Concentrated solar power, or CSP, is usually thought of as a way to create and store large amounts of solar energy to make electricity. In theory, it is no different than using a magnifying glass to burn your initials on a piece of wood. Concentrating the sun’s rays can create intense heat. That heat can be captured in any number of storage mediums. Water, molten salt, and molten silicon are three of the most commonly used.
What makes CSP technology so appealing is that is allows time-shifting of solar power. Heat water, or salt, or silicon during the day when the sun is shining brightly, then use that stored heat to create electricity later after the sun sets but demand for electricity is high. Typical CSP installations today are capable of creating massive amounts of electricity. In Dubai, a 700 megawatt system is under development. 100 megawatts is about the smallest size that is economically feasible, according to most experts.
Now Swedish company Azelio says it has developed new technology that could make concentrated solar power suitable for projects as small as 500 kilowatts or as large as 20 megawatts, according to a report in Renewable Energy Magazine. The company states the technology is able to generate clean electricity on demand, around-the clock, in a distributed way, and is more cost efficient than competing technologies.
The key to the Azelio system is that is uses molten aluminum to store heat and a Stirling engine to generate electricity. Most CSP sytems use the stored heat to create steam, which is then used to power conventional turbines to generate electricity.
The Stirling engine was invented by Scottish minister Robert Stirling in 1816. It operates using heat from an external heat source and is more efficient than an internal combustion engine. Unlike a steam engine, the Stirling engine is a closed system in which a medium — usually air — is constantly heated and cooled without being exhausted to the surrounding atmosphere.
“Showcasing this technology is a great milestone for Azelio. We have now proven that this world-unique solution works and together with our partners we will continue the development and commercialization. Low cost and clean electricity that is made accessible on demand also in remote locations at all hours of the day is really a game changer,” said Jonas Eklind, CEO of Azelio.
We recently reported on new facilities from Fraunhofer that combine solar power installations with agricultural activities in a way that makes land use more efficient and productive. Such systems could be especially useful to remote communities that do not have access to traditional electrical grids. The Azelio system is another example of how to bring electrical power to those remote areas without the expense of building out traditional electrical grids, a process that is often prohibitively expensive.