Risks arising from the mixing of hydrogen in the distribution, transport and storage system of natural gas

Abstract

With the growth of the population, humanity’s energy consumption has increased dramatically. In parallel, the use of natural gas (and/or other fossil fuels) has led to a significant increase in the emission of greenhouse gases (GHGs). Nowadays, there are numerous eff orts aimed at mitigating GHGs. Among these, the European Union has set a goal to become climate-neutral by 2050, which means that it will not produce greenhouse gas emissions through its economic activities (it will offset the emissions it produces, making it ‘net-zero’). The potential of hydrogen as a ‘new’ alternative fuel has been in the public consciousness for years. On July 8, 2020, the European Commission announced the ‘Hydrogen Strategy for a Climate-Neutral Europe’, whose main objective is to achieve decarbonization through developments, research, investments, and innovations utilizing hydrogen [1]. In this context, the idea of using existing natural gas networks for injecting natural gas with varying proportions of hydrogen has been proposed. It is worth mentioning some EU projects that aim at investigate the aforementioned proposal: NaturalHy, HIPS-NET, GRHYD, HyDeploy@Keele.
There has not yet been a unified European stance regarding the injectable hydrogen content in natural gas networks, which would serve as the basis for transportation and trade between individual countries [4]. Hungary’s National Hydrogen Strategy has a key objective for the distribution network, aiming at a minimum 2% H2 volume ratio blend into the natural gas system by 2030.
It is clear that numerous eff orts and research are focused on integrating hydrogen into the natural gas network. Hydrogen has significant differences compared to natural gas, raising various technical, economic, and safety questions in both distribution, transportation, storage, and utilization processes. Current regulations and standards only partially or do not address hydrogen and its associated specific conditions at all. Therefore, it is necessary to review and amend the regulations to meet the challenges associated with any use of hydrogen and ensure the mutual safety of people and the environment. In this article, we examine the expected operational and technical issues that may arise concerning domestic distribution and transportation pipelines, as well as gas storage, assuming the injection of hydrogen-rich natural gas. Due to the constraints of this publication, it is not possible to provide a comprehensive, detailed description of the risks related to the mentioned areas, so we aim to capture only some of the more significant aspects and present them. To obtain a comprehensive view of the risks in different areas, we consulted with experts from OPUS Tigáz Zrt., Földgázszállító Zrt., and Magyar Földgáztároló Zrt., who greatly contributed their professional knowledge.