The Truth About Hydrogen

by Patrick Molloy and LeeAnn Baronett (Rocky Mountain Institute) ... There are four major sources for commercial production of hydrogen, three of which require fossil fuels: steam methane reformation (SMR), oxidation, and gasification. The fourth source is electrolysis, which separates water into its constituent elements (hydrogen and oxygen) using electricity. When that electricity is produced through renewable resources you can have zero carbon green hydrogen. This is the only non-fossil fuel means of hydrogen production. The SMR process, which emits CO₂, requires substantial heat to chemically separate the hydrogen from the methane molecules. When the emissions of that process are not captured, it is referred to as grey hydrogen. When carbon capture and storage (or carbon capture, utilization, and storage) is attached to a facility, it is referred to as blue hydrogen. In addition to SMR, hydrogen can also be synthesized from oil via partial oxidation, or from coal via gasification.

CO₂ emitted as a byproduct of SMR hydrogen production accounts for approximately 6 percent of GHG emissions from petroleum refineries in the United States, and up to 25 percent of the GHG emissions from an individual refinery. By source, hydrogen via natural gas accounts for 48 percent of global production, while oil-based production accounts for approximately 30 percent, and coal accounts for 18 percent. Green hydrogen, produced through the electrolysis process using renewable energy, currently accounts for only 4 percent of global production.

The vast majority of hydrogen production today falls into the category of grey hydrogen, as current production relies on fossil fuels and separates the hydrogen and carbon elements. Carbon capture technologies can reduce the carbon emissions by 71–92 percent but the technology is still in a relatively nascent stage. There are also concerns around the storage space necessary for captured carbon. The current movement is toward scaling green hydrogen development and moving away from SMR-based hydrogen. This transition has the benefit of adding demand for a more rapid renewable energy rollout in some of the better renewable energy regions across the United States.

Hard-to-abate industry sectors constitute 40 percent of global greenhouse gas emissions. These sectors need a comprehensive approach to decarbonization and they need it now. They need electrification but they also need clean molecular energy. These are not mutually exclusive efforts but can, when structured correctly, work in coordination to facilitate the rapid change that is called for. The pathway to scaling up green hydrogen will require substantial buildout of our renewable energy resources across the globe and the understanding that there are still battles to be fought to meet these targets.

The ETC’s Mission Possible report, Shell’s Sky Scenario, and the International Energy Association’s below 2 degrees Celsius scenario all show well-developed pathways to decarbonizing the hard-to-abate sectors, and those pathways all require substantial global hydrogen growth. Whether it is in trucking with Nikola’s recent launch, or in industrial process innovations like green aluminum or green steel, there is one thing that nearly all major energy mix studies have shown: we will need more hydrogen in our energy mix to keep global warming below 1.5 degrees. READ MORE