UC Davis Institute of Transportation Studies

With recent economic, political, and social events worldwide, reliability in the energy sector is growing more valuable, and the surrounding issues are gaining visibility. Increasingly, concerns about energy supply security (and climate change) have led to proposals to shift away from oil dependence to wide use of alternative transportation fuels, such as biofuels or hydrogen. Hydrogen is of particular interest because it offers multiple societal benefits. It is often asserted that hydrogen would enhance energy reliability because it can be made at diverse scales from many primary resources. But no studies have systematically assessed reliability. There are many questions surrounding energy system reliability – especially when considering a future fuel like hydrogen. How should reliability be defined and evaluated? And would a transition to hydrogen increase or decrease reliability? This paper presents a general method to assess reliability in energy supply systems. The technique uses qualitative ratings from an expert panel regarding a set of reliability metrics. We illustrate the method by evaluating two hydrogen pathways: 1) centralized steam reforming of imported liquefied natural gas and pipeline distribution of hydrogen, and 2) on-site electrolysis of water using electricity produced independent of the grid. We found the second pathway to be more reliable, primarily due to the distributed nature of the system and the lack of hydrogen transport. The application intends to demonstrate how the method is applied, however, and the results should be regarded as preliminary. In future work, the method could be extended to compare reliability among different fuel pathways.