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The Joint Institute for Strategic Energy Analysis (JISEA) increases the impact of its analysis by staying engaged in and helping to shape the global energy dialogue. News and blogs about JISEA, JISEA leadership, JISEA partners, and JISEA programs are highlighted below.

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Standardized Geothermal Turbines Could Reduce Plant Capital Costs

October 23, 2018 — Currently, the geothermal turbine market is driven by developer demand for plant efficiency and consists of custom turbines designed specifically for the varying conditions at different geothermal fields.

In practice, a standard turbine design would likely operate at off-design conditions, resulting in lower efficiencies, less electricity generation, and less revenue than a custom turbine design. However, the upfront capital cost savings could offset future revenue losses. In order to determine the commercially favorable operating range of a standard geothermal Organic Rankine Cycle (ORC) turbine compared to custom design, we created a process flow model at a given design point of the standard size (5-MW) turbine by using an off-design efficiency curve.

We analyzed over 63 off-design cases by changing inlet geothermal brine temperature and inlet mass flow rate. The results showed that the net capital cost savings from a standard design versus a custom design turbine at the standard design turbine point for the modeled 5-MW case study may reach up to $2.3 million, while the difference in net present value (NPV) could reach up to $1.4 million.