Heber Binary Geothermal Demonstration Power Plant

Historic Project: Groundbreaking Work From Earlier in Fluor’s History

Client: San Diego Gas and Electric Company

Location: Heber, CA, U.S.

Business Segment: Energy Solutions

Industries: FuelsPower

Map showing the location of Heber Binary Geothermal Demonstration Power Plant

Executive Summary

Fluor provided engineering, procurement and construction liaison services for the 70-megawatt electrical Heber Binary Geothermal Demonstration Power Plant in Southern California. This was the world's first commercial-sized geothermal power plant utilizing the binary-cycle energy conversion method.

We also conducted a feasibility study and major equipment identification to prove plant operability and economics and selected the working fluid best suited to the geothermal resource characteristics.

Client's Challenge

This conversion system permitted exploitation of moderate temperature geothermal resources considered non-recoverable by the more conventional flash steam cycle. This working fluid was a mixture of hydrocarbons, 90% isobutane and 10% isopentane. The Heber plant used geothermal brine at 360° F, which was pumped to the surface by use of downhole pumps.

Upon completion, Heber was the largest geothermal plant of its type in the United States at the time.

Fluor's Solution

The brine was retained under pressure and in the liquid state as it was pumped to brine/hydrocarbon heat exchangers. The tube-side flow of brine through the exchanger transferred heat energy to the shell-side hydrocarbon prior to re-injection. The brine loop was a closed system making no contribution to environmental pollution.

The Heber hydrocarbon turbine required special tooling for the blading because of the high mole weight of the hydrocarbon and in the casing to accommodate the no-leak, compressor type of seals. These special design features and the non-corrosive nature of the working fluid would help ensure that the turbine provided high reliability and exceptional durability. These were further enhanced by the incorporation of a plant-wide distributed control and monitoring system.