In August this year the paper“How green is blue hydrogen?” hit the academic press. Co-authored by Professor Howarth of Cornell University, the paper makes the case that reforming natural gas alongside carbon capture and storage (CCS) to produce blue hydrogen can generate more than 20% more greenhouse gas (GHG) emissions than the direct use of natural gas.
This conclusion follows an analysis of two blue hydrogen plants, one in the US and one in Canada, and, importantly, is based on two key assumptions: fugitive methane emissions from natural gas production are set at 3.5% following analysis of US leakage statistics, and the power supply for the CCS process is supplied from gas-fired generation. In addition, the two plants reviewed utilise steam methane reforming (SMR) technology, which is less efficient and has a lower carbon capture rates than autothermal reforming (ATR).
The need for caution in taking the Howarth paper at face value was highlighted within weeks of publication, as noted by the SINTEF blog article Assumptions Matter When Assessing Blue & Green Hydrogen.
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