Discover how AECOM is supporting a proposed pumped storage hydro scheme in Argyll, which could strengthen grid resilience, support renewable energy, and deliver long‑term regional value.
Scotland’s electricity system is undergoing a profound shift. Wind and solar generation continue to expand rapidly, accelerating progress toward net zero. But these sources are inherently variable. Their output does not always align with demand, leading to periods when renewable electricity is curtailed while fossil fuel generation is still required to meet peaks.
Long‑duration energy storage is critical to closing this gap. It enables surplus renewable power to be stored when generation is high and released when the system needs it most. Without sufficient storage, the resilience, affordability and decarbonisation of the power system are harder to achieve.
Pumped storage hydro (PSH) remains one of the few proven technologies capable of delivering this function at scale. Scotland’s geography and hydroelectric heritage make it well placed to host PSH, but suitable sites are limited. Projects are technically complex, capital intensive, and subject to rigorous environmental and planning scrutiny.
The proposed Balliemeanoch Pumped Storage Hydro project, located in Argyll, responds directly to this system‑wide challenge.
Watch the video above to learn more about the Balliemeanoch pumped storage hydro scheme
A next‑generation pumped storage scheme
Balliemeanoch sits within a small but strategically important group of next‑generation PSH projects emerging in the UK after decades of limited investment in long‑duration storage. While Scotland already hosts most of the UK’s operational PSH capacity – much of it built in the mid‑20th century – new schemes are required to respond to today’s scale of renewable deployment, evolving grid services and heightened resilience requirements.
The project is proposed with an installed generation capacity of up to 900 megawatts (MW) and an energy storage capacity of approximately 13,500 megawatt hours (MWh).
Balliemeanoch would operate using two reservoirs at different elevations: an upper reservoir formed close to Lochan Airigh and a lower reservoir utilising Loch Awe. During periods of surplus electricity, water would be pumped uphill. When demand is high, water will be released through underground turbines to generate power. Much of the infrastructure, including waterways and the power cavern, are located underground which reduces surface impacts in a sensitive landscape.
AECOM has been supporting the project across its early lifecycle, providing integrated engineering design, environmental assessment, planning support, construction engineering input and programme management. Our role has focused on bringing disciplines together from the outset, enabling informed decisions and helping to manage risk on a nationally significant infrastructure project.
If consented and delivered, Balliemeanoch would represent one of the largest pumped storage hydro schemes in development in the UK.
Design shaped by place, policy and people
Environmental and social considerations have been central to Balliemeanoch’s development from the earliest stages. The site was identified through a Scotland‑wide assessment of potential PSH locations, balancing technical feasibility with environmental sensitivity.
We supported an iterative design process informed by extensive baseline surveys, stakeholder engagement and public consultation. This approach led to refinements aimed at reducing landscape and visual effects, avoiding sensitive peatland where practicable, and embedding mitigation and enhancement measures across ecology, water and cultural heritage.
The project is being progressed under Scotland’s Section 36 consenting regime and aligns with National Planning Framework 4, which identifies pumped storage hydro as a National Development. This policy context recognises the strategic importance of long‑duration energy storage in addressing climate change, energy security and system resilience, while still requiring detailed assessment of local impacts.
Digital engineering and coordinated information management have been embedded throughout the planning‑stage design. Shared models, structured technical documentation, and disciplined interface management between engineering and environmental teams have supported clarity as the design evolved and helped provide a robust evidence base for consent.
Planning applications were submitted in July 2024, with a targeted grid connection date of 2032, subject to consent and further design development.
Long‑term value beyond the asset
If consented and delivered, Balliemeanoch would represent one of the largest pumped storage hydro schemes in development in the UK. Its value extends beyond megawatts and storage hours.
During construction, the project is expected to support up to 1,000 jobs at peak, alongside wider benefits for the Scottish supply chain. Over its operational life, the scheme would help reduce renewable curtailment, strengthen grid resilience, and support Scotland’s role as a net exporter of low‑carbon electricity.
Balliemeanoch demonstrates how integrated planning, engineering, and environmental expertise can support complex energy infrastructure in sensitive landscapes. More broadly, it reflects a shift toward system‑scale thinking – where individual assets are designed not in isolation, but as part of a resilient, low‑carbon energy network.
Header image: Loch Awe, Argyll and Bute, Scottish Highlands