There are many shades of hydrogen. If green or electrolytic hydrogen is the goal and grey is where we are today, what are the prospects for blue and turquoise or blue-green hydrogen? With blue hydrogen, the idea is to add carbon dioxide (CO₂) capture to conventional steam-methane reforming processes. They are the ones that produce the grey hydrogen that is mostly used for fertilizers, petroleum and chemical processes.
For tonnage applications in the UK and elsewhere, a role for blue hydrogen is recognised in the national hydrogen plan. In North East England, for example, there are sources of natural gas, via pipeline, offshore CO₂ storage or sequestration facilities and a local network of actual or potential chemicals and high temperature heat users. With a well-structured regulatory framework, this is a clear win for fossil fuel hydrogen – although there is one cloud on the horizon. It concerns fugitive or upstream methane emissions.
A recent paper from Cornell University claims that blue hydrogen may be worse than gas or coal. On closer inspection it seems that, from a European viewpoint, the American assumptions about leaks and cycle efficiencies are too pessimistic and blue hydrogen should be seen as a low-but-not-zero emissions hydrogen source.
Another possibility is to compress and flash the resulting CO₂ to liquid and transport it to collection hubs by trucks, trains or ships. This broadens the reach of blue hydrogen and overcomes the apparent lack of accessible, large-scale gas fields that are suitable for sequestration.
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