Is “Blue” Hydrogen “Green”?

In the effort to decarbonize the nation, “blue” hydrogen has quickly carved its own place in discussions about environmentally friendly fuel sources. Several recently published studies now question whether the narrative around the fuel accurately depicts hydrogen’s true emissions profile.


“Blue” hydrogen – dubbed “blue” because its manufacture generates some emissions– is hydrogen derived from natural gas with applications including home heating, power generation, and potentially fuel for vehicles. The process of harvesting hydrogen from methane is called steam methane reform (SMR), in which a reaction between methane gas, steam, and a catalyst produces hydrogen. At this stage of the process, the hydrogen is known as “gray” hydrogen. What turns “gray” hydrogen “blue” is a second process called carbon capture and sequestration (CCS).


Carbon dioxide is a natural byproduct of the SMR process and is oftentimes emitted into the atmosphere. CCS is a process in which those emissions are captured and stored, thus eliminating approximately 50 to 90 percent of carbon emissions from hydrogen production, according to a study by consulting from ICF. When the SMR process is combined with CCS, “gray” hydrogen becomes “blue”. Hydrogen, when burned, does not emit any carbon dioxide.


Hydrogen has grown to become a key fuel source in the future energy mix. In fact, President Biden’s climate plan specifically discusses hydrogen, naming several plans to facilitate the development of “green” hydrogen, which uses renewable energy sources to split hydrogen and oxygen atoms from water molecules through a process called electrolysis. Additionally, an infrastructure bill in the Senate has partitioned around $8 billion for the development of hydrogen “hubs”.


One study conducted in a joint effort between scientists from Cornell University and Stanford University challenges the notion that blue hydrogen is actually green. In their study, the researchers argue that carbon dioxide emitted throughout the extraction and processing of natural gas negates the potential benefits of using blue hydrogen. In fact, the article states that “there really is no role for blue hydrogen in a carbon-free future”. Going further, the researchers argue that burning the natural gas used for making blue hydrogen would be a better alternative than the use of blue hydrogen, arguing that “blue hydrogen has emissions as large or larger than those of natural gas used for heat”.


However, some believe that though blue hydrogen is not as clean as often touted, it is a crucial bridge to developing green hydrogen at scale. One such entity is the growing hydrogen power company Plug Power. In response to the Cornell-Stanford study, representatives from Plug Power noted that blue hydrogen “isn’t even made yet in large quantities,” and that “Plug Power is instead building its own green hydrogen factories across the country…and (moving) on from the gray hydrogen that is standard today”.

The differing arguments surrounding the topic of hydrogen identify a need for more research to be conducted about the fuel’s environmental and economic viability.




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