A food-waste initiative was conducted at two university canteens in the UK and India to examine food-waste attitudes and opportunities for food-waste reduction. Interventions were carried out to reduce food waste in both canteens. In the Indian canteen, postintervention data also included COVID-19-related changes, such as a change from self-service to table service, as well as reduced menu choices and an improved estimation of the number of students requiring meals. Surveys and focus groups were conducted with students to better understand their food-waste-related attitudes, while interviews were carried out with university staff to better understand food-waste management. The study in the UK university canteen found that introducing table cards, posters, and signs led to food-waste reductions of 13%. Meanwhile, the study in the Indian university canteen found that the interventions and COVID-19 impacts led to food-waste reductions of 50%. Concerning food-waste-related differences between the UK and India, culture and food preferences were key reasons for food waste in India, with 40.5% more participants in India stating that they wasted food because the ‘food didn’t taste good’. Students in India were more concerned about social issues and food poverty related to food waste, with around 9% more participants stating that the ‘food could be used by others’. Meanwhile, students in the UK were more bothered by the economic and environmental impacts of food waste, with around 31% more participants stating food waste is ‘a waste of money’, and is ‘bad for the environment’ when compared to India. Key opportunities for both countries included adopting food-sharing initiatives, informed menu choices, and meal planning, as well as student-led engagement projects.

Hydrothermal carbonisation is a promising technology for greenhouse gas (GHG) mitigation through landfill avoidance and power generation, as it can convert high-moisture wastes into bio-coal which can be used for coal substitution. The GHG mitigation potential associated with landfill avoidance of high-moisture food waste (FW) generated in India, China and the EU was calculated and the potential for coal substitution to replace either grid energy, hard coal, or lignite consumption were determined. Different HTC processing conditions were evaluated including temperature and residence times and their effect on energy consumption and energy recovery. The greatest mitigation potential was observed at lower HTC temperatures and shorter residence times with the bio-coal replacing lignite. China had the greatest total mitigation potential (194 MT CO2 eq), whereas India had the greatest mitigation per kg of FW (1.2 kgCO2/kg FW). Significant proportions of overall lignite consumption could be substituted in India (12.4%) and China (7.1%), while sizable levels of methane could be mitigated in India (12.5%), China (19.3%), and the EU (7.2%). GHG savings from conversion of high-moisture FW into bio-coal and subsequent coal replacement has significant potential for reducing total GHG emissions and represents in India (3%), China (2.4%), and the EU (1%).

Pig manure currently results in sizeable greenhouse gas emissions, during storage and spreading to land. Anaerobic digestion and hydrothermal carbonisation could provide significant greenhouse gas mitigation, as well as generate renewable heat and power (with anaerobic digestion), or a peat-like soil amendment product (with hydrothermal carbonisation). The greenhouse gas mitigation potential associated with avoidance of pig manure storage and spreading in the UK, EU, and China, as well as the potential to provide heat and power by anaerobic digestion and soil amendment products by hydrothermal carbonisation was herein determined. In each case, the mono-conversion of pig manure is compared to co-conversion with a 50:50 mixture of pig manure with grass. Anaerobic digestion displayed a greater greenhouse gas mitigation potential than hydrothermal carbonisation in all cases, and co-processing with grass greatly enhances greenhouse gas mitigation potential. China has the largest greenhouse gas mitigation potential (129 MT CO2 eq), and greatest mitigation per kg of pig manure (1.8 kgCO2/kg pig manure volatile solids). The energy grid carbon intensity has a significant impact on the greenhouse gas mitigation potential of the different approaches in the different regions. Pig manure is generated in large amounts in China, and the energy generated from biogas offsets a higher carbon intensity grid. Greenhouse gas savings from the anaerobic digestion of pig manure and grass have been calculated to provide a significant potential for reducing total greenhouse gas emissions representation in China (1.05%), the EU (0.92%), and the UK (0.19%). Overall, the utilisation of pig manure could bring about substantial greenhouse savings, especially through co-digestion of pig manure with grass in countries with large pig farming industries and carbon intense energy mixes.