Achieving Net-Zero Emissions with Blue Hydrogen
Blue hydrogen refers to hydrogen produced from natural gas through a process called steam methane reforming (SMR) or autothermal reforming (ATR), coupled with carbon capture and storage (CCS) technology. The term "blue" refers to the utilization of CCS to capture and store the carbon dioxide (CO2) emitted during the hydrogen production process, thereby reducing greenhouse gas emissions.
Here's how the typically works:
Hydrocarbon Feedstock: The primary feedstock for blue hydrogen production is natural gas, which is predominantly composed of methane (CH4). Natural gas is a readily available and affordable source of hydrogen.
Steam Methane Reforming (SMR) or Autothermal Reforming (ATR): The natural gas is reacted with steam (in the case of SMR) or a combination of steam and oxygen (in the case of ATR) at high temperatures to produce a mixture of hydrogen (H2), carbon monoxide (CO), and CO2.
Carbon Capture and Storage (CCS): In blue hydrogen production, the CO2 produced during reforming is captured before it is released into the atmosphere. CCS technologies capture the CO2, typically by using solvents or membranes, and then it is compressed and transported to suitable storage sites, such as depleted oil and gas reservoirs, deep saline aquifers, or geological formations, where it is permanently stored underground.
Hydrogen Purification: The gas mixture from reforming, which contains hydrogen, CO, CO2, and other impurities, is purified to separate and obtain high-purity hydrogen. This purification process often involves the shift reaction, which converts CO into additional hydrogen and CO2.
The resulting blue hydrogen is a clean-burning fuel with lower carbon emissions compared to traditional hydrogen production methods that do not incorporate carbon capture and storage. By capturing and storing the CO2, blue hydrogen can significantly reduce the greenhouse gas emissions associated with hydrogen production from natural gas.
As the world continues to transition to a low-carbon economy, blue hydrogen can play a role in decarbonizing sectors that are challenging to electrify and where renewable hydrogen sources are not yet widely available or economically viable.