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The way we produce electricity has changed; we are no longer compelled to rely on expensive, polluting fossil fuels and instead have opted for cleaner and cheaper sources.
Power generation in the future is likely to consist of a mix of low-carbon sources such as renewables, hydro and nuclear power. But while renewable sources like the sun and wind now supply a large proportion of our energy, they are intermittent, only generating energy at certain times.
To reap the full benefits of renewables, we must store some of the energy when it is generated and use it in peak demand. One way to do this is with stationary energy storage in the form of batteries.
Improving Infrastructure
The amount of energy produced via renewables worldwide is increasing. At the same time, old-fashioned coal and gas power plants are being decommissioned. This is having a knock-on effect on the structure and future evolution of the electricity grid, driving the need for energy storage.
Battery and stationary energy storage technology is considered key to success in a carbon-constrained world. It introduces flexibility into power systems and enables the optimal use of variable electricity sources such as solar and wind energy while ensuring consumers continue to receive an uninterrupted electricity supply.
Storage and battery technology are growing rapidly. Almost 4 GW of battery storage systems (BSS) went online worldwide in 2018, which was expected to have doubled by the end of 2020.
Utility or grid-scale batteries are stationary batteries with capacity ranges from several up to hundreds of megawatt-hours. Grid-connected storage systems are used for many purposes, from small-scale home storage systems to multi-megawatt batteries that help balance services and mitigate grid congestion, blackouts, and brownouts.
They can connect to the distribution or transmission network and support the grid by providing system operation services and solar photovoltaic and wind generators, defer energy at peak generation, and provide grid reinforcements. Meanwhile, ancillary services benefit from batteries for grid stabilization.
Old vs New Technologies
Lithium-ion (Li-ion) batteries dominate the commercial market. These batteries pack lots of energy in a small space and are easy to install on a large scale. Their widespread use in cars and portable devices (where they are likely to prevail for some time) also means their cost has reduced over time. This is encouraging for their use in stationary energy storage systems.
However, they have a relatively short operating life and can generate heat rapidly. To deal with the intermittency in energy generation from renewables and fluctuations in demand throughout the day, battery storage on a commercial, grid-scale is required; it needs to be large, stable, and long-lasting. It is unlikely Li-ion batteries are up to the job.
One promising area is the use of vanadium instead of lithium. Vanadium redox (or flow) batteries are based on the flow of electroactive species. They are fully constrained, non-flammable, compact, reusable over semi-infinite cycles, and are expected to have over a 20-year lifetime. These batteries can offer almost unlimited energy capacity if their storage tanks are large enough.
Despite vanadium being safer and more readily available than lithium, the commercialization of vanadium-based batteries is being prevented by the metal’s high cost. Success relies on the cost of the metal decreasing, or the battery chemistry improving – or both.
Other Technologies
While the focus seems to be set firmly on batteries for energy storage, there are other development options, including hydrogen technologies, use of thermal energy, Compressed Air Energy Storage (CAES), and Gravitational Energy Storage (GES).
Other storage technologies are already in use. Up to 99% of grid storage is currently provided by pumped hydro storage. Surplus electricity is used to pump water up to a reservoir behind a dam, which is released to drive turbines and generate electricity when demand is high. However, geological and environmental constraints mean it is not suitable for universal use.
There are also models based on battery systems management, such as virtual power plants (VPP). These webs of dispersed, power generating units are linked through a central control but independently owned and operated. They support the grid by smartly distributing the power generated by the individual units during periods of peak load while trading the combined power generation/consumption of networked units on the energy exchange.
The Vehicle to Grid (V2G) approach exploits electric vehicle batteries, which have a considerable capacity, to provide subsidiary services to the power grid. This can improve the resiliency of the grid while also reducing costs.
Conclusion
The increasing adoption of renewable energies and the evolving power grid represents a considerable opportunity for stationary energy storage. The acceptance of renewable energy targets, improvements in the grid, and decommissioning of outdated power plants contribute to the implementation of energy storage systems. However, they also remain under the political influence of each country’s government.
As we continue to generate more energy from renewable, intermittent sources, stationary energy storage solutions and management systems are necessary to ensure the continuous supply of electricity we have become accustomed to.
References and Further Reading
Conca, J. (2019) Energy's Future - Battery and Storage Technologies. Forbes [Online] https://www.forbes.com/sites/jamesconca/2019/08/26/energys-future-battery-and-storage-technologies/?sh=1bdb69fe44cf. Accessed 10 March 2021.
Gatti, D (2021) The Future Evolution of Batteries for Stationary Applications IDTechEx [Online] https://www.idtechex.com/en/research-article/the-future-evolution-of-batteries-for-stationary-applications/22985. Accessed 10 March 2021.
Gatti, D et al. (2021) Batteries for Stationary Energy Storage 2021-2031. IDTechEx [Online] https://www.idtechex.com/en/research-report/batteries-for-stationary-energy-storage-2021-2031/790. Accessed 10 March 2021.
Kairies, K. (2019) Market and technology development of stationary battery storage systems in Europe. Energy Storage News [Online] https://www.energy-storage.news/blogs/market-and-technology-development-of-stationary-battery-storage-systems. Accessed 10 March 2021.
IRENA (2019) Innovation landscape brief: Utility-scale batteries. International Renewable Energy Agency [Online] https://www.irena.org/-/media/Files/IRENA/Agency/Publication/2019/Sep/IRENA_Utility-scale-batteries_2019.pdf. Accessed 10 March 2021.
Next Kraftwerke. Virtual Power Plant. Next Kraftewerke [Online] https://www.next-kraftwerke.com/vpp/virtual-power-plant. Accessed 10 March 2021.
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