The power of battery storage: how batteries and their alternatives are evolving
Alternatives to batteries are on the rise. Read on to find out how the development of battery storage technologies is integral to the transition from fossil fuels to renewable energy.
7 Jun, 21
Developing battery storage solutions is key to enabling the transition to clean energy, providing a way for renewable sources of generation to provide base-load electricity supply.
Large quantities of intermittent supply will need to be integrated into power grids around the world. In fact, around 10,000 gigawatt-hours of energy storage capacity, including batteries, will be needed by 2040 to meet climate goals –– which is 50 times the size of the current market, according to the International Energy Agency (IEA).
Utility-scale storage systems, typically based on lithium-ion batteries, have so far primarily been deployed in Australia, Germany, Japan, the UK, and the US. The Americas are set to overtake Asia-Pacific as the largest battery storage market by 2025, with global storage capacity rising by 70GWh to 729GWh by 2030.
Despite the COVID-19 pandemic, global investment in battery storage increased by almost 40% last year to $5.5 billion, according to the IEA. Strong momentum in the sector and a large project pipeline are set to continue the trend in 2021.
Let’s look at some of the different forms of battery storage available today and the role they’re playing in the energy transition.
The changing nature of battery storage
Battery storage systems are used to provide balancing services for electricity grid operators, and are increasingly being installed alongside solar and wind farms to store power for use overnight when the sun isn’t shining or when wind levels are low. Batteries can make power grids more resilient and provide backup to reduce blackouts in countries where grids can become overloaded by demand outpacing insufficient supply.
Battery installations have so far been predominantly based on lithium-ion batteries. But other battery technologies are emerging that could form part of the energy infrastructure of the future.
Redox flow batteries
Redox flow batteries, typically using the metal vanadium, have a relatively low energy density so they are not a replacement for lithium-ion batteries in electric vehicles. However, they have advantages in stationary energy storage applications as space and weight are less of a concern and installations can be scaled up to meet the required capacity.
Vanadium redox flow battery (VRFB) technology is based on liquid vanadium electrolyte that unlike lithium-ion, does not degrade over time and is dissolved in a non-flammable, water-based solution to generate electricity.
While lithium-ion batteries can replace peaking power plants that are called on to meet spikes in electricity demand, redox flow batteries can shift renewable output from the middle of the day to when it is most needed every day. And they can do this while maintaining their recharging capabilities throughout the 20–30-year life of the solar or wind installation.
VRFB installations in places like China, Japan, and Australia have been small so far, but there are plans for large installations of around 100MW. UK-based VRFB developer Invinity Energy Systems has signed a deal with Germany’s Siemens Gamesa Renewable Energy to develop grid-scale batteries. Bushveld Minerals, a vanadium mining company that has previously invested in Invinity, is also part of a consortium that owns VRFB producer Enerox and has its own Bushveld Energy subsidiary.
In the same way that solid-state hard drives offer more efficient and stable data storage than previous technologies, solid-state lithium batteries use solid electrolytes that offer higher energy density and do not carry the same safety risk as lithium-ion batteries. They require fewer safety components, so save valuable space, allowing for larger capacity in a single installation. They also have a longer lifespan and are not affected by external factors such as temperatures like lithium-ion batteries.
South Korea’s Samsung SDI has been exhibiting solid-state battery technologies since 2013. Mass adoption is some way off, however, as the cost of producing solid-state batteries is high. And the solid electrolyte requires lithium metal, whereas most of the lithium mined globally is in the form of lithium salts that are used in liquid electrolytes.
Lithium-air batteries create a reaction that uses oxidation of lithium in the anode taking oxygen from the air, and the reduction of oxygen molecules in a carbon cathode, to generate energy. This provides a much higher energy density than lithium-ion and the use of oxygen makes for the lightest possible batteries.
However, there is still work to be done on reducing the safety risk of using a highly reactive pure lithium anode, and increasing the technology’s low charging efficiency. UK-based chemicals producer Johnson Matthey has been working with the University of Liverpool to research minimizing the reactivity that degrades the performance of the electrolyte during battery cycling, increasing the performance and stability.
The energy density of lithium batteries has increased in recent years, as manufacturers have experimented with different combinations of materials in the cathode and anode. Costs have fallen sharply over the past decade, making batteries viable for more projects. Although grid costs are flat or even rising, the cost of a four-hour duration lithium-ion battery system is forecast to decline by 68% to $104 per kilowatt hour (kWh) by 2050, down from $320/kWh in 2020, according to Bloomberg.
The use of lithium-iron-phosphate (LFP) cathodes gave way to lithium nickel-cobalt-manganese (NCM) in various quantities, which offers a larger storage capacity but raises safety issues. There are also concerns about the sourcing of cobalt metal, which is subject to large price swings. In some cases, manufacturers have chosen to opt for LFP batteries to allay safety concerns and encourage adoption.
Lithium-ion battery anodes are typically based on graphite. As manufacturers look for ways to increase the time between battery charges, some are turning to silicon metal as an alternative. Companies like Norwegian silicon producer Elkem and US battery materials startup Group14 Technologies are starting to supply manufacturers with battery-grade silicon for anodes to substitute graphite.
Emerging alternatives to batteries
While battery technologies have clear advantages, they are based on relatively rare and expensive metals that can also have high environmental costs. Researchers are starting to look beyond batteries altogether to alternative technologies that can affordably store large amounts of energy with a lower carbon footprint.
Hydrogen fuel cells
Unlike lithium, hydrogen produces only water as a byproduct, making it cleaner to produce and recycle. It also has a much higher energy density. Many executives in the automotive and industrial sectors view hydrogen as the long-term solution to clean energy storage.
However, extracting large amounts of hydrogen from water is currently only cost-effective using fossil fuels. Research and investment are focusing on green hydrogen, which is produced using renewable energy, and governments around the world have started to release hydrogen strategies for the coming years.
Japanese carmaker Toyota has long been working on hydrogen fuel cell technology and sells the first mass-produced hydrogen-fueled car, the Mirai. In 2019, it installed a stationary fuel cell generator at one of its plants in Japan to test its commercial viability.
However, widespread adoption of hydrogen fuel has so far been limited as it is more flammable than gasoline and dangerous to transport in large quantities, posing an even larger risk of explosion or fire than lithium. Solving the safety issue will be key to making hydrogen a viable alternative.
Supercapacitors hold less energy than batteries, but they can discharge and recharge energy more efficiently than batteries. Researchers have recently found that using thin sheets of graphene, which has a large surface area that can store energy, can increase the amount of energy that supercapacitors can hold. Graphene sheets would also save weight and allow for alternative designs to the standard battery packs.
Graphene is yet to be produced in sufficient quantities to be used for energy storage, but it could provide a new form of storage technology in the future.
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