Divergence of trends in US and UK aggregate exergy efficiencies

Produced as part of the Understanding green growth and climate-compatible development CCCEP research programme theme

National exergy efficiency analysis relates to the quality of primary energy inputs to an economy with end useful work in sectoral energy uses such as transport, heat and electrical devices. This approach has been used by a range of authors to explore insights to macro-scale energy systems and linkages with economic growth.

However, these studies use a variety of exergy and useful work calculation methods with sometimes coarse assumptions, which inhibit comparisons. Building on previous work, this paper contributes towards a common useful work accounting framework, by developing more refined methodological techniques for electricity end use and transport exergy efficiencies.

Applying these advances to national exergy efficiency analyses for the US and UK for 1960 to 2010 reveals divergent aggregate exergy efficiencies: US efficiency remains stable at around 11%, whilst UK efficiency rises from 9% to 15%. The US efficiency stagnation is due to “efficiency dilution” effects, where greater use of lower efficiency processes (eg. air-conditioning) outweighs device-level efficiency gains.

The results demonstrate this is an important area of research, with consequent implications for national energy efficiency policies and our understanding of the mechanisms of economic growth.