The Waste Heat Recovery (WHR) project, carried out by researchers from Queen’s University Belfast and industrial collaborators Thermtech, NI Water and AgriAD; focused on improving the efficiency of NI’s first generation of anaerobic digestion plants where utilised stationary engines to provide renewable electricity to the grid, with little or no application for the heat produced during biogas combustion.
The research focused on designing and validating a low-grade heat recovery system using supercritical Organic Rankine Cycles to generate additional electricity from low grade heat normally lost to the environment. The team developed thermodynamic models, designed a circuit, and adapted an existing QUB test rig to validate the system. The project demonstrated that a typical AD plant could generate an additional 400,000 kWh of electricity annually, equating to £40k in extra income and powering around 1,200 homes. Scaling this across Northern Ireland’s 90 AD plants could yield £5M in annual revenue and electricity for 15,000 homes.
Industrial partners—including AgriAD, Thermtech, and Northern Ireland Water—benefitted from feasibility models tailored to their operations. AgriAD, for example, gained insights into upgrading biogas systems for electricity generation. The project also informed policy discussions around renewable heat and energy efficiency.
The project advanced the technology from TRL 2 to TRL 4, with further R&D needed to improve efficiency and reduce costs. It exemplifies CASE’s impact in supporting commercially viable, sustainable energy technologies and enhancing the competitiveness of Northern Ireland’s biomass sector.