The Faraday Institution – Written evidence (LES0009)


Introduction to organisation

The Faraday Institution is the UK’s flagship programme for electrochemical energy storage research, skills development, market analysis and early-stage commercialisation. It brings together research scientists and industry partners on major projects with commercial potential to reduce battery cost, weight, and volume; improve performance and reliability, and develop whole-life strategies including recycling and reuse. The Faraday Institution regularly publishes evidence-based assessments of the market, economics, commercial potential, and capabilities for energy storage technologies and the transition to an electrified economy.



To reach the government's goals of a fully decarbonised power grid by 2035 and Net Zero by 2050, enhancing medium and long-duration energy storage is crucial. These facilities are integral in managing the intermittent nature of renewable energy sources such as wind and solar.


Various energy storage solutions are necessary for long-duration needs, spanning a range of cycle lengths from seconds to annual, to effectively balance energy supply and demand. Different technologies have emerged to meet these needs. Battery technologies are vital, evolving rapidly with advancements in lithium-ion and sodium-ion batteries for shorter duration applications. The Faraday Institution is spearheading initiatives to foster research and commercialisation in the battery technology space. Further research is needed, especially focusing on redox flow and metal-air batteries, which are emerging as promising options for medium-duration storage.



1. How much medium- and long-duration energy storage will be needed to reach the Government’s goal of a fully decarbonised power grid by 2035 and net zero by 2050, and by when will it need to be ready?

Grid storage has a particularly important role to play in delivering a net zero electricity system, as storage is needed to manage the intermittency of wind and solar. The shift to renewables means that energy supply will now increasingly be determined by the strength of the wind and sun. Energy storage can be useful at times when intermittent generation is strong, but demand is weak and vice versa. This increases the profitability of renewables, reducing their need for subsidy and their cost to consumers.


The potential demand for energy storage depends on the cycle duration required, specifically whether it is annual, weekly, daily, hourly or per second. The following estimates are:


Figure 1: System needs for storage by different “cycle” lengths required

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Source: TNEI (2022). A Zero Carbon Energy System: The Operability Challenge.


Further evidence is also given in a recent publication by the Royal Society, Large-scale electricity storage (September 2023).



3. Which technologies can scale up to play a major role in storage?

Easy access to stored energy is vital for power systems, currently sourced from conventional thermal generation and natural gas reserves. A Net Zero system, due to the unpredictability of renewables and increasing electrification, will need increasing amounts of storage as renewable penetration increases. The demand for energy storage will likely be met by a wide range of technologies, each with different characteristics which make them suited to short, medium or long-duration storage. Potential technologies include pumped hydro storage (PHS), compressed air energy storage (CAES), liquid air energy storage (LAES), hydrogen and batteries. Each technology has different storage durations and power capabilities as illustrated in Figure 2.


PHS offers high energy capacity and long-duration storage capabilities, making it ideal for large-scale energy storage and balancing of the grid over longer time periods. In addition, PHS is affordable thanks to long asset lifetimes and relatively high round trip efficiencies. However, PHS can only be deployed in geographically suitable areas which limits its potential, as well as the high cost of construction and long lead times.


CAES and LAES also offer high energy capacity but typically have shorter storage durations compared to PHS. One of the main drawbacks of CAES/LAES technologies is the inherent higher cost per kW, driven by high capital expenditure associated with civil engineering works and the cost of equipment, such as turbines and generators. As a result, there is the risk that these technologies will not be commercially competitive in providing flexible storage solutions over periods of days to months.


Battery technologies offer lower energy capacity but can deliver power quickly and efficiently, making them suitable for short-duration energy storage and ancillary services. Conversely, battery technologies have lower capital costs, but their operating costs may be higher due to the need for periodic replacement of batteries.


Figure 2: ESS landscape as a function of storage duration and power rating

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Source: Rho Motion (2023). Market and technology assessment of grid-scale energy storage.


When discussing battery technologies for energy storage applications, it is important to note the wide range of battery technologies that are under development. Different types of batteries, such as lithium-ion, sodium-ion and redox-flow, have different storage durations and power capabilities, that make them suitable for different use cases (Figure 3).


