In 2024, Network Rail Ltd commissioned the project "Case Study: Assessment of a Micro-Hydropower System in a Drainage System" to address a defined challenge in the energy sector. The assignment combined computational fluid dynamics (CFD) with a decision-focused engineering study. Its purpose was to explain the governing physical behaviour, identify the variables controlling performance, and convert the findings into practical recommendations for design, operation and future development.

Water for energy at the urban scale means harnessing the potential energy of water for recovery/saving, generation, and storage. Electricity generation using the kinetic energy of different sources of running water in urban areas triggers the Incorporation of micro-hydropower turbines (MHP) to produce energy from sustainable energy resources. In this project, our team conducted a feasibility study to assess the effectiveness of a suitable hydropower design/technique for the Transpennine Route Upgrade (TRU) project using CFD to generate energy from this renewable source. TRU is a multi-billion pound project for railway improvement and this CFD project included simulating different scenarios for downpipes and drainage system and calculating the potential power output from an MHP turbines.

The methodology centred on a hydraulic CFD model of the downpipes and drainage arrangements considered for micro-hydropower recovery. The representation retained the available drops, pipe sections, junctions and candidate turbine positions that determine flow rate, head and hydraulic losses. Boundary and operating conditions covered representative drainage flows and alternative system or turbine configurations associated with the rail-upgrade project, with material, fluid and equipment properties assigned from the available design information. Resolution was concentrated in regions where steep velocity, thermal, concentration or phase gradients were expected, while the overall model remained efficient enough to compare several credible configurations. This balance allowed system-level performance to be linked to the local mechanisms responsible for it.

The assessment compared micro-hydropower placement and drainage-layout variants. Performance was judged using flow rate, velocity, available head, pressure loss, turbine operating condition and estimated renewable power output. Results were reviewed through quantitative summaries and engineering visualisations, such as contours, vectors, streamlines, sections and time histories, selected to suit the physics. Important assumptions and operating uncertainties were considered so that the recommendations relied on repeatable comparative trends rather than a single nominal case.

For Network Rail Ltd, the principal value was a feasibility evidence base for recovering useful energy from an existing urban drainage asset. The final evidence linked each recommendation to the relevant model or process output, making it suitable for internal design reviews, supplier or contractor discussions and, where applicable, planning, safety or regulatory dialogue. The work also created a reusable baseline that can be updated as geometry, operating data or test results become available, reducing the cost and risk of later design iterations.

A disciplined quality-control workflow supported the analysis. Geometry, units, mass and energy balances, boundary-condition consistency and solver convergence were checked before options were ranked. Mesh or parameter sensitivities were used where they were most likely to affect the engineering conclusion, and limitations were documented explicitly. This ensured that the study remained traceable and reproducible rather than relying on isolated simulation images.