In the UK, the National Grid must operate approximately 10% of its load on Combined Cycle Gas Turbines (CCGT) even when surplus wind and solar energy is available. This ensures grid stability by responding to fluctuations in both generation and demand.
Short-term grid storage, capable of sustaining power for several hours, is essential to reduce dependency on gas and enable short periods of fully renewable operation.
Longer-term, excess renewable generation can be initially managed using demand-side response mechanisms such as Agile Octopus. These pricing incentives encourage consumers to charge electric vehicles and run high-demand applications during peak renewable production.
However, for periods with little to no renewable generation, storage solutions capable of retaining energy for several days are required. Future developments will focus on advanced battery technologies like Vanadium Flow and hydrogen-based storage solutions.
Battery Storage Technologies
- Lithium-ion (Li-ion) Batteries: Widely used for grid-scale applications due to high energy density, long cycle life, and fast charging. Companies such as Tesla, LG Energy Solution, and Panasonic are leading the market, deploying large-scale lithium-ion battery solutions for renewable energy integration and grid stabilization. However, scalability challenges, material constraints, and safety risks remain.
- Vanadium Redox Flow Batteries: These batteries store energy in an electrolyte solution, allowing large storage capacity with long discharge durations and extended cycle life. Invinity Energy Systems and Sumitomo Electric have been at the forefront of commercializing vanadium flow battery technology, promoting its use for long-duration grid storage solutions.
- Iron Flow Batteries: A newer alternative to vanadium flow batteries, using iron-based electrolytes that are abundant, cost-effective, and highly durable for long-duration energy storage. ESS Inc. is one of the primary developers of this technology, aiming to provide reliable and sustainable energy storage for large-scale applications.
- Lead-Acid Batteries: Historically used for backup power but unsuitable for modern grid storage due to low efficiency and limited lifespan. Exide Technologies and EnerSys have been major producers of lead-acid batteries, though they are now largely focused on industrial and backup power solutions rather than grid-scale storage.
- Solid-State Batteries: A promising evolution of Li-ion batteries with solid electrolytes for improved energy density and safety, though still in the development phase. Companies such as QuantumScape and Solid Power are working to commercialize solid-state battery technology, aiming to revolutionize energy storage with enhanced performance and durability.
- Sodium-Sulfur (NaS) Batteries: Operate at high temperatures with high energy densities and have been implemented in some grid-scale applications, particularly in Japan. NGK Insulators has been a key player in this market, developing and deploying NaS battery technology for grid applications worldwide.
Hydrogen as a Storage Mechanism
Hydrogen offers a scalable and versatile solution for long-term energy storage. Excess renewable energy can power electrolysis to produce hydrogen, which can then be stored and later converted back to electricity using fuel cells or turbines. Companies such as ITM Power, Plug Power, Ballard Power Systems, and Nel ASA are investing heavily in hydrogen electrolysis and fuel cell technologies, driving advancements in long-duration energy storage solutions.
Advantages:
- Scalability: Large storage capacity suitable for long-term and seasonal variations.
- Versatility: Usable in power generation, transportation, heating, and industrial applications.
Challenges:
- Efficiency: The round-trip efficiency (electrolysis to power generation) is currently lower than batteries.
- Infrastructure: Requires significant investment in storage facilities, pipelines, and distribution networks.
UK’s Largest Grid Storage Facilities
Dinorwig Power Station – North Wales
| Facility Name | Capacity (GWh) | Power Output (GW) | Run Time |
|---|---|---|---|
| Dinorwig Power Station | 9.1 | 1.7 | 5h |
| Cruachan Power Station | 7.0 | 0.44 | 15.9h |
| Foyers Power Station | 6.3 | 0.3 | 21h |
| Ffestiniog Power Station | 1.4 | 0.36 | 3.9h |
| Minety Battery Storage | 0.266 | 0.1 | 2.66h |
| Clay Tye Battery | 0.198 | 0.099 | 2h |
| Pillswood Battery | 0.196 | 0.098 | 2h |
| Whitelee Battery Energy Storage | 0.05 | 0.05 | 1h |