Lithium-ion and sodium-ion batteries are more suitable for shorter duration, serving a broad range of grid flexibility applications (e.g. arbitrage, load shifting) due to their high energy, power capacity and quick response times. The fast response of lithium-ion batteries allows for revenue stacking by participating in various markets, such as wholesale, balancing, capacity and ancillary services, which enhances the technology's market performance. Lithium-ion batteries account for over 80% of the energy storage installed in the past 5 years and will continue to dominate the demand for short-duration energy storage (<4 hours). Sodium-ion batteries have similar characteristics to lithium-ion batteries and will be applicable to the same market segment as lithium-ion. While they are not yet produced at scale, sodium-ion batteries have the potential to be cheaper than lithium-ion batteries.


Although most ESS installations with lithium-ion batteries have a storage duration of 2 hours or less, there have been significant efforts to increase their storage duration above 4 hours, potentially making them applicable for medium-term storage applications. The world's largest energy storage installation, based in California, is a 0.75GW/3GWh installation providing 4 hours of storage.[1] Another example is the Tumbleweed project in California, which will use lithium-ion batteries to provide 8 hours of storage to the California Independent System Operator grid. The project totals 69MW/552 MWh in storage and is expected to come online in 2026.[2] These projects highlight the potential for lithium-ion, and potentially sodium-ion as well, to be used in medium storage applications.


Redox flow is also applicable or highly plausible across most applications (e.g. steady power requirements, grid stability), with the exception of backup power due to its relatively lower power capability and longer discharge duration. From a broader perspective, flow batteries have advantages like scalability, longer cycle life and extended storage durations. Though not suitable for electric vehicles, which have resulted in lesser investment compared to lithium-ion and sodium-ion batteries, they remain a viable solution for the UK's longer-duration energy storage needs.


Vanadium flow batteries emerge as a preferred choice for applications like generation firming, generation smoothing and load shifting. This preference stems from their ability to deliver high power over longer-duration charge/discharge cycles, as well as being one of the most technically mature redox flow technologies. With a focus on consistent energy output, they excel in providing steady and sustained power over extended durations. Their slower charge and discharge rates complement their application in ensuring efficient energy management and grid stability. Vanadium, as a chemistry, is especially favoured due to its unique ability to store energy across different oxidation states. However, potential drawbacks include concerns over cost and toxicity. Flow batteries could capture about 6% of the total BESS market by 2040.


Figure 3: Battery energy storage as a function of storage duration and power rating

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Source: Rho Motion (2023). Market and technology assessment of grid-scale energy storage.


Metal-air batteries, encompassing varieties like zinc-air and lithium-air, bring their own strengths, particularly in the realm of grid-scale storage. They stand out for their rapid response times combined with long discharge durations, making them especially suitable for backup power applications. Their high energy density ensures sustained power supply over extensive periods, aligning with their application during power blackouts or emergencies. Yet, they have challenges in the realms of efficiency, cost and durability. One significant limitation is their restricted cycle life, which makes them less apt for applications requiring frequent charge and discharge cycles, such as peak capacity, generation firming, generation smoothing, arbitrage and load shifting.



4. What policy support is currently in place to support deployment of storage technologies? Is it sufficient to support deployment at scale?

While not a formal policy, the UK government's funding of battery research through the Faraday Institution and Faraday Battery Challenge indicates there is currently a strong policy commitment to advancing energy storage research and commercialisation in the UK.


The Faraday Institution is the UK’s flagship programme for electrochemical energy storage research, skills development, market analysis and early-stage commercialisation. It brings together research scientists and industry partners on major projects with commercial potential to reduce battery cost, weight, and volume; improve performance and reliability, and develop whole-life strategies including recycling and reuse. The Faraday Institution regularly publishes evidence-based assessments of the market, economics, commercial potential, and capabilities for energy storage technologies and the transition to an electrified economy.


The Faraday Institution is a key element of the Faraday Battery Challenge which was launched in 2018.


The Faraday Institution research programme into energy storage spans 10 major research projects:


This large-scale, research programme is multidisciplinary, highly collaborative and draws together the best of UK university research groups and industrial partners. Research topics are selected through a rigorous peer review process involving expert academic and industrial stakeholders, as well as consideration of the impact on the UK economy.



5. How well developed is the UK industry across different storage technologies, such as hydrogen or redox flow batteries? How does the UK compare to global competitors in these industries?

