• Energy Research
• 8. Economic growth close

Abstract Resource efficiency is a key component of sustainable policies and practices, particularly in industries with high energy demands. Using empirical data, this paper evaluates the long-term performance (1960–2009) of the United Kingdom steel sector through the exergy-based metrics of “resource efficiency” and “useful exergy efficiency”. The analysis is broken down into two production pathways: the basic oxygen furnace and the electric arc furnace. The scope includes electricity generation and steel refining. It incorporates energy and material inputs, as well as by-products as useful outputs. The exergy-based indicators demonstrate the benefit of measuring both the quality and quantity of resources. The results are contextualised to gain insights into the long-term impact of political and socioeconomic transitions on resource consumption trends. Over the period, the sector’s overall resource efficiency went from 19% to 32%. Between 2% and 4% of this improvement results from the reincorporation of by-products into production processes. The basic oxygen furnace route’s resource efficiency increased by 9% whilst the electric arc furnace route rose by 20%. These improvements occurred via the promotion of successful energy saving policies rather than the diversion of large amounts of scrap inputs into the furnaces. This paper shows that both the resource efficiency and useful exergy efficiency indicators are a valuable complement to the benchmark metrics (energy intensity and material efficiency). This is because they can quantify the interactions and trade-offs between energy and material flows.

Abstract Energy and materials support food production, maintain and expand material stocks (e.g. buildings and roads) and provide services. In this paper, an exergy-based approach is used to provide an integrated perspective on the evolution of societal resource flows and stocks. The scope of this analysis is from resource extraction (primary exergy stage) to end uses such as low temperature heating and illumination (useful exergy stage). From 1900 to 2010, global exergy consumption at the primary stage increased from 115 to 903 EJ/year, of which 88–89% corresponded to energy flows, including food and feed. Useful exergy flows increased from 9 to 148 EJ/year, of which 47%, in 2010, was contained within material goods. Primary to useful efficiency doubled from 8% in 1900 to 16% in 2010. However, this improvement is far from that which is required to achieve climate targets for 2060. The amount of resource flows required per unit of economic activity decreased at both the primary (from 58.5 to 17.0 GJ/$) and useful (from 4.7 to 2.8 GJ/$) exergy stages, indicating relative decoupling. The exergy in stocks went from 91 to 820 EJ. Stock intensity reduced from 46.2 to 15.5 GJ/$-year−1 due to a shift in stock composition rather than dematerialisation in mass terms. Future research needs to identify the relationships between resource flow intensity and stock intensity in order to meet sustainability targets, including those linked to future resource demand. The scope could be expanded to include additional resources such as water and rare earth metals.

Intensified mineral consumption and reserve depletion means that it is becoming increasingly important for policymakers to account for and manage national mineral capital. Exergy replacement costs (ERC), an indicator based on the second law of thermodynamics, provides a physical value of mineral loss. When only a unit mass analysis is used, the role of scarcer minerals, such as gold, is obscured. ERC can identify those minerals which are most critical and more difficult to re-concentrate. This paper compares the mineral depletion of that of Colombia and Spain for 2011, both in mass and ERC terms. The Colombian mineral balance for that year is predominately based on fossil fuel extraction and exports, whilst Spain produced industrial minerals but relied heavily upon metals and fossil fuel imports. Using exergy replacement costs, an economic analysis was carried out to determine the impact of mineral extraction, in monetary terms, should the cost of re-concentrating such minerals be taken into account. In 2011, the GDP derived from the extractive sectors of either country did not compensate the mineral resource loss, meaning that mineral patrimony is not being properly evaluated.

Abstract The transport sector is supported by the continuous provision of energy and material flows and material stocks. However, most resource accounting methods do not assess the role of material accumulation in the delivery of mobility, as a service. Using a UK-based case study, we evaluate the service contribution of both resource stocks and flows in the provision of the passenger-kilometres (pkm) travelled nationally by UK-registered cars between 1960 and 2015. For flows we considered diesel and petrol. For stocks we considered steel, aluminium, and plastics, among others. We used six indicators to analyse the interactions between stocks, flows and service. Our results show that the fuel efficiency of cars increased from 0.46 to 0.69 pkm/MJ over the period. However, there was a decrease in stock efficiency from 24.9 to 17.1 pkm/kg-year. Resource productivity increased from 0.42 to 0.61 pkm/MJ. Stock expansion rate decreased from 0.16 to 0.03 year−1 while the specific CO2 embodied impact reduced from 2.4 to 2.0 tCO2/tonne of resource flow. Consumer preferences for heavier larger vehicles and sociodemographic changes linked to workplace expectations, commuting and urbanisation patterns are key factors influencing UK car stock efficiency. While fuel efficiency has improved and will continue to do so via the mass adoption of electric vehicles, due to policy and legislative developments, there are still sustainability concerns linked to their heavier weight and the environmental impact of their increased material complexity.