Lifetime greenhouse gas emissions from offshore hydrogen production

With a limited global carbon budget, it is imperative that decarbonisation decisions are based on accurate, holistic accounts of all greenhouse gas (GHG) emissions produced to assess their validity. Here the upstream GHG emissions of potential UK offshore Green and Blue hydrogen production are compared to GHG emissions from hydrogen produced through electrolysis using UK national grid electricity and the 'business-as-usual' case of continuing to combust methane. Based on an operational life of 25 years and producing 0.5MtH(2) per year for each hydrogen process, the results show that Blue hydrogen will emit between 200-262MtCO(2)e of GHG emissions depending on the carbon capture rates achieved (39%-90%), Green hydrogen produced, via electrolysis using 100% renewable electricity from offshore wind will emit 20MtCO(2)e, and hydrogen produced via electrolysis powered by the National Grid will emit between 103-168MtCO(2)e, depending of the success of its NetZero strategy. The 'business-as-usual' case of continuing to combust methane releases 250MtCO(2)e over the same lifetime. This study finds that Blue hydrogen at scale is not compatible with the Paris Agreement, reduces energy security and will require a substantial GHG emissions investment which excludes it from being a 'low carbon technology' and should not be considered for any decarbonisation strategies going forward. (c) 2023 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).