Can Bill Gates' energy storage solution replace lithium-ion batteries?

Renewable energy sources such as wind and solar are becoming cheaper than fossil fuels in much of the world, but they require storage to become viable, stable sources of energy, and the search for alternative energy storage methods is urgent.

On a windswept sea wall on England's north Kent coast, Mary King points to miles of empty, marshy farmland that will soon be home to thousands of solar panels and one of the country's largest battery installations. Such battery plants will become a familiar sight in Britain and elsewhere.

On November 18, British Prime Minister Boris Johnson pledged to install enough wind turbines to provide electricity to every home by 2030, but this will require solutions to manage intermittent energy supplies.

That’s why we need batteries, devices that store electrical energy as chemical energy. Lithium-ion batteries, used in mobile phones and Tesla electric cars, are currently the dominant energy storage technology, and are being deployed from California to Australia and, most likely, Kent to help grids manage surging renewable energy supplies.

Tesla Chief Executive Elon Musk has said he expects the company's energy business, which includes solar power and giant lithium-ion batteries for the electric grid, to be as big as its auto business in the long term.

But cheaper, longer-lasting energy storage technologies are needed in addition to lithium-ion batteries to completely replace fossil fuel power plants and achieve 100% renewable energy, most of which are not yet cost-effective. Currently, gas-fired power plants bridge the gap with renewable energy, providing a steady supply of energy for longer periods of time than current batteries can provide.

As part of the UK government's green industrial revolution, the government has launched a £1 billion Energy Innovation Fund to help commercialise new low-carbon technologies, including the liquid air battery being built by Highview Power outside Manchester.

Lithium-ion batteries are currently the dominant storage technology and are being deployed around the world to help grids manage surging renewable energy supplies.

Without energy storage, it will be difficult for countries to significantly reduce their use of natural gas and coal-fired power plants, or to reduce the harmful effects of climate change, such as rising sea levels and extreme weather conditions.

Companies are racing to develop the next breakthrough, including battery technology that uses abundant raw materials, volcanic rock, liquid air storage tanks and systems for lowering heavy objects into abandoned mines, to unlock large-scale renewable energy by mid-century. It's backed by several prominent business leaders, including Microsoft founder Bill Gates and SoftBank's Masayoshi Son. 

“All of these technologies are going to be needed if we want full decarbonization,” said Rory McCarthy, an analyst at energy consultancy Wood Mackenzie. “But the scale of investment you need is in the billions of dollars to make a difference.”

Zero inventory supply chain 

Every day, the grid must constantly match supply with demand, a process that becomes more difficult when you strip out the coal and gas plants that provide a reliable, steady supply of energy. Donald Sadoway, a Canadian chemistry professor at MIT, likens the grid to “the world’s largest supply chain, but with zero inventory.”

Hornsdale Power Reserve, one of the world's largest lithium-ion batteries, built by Tesla, near Jamestown, South Australia

Renewable energy provided a record 47% of Britain’s electricity in the first quarter of this year. However, that success created a problem just weeks later, when energy demand fell by as much as 20% after the first national coronavirus lockdown in March. When renewables reached around 50% of total generation, the national grid’s job became harder and it needed help from the large spinning turbines at fossil fuel plants to smooth out the system’s volatility.

The fall in demand means renewables now make up more than half of the energy mix, forcing engineers at the National Grid's control centre to perform a delicate balancing act, part of which involves increasing the use of energy storage. Supporters say this vindicates the expansion of the technology.

It turned out to be a test case for how the grid will look in the future, when a greater share of renewable energy is produced, said Peter Kavanagh, chief executive of Harmony Energy, which supplies power to the grid from six Tesla lithium-ion batteries in Poole on England’s south coast.

“In many countries, solar and wind are the cheapest forms of electricity generation, but once renewables form a certain scale in the energy mix, they need to be stored, as we have seen during the pandemic,” he said. “The pandemic has proven the business case for battery storage five years in advance.”

