University of Limerick
Styles_2020_Emissions.pdf (1.03 MB)

Emissions down the drain: Balancing life cycle energy and greenhouse gas savings with resource use for heat recovery from kitchen drains

Download (1.03 MB)
journal contribution
posted on 2020-09-16, 10:40 authored by Isabel Schestak, Jan Spriet, David Styles, A Prysor Williams
Although the food service sector is a major user of water, the potential for heat recovery from commercial kitchens’ drain water remains largely unexplored. For the first time, we compare the life cycle environmental burdens of producing and installing a heat recovery system with the environmental credits arising from energy savings for a restaurant case study, and for the entire UK food service sector. Life Cycle Assessment was applied to determine the impacts of heat recovery systems made from different materials and comprising a heat exchanger in the shape of a concentric double-walled pipe, pipework and fittings. The design option with the smallest environmental footprint combined a heat exchanger made out of polypropylene-graphite (PP-GR) with polyethylene pipework, exhibiting 80–99% less environmental impact compared with components made out of (35% recycled) copper. Contrasting the environmental impacts of two heat recovery set-ups with energy savings shows that a PP-GR based system pays back all burdens of the seven assessed environmental impact categories, within two years, while payback times for the copper-based system vary depending on the replaced energy source, and can exceed the 10 year operational lifetime of the system. When looking at typical flow-rates in UK food outlets, net environmental savings can be realised across all analysed impact categories above a threshold water consumption of 555 L/day, using current technology. Extrapolation to the UK food service sector indicates annual greenhouse gas emission mitigation potential of about 500 Gg CO2 equivalent.



Journal of Environmental Management;271, article: 110988




peer-reviewed The full text of this article will not be available in ULIR until the embargo expires on the 26/06/2022

Other Funding information



This is the author’s version of a work that was accepted for publication in Journal of Environmental Management, 2020, 271, article 110988 . Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Environmental Management,



Usage metrics

    University of Limerick


    No categories selected


    Ref. manager