The Current State of Play in Energy Storage Systems (ESS) in the UK and the role of Scotland.

Written by Ypatios Moysiadis.

Energy Storage Systems (BESS) are now a cornerstone of the UK’s transition toward a low-carbon, flexible, and resilient energy system. As the share of intermittent renewable generation like wind and solar grows, energy storage especially in the form of chemical battery storage (BESS) is increasingly recognised as an essential solution for balancing the grid, providing rapid-response services, and maximising the value of renewable energy. In 2025, the UK finds itself at a pivotal moment in especially in BESS development, with several gigawatts of operational capacity and a rapidly growing pipeline of advanced projects. Scotland finds itself playing an integral part on this transition.

1. Installed Capacity and Development Pipeline

As of 2024/25, the UK has installed approximately 4.3 GW of grid-scale BESS. This is a significant increase compared to only a few hundred megawatts in 2018. Looking forward, the UK government and industry stakeholders aim to grow installed capacity to 30 GW by 2030, reflecting the Clean Power Strategy goals. There are currently approximately 87 GW of BESS projects in various stages of planning and development (approximate figures – Consented 30.5 GW, Submitted for Planning 26 GW, Submitted for Planning 26 GW, Under Construction 4.5 GW). While BESS is dominating as the mainstream technology there are also pumped hydro projects in play which at the moment offer a long-duration solution.

In Scotland, a number of large-scale energy storage projects are leading the charge:

• Zenobe’s Blackhillock Project: 200 MW / 2 hours, already operational, expanding to 300 MW
• Copenhagen Infrastructure Partners (CIP): Developing three projects totalling 1.5 GW / 3 GWh in Lanarkshire and Fife
• Pumped Hydro Projects: Including Coire Glas (1.3 GW / 30 GWh), Earba (1.8 GW / 40 GWh), and Fearna (1.8 GW / 37 GWh)

2. Technology Trends

Recent years have seen a notable shift toward larger and longer-duration BESS units. Two-hour systems are now the standard, and projects offering four to six hours of discharge are increasingly viable as revenue stacking and grid needs evolve. Grid-forming inverters are also emerging as a key technology, providing essential system stability services.

Innovations are also being made in alternative long-duration storage technologies such as liquid-air energy storage and thermal batteries, with pilot projects underway to complement traditional lithium-ion systems.

3. Revenue Stacking: The Economic Engine

No single revenue stream in the UK is currently sufficient to fully support a BESS investment. This has led to the widespread use of revenue stacking, where a single asset participates in multiple markets over time to maximise returns. Key revenue streams include:

• Wholesale Arbitrage: Buying low and selling high during price swings
• Balancing Mechanism (BM): Providing fast-response energy to maintain grid frequency
• Ancillary Services: Including Dynamic Containment, Regulation, and Moderation
• Capacity Market: Fixed income for being available during peak demand
• Curtailment Management: Especially in co-located wind and solar projects

Revenue stacks are now highly dependent on project location, technology capabilities, and operator expertise. For example, assets in Northern Scotland can earn more through constraint management and curtailment services, while those in southern England excel in arbitrage.

Tolling agreements are also gaining popularity, with asset owners leasing operational rights to traders for a fixed or shared return. Gresham House, for instance, has signed agreements yielding up to £57,000/MW/year based on publicly available information.

4. Regulatory Landscape and difference between Scotland and England.

The UK regulatory framework for BESS has improved, but key challenges remain:

• Planning Regimes: In England, battery projects below 50 MW can be consented locally, while in Scotland anything over 50 MW requires national consent. This increases complexity and timelines.
• Grid Charges: Transmission Network Use of System (TNUoS) charges remain a barrier, especially in Scotland where BESS is treated as a generator and subject to full charges despite its grid-balancing benefits.
• Market Access: Ofgem has removed many market participation barriers, but issues around co-location metering, revenue stacking eligibility, and long-duration incentives remain unresolved.
• Fire Safety and Public Engagement: As battery systems grow larger, fire safety planning and community acceptance have become more prominent issues.

5. Challenges and Risks

Despite strong momentum, BESS development faces notable challenges:

• Grid Congestion and Connection Delays: Long delays in securing grid connections are widespread, particularly in Northern Scotland. These issues are being reviewed under the National Energy System Operator (NESO) reforms, which aim to streamline and prioritise connections. However, developers still face years-long wait times, uncertain delivery dates, and limited transparency on queue management.
• Revenue Volatility and Market Saturation: Ancillary service markets such as Dynamic Containment and Regulation have become saturated, with falling prices and increasing competition. This puts pressure on merchant business models and requires greater sophistication in trading strategies.
• Planning and Permitting Complexity: Scottish planning frameworks require national consent for projects over 50 MW, leading to longer timelines and more rigorous scrutiny. This contrasts with the more streamlined system in England and may deter investment north of the border.
• Battery Degradation and Performance Risk: The economic lifespan of lithium-ion batteries is limited by cycle count and calendar ageing. This affects long-term performance and financial projections, especially for assets exposed to heavy cycling from arbitrage markets.
• Regulatory and Market Design Uncertainty: Key gaps persist in the design of markets for long-duration storage, co-location rules, and equitable access to ancillary services. The NESO reform process is expected to address some of these issues, but full implementation is still several years away. In the interim, developers face fragmented rules and inconsistent treatment across network operators and market platforms.
• Grid Charges Disincentivising Storage: The continued application of TNUoS charges to BESS in Scotland discourages investment, as systems are charged like traditional generators despite providing net benefit to the grid.
• Safety and Public Perception: High-profile BESS fires globally have increased local scrutiny during planning consultations. Developers must now incorporate robust fire suppression systems and engage communities early to avoid delays.

6. Positives and Growth Drivers

There are many positives supporting the UK BESS market:

• Strong Government Support: Clean Power Strategy, 2030 targets, and ESO flexibility initiatives
• Investor Confidence: High levels of capital from institutional investors (e.g., CIP, Gresham House, Gore Street)
• Market Maturity: More sophisticated trading platforms, AI-powered optimisers, and vertically integrated operators
• Technology Advancement: Falling battery costs, improved efficiency, and wider system roles (grid-forming, inertia)
• Declining Capital Expenditure (CAPEX): Between 2020 and 2025, capital costs for lithium-ion BESS systems have declined significantly. Industry data suggests a 15–30% reduction, driven by lower cell prices, improved manufacturing efficiencies, and better balance-of-system designs. For example, a 1 MW / 1 hr BESS system cost approximately £700,000–£800,000 in 2020. As of 2025, this has decreased to about £550,000–£600,000, reflecting a 20–25% drop. This reduction makes larger and longer-duration projects more financially viable, enhancing internal rates of return (IRRs) and attracting broader investment interest.

7. Conclusion: The Path Forward

The UK’s battery energy storage market is transitioning from early deployment to industrial maturity. While policy gaps and technical barriers remain, the foundations for a robust storage-led future are firmly in place. Strategic grid investments, regulatory clarity, and long-duration incentives will be key to unlocking the next wave of BESS development.

Scotland, with its rich renewable potential and ambitious grid-scale storage projects, will be at the heart of this transition. The coming years will define not just the economics of BESS but its role as the backbone of a resilient, renewable-powered UK electricity system.