Figure of Merit Analysis of a Hybrid Solar-geothermal Power Plant

Cheng Zhou, Elham Doroodchi, Behdad Moghtaderi

The University of Newcastle, Callaghan, NSW 2308, Australia.

DOI: 10.4236/eng.2013.51B005                

Abstract

Figure of merit analysis is a general methodology used to evaluate whether a hybrid power plant could produce more power than two stand-alone power plants. In this paper, the assessment methodology using figure of merit analysis was re-examined for a hybrid solar-geothermal power plant. A new definition of the figure of merit was introduced specifically for a solar boosted geothermal plant to include both the technical and economic factors. The new definition was then applied in a case study of a hypothetical demonstration hybrid solar-geothermal power plant in Australia. The power plant was considered to have a typical net power output of 2.2 MW with a solar energy fraction of 27%. The analysis was performed to compare the power output and capital cost of the hybrid plant with the state-of-the-art (SoA) and existing stand-alone solar and geothermal plants. Based on the new definition, the hybrid plant was found to generally outperform the two existing stand-alone plants. Moreover, at an ambient temperature of 5 °C, the hybrid plant was found to outperform the SoA stand-alone plants when the geothermal temperature was greater than 150 °C. For geothermal temperature of 180 °C on the other hand, the hybrid plant outperformed the SoA stand-alone plants at ambient temperatures lower than 33 °C.

Keywords

Figure of merit; Hybrid renewable energy system; Solar; Geothermal; Power generation

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	H. E. Khalifa, R. Dipippo and J. Kestin. “Geothermal preheating in fossil-fired steam power plants,” Pr°Ceedings of the 13th Inters°Ciety Energy Conversion Engineering Conference, Warrendale, PA, USA, 1978.
[2]	Sargent & Lundy LLC Consulting Group, “Assessment of parabolic trough and power tower solar technology cost and performance forecasts,” 2003. http://www.nrel.gov/d°Cs/fy04osti/34440.pdf
[3]	R. Dipippo, “Small Geothermal Power Plants: Design, Per-formance and Economics,” Geo-Heat Center Quarterly Bulletin, Vol. 20, No. 2, June 1999.