Currently, more than 97% of the world's energy storage methods use electricity to pump water to high-level reservoirs, and then release the water to drive turbines to generate more electricity, which is called "pumped storage". Reservoirs are a way to store energy. But these systems are greatly affected by the geographical environment and may be limited by the increasing scarcity of water resources in the future.

The advantage of lithium-ion batteries is that they can be placed anywhere and can deliver power to the grid very quickly, just like electric cars. They can react within milliseconds and can generally provide up to four hours of storage, helping the grid deal with sudden outages in power generation, but in the long term the cost is too high. In the UK, most large lithium-ion batteries provide 30-90 minutes of energy.

Redox flow battery

Alternative technologies that can store large amounts of energy more safely for longer periods of time would make wind and solar more integrated. But they would need to be scaled up quickly to meet growing demand and be cost-competitive.

In January, the California Energy Commission, the state’s main energy policy and planning agency, called for long-duration energy storage that could provide more than 10 hours of energy, enough to store a day’s worth of solar energy for use overnight.

One of the winning bidders was Inveniti Energy Systems, which uses large batteries based on vanadium, a raw material used by the steel industry to make metals stronger. First developed by NASA in the 1970s, these redox flow batteries use large, individually charged tanks of electrolyte to store energy, making them easier to scale up than traditional batteries.

A vanadium mine pit in Bahia, Brazil. Matt Harper of Invinity Energy Systems, which uses the material, said vanadium batteries could store eight to 10 hours of renewable energy during the day and tap into it when demand peaks.

Matt Harper, the company's chief commercial officer, said vanadium batteries can store eight to 10 hours of renewable energy during the day and deploy it during peak demand periods, or at night, setting a floor for electricity prices. Because vanadium batteries use a water-based electrolyte, they are more likely to extinguish a fire than to start one, he said. They also have a longer lifespan than lithium-ion batteries and can last 30 years.

In the center of Dalian, in northeastern China, Rongke Power is building the world's largest vanadium battery. With a capacity of 800 megawatt hours, it will be more than three times the size of the world's largest lithium-ion battery installation in California. It will help Liaoning Province better integrate wind power into its grid.

"Installing large-scale lithium-ion batteries in the city center is not allowed (due to safety concerns)," said Li Bin, marketing director of Rongke. "The safety issues of lithium-ion batteries have not been resolved."

However, vanadium prices fluctuate greatly, soaring to $127/kg in November 2018 and now falling to $25/kg, which may have an impact on production costs.

Siemens volcanic rock energy storage

Those looking for other storage options are avoiding batteries altogether and trying natural and physical solutions like pumped water, which can dispatch energy over 20 hours without the need for natural reservoirs.

"Welcome to the Neolithic Age" is written in purple lettering on the facade of a gray concrete windowless building on the outskirts of Hamburg, Germany, at a plant operated by Siemens Gamesa, the world's second-largest wind turbine maker.

Siemens Gamesa's Hamburg plant uses 1,000 tons of volcanic rock from Norway to store 130 megawatt-hours of energy in the form of heat, providing enough energy to power around 3,000 German households, or about 750 electric vehicles.

The volcanic rock is first heated to at least 600°C using electricity. The energy can be stored for a week, but the goal is to dispatch the electricity overnight. Hasan Oezdem, head of innovation projects at Siemens Gamesa, said the system could be installed in coal-fired power plants that are facing retirement and use their turbines.

“You can turn them into giant storage facilities,” he said. “The biggest utilities are struggling to regenerate themselves because you can’t sell them, no one’s buying coal plants. What we offer is to keep them running for green purposes.”

On the outskirts of Manchester, a similar project is taking shape on the site of a decommissioned power plant, using containers of liquid air rather than volcanic rock. Highview Power broke ground on the 250MWh plant at Trafford Energy Park in November after winning a £10 million grant from the UK Department for Business, Energy and Industrial Strategy.

“Lithium-ion batteries are great technology, but they are too small for the challenges facing the grid,” said Javier Cavada, the company’s chief executive. “The business model for long-duration storage is to make sure all the wind and solar generation is used.”

Wind turbines off the coast of Essex, England. British Prime Minister Boris Johnson has pledged to install enough wind turbines to power every home by 2030.