renewable Energy Laboratory, Report No. NREL/TP-500-38060.
7.
Holman
,
J.
,
2009
,
Heat Transfer
,
McGraw Hill
, New York.
8.
Churchill
,
S. W.
, and
Chu
,
H. H. S.
,
1975
, “
Correlating Equations for Laminar and Turbulent Free Convection From a Vertical Plate
,”
Int. J. Heat Mass Transfer
,
18
(
11
), pp.
1323
1329
.10.1016/0017-9310(75)90243-4
9.
International Towing Tank Conference,
2011
, “
Recommended Procedures—Fresh Water and Sea Water Properties
.” Available at: http://ittc.sname.org/
10.
National Physics Laboratory, Kay and Laby, “
Physical Properaties of Sea Water
,” accessed Dec. 2012. Available at: www.kayelaby.npl.co.uk
11.
Farrugia
,
R. N.
, and
Sant
,
T.
,
2011
, “
Wied Rini II—A Five Year Wind Survey at Malta
,”
Wind Eng.
,
35
(
4
), pp.
419
432
.10.1260/0309-524X.35.4.419
12.
Farrugia
,
R. N.
,
Sant
,
T.
,
Mifsud
,
P.
, and
Sant
,
G.
,
2012
, “
The Application of MCP Techniques and CFD Modelling for Wind Resource Assessment in a Mediterranean Island Context
,”
Proceedings of the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics
, Malta, July 16–18, (HEFAT2012). Available at: http://edas.info/web/hefat2012/home.html
13.
Farrugia
,
R. N.
, and
Sant
,
T.
,
2013
, “
Mediterranean Inshore Wind Resources: Combining MCPs and CFD for Marine Resources Quantification
,”
Wind Eng.
,
37
(
3
), pp.
243
256
.10.1260/0309-524X.37.3.243
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