Size: 10KW to 100MW+

Several small scale installations in operation; utility-scale installations slated for construction in 2010

Applications appropriate for both utility-scale projects and stand-alone distributed energy projects

In this case the system consists of a solar concentrator in a dish structure that supports an array of curved glass mirrors. The parabolic dish tracks the sun throughout the day and concentrates the radiation onto the heat absorption unit of a Stirling engine. The focused solar thermal energy is then converted to grid-quality electricity. The conversion process involves a closed cycle, high-efficiency solar Stirling engine using an internal working fluid (usually Hydrogen or Helium) that is recycled through the engine. The working fluid is heated and pressurized by the solar receiver, which in turn powers the Stirling engine.

The dish Stirling systems have decades of recorded operating history. For over 20 years, the Stirling Energy System (SES) dish has held the world’s efficiency record for converting solar energy into grid-quality electricity, and in January 2008, it achieved a new record of 31.25% efficiency rate.

Dish Stirling Systems are flexible in terms of size and scale of deployment. Owing to their modular design, they are capable of both small-scale distributed power output, and suitable for large, utility-scale projects with thousands of dishes arranged in a solar park (two plants in the US totalling over 1.4GW are slated to begin construction in 2010 using the Stirling Energy Systems (SES) technology).

This technology uses no water in the power conversion process (either for steam generation or cooling) and the only water needed is for the washing of the mirrors, a key differentiator from other solar thermal platforms. Dish Stirling technologies are furthermore attractive due to their high efficiency and modular design, which gives the systems several key advantages, including a higher degree of slope tolerance and siting flexibility, meaning it does not require flat land, significantly reducing grading costs and environmental impact; high overall availability due to the fact that there is no singular point of failure and scheduled maintenance on the dishes can occur on individual units while the others continue to generate power; and a low-cost of manufacture and deployment as a result of high-throughput automotive style production and assembly.

Although certain Dish Stirling systems have been tested and proven for over two decades with no appreciable loss in the key performance criteria, there are currently no utility-scale plants in operation, however recent strategic investments by established renewable energy companies, such as the $100 million investment by Ireland’s NTR in Stirling Energy Systems (SES), have signalled renewed interest and potential for accelerated commercial deployment for utility-scale applications. Currently, there is a pilot plant running at the Sandia National Laboratories in New Mexico in association using Stirling Energy Systems, and a 60 dish commercial installation (1.5MW) will be completed in Q4 2009 in Arizona.