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Linear Fresnel Technology added to System Advisor Model's Capabilities

February 8, 2012

 A promising Concentrating Solar Power (CSP) technology that uses a stationary receiver tube and an array of mirrors mounted near the ground can now be accessed within the System Advisor Model (SAM), which predicts annual energy production, hourly performance and return on investment.

The U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) teamed with the Electric Power Research Institute (EPRI) of Palo Alto, Calif., to develop a new direct-steam-generation (DSG) linear Fresnel model in SAM.

CSP technologies use mirrors to reflect the sun toward a receiver that absorbs heat and transfers it to a working fluid. The hot liquid boils water to produce steam which drives a turbine, producing electricity. CSP is a utility-scale technology that is ideally suited for sunny climates such as the American southwest, arid sections of Spain, the Middle East, and North Africa.

The linear Fresnel technology uses an array of low-profile rotating mirrors that reflect sunlight to a fixed receiver. The mirrors and receivers are arranged in series, and each collector loop may be a kilometer or more in length. The low-profile reflector architecture enables high concentrated flows while reducing wind loads and structural cost.

“The first linear Fresnel design modeled in SAM is a direct-steam system”, said NREL’s Mike Wagner, who co-wrote the software program. Soon, a linear Fresnel system that uses high-temperature molten salt for storage will be added to the SAM repertoire.

“One of the drivers for starting with the direct-steam model is that it operates at temperatures that integrate well with existing coal-fired power plants,” said Wagner, a mechanical engineer who is the project leader for power-tower research and development at NREL. “Utilities are very interested in how this technology performs compared to other CSP technologies.”

NREL and Sandia National Laboratories developed SAM – originally called the Solar Advisor Model – and made it available to the public for the first time in 2008. SAM uses information on weather, system design, geography, cost and many other variables so utilities and their potential financiers can know in detail the best places to site the technologies, the amount of energy they produce, and the likely return on investment. The quasi-steady-state model in SAM allows users to investigate energy and fluid flows, operating temperatures, and pressure drops.

The new linear Fresnel tool in SAM is designed to provide useful information, including full performance and financial results in seconds per simulation, for utilities, policy-makers, and researchers on the linear Fresnel. The model was developed with involvement from the linear Fresnel industry to ensure realistic and useful output that applies to current and future technology solutions.

The new linear Fresnel model is available in the current SAM release at

The Electric Power Research Institute, Inc. (EPRI, is an independent, nonprofit, organization which conducts research and development to help address challenges in electricity, including reliability, efficiency, health, safety and the environment, for the benefit of the public.

NREL is the U.S. Department of Energy's primary national laboratory for renewable energy and energy efficiency research and development. NREL is operated for DOE by the Alliance for Sustainable Energy, LLC.
Visit NREL online at

—William Scanlon