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0 The International Energy Agency estimates that global renewable capacity could rise as much in 2022-2027 as it did in the previous 20 years. Due to the intermittent nature of renewable energy sources—the sun doesn’t always shine, and the wind doesn’t always blow—energy storage becomes increasingly crucial. As a result, when solar panels receive a lot of sunlight and wind turbines spin quickly, we need to discover a means to store excess energy.
Batteries would seem to be the logical solution. However, there are several challenges to resolve first, including high costs and a need for more standardization of technical requirements. We need to find innovative ways to store renewable energy without batteries.
Innovative Ways to Store Renewable Energy.
- Pumped Hydro Energy Storage
Hydropower is, by far, the world’s largest source of renewable electricity generation. Pumped hydroelectric storage operates by pumping water from a lower reservoir into a higher reservoir, then releasing water and passing it downwards through turbines to generate power as and when required. When electricity demand prices are low, water is pumped to a higher reservoir. The water is then released when the electricity demand rises. According to the International Hydropower Association, pumped storage makes up to 94% of the world’s energy storage, with the potential to scale even further.
2. Gravity-based Energy Storage
Giant bricks are not typically what come to mind when someone mentions “energy storage,” but they are a crucial component of a gravity-based system. This system could assist in managing the world’s growing reliance on renewable electricity generation. Gravity-based energy storage operates similarly to principles of pumped hydroelectric storage. It uses the energy produced when renewable generation is high to raise thirty-tonne bricks into the air inside a special building that acts as an energy vault. The elevation of the bricks results in them storing what is known as potential energy. Potential energy is similar to the kind of energy held in a spring when you stretch it; releasing the spring releases the energy stored. Once the brick is lowered, it releases kinetic energy that can be fed into power grids. The blocks are all stored within modular buildings that can be built up in units of ten megawatt-hours to whatever size is required.
3. Compressed Air Energy Storage
Compressed air energy storage involves moving energy underground. It uses surplus power to run a rotary compressor that condenses air. This air is highly pressurized and is then packed into an underground cavern or container. It can then later be released, heated and expanded in a turbine to generate power. This approach has been in use since the 1870s, but currently, there are only two commercial-scale CAES plants in operation, one in the US and another in Germany.
4. Liquid Air Energy Storage
Energy can also be stored in liquid air in addition to compressed air. Storing energy in liquid air is accomplished by using surplus renewable energy to run a liquefier, which cools and compresses air to -196°C before turning it into a liquid. It can then be released, heated, and converted into a gas that drives energy turbines. Until then, it is held in a tank. The fact that LAES uses current technology with a lifetime of more than 30 years and is easily accessible is one of its main advantages. However, doing so results in energy losses and lowers LAES efficiency to between 50 and 70 percent. This lower efficiency rate could endanger the feasibility of LAES as it is significantly less efficient than lithium-ion batteries, which are about 99% efficient.
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