Global research and application continue to improve our understanding of the various contributions to greenhouse gas emissions and ways to mitigate these, and in this issue of Proceedings of the Institution of Civil Engineers – Energy we have an opportunity to learn from a number of examples. These case studies are really useful, given so many regions and organisations are struggling with very similar issues. I have been working recently with the North of Tyne Combined Authority in the UK, to evaluate the greenhouse gas emissions for the region. We are building an evidence hub, so that we can build up a strong data set to help decision makers prioritise the big hitters such as the transport and domestic sector. The data will also help with tracking of the impact of interventions. But what interventions? Often it is horses for courses, or certain solutions for particular contexts. This issue presents a range of contexts and solutions, for Iran, Brazil and North Korea.
Finding alternatives to fossil fuels is not always straightforward, and can lead to problems elsewhere – for example, in increased demand for critical raw materials or in land and water pollution. Our first paper, by Kadapure et al. (2023), looks at biodiesel from non-edible oils, particularly waste cooking oils. Purification processes involving catalysts and solvents were reviewed, recognising that some methods have issues relating to cost, pollutants and difficulties in scale-up. The authors identify that deep eutectic solvents (DES), as a co-solvent, show early promise in improving the yield and purity of biodiesel. This is a valuable contribution to the global problem of sustainable liquid fuels, particularly given the ‘harder-to-decarbonise’ transport applications of marine and aviation. Most of marine global emissions arise due to the shipping trade between global markets, and this movement of goods is predicted to increase through to 2050 and beyond (Müller-Casseres et al., 2021). Aviation energy use is also projected to increase, and biofuels are part of the picture in the decarbonisation of aviation, although Dray et al. (2022) expect aviation biofuels to be supply-constrained. Biodiesel from waste cooking oil is also being used in buses and heavy goods vehicles, and it is vital that we ensure that the biodiesel is a sustainable long-term alternative and is robust to claims of ‘greenwashing’.
Agricultural energy demand is a significant concern for many economies across the globe. As we pursue clean, fair energy transitions, the economic robustness of our agricultural sectors is vital, to ensure we are able to sustain the global population. Agriculture is a major consumer of chemicals, water and energy. Firouzabadi et al. (2023) have investigated the efficiency of irrigation pumping stations for agricultural applications in Iran, looking at both electric and diesel-driven, pumping stations. The mean efficiency for diesel pumping stations was 14.1% and for electric pumping stations the mean efficiency was 58.3%. The authors identified that lower-than-expected performance was due to poor foundations, and wear and tear. There could, therefore, be some fairly simple improvements to pumped irrigation systems which could improve performance and consequently reduce energy consumption and associated fuel cost.
Demand for energy, to deliver air conditioning services, is expected to increase significantly under even the most optimistic climate change scenarios (Bell et al., 2022). The Chartered Institution of Building Services Engineers espouses efficient energy systems in buildings, along with reducing the need for energy systems through excellent design, and considering generation by cleaner methods to provide the energy input to the energy system (be that heating, cooling, air conditioning, ventilation, or small power systems). Da Costa et al. (2023) investigated the optimal operation of three chillers as part of an airport air conditioning system. They were able to demonstrate the measured coefficient of performance (COP) of 5.95 could be improved to 6.73 through minor changes to the operation of the system during recommissioning, delivering a saving of 13% of the energy consumption. This could be a not insignificant contribution to help negate the upward pressure on energy demand to deliver cooling under future climates.
The final paper in this issue is a study of the municipal solid waste (MSW) sector in Pyongyang, developing a new framework to understand the material flows in a waste stream (O et al., 2023). Clearly, a key element to this type of analysis is where to draw the system boundaries. The authors show the potential energy benefit of MSW recycling, energy recovery, composting and landfill, as well as the avoided greenhouse gas emissions for each waste treatment option. Interestingly, given the two indicators are correlated, the authors suggest that just an emissions calculation, or energy calculation, could be sufficient in order to determine the best options for waste treatment.
The climate emergency touches on every aspect of human activity across the globe. Research presented here on biodiesel, waste, air conditioning and water irrigation pumping contributes to global understanding of mitigation of climate change. I hope you enjoy reading these papers, and reflecting on how they could be the right horse for your course.
