Inter-country comparisons of energy system performance with the energy trilemma index: An ensemble ranking methodology based on the half-quadratic theory

The World Energy Council annually publishes the Energy Trilemma Index (ETI) to highlight an economy's challenges in balancing the Trilemma and opportunities for improvements in meeting energy goals at present and in the future. The ETI is constructed by taking the arithmetic average of energy security, energy equity (accessibility and affordability), environmental sustainability. This paper proposes an ensemble ranking methodology based on the half-quadratic theory, for measuring and comparing country-wide energy system performance using the ETI data. Specifically, all possible importance orders among energy security, energy equity, environmental sustainability are described as the ranked dimension weights to derive a new decision matrix with the country-specific rankings as elements. Then a half-quadratic programming approach is presented to estimate the ensemble ranking, along with the development of consensus index and trust level to indicate the level of agreement and reliability of the final ensemble ranking. An empirical study using the ETI 2020 data of 30 International Energy Agency (IEA) member countries is performed to demonstrate the implementation of the our methodology.