One of the major issues with renewable energy technologies like solar and wind power is that energy generation tends to be intermittent — i.e. the sun doesn’t always shine and the wind doesn’t always blow. Therefore, in order for such technologies to be capable of meeting our needs without the support of fossil fuels, we need to find effective and commercially viable ways to store energy. That’s why the guys at Highview Power Storage are getting particularly excited about their most recent technology – the CryoEnergy System (CES). CES takes excess energy generated and uses it to run refrigeration units which cool air down to a temperature of -196C (-320.8F), at which point it liquefies. The liquid air, also known as cryogen, can be stored in an insulated tank, and at times of peak-demand, when the direst output of existing energy sources cannot meet the demands of a power grid, this liquid air is released to generate energy.
Solving the energy storage problem would be a huge step towards emission-free power generation on a global scale. Once Highveiw’s CryoEnergy Storage system stores and releases air, the liquid boils, regasifies and expands by up to 700% when heated above -196C (so even room temperature can superheat it). This mega-high-pressured gas is then used to spin turbines which then power a generator.
The only by-product of the CES process is cold air, but what about its efficiency? When exposed to ambient air temperatures, the cryogen gas returns about 50% of the energy used in creating it. But as the amount of stored air increases so does the intensity of the regasification process, resulting in an efficiency of up to 70%. The process is perfect for facilities that generate large volumes of waste heat, as this could boost the efficiency of CES. Furthermore, the cold air produced by the process could even be used for air conditioning, refrigeration or even to create more liquid air. All of this increases the efficiency of the entire process.
When all the criteria for energy storage is taken into consideration, the use of batteries is inferior to CES. While high-efficiency batteries can yield 1 kW of power, they cost about US $4,000 which is 4 times the cost required by CES to produce the same power
A pilot project, fully integrated into the UK’s national grid, is currently in operation and is being supported by the Department of Energy & Climate Change and UK-based utility SSE (Scottish & Southern Energy). Highview plans to have a 3.5 megawatt (MW) commercial-scale plant operational by 2012, with the aim of increasing capacity to 10MW by 2014.
In the race to find the innovative energy storage solution that can take our renewable energy ambitions to the next level, CES provides the most efficient, economic and environmentally-friendly answer. So far.
Pictures courtesy of Brightview Power Storage