Concentrating & storing solar

CSP plants are renewable power systems that use the sun’s radiation to generate electrical power. At the core of CSP technology are the mirrors that collect and concentrate the sun’s radiation. Unlike PV technologies, which convert sunlight directly into electricity, CSP plants first use the solar radiation to generate thermal energy, which is stored and then later used to produce power. This aspect is important as thermal energy can be easily and cheaply stored and used at different times, allowing CSP plants to provide low cost dispatchable electricity.

The history of commercial CSP plants started in the USA in the second half of the 1980s. This technology has proven to be very reliable, to the point that most of the plants installed in California between 1985 and 1990 continue to operate today, beyond their life expectancy of 25–30 years. There has been a large growth in global uptake of CSP since 2006. Like wind and solar PV before it, rapid compound growth is achievable once market signals are established. Up until 2013, nearly all existing CSP plants were based on the parabolic trough technology. Tower plants are now increasingly favoured for their capacity to achieve higher temperatures (600ºC compared to 400ºC for a linear system) and more cost‑effective storage.

The CSP systems built to date use steam turbines to generate electricity in a similar manner to fossil fuel fired power stations. These power plants are attracting increasing interest due to their ability to store large amounts of energy and provide low cost dispatchable electricity. The current industry standard approach is to use a mix of molten nitrate salts as a heat storage medium that is moved between a ‘cold’ tank at around 290ºC to a ‘hot’ tank at close to 400ºC for a linear system or 600ºC for a tower system.

In a power grid increasingly weakened by the penetration of non-dispatchable wind and solar PV, Quasar Energy’s CSP plant is designed to provide valuable grid strengthening services. This is possible as a consequence of using steam turbines
that produce power through synchronous generation. This configuration provides the same inertia benefits as from conventional gas and coal plants. Furthermore, the turbines are specifically customised for fast start and are capable of ramp rates of 10% per minute.