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Power Plant Modeling and Simulation

NREL conducts advanced modeling and simulation of geothermal power plants to develop innovative ways of integrating geothermal power into the electricity grid.

Binary geothermal plant.
NREL models geothermal flexibility, which enhances the benefits of geothermal plants to grid operators and end users.


NREL's modeling and simulation capabilities offer an efficient approach for plant design, operation optimization, and life-cycle techno-economic assessment.

  • Power plant power cycling modeling
    We model binary-fluid power cycles, steam-Rankine cycles, and other advanced power cycles under design and off-design operation conditions. Real power plant operation data have been adopted for the validation of power cycle modeling to improve operational efficiency and market demand matching.
  • Flexibility modeling
    We model the technical and economic potential for geothermal power plants to operate flexibly as variable renewables are deployed in increasing numbers on the grid.
  • Techno-economic potential analyses
    We analyze the techno-economic potential of power plants under various grid scenarios to help operators meet market demand and maximize their resources.

Flexible Geothermal Generation

As more variable renewable technologies such as solar and wind are deployed, the flexibility of geothermal energy can be an asset to the electric grid. Flexible geothermal can help firm the system, allowing for imbalance, and provide supplemental reserve and ancillary services such as frequency control and capacity.

Ormat's Puna geothermal facility in Hawaii provides flexible capacity for grid support using automatic generation control. At Puna, the geothermal power plant's conversion of fuel to electricity is completely in the control of the plant operator, and changes to electrical output can occur quickly, with up to 30% of nominal output per minute.  NREL engineers and analysts are looking at innovative new ways to deploy this flexible capability at geothermal plants throughout the U.S.

Resource Hybridization

NREL works with industry and national laboratory partners to develop innovative geothermal-solar thermal hybrid designs. For one such project—in partnership with U.S. Geothermal Inc., Idaho National Laboratory, and POWER Engineers—researchers developed a concept to use concentrated solar thermal energy first in a high-pressure steam topping turbine and then as an additional heat source to the Raft River geothermal binary power plant in Idaho. The approach yielded an economically attractive design through lower capital cost, higher net output, and higher efficiency. An unexpected result was the option to incorporate solar thermal storage into the hybrid cycle for 4 or 8 hours at a cost far below battery storage of electrical energy.

NREL has also investigated the potential to use geothermal during and after the oil/gas production cycle and at other fossil fuel thermal/power generation units. NREL has experience and expertise in developing, optimizing, and assessing hybrid system concepts.


Using Concentrating Solar Power To Create a Geological Thermal Energy Reservoir for Seasonal Storage and Flexible Power Plant Operation, Journal of Energy Resources Technology (2021)

Assessing Geothermal/Solar Hybridization – Integrating a Solar Thermal Topping Cycle into a Geothermal Bottoming Cycle with Energy Storage. Article No. 115121, Applied Thermal Engineering (2020)

Hybridizing a Geothermal Power Plant with Concentrating Solar Power and Thermal Storage to Increase Power Generation and Dispatchability, Applied Energy (2018)

Solar-Driven Steam Topping Cycle for a Binary Geothermal Power Plant, NREL Technical Report (2018)

Achieving a 100% Renewable Grid: Operating Electric Power Systems with Extremely High Levels of Variable Renewable Energy, IEEE Power and Energy Magazine (2017)

Global Value Chain and Manufacturing Analysis on Geothermal Power Plant Turbines, Transactions (2017)

View all NREL publications about geothermal research.


Guangdong Zhu

Senior Researcher