The transition to renewable energy faces a persistent challenge: how to maintain reliable electricity supply when solar panels go dark and wind turbines stand still. While solar and wind already account for over one-third of the United Kingdom's electricity generation, their inherent intermittency demands innovative storage solutions beyond conventional batteries.
Nathan Ritson, technical manager at renewable energy supplier Good Energy, articulates the fundamental problem facing grid operators. "With the good old British weather, you find you're over-generating at certain times, and under-generating at others," Ritson explains. Grid-scale battery storage has become increasingly common for balancing supply and demand, but three emerging technologies may soon play crucial supporting roles in energy infrastructure.
Flywheels: Ancient Concept Meets Modern Engineering
The flywheel represents one of humanity's oldest mechanical concepts, first conceptualized by Leonardo da Vinci and later refined by Scottish engineer James Watt for steam engine applications. The principle remains elegantly simple: renewable energy sources spin a rotor, storing energy as motion that can later be released to generate electricity.
Independent energy consultant Eugene Bryce identifies several compelling advantages of flywheel technology. The systems can last for decades, far outliving batteries that degrade much sooner. They operate with up to 90 percent efficiency and can be charged and discharged very rapidly, making them ideal for delivering power precisely when the electricity grid requires it.
The technology faces challenges, including relatively high upfront costs and scalability limitations. However, Bryce suggests that flywheels could prove valuable when combined with battery systems. The world's largest flywheel installation recently connected to the grid in China's Shanxi province. The Dinglun Flywheel Energy Storage Power Station consists of 120 high-speed magnetic levitation flywheels with a combined capacity of 30MW, sufficient to power approximately 10,000 United Kingdom homes.
Liquid Air: Transforming Atmosphere Into Storage
Liquid air technology, first seriously proposed in the 1970s, represents a relatively new approach to energy storage. The process begins with air compression to very high pressure using surplus electricity. The pressurized air then passes through a complex heat exchanger system, cooling until it reaches a liquid state. When energy demand rises, the liquid is pumped out as a gas to drive turbines and generate electricity, similar to steam-driven conventional power stations.
Growing demand for energy storage has renewed interest in this method. Liquid air specialist Highview Power is constructing the world's first commercial-scale application in Manchester, scheduled to come online in 2027. The facility will capitalize on electricity price fluctuations, using cheap power to create the storage solution and releasing the air to generate electricity when demand exceeds available supply.
Shaylin Cetegen, an energy storage specialist at the Massachusetts Institute of Technology, told the BBC that liquid air "stands out as a particularly cost-effective option for large-scale storage," despite potentially challenging initial economics.
Molten Salt: Storing Solar Energy After Sunset
Molten salt technology offers a solution to a seemingly impossible challenge: generating solar electricity during nighttime hours. Concentrated solar plants in Spain, Morocco, and elsewhere employ vast mirror arrays to heat thermal oil, producing steam to drive turbines. Some facilities focus heat on special salt mixtures that retain thermal energy for extended periods, including overnight. When electricity is required, the hot molten salt is pumped to a steam generator, producing superheated steam to drive turbines.
Beyond electricity generation, industry increasingly recognizes salt's potential for storing heat required in industrial processes. Norway's Kyoto Group has developed a heatcube design that uses renewable electricity to heat salt tanks when prices are low. The stored heat, released as steam, can be used on-site for applications such as sterilizing goods during food production.
This approach represents one of numerous innovations using salt, sand, or other mediums that promise to revolutionize heat generation and storage for industrial and potentially domestic applications. Robert Barthorpe, a storage expert at the University of Sheffield, told The Guardian that molten salt "is a fantastic technology, offering high temperatures at industrial scale" and predicted it would become "an important part of the energy mix."
As renewable energy continues its rapid expansion, these diverse storage technologies offer complementary solutions to the intermittency challenge. While batteries will undoubtedly remain central to grid management, flywheels, liquid air systems, and molten salt storage may prove essential components in achieving a reliable, fully renewable energy future.