STELA World | STE/CSP Technologies > Linear Fresnel Reflector
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STE/CSP Technologies > Linear Fresnel Reflector

Fresnel Collector - PSA

Fresnel Collector - PSA

Photo Credit: ©Ferrostaal-Hauke Dressler / PSA

Linear Fresnel Reflectors (LFR) are also based on solar collector rows or loops. However, in this case, the parabolic shape is achieved by almost flat linear facets. The radiation is reflected and concentrated onto fixed linear receivers mounted over the mirrors, combined or not with secondary concentrators. One of the advantages of this technology is its simplicity and the ability to use low cost components. Direct saturated steam systems with fixed absorber tubes have been operated at an early stage of use with LFR technology. This technology eliminates the need for HTF and heat exchangers. Increasing the efficiency depends on superheating the steam. Superheated steam up to 500°C has been demonstrated at pilot plant scale and the first large commercial superheated LFR plant has recently begun operation.

Since steam is the working fluid, LFR technology is usually fitted with a steam storage system. Molten salt storage systems can be also implemented. Furthermore, PCM storage systems are currently demonstrated at pilot plant scale.

There are almost more than 200 MW of LFR plants in operation or under construction. After a first pilot scale application in Australia, a few new pilot plants were developed and tested in Spain and the United States. In 2012, the first commercial 30 MW Puerto-Errado 2 plant began operating in Spain. France has already constructed two LFR pilot plants and is currently building two additional commercial plants with this technology.  Sized 9 MW and 12 MW, and named Llo and Alba Nova 1, these plants are being built by CNIM and SOLAR EUROMED, respectively. In Australia, two plants are currently operating with this technology, sized 6 MW and 9.3 MW. A 44 MW plant is also under construction at Kogan Creek. In India, Reliance Power has completed and connected to the grid a 125 MW Compact LFR plant, designed and constructed by AREVA Solar, in November 2014 (see Case Study Dhursar).

More than 200 MW of LFR plants are currently operating or under construction. After a first pilot scale application in Australia, a few new pilot plants were developed and tested in Spain and the United States. In 2012, the first commercial 30 MW Puerto-Errado 2 plant began operating in Spain. France has already constructed two Linear Fresnel pilot plants and is currently building two additional commercial plants with this technology. Sized 9 MW and 12 MW, and named Llo and Alba Nova 1, these plants are being built by CNIM and SOLAR EUROMED, respectively. In Australia, two plants are currently operating with this technology, sized 6 MW and 9.3 MW. A 44 MW plant is also under construction at Kogan Creek. In India, Reliance Power has completed and connected to the grid a 125 MW Compact Linear Fresnel Reflector plant, designed and constructed by AREVA Solar. (see Case Study Dhursar)

Compared to other technologies, the investment costs per square meter of collector field using LFR technology tend to be lower because of the simpler solar field construction. Also, the use of direct steam generation promises relatively high   conversion   efficiency   and   a   simpler thermal cycle design. The Fresnel design uses less expensive reflector materials and absorber components. It has lower optical performance and thermal output but this is offset by lower investment and operation and maintenance costs. The Fresnel system also provides a semi- shaded space, which may be particularly useful in desert climates for agriculture. Acting like a large, segmented blind it could shade crops, pasture and water bodies to protect them from excessive evaporation and provide shelter from the cold desert sky at night. Many improvements in the absorber tubes and the geometry are under development. Some of those ongoing improvement efforts relate to the shape and the disposition of mirrors to accommodate some of the peculiarities of this technology.

Therefore, LFR offers high thermal performance and low cost, as well as various cost competitive thermal energy storage solutions. Hence, LFR is becoming one of the STE technologies capable of achieving very low LCOE costs.

In addition to electricity generation, LFR technology is also quite useful for direct thermal applications, such as cooling or industrial process heat applications. Very low cost LFR collectors are providing 200°C-300°C steam solutions at a competitive cost for process heat applications such as desalination, food processing and pharmaceutical industries. Low cost LFR collectors are providing 250°C-500°C steam solutions at very competitive cost to hybrid STE – fuel fired combined cycle or Enhanced Oil Recovery applications.

Summary

In the Fresnel plants linear reflectors concentrate the sun into an absorber tube quite similar to the parabolic trough plants. As the concentration factor is smaller than in parabolic trough plants lower temperatures are normally achieved in the heat transfer fluid. That is why most of the plants which have been designed until know has chosen saturated steam as the only working fluid in both the solar field and the turbine. This concept claims to be cheaper than the parabolic trough, but it has lower optical and thermodynamic efficiency and it is not so suitable for storing energy in molten salt tanks. In Europe, 2 plant based on the Fresnel principle is currently operating (in total 31.4 MW) and another one have been announced (12 MW).

  • Uses flat mirror design to concentrate sun, enabling simpler production and installation
  • Enables other industrial uses such as steam processing
  • Plant size between a couple MW to 200 MW.
  • Temperature of the working fluid: 300ºC. New plants that could reach up to 500ºC are been tested.
  • Heat storage capabilities are under investigation
  • Solar energy to electric power performance: Design point 14%. Annual 10%.
  • Prices of PPA that will make projects feasible: between 13 and 20 c€/kWh depending on the level of solar radiation, size of the plant, capacity factor, financial conditions, etc.
Case Study

Reliance Power’s 125 MW STE project, located at Jaisalmer District, Rajasthan, India, was successfully connected to the grid in November 2014. It is the largest solar thermal power plant in Asia and also the world’s largest STE project based on CLFR technology. This STE plant is part of the first phase of an ambitious Indian program, the Jawaharlal Nehru National Solar Mission, which aims to install 22,000 MW of solar power capacity by 2022. This project’s 125 MW can generate up to 280 GWh of electricity every year.

Rajasthan Sun Technique Energy, a wholly owned subsidiary of Reliance Power, was awarded the contract to build a 250 MW STE project in April 2012. The innovative CFLR technology for the project, provided by AREVA Solar (US subsidiary of AREVA SA, France), is simple in design, requires less land and is more efficient than other solar thermal technologies available.

When completed, the 250 MW STE project will result in the avoidance of nearly 557,000 metrics tons of CO2 emissions a year, compared to a similar sized coal-fired power generation plant. At peak, this project will create 500 construction jobs and 40 O&M positions

Source: AREVA Solar

Puerto Errado 2 (PE2), the 30 MW solar thermal power station built by Novatec Solar using linear Fresnel technology, has been operating since August 2012 in Murcia, Spain. The technology uses direct steam generation and, unlike other solar thermal technologies, does not require heat exchangers and oil-filled absorber tube networks for heat transfer. Instead, this highly economical and proven concept utilizes compact, almost flat glass mirrors, with a mirror surface of 302,000 m2. The uniquely efficient solar boiler produces superheated steam directly at a temperature of up to 270o C and a pressure of 55 bar.
PE2’s electrical output is generated exclusively by solar power and produces approximately 50 million kWh of electricity per year, enough to power 15,000 Spanish homes. Annually, this avoids the generation of over 16,000 metric tonnes of CO2 emissions.
Source: Novatec solar and ABB