Batteries, especially the lithium-ion variety used in mobile phones and electric cars, are likely to dominate the $44 billion or more spent on energy storage by 2024, according to Bloomberg New Energy Finance. Trouble is, they’re not the solution to all needs.
As well as the environmental impact of mining lithium, which has been blamed for starving flamingos in northern Chile, batteries lose their charge over time. They can balance minute-to-minute shifts in supply. But they can’t absorb solar power generated in summer, say, and deliver it in winter.
“We’re going to need a whole range of solutions to keep the lights on," said Michael Liebreich, founder of Bloomberg New Energy Finance. “If your problem is that the sun doesn’t shine in winter, are you really going to buy a battery, charge it once a year during summer and use it once a year in winter? I don’t think so. You can’t just jump to batteries as the single solution."
Storage devices are crucial to expanding the wind and solar industries and curtailing pollution because they allow what’s generated now to be consumed later. Just as refrigeration changed the way we handled food in the 20th century, energy storage will give grid operators and rooftop-solar consumers flexibility about when to use the power they produce—reducing the number of big power plants the world needs.
Here’s the leading energy storage projects on the drawing board that go beyond lithium-ion batteries:
Long before batteries, electricity was stored through plants that pump water uphill to a reservoir and release it through turbines when it’s needed. It’s long-lived enough to be hold solar power generated in the summer for use in the winter. Hydropower is renewable energy’s oldest technology and accounts for well over 90% of energy storage, according to the US Department of Energy.
As well as classic hydroelectric stations, tidal lagoons may also offer energy storage in a similar way by holding water for short periods, according to Tidal Lagoon Power Ltd, which is planning to build six lagoons around the UK coast line.
Trains can double as storage. In April, Advanced Rail Energy Storage won approval from the Nevada Bureau of Land Management for a $55 million project using rail locomotives.
ARES will build a 6-mile uphill rail corridor involving heavily-loaded trains. When power’s cheap, trains will be pushed up a hill. When the power is needed, they’ll be released down when power’s needed, supplying it back to the grid through an overhead wire.
Chief executive officer Jim Kelly reckons the system can be deployed at about 60 percent of the cost of an equivalent pumped-hydro facility. The nine-month construction program is expected to start in the second quarter of 2017. Once complete, it could run for 40 years.
Compressed air storage sequesters a gas underground so it can be released later to drive a generation turbine whenever needed.
One project in Toronto sends the air underwater where it’s stored in balloons. When demand for power rises, the air comes back to the surface through a pipe, where it’s converted into electricity.
Compressed air storage requires a specific type of rock formation. The world has a handful of existing projects—one in Huntorf, Germany and another in McIntosh, Alabama. Several large scale projects have been put on ice, including the Iowa Stored Energy Plant near Des Moines and Dresser-Rand Group’s 317-megawatt Apex Bethel Energy Center in Anderson County, Texas.
Companies including carmaker Audi are developing power-to-gas technology that turns excess energy into hydrogen using electrolysis. The hydrogen can be directly injected into a gas network, or “upgraded" into methane and used as a substitute for natural gas.
Siemens, the world’s biggest power-equipment maker, is working on an approach that turns hydrogen into a clean ammonia, that could potentially provide emissions-free fertilizer that could be used by farmers everywhere.
Advocates say it can deliver both long and short-term back up power since the gas can be trapped indefinitely. That means it can shift electricity made in summer for use in the winter. It isn’t yet clear whether the economics will stack up.
Flywheels look nothing like a traditional battery. Think of a spinning drum that stores the kinetic energy in a way that can be made into electricity. Power is used to start the wheel turning. Then when electricity is in short supply, the flywheel turns a motor that generates electricity. They can deliver either short bursts or for longer periods.
Railway Technical Research Institute, a Tokyo-based developer of railroad technologies, is working on a flywheel that uses superconducting magnetic bearings that allow the wheel to spin with less friction. Its system also uses a plastic that’s reinforced with carbon fiber, making the flywheel stronger and faster. The bearings allow the flywheel to float without making contact with its housing, reducing energy lost through friction.
Railway Technical is developing the flywheel technology with Furukawa Electric Co. and Mirapro Co. They have set up a flywheel system at a 1-megawatt solar park in Japan’s Yamanashi prefecture. Temporal Power Ltd and Beacon Power Corp. are also pursuing flywheel systems. Bloomberg