FRENELL Technology

FRENELL CSP plant concepts are based on three key components – the solar array, the thermal energy storage system and the power plant block.

Collector system

The collector system designed by FRENELL comprises flat, glass-based reflectors which are focused together onto a fixed, linear receiver. Vacuum-insulated absorber tubes are fitted in the focal line, in which molten nitrate salt is warmed to as much as 550 °C.

The modular design of the collector allows almost continuous adjustment of the solar array sizes to the demand for solar energy or the site area of a project. The gradient of up to 6 % helps to minimise or even eliminate the need for earthworks on hilly ground.

Thermal storage tanks based on liquid salts - by FRENELL

Thermal energy storage systems from FRENELL are based on molten nitrate salts. The liquid salt heated in the solar array during the day is buffered in insulated tanks known as “hot salt storage tanks”. From there, pumps move the liquid salt through heat exchangers, thereby generating hot steam. The liquid salt that is cooled as part of the process is fed back to the cold salt storage tanks before being pumped through the solar array again the next day. Once there, it is heated to the target temperature and returned to the hot salt storage tanks.

High redundancy and easy scalability

FRENELL’s storage systems are designed as multiple modular storage tanks. The modular concept enables a high degree of preliminary planning, thus reducing engineering and construction times. Additionally, the redundancy also helps to increase the average annual availability of the overall power plant.

Earn money from grid surpluses

Growth in the market share of volatile energy generators such as wind and photovoltaics brings price fluctuations in the electricity market. Increasingly, brief surpluses give rise to extremely low or even negative spot market prices in the grid. Thermal storage tanks from FRENELL offers an interesting economic opportunity. By heating the tanks using surplus electricity from the grid, the additional stored energy for electricity generation can then be used during times of higher spot market prices

Power plant block – redefining advanced, tried and tested technology

The power plant block is based on state-of-the-art steam turbines of the kind used reliably for decades in gas and steam turbine power plants. The key difference is that the hot steam needed is generated by stored solar heat rather than by fossil fuel-powered steam boilers. As such, CSP power plants from FRENELL offer the prospect of taking the advanced, highly efficient technology that has been developed for fossil fuel power plants, along with all of its proven benefits, and putting it to use for CO2-free electricity generation.

Maximum grid-friendly control

CSP power plants from FRENELL deliver an incomparably high contribution to electricity grid stabilisation and to their failsafe performance in what is an increasingly challenging environment.

Load cycling capability

With rapid control capability of the liquid salt circuit, the output of a FRENELL CSP power plant can be adjusted from 0 to 100 % within minutes to cope with fluctuating demand in the grid. The load cycling capability of CSP power plants from FRENELL thus surpasses coal and gas-fired power plants that were previously used to ensure control capability.

Grid frequency stabilisation

State-of-the-art control of a steam turbine generator uses the rotating flywheel mass of the steam turbine and generator to counter fluctuations in the grid frequency within just a few milliseconds.

Black start (restoration) capability

FRENELL power plants can be started up independently in the event of a blackout, thus helping to quickly overcome the difficulties of electricity grid blackouts.

Clever design for automatic cleaning

The fully automatic collector cleaning units developed by FRENELL ensure maximum performance while at the same time minimising water consumption and maintenance costs.