Digging deep: How pumped hydropower storage will shape the future of energy

By balancing supply and demand, pumped hydropower storage helps stabilize the electrical grid, reducing the need for additional power plants and associated environmental impacts. However, constructing reservoirs and associated infrastructure can lead to significant land use changes, water quality impacts, GHG emissions in construction phases, and evaporation losses.

To mitigate these impacts, careful planning and collaborative project management is essential.

Beyond the visible components of dams and reservoirs, the underground of pumped storage infrastructure ensures the efficient and reliable operation of PHS projects with minimum environmental and visual impact

The link between reservoirs usually entails sharp gradients and necessitates a balance between hydraulic efficiency and the realities of construction, particularly concerning budget, timeline, and transportation of materials.

PHS and the tech that drives it

Advanced modeling tools and simulation software are often used to refine designs and predict performance under different operating scenarios.

Design refinement uses modeling to simulate design scenarios, optimizing the layout and dimensions of caverns, penstocks, tailrace tunnels and other hydraulic structures to achieve the best balance between efficiency and cost.

Performance prediction software predicts how the systems perform under different operating conditions, allowing for fine-tuning the design to ensure reliable and efficient operation.

Closed-loop systems—a practical application in PHS—allow for two reservoirs connected by a tunnel or pipeline, with water cycled without relying on natural water bodies. Modeling and simulation software ensure minimal energy loss and maximum efficiency, while control systems manage water levels and flow rates, preventing issues such as overtopping or underperformance.

Advanced simulations help design control systems and manage various scenarios, improving efficiency and practicality.

Geotechnical investigations

These investigations help form a clear understanding of the subsurface conditions, ensuring the stability and safety of the infrastructure. Site characterization explores the geological and structural geology on site; geophysical surveys use non-invasive techniques to map subsurface features and identify potential geohazards without disturbing the site.

Site characterization

• Ground conditions: Exploring the geological and structural geology of the site with a reasonable level of information about the insitu ground conditions like insitu stress, faults, weak and strong soil, and rock are essential information for an optimized design.
• Soil and rock behavior: Evaluating the physical and mechanical properties of soil and rock, such as type, strength, deformability, swelling potential, and time dependent behavior is essential for designing stable foundations and structures.
• Groundwater assessment: Understanding groundwater condition, including its level, flow and ground permeability, helps in designing effective water management systems and preventing issues like seepage and erosion.

Geophysical surveys

• Non-invasive techniques: Methods like seismic refraction, electrical resistivity, and ground-penetrating radar are used to map subsurface features and identify potential geohazards without disturbing the site.
• Geohazard identification: Detecting hazards such as sinkholes, faults, karst, rock falls, debris flow and unstable slopes is critical for ensuring the safety and longevity of the PHS infrastructure.

Subsurface investigations

• Drilling and sampling: Boreholes are drilled to collect soil and rock samples, which are then analyzed in laboratories to determine their properties and suitability for construction.
• In-situ testing: Tests like the standard penetration test (SPT) and cone penetration test (CPT) on soil, and packer test, hydraulic fracturing test, over-coring test, and the pressure-meter test on rock provide reliable data from soil and rock strength and index data.

Laboratory testing

• Material properties mechanical tests like Uniaxial and Triaxial Compressive testing of soil and rock samples in laboratories help determine parameters like shear strength, deformability, and bearing capacity, which are vital for design decisions.
• Quality control: Ensuring the materials used in construction meet the required standards and specifications is crucial for the project's success.

Subsurface utility engineering

• Utility mapping: Identifying and mapping existing underground utilities helps avoid conflicts during construction, reducing the risk of delays and additional costs.

Monitoring and instrumentation

• Ongoing monitoring: Installing instruments to monitor ground movement, water levels, and other parameters during and after construction helps ensure the stability and safety of the PHS system.

Environmental expertise

PHS projects extend beyond technical challenges, offering the opportunity to contribute to the global energy transition.

PHS projects with underground infrastructure offer significant advantages. By minimizing surface disruption, these systems reduce their impact on ecosystems and optimize land use, making underground PHS an attractive option for regions where land availability or ecological concerns present challenges. PHS supports the integration of renewable energy sources like wind and solar by providing a reliable way to store excess energy and release it when needed, reducing reliance on fossil fuels.

By balancing supply and demand, PHS helps stabilize the electrical grid, which can reduce the need for additional power plants and associated environmental impacts. However, constructing reservoirs and associated infrastructure can lead to significant land use changes, water quality impacts, GHG emissions in construction phases, and evaporation losses.

To mitigate these negative impacts, careful planning and project management is needed with expertise in environmental assessments, design optimization, monitoring and management, feasibility studies, and the sequencing of construction activities.

Construction sequencing and underground infrastructure

Feasibility studies and the sequencing of construction activities must align with broader project milestones, which can span 10 to 15 years from initial investigations to commissioning.

Identifying all tasks, such as excavation, tunnel construction, and installation of turbines and generators, requires expert-level understanding of the dependencies between tasks in order to assign effective timelines and resource allocation.

This sequencing is particularly relevant to underground infrastructure where project milestones inform timelines: design, excavation, structure construction, installation, and commissioning must align with full-scale operational goals. Delays in one phase can cause a ripple effect, leading to scheduling conflicts in subsequent phases. For example, if excavation is delayed, it can postpone the installation of turbines and other critical infrastructure. This can result in increased costs; prolonged use of labor, equipment, and materials; penalties for not meeting contractual deadlines; and disputes with contractors and stakeholders.

Construction sequencing expertise can mitigate the impact of delays by employing effective planning, risk management, clear communication, and regular monitoring of progress and making necessary adjustments to keep the project on track.

What’s next?

Pumped hydropower storage (PHS) has become a cornerstone of the renewable energy transition. As the global demand continues to grow, Hatch’s commitment to innovation and collaboration ensures that it is at the forefront of this evolution, delivering solutions that meet the highest standards of technical excellence and environmental stewardship. For tunnel engineers and energy enthusiasts alike, PHS represents not just a technological achievement, but a pathway to a more sustainable future.

Hatch’s multidisciplinary approach integrates structural, geotechnical, mechanical, electrical, and tunnel engineering, ensuring that every aspect of the project is addressed holistically and collaboratively. Contact us to find out more on how we’re innovatively tackling the energy transformation and helping our clients solve their toughest infrastructure challenges.