Assessing the potential for energy recovery from the discharge of storm water run-off

A limited number of previous studies have explored the viability of energy recovery from storm water retention ponds and suggest that the potential for this is worth pursuing. This paper develops a novel screening tool for the evaluation of the energy recovery potential at a given storm water storage site and provides a new specific methodology for conducting a preliminary analysis to determine whether it is worth proceeding further in terms of subsequent detailed design and implementation. The application of the tool to two case studies highlights a number of critical dependent factors suggesting that energy recovery from storm water discharge is likely to be limited to locations that have abundant rainfall relatively evenly distributed around the year, a large contributing catchment and steep slopes. Scheme viability is judged by the revenue capable of being generated by the installation over a 20-year payback period. In both cases examined, the investment recovery was found to be low (3 and 14%). An envelope of where energy recovery might be feasible to provide a typical annual electrical output consistent with other viable micro-hydropower schemes is presented. The procedures can be of practical use to asset owners and local authorities where retention ponds are being planned.