INDUSTRY News
Heat pumps could reduce biogas carbon footprint by 36%
An alternative source of heat could signifi cantly reduce the carbon footprint of a process that turns food waste into power, suggests new research. A University of Glasgow led team of scientists have demonstrated that using air-source heat pumps to support anaerobic digestion could cut the carbon emitted during the production of biogas by over a third. The team’s fi ndings could support ongoing eff orts to decarbonise national electricity grids and enable remote communities to locally produce their own low carbon power.
“All waste releases gas when it decays, some of which can be harmful to the environment. By harnessing that gas as a source for power production instead of letting it decay naturally, we can take strides towards the circular, net-zero economy that we urgently need to build, and reduce the impact of climate change,” said Dr Siming You, from the University of Glasgow’s James Watt School of Engineering.
Biogas is a mixture of methane and carbon dioxide, released during anaerobic digestion, where micro-organisms in oxygen-free conditions break down biodegradable materials like food waste and sewage sludge. This biogas can then be burned to turn turbines, generating low-carbon electricity. Machines called bioreactors are used to maintain the optimal temperature during anaerobic
digestion to maximise the generated amount of biogas. The researchers set out to investigate how the carbon footprint of bioreactors heated by air-source heat pumps – which draw ambient heat from the air in a low- carbon process – would compare over the length of their lifetime to conventional heating systems that use boilers powered by natural gas. They created a computer model of the thermodynamics of heat pumps, which they coupled with a machine learning model to train the system from a database of existing research. The new model was then tested by providing it with real-world data to ensure it produced accurate results. The model confi rmed that heat pumps
would emit signifi cantly less carbon than the baseline natural gas system when used to process food waste and sewage sludge – some 28% lower at temperatures of 55°C. At a lower temperature of 37.5°C, the carbon footprint of the process was reduced even further, to 36%. “This model is the fi rst technical and
environmental assessment of just how useful air-source heat pumps can be in decarbonising the process of producing biogas. The results suggest that there’s a signifi cant role for heat pumps in supporting low-carbon anaerobic digestion, which could help inform future planning for municipal waste management facilities to help reduce their carbon footprint,” said Dr You.
6 February 2023 | Automation
automationmagazine.co.uk
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