Life cycle environmental and economic sustainability of energy and resource recovery options in the food and drink sector in the UK

Abstract

The food supply chain is responsible for 30% of the global energy consumption and for 9.7 Gt CO2 eq./yr. Various energy saving and resource recovery options have been developed and applied in the food and drink industry to minimize the sector’s energy consumption. However, there is limited understanding of their environmental and economic implications and a whole systems approach is needed to identify the most sustainable options for improving the sustainability of the sector. Therefore, this PhD research aimed at addressing part of this gap by looking at potential energy saving and resource recovery options available for two key food and drink products in the UK, cheddar cheese and coffee. In the case of coffee, ground and instant coffee products have been considered as follows: espresso, latte, cappuccino, americano, drip-filter, coffee pods, spray-dried instant, freeze-dried instant, and instant mix. This has been achieved by evaluating their environmental and economic sustainability via life cycle assessment (LCA), life cycle costing (LCC), and economic value added (VA). The findings of the environmental and economic assessments have been integrated using multi-criteria decision analysis (MCDA) and eco-efficiency tools to identify the most sustainable options in the cheese and coffee sectors. For the cheese sector, the focus has been on energy efficiency options in the manufacturing process and valorisation of whey wastage considering a base case that reflects current practices where whey is treated as wastewater (Option 1), heat integration (Option 2), a combination of heat integration with whey valorisation via anaerobic digestion to produce biogas (Option 3), and via fermentation to produce bioethanol and animal feed (Option 4). The results indicate that Option 4 is the best across all impacts and costs as this reduces gate-to-gate climate change (CC) impact by 112% and LCC by 158% compared to the base case. Also, 14 out of the other 18 impacts estimated for Option 4 are net negative. Option 3, on the other hand, has higher environmental impacts than the current practice, making it the worst alternative. At the UK sectoral level, the implementation of Option 4 changes could reduce the annual CC impact of the UK’s food and drink sector by around 0.15% and primary energy demand by 0.34%, while increasing the VA of cheese by up to 11%. For the coffee sector, various opportunities for improvement have been evaluated along the life cycle. In the case of the end-of-life treatment of spent coffee grounds (SCGs), five different treatment and valorisation options have been considered: i) fuel pelletizing; ii) combination of transesterification and pyrolysis; iii) pyrolysis; iv) combination of transesterification and fermentation; and v) anaerobic digestion. At the production stage, emissions from roasting and the packaging are the main hotspots for ground and instant coffee. To minimize the impacts, silverskin wastage from roasting can be used as fuel and the packaging of ground and instant coffees can be changed. Consequently, the CC and other impacts of the industry could be reduced by 4.3-4.5% and 0.1-43.7%, respectively. At the consumption stage, three functional units have been considered: one serving, 1 l of coffee, and 100 mg of caffeine. Freeze-dried and spray-dried instant coffees are the most sustainable for one serving and 1 l while coffee pods are the best product per 100 mg of caffeine. For the valorisation of SCGs, the results show that pyrolysis is preferable as it is the best for six out of 19 environmental impact categories, including the CC impact, also being the best for economic sustainability. The eco-efficiency results suggest that espresso is the most eco-efficient type of coffee and could be further improved if SCGs are treated and valorised via pyrolysis. This study has also demonstrated that energy saving and resource recovery options are not necessarily more sustainable than current practices. Ther

Date of Award	1 Aug 2022
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Robin Smith (Supervisor), Adisa Azapagic (Supervisor) & Rosa Cuellar Franca (Supervisor)