To answer this question, the UK capabilities across the battery technologies highlighted in our response to question 3 will be discussed in turn.


Lithium-ion and sodium-ion batteries – The UK has significant knowledge and expertise in the assembly of battery packs for energy storage applications. This involves assembling cells (which are not yet manufactured in the UK for energy storage applications) into modules and packs of different sizes depending on the end application. Example companies who are working in this space include Zenobe and Connected Energy who are both developing ESS installations using 2nd life batteries. However, most of the ESS installations under construction in the UK are using imported batteries and systems. An example of this is the SSE Renewables 150MW project which just began construction in Ferrybridge: the batteries are being provided by Sungrow Power UK Ltd, a subsidiary of Sungrow Power Supply Ltd, a China-based developer.[3] The global leaders of lithium-ion based ESS providers are Chinese-based battery manufacturers.


Sodium-ion batteries are a nascent technology yet to be manufactured at scale. However, they have the potential to be significantly cheaper to produce than lithium-ion batteries and should be considered as a future energy storage technology. While the UK has some expertise in this area through companies such as Faradion (sodium-ion battery developer) and AceOn (battery specialist, has developed small-scale ESS with sodium-ion), the world-leading companies in this space are also based in China.


Redox flow batteries – Redox flow technology is not as commercially mature as lithium-ion, and there are few examples of ESS installations using redox flow battery technology (compared to the existing large number of lithium-ion based installations). However, the UK has expertise in this area from Invinity Energy Systems, a leading company in the development of vanadium redox flow batteries. Invinity was recently awarded £11 million in funding from the Department of Energy Security and Net Zero to build a 30MWh system, the largest grid-scale battery ever manufactured in the UK.[4] This system will be configured to provide storage for 4 hours and is expected to be the largest long-duration battery asset connected to the UK grid. This demonstrator will represent a significant step forward for flow batteries and allow the technology to be benchmarked against lithium-ion assets currently connected to the grid.


Metal-air batteries – Although the UK has significant expertise in researching metal-air battery systems, there is little to no UK-based industry developing metal-air energy storage systems for the grid. The world-leading company developing metal-air systems is Form Energy, who are working to develop iron-air long-duration storage systems to provide 100 hours of energy storage at low cost. This technology has the potential to enable a much higher renewables penetration on the grid. However, it should be noted that it is not yet proven to work at scale. Form Energy is currently constructing a large manufacturing base in the USA and has plans for several 10MW/1,000MWh scale demonstrators.



6. Beyond the cost of deploying long-duration energy storage, what major barriers exist to its successful scale up (e.g. the availability of a skilled workforce, the ability to construct the necessary infrastructure on time, or safety concerns around new technologies)?

Beyond the financial aspects of implementing LDES, several significant barriers could impact its successful scalability. These factors include the availability of a skilled workforce, the timely construction of essential infrastructure, and the safety and security of deploying new technologies.


The electrification of the passenger automotive sector offers a relevant comparison of the need for a skilled workforce, charging infrastructure and a safe operating environment. A notable initiative in this regard is the collaborative effort involving the Faraday Institution, WMG and High Value Manufacturing Catapult to create the blueprint for a National Electrification Skills Framework and Forum (NESFF)[5]. Starting with the automotive skills challenge, this framework was envisioned to extend beyond passenger automotive to encompass various transport modes (such as LGV, HGV, rail, aviation, and maritime) as well as stationary energy storage solutions. This effort will be operationalised as has been recently announced by UK Government[6].


At the heart of this framework lies the concept of foresighting, which involves the cooperation of industrial stakeholders, accrediting bodies, and training providers to identify existing training provision along with critical gaps in the curriculum that must be developed. Equally significant is the need for a unified national approach to reskilling, upskilling, and new-skilling the workforce, to ensure the provision of high-quality, accredited training can be delivered in real-time and at the point of need. The NESFF will pursue a combination of modular short and long courses, as well as continuous professional development, to develop the competencies needed to achieve electrification goals across diverse sectors.


