Three ways to achieve net zero grid energy storage

Whether it’s absorbing power or delivering electricity necessary to keep the grid stable, in energy storage, timing is everything.

FREMONT, CA:  Low-carbon and renewable power sources will become the norm as the country moves toward net zero emissions. Still, it’s not as simple as swapping in renewables for the fossil fuels the Grid was constructed around.

Weather-reliant sources, like wind and solar, are intermittent – meaning other sources are necessary when there’s little wind or no sunlight to meet the country’s electricity demand. Equally as hard to manage, still, is what to do when there’s an excess of power being generated at times of low demand.

Energy storage provides a low-carbon means of delivering power at times of low supply and absorbing any abundance of generated power when demand is low. Supporting balance and stabilizing the Grid as the electricity system convert through a range of low-carbon and renewable technologies, the energy storage on the UK grid will be required to expand from 3 GW today to over 30 GW in the coming decades.

The storage solution
Even as the UK’s electricity system converts fossil fuels to renewables, the Grid operates similarly. Central to that is the precept that the electricity supply being generated must often match the demand on a second-by-second basis.

Uncertain power on the system can cause power outages and damage equipment. Therefore, the national Grid must be able to call on reserve power sources to satisfy demand when supply is low or pay to reduce renewable sources’ output when demand drops.

Whether it’s absorbing power or delivering electricity necessary to keep the grid stable, in energy storage, timing is everything.

There are three main periods electricity storage needs to operate over:

Fast-acting, short-term electricity
Because electricity supply must often match demand, sudden changes mean the Grid must respond instantly to guarantee frequency and voltage remain stable and electricity is safe to use.

Batteries are reviewed as the quickest technology for responding to a sudden demand spike or an abrupt supply loss.

Battery technology has matured rapidly in recent decades as innovations like lithium-ion batteries, such as those used in electric cars, and appearing solid-state batteries become more affordable and more commonplace. This makes it more work to deploy large-scale installations that can absorb and store excess power from the Grid.

Batteries are good for near-instant responses. It can be a question of milliseconds for a battery to deploy power. Batteries can respond if there’s a sudden problem with frequency or voltage – it’s unique to them.

The rate at which batteries can deploy and absorb electricity makes them beneficial grid assets. Still, even very large battery setups can only discharge power for around two hours. So if, for example, the wind dropped off for a long period, the Grid needs a longer-duration supply of stored power.

Powering daily changes in supply, demand, and the Grid
When managing the daily supply and demand variations, the Grid must call on power reserves when there are abrupt variations in the weather or electricity demand from users. Pumped storage hydropower offers a low-carbon way to quickly provide huge amounts of electricity for periods that can pass as long as eight or even 24 hours.

The technology operates by moving water between two water reservoirs at different elevations. When there is an electricity demand, water is released from the upper reservoir, which bends down a series of pipes, spinning water turbines, producing electricity. Still, when there is an excess of power in the electricity system, the same turbines can revoke and absorb electricity to pump water from the lower to the upper reservoir, storing it there as a massive ‘water battery.

Long-term electricity solutions
Still, as they exist today, storage technologies cannot alone offer all the solutions the UK will need to accomplish its net-zero targets. While technologies similar to pumped storage can generate for the better part of a day, longer periods of adverse conditions for renewables will need new approaches.

Gas power stations made up for the shortfall in the country’s primary renewable power source. But in a net zero future, such answers will be feasible if they’re part of carbon capture and storage systems or substituted by other carbon neutral or energy storage solutions.

Generating enough power to provide an electrified future, taking pressure off the Grid, and providing balancing services will require various technologies working in tandem over elongated periods.

Interconnectors with neighboring countries, for instance, can work alongside storage solutions to shed excess power where there is greater demand. Likewise, extra electricity could be used for electrolysis to produce hydrogen rather than curtailing wind or solar power. Other functions may incorporate demand-side response, where heavy power users are incentivized to reduce their electricity utilization during peak periods helping to reduce demand.