7 November 2023
Energy storage – the missing piece of the net zero puzzle?
With the deadline to reach a net zero power system approaching, enhancing the UK’s ability to maximise renewable power generation is a must.
Our country has already demonstrated a remarkable ability to ramp up its renewable generation capacity, with a record high of.
Yet, according to the , over 78% of the UK’s total energy consumption in 2022 was generated from oil, gas and coal. So, if energy from solar, wind and other renewable sources is widely available, why are we still so reliant on fossil fuels? The answer could, at least partially, lay in a lack of energy storage capacity.
“In the UK, the net zero conversation has traditionally focused on electrification through renewable sources,” explains Victoria Mustard, Decarbonisation Strategy Lead at Xoserve. “However, natural gas plays a crucial role in electricity generation. Gas power stations burn natural gas to generate electricity, providing affordable and secure power supply to respond to consumer needs. As we transition away from fossil fuels, it is imperative that we research low or no-carbon alternatives to natural gas to ensure flexibility and security of supply.”
Why energy storage is needed
According to , the potential for wind and solar power generation in the UK exceeds our projected future electricity demand. However, the intermittency of these power sources mean that renewable power generation must be supported by reliable energy storage to ensure supply in case of overcast or low-wind weather conditions.
By analysing weather patterns over several decades, researchers have concluded that, to compensate for the unavailability of wind and solar power at times of low generation, several tens of TWhs of long-duration storage will be needed.
Historically, this has been provided by fossil fuels such as natural gas, which ensured cheap storage at a very large scale across time frames of up to several years. In fact, , and contributes three to four TWh towards daily balancing, and over 100 TWh between seasons and years. But with the deadline to reach a net zero power system in sight, relying on natural gas as we do today, will no longer be an option.
Could batteries help stabilise the grid?
It’s unlikely that the right amount of storage capacity will be provided by one silver-bullet technology. To achieve our net zero goals, it’s far more likely that we will need a combination of different solutions.
There is a vast range of storage technologies available, but there are several considerations to be made to choose the most suitable. Among other things, we will need to consider availability and long-term reliability, as well as how much the cost of storage will impact the final cost of electricity.
Lithium-ion batteries can provide much-needed short term supply to satisfy the need to quickly regulate grid voltage and frequency. Their ability to respond very rapidly can help deal with last minute fluctuations in supply and demand – ensuring that consumer needs are met no matter what.
However, relying on batteries alone will not be possible. According to the Royal Society report, the UK will need up to 100 TWh of storage to support our increased electricity needs in 2050, but even the , the world's largest online grid-scale battery, has a capacity of only 3 GWh. Based on this data, the UK would need to build at least 34,000 facilities in less than 30 years. Moreover, batteries become less efficient over time, meaning that their ability to provide reliable and low-cost back-up supply gradually decreases.
The potential of hydrogen
Hydrogen holds great potential to contribute to the electricity grid’s security and flexibility. In fact, the Royal Society report suggests that future electricity demand could be met by wind and solar supply supported by hydrogen, if a hydrogen storage capacity of around 60 to 100 TWh can be produced.
The conditions for this are ideal, as the UK has vast availability for solution-mined salt caverns for hydrogen storage. Moreover, our existing gas distribution grid could be upgraded and repurposed to transport low-carbon gases like hydrogen or biomethane.
Given hydrogen’s promising role in the future energy mix, the UK Government has recently launched a consultation on the benefits and challenges of moving forward with the blending up to 20% of hydrogen in our current gas distribution system. This would spur investment in hydrogen production and storage, stimulating the growth of a thriving hydrogen economy.
With sufficient production and storage capacity nationwide, it is likely that hydrogen could become the solution of choice to keep our grid balanced and ensure a secure electricity supply.
Technologies to complement hydrogen storage
Hydrogen’s potential to store huge amounts of energy for long periods of time makes it a crucial technology to support the clean energy transition. But it’s important to remember that there are other solutions that could contribute to a more flexible and resilient grid.
Biomethane, for example, could be used instead of natural gas to produce electricity at times of low renewable generation. Biomethane is produced from upgrading biogas, which can be obtained through the anaerobic digestion of organic material such as food waste or agricultural byproducts. As such, the use of this biomethane for energy storage would contribute to carbon neutrality while also providing a perfect example of a circular economy.
Compressed air energy storage (CAES) also represents a promising alternative. According to the , CAES could not provide the large-scale, long-term storage needed to support a power system entirely based on renewables. However, it could reduce the need for hydrogen generation, helping to drive down its cost.
Finally, it’s worth mentioning that natural gas can be coupled with carbon capture, utilisation and storage (CCUS) to further contribute to the grid’s flexibility while minimising CO2 emissions. However, this would provide a short-term solution and would not remove the need for larger-scale storage.
The potential of these complementary technologies is significant, but it is likely that hydrogen will remain the most important energy storage solution for the foreseeable future. In fact, the recommends that the UK scale up hydrogen storage, and sets out proposals to encourage the private sector to invest in building dedicated networks.
The UK’s renewable energy generation capacity means that achieving a carbon neutral power system is within reach. But to realise a truly sustainable, resilient and affordable grid, rethinking our energy storage strategy will be paramount.
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