Solar thermal energy is on the rise thanks to a technology that enables the storage of energy for cloudy days.
When it comes to renewable energies, most of us think of a solar panel on a roof or a wind turbine on the top of a hill. But less known to the general public, solar thermal power has a big potential including in developing countries. IEC TC 117: Solar thermal electric plants, is paving the way with the relevant Standards.
Also going by the name of concentrating solar thermal power (CSP), solar thermal electricity is on a strong growth trajectory. Spain and the USA have the largest installed capacity but new facilities have been built recently in Morocco and South Africa.
CSP technologies use reflective material such as mirrors to concentrate the sun’s heat. That heat then drives steam or gas turbines to produce electricity. One of the important selling points of CSP, compared to other forms of renewable energy, is that most solar thermal electricity plants can store heat during the day and convert it into electricity at night time. This means that the supply of energy from the sun can generate electricity 24h/day – which in other words is a constant supply. In order to do so, Solar thermal electricity plants have to be built in sun-drenched locations and this why they are te be found in aeras such as Andalusia in Spain or in the Sahara desert in Morocco.
While various fluids such as water or synthetic oil have been used to produce steam, new installations are increasingly employing molten salts. The heated salts generate steam and are easy to store, decoupling energy collection from energy generation.
A large amount of R&D is focusing on technologies which lower the costs of CSP and make it more efficient. Research projects include a US lab’s high-temperature falling particle receiver, in which sand-like ceramic particles are heated as they fall through a beam of highly concentrated sunlight focused by an array of mirrors. The falling-particle receiver can process heat at significantly higher temperatures than existing CSP technologies (up to 1000 °C and higher), which can increase power cycle efficiencies and reduce costs. Like molten salt, the particles can conveniently be stored.
IEC TC 117 was established in 2011 to draft International Standards in the CSP field, auguring the growth of solar thermal capacity across the globe. It has recently issued its first publications, including IEC TS 62862-1-2:2017 and IEC TS 62862-1-3:2017 giving guidelines for the creation of annual solar data sets, which are indispensable to simulate plant power production.