Short-term vs long-term reliance: Development of a novel approach for diversity of fuels for electricity in energy security

Diversity in fuels for electricity is widely considered as a factor in the long-term energy security and the degree of reliance is based upon accounting for energy generation by power source. However, it is essential to also consider short-term risk such as sudden supply interruptions in the evaluation of diversity. As there is a significant interaction between long- and short-term energy security, the reliance on energy sources for a continuous energy supply shall be analyzed from both long- and short-term perspective for well-understanding of diversity in fuels for electricity. In this study, the concept of long-term and short-term diversity in fuels for electricity is discussed and defined as the first step. Then, a methodology is developed to assess the dynamic vulnerability of a simplified single energy source-driven electricity system to the disruption of continuous power supply, where the disruption is arising from a sudden disturbance to the system. Through the quantitative analysis, the different degree of reliance and the inverse trend by each power source between short- and long-term vulnerability in the distributed and centralized networks were identified. The notable difference in the degree of diversity in fuels for electricity between the conventionally applied long-term notion and the newly developed short-term notion was also identified. For example, in some cases in a simplified distributed network, we discovered that the long-term vulnerability of solar PV was 2.7 times higher than that of battery, whilst for the short-term vulnerability this trend is reversed and the vulnerability of battery was 1.2 times higher than that of solar PV. Based on these findings, we conclude that the design policy of the electricity supply system should be reconsidered in terms of evaluating diversity in fuels for electricity.