Exergy analysis of Nepal and the United Kingdom for low-carbon economy
Energy and material consumption is associated with greenhouse gas emissions that aggravate climate change. With the strong coupling of resource consumption and economic growth it is ambiguous whether continued economic growth is compatible with the environment-related sustainable development goals (SDGs). Increasing resource efficiency is a key strategy to lower environmental burdens by reducing the overall resource consumption, sustainably transitioning to a low-carbon economic growth and improved human well-being. However, conventional studies do not analyse how efficiently a system utilises both energetic and non-energetic resource ignoring the interconnectedness and frequently interchangeable nature of material and energy flows. This study attempts to utilise exergy analysis at national level for Nepal and the UK to understand the efficiency of both economies, understanding the resource flow through different end-use sectors. This study collates resource data from the UN IRP Global Material Flow Database and IEA country profile, the exergy conversion data from the exergy calculator and the average end-use exergy efficiency from previous studies. Methodological variations produce inconsistent results that call for a solid framework.
The exergy analysis estimates the resource efficiency of Nepal and the UK to be 19.5% and 19% for the year 2019. This in comparison to previous studies is higher as it includes non-energetic natural resources whose exergy values are embodied in the product in the resource conversion chain. The residential sector shows highest exergy loss for both economies which has high potential for leveraging the input exergy. The dependency of fossil fuel in the UK and the high use of decentralised biomass in Nepal ring the alarm for mitigation actions towards making these country sustainable in terms of cleaner form of energetic resource for drive, heating, and cooking.
The uncertainties associated with the specific exergy and the exergy efficiency conversion values are estimated using Pedigree matrix and Monte Carlo Simulation. The uncertainty analysis shows that the largest source of uncertainty lies in the specific exergy of aggregated resources (49% to 83%) as well as the allocation of resource enduse. Transportation sector provides the most certain results for both economies while the industrial sectors show highest uncertainties of 24% and 30% for Nepal and the UK. These findings can further be used for the development of effective resource efficiency policies and monitoring its progress for low carbon transition.