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Dish/Engine Research and Development

As part of its research program in concentrating solar power (CSP), the U.S Department of Energy (DOE) sponsors research and development (R&D) for dish/engine systems. The goals for dish/engine R&D are to

  • Improve the performance and lower the cost of dish/Stirling systems (where a Stirling engine is a specific type of thermodynamic heat engine)
  • Provide optical modeling and testing support to the dish/Stirling industry.

This page summarizes key dish/engine R&D activities by the National Renewable Energy Laboratory (NREL) and Sandia National Laboratories to attain the above goals in three areas:

Dish Solar Field R&D

The dish/engine solar field consists of a dish structure, the associated mirrors, and an engine at the focal point of the mirrored dish. Our R&D aims to support industry as it develops dish/Stirling systems for utility- and distributed-energy markets.

In the area of optical characterization and flux mapping, we use the Video Scanning Hartmann Optical Test (VSHOT) and a beam characterization system to support onsite or field measurements of concentrators for CSP systems. VSHOT is described more fully in the trough R&D section.

Photo of three rows of dish/engine solar systems, each containing two systems. The dishes are all pointing in the same direction, and each consists of a series of rectangular mirrors assembled into a dish structure.

These dish/Stirling units are being tested at Sandia National Laboratories in Albuquerque, New Mexico.
Credit: Sandia National Laboratories

Power-Cycle and Total Plant R&D

DOE supports Stirling Energy Systems (SES) in designing, developing, installing, and testing pre-production prototype 25-kilowatt dish/Stirling systems. This work supports commercialization for large deployments, as well as consulting on advanced component and system designs for manufacturing.

  • We support specially developed software for characterizing and improving reliability, which includes root-cause analysis, prioritization, data reduction, modeling, and design support. Redeveloping control systems for engines and dishes is directly tied to field operations experience.

  • We participate in the Design for Manufacturing and Design to Cost process, providing solar expertise, optical and thermal modeling, design-tool development, and consultation. Our characterization and improvement of system performance helps to reduce costs.

In 2007, our activities resulted in a world record of 31.25% for net solar-to-electric conversion efficiency. Also, the weight of the dish structure was reduced by 25%. And the optical analysis tools developed for dish systems are also proving useful for troughs and power towers.

Photo of a row of four Infinia dish/Stirling systems oriented in the same direction. Each system is a smooth reflective dish on a short pole structure, with an arm that extends from the center of the dish to hold the Stirling engine at the end.

Four Infinia dish/Stirling systems are demonstrating that CSP can provide distributed power generation.
Credit: Infinia Corporation

We are also developing a small-scale dish/Stirling system with Infinia Corporation that can be applied to the distributed generation market in the range of hundreds of kilowatts. A free-piston Stirling engine has demonstrated remarkable reliability at the 1-kilowatt scale and may also do so at the 3-kilowatt scale. We are installing 2 to 3-kilowatt prototype test units and performing reliability, performance, and control tests and assessments.

Industry Support

NREL and Sandia experts are providing technical support to industry to ensure that dish/engine systems are built at minimum cost and maximum operational success. As mentioned in the section above, DOE supports work with Stirling Energy Systems. But other technical activities support the awardees of financial opportunities for concentrating solar power. The complete list of DOE-funded CSP projects is available on the Concentrating Solar Power Industry Projects page that specifically includes the dish/engine industry projects.