The Faraday Battery Challenge now supports the NESFF, and has designated Coventry University to lead this nationally coordinated skills effort and take it forward. We recommend that any LDES training effort first engage with this body for guidance and perhaps to tackle the skills challenges associated with LDES. This would involve conducting a workforce analysis to determine the required number of skilled professionals (including electricians, electric technicians, engineers, and data modellers) and the necessary provisions for their gradual development and deployment.



7. What steps should the Government take now to ensure this storage can come online later in the current decade?

The UK Government could continue to fund long-term research into energy storage, particularly in redox flow batteries and metal-air batteries.


Redox flow batteries excel in applications requiring longer discharge durations, reduced response time and competitive round-trip efficiency characteristics compared to non-electrochemical energy storage technologies. Redox-flow batteries offer some advantages over traditional lithium-ion batteries, such as scalability, longer cycle life, and flexible discharge durations trending to longer-duration, which means they can support both short-term and long-term ESS needs. Flow batteries are likely to be particularly useful for meeting the demand for longer-duration storage.


Flow batteries, similar to metal-air batteries, are too large to be deployed in EV applications. As such, neither have benefitted from the significant investment in research and development that lithium-ion and sodium-ion batteries are receiving. The Faraday Institution has funded a few small-scale projects around the development of new electrode materials and battery designs for zinc-flow batteries as well as lead/lead oxide flow batteries. There are also other UK-based research institutions which are actively working on flow batteries. However, there are still several challenges that need to be addressed to fully realise their potential, which could be explored in further research.


The favoured chemistry for flow batteries is currently Vanadium, primarily due to its ability to stay in solution through a range of oxidation states, allowing for a greater degree of energy storage. However, Vanadium of suitable quality for flow batteries is expensive and, additionally, in some forms can be toxic. Developing a new electrolyte, that uses different transition metals as the active ingredient, may reduce cost. There are multiple avenues that electrolyte development can take, such as organic, carbon-based electrolyte solutions. A commercial example of novel flow battery technologies can be seen by US-based firm, ESS Inc, who have pioneered an iron flow battery that has reduced the cost curve of energy storage. The company claims that iron-flow batteries provide a more harmonious mix of energy storage, cost and ESG credentials than those of flow batteries for Vanadium and Zinc but beyond ESS Inc there is a limited commercial application for alternative electrolytes.


Metal-air batteries, including zinc-air and lithium-air batteries, offer unique performance characteristics. They exhibit relatively fast response times (lower than lithium and sodium-ion) and can support long discharge durations, making them suitable for specific grid flexibility applications. However, challenges remain in optimising their round-trip efficiency.


Metal-air batteries have garnered significant interest in recent years as a potential solution for large-scale and long-duration energy storage. As the technology operates using oxygen from the air (as a cathode), high theoretical energy densities can be achieved. However, current challenges related to efficiency, cost, and durability hinder widespread deployment. In a similar manner to flow batteries, this technology has not benefitted from the high level of research and development that technologies aligned to EV applications have received. As such, the technology is well positioned to benefit from further research and development into new materials that can enhance the efficiency of the oxygen reduction reaction (ORR).


A good example of the commercial application of metal-air batteries is observed with another US-based firm, Form Energy. The company is leading the development of Metal-air batteries, with a commitment to build multiple plants. Most recently, it announced plans to develop a metal-air battery in Georgia, with a duration of 100 hours at 15MW. Form Energy has opted to use Iron-air batteries which significantly reduces the cost of the battery, given iron is a relatively cheap material.


As the UK’s flagship national programme for electrochemical energy storage research and early-stage commercialisation, the Faraday Institution was intended from the outset to have a long-term mandate, allowing a sufficient period to achieve research breakthroughs and to commercialise them for the benefit of the UK economy. However, the Faraday Institution is currently funded only until March 2025. For the UK to benefit from the transition to a fully electric future across transport and grid applications, a long-term commitment to R&D for a variety of battery energy storage technologies will be required.


8 September 2023



[1] Moss landing: World’s biggest battery storage project is now 3GWh capacity

[2] Eight-hour lithium-ion project wins in California long-duration energy storage procurement.

[3] SSE Renewables breaks ground with its 150MW battery storage project at Ferrybridge

[4] Invinity to Build the Largest Grid-Scale Battery Ever Manufactured in the UK

[5] The Opportunity for a National Electrification Skills Framework and Forum, September 2021

[6], 4 September 2023