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Coal Gasification

DOE's Office of Fossil Energy supports activities to advance coal-to-hydrogen technologies. DOE anticipates that coal gasification could be deployed in the mid-term time frame.

How Does It Work?

  • Coal is converted into a gaseous mixture of hydrogen, carbon monoxide, carbon dioxide, and other compounds by applying heat under pressure in the presence of steam and a controlled amount of oxygen (in a unit called a gasifier). The coal is broken apart chemically by the gasifier's heat, steam, and oxygen, setting into motion chemical reactions that produce a synthesis gas, or "syngas"—a mixture of primarily hydrogen, carbon monoxide, and carbon dioxide. The carbon monoxide reacts (in a separate unit) with water to form carbon dioxide and more hydrogen. Adsorbers or special membranes can separate the hydrogen from this gas stream.

    Chemically, coal is a complex and highly variable substance. The carbon and hydrogen in coal may be represented in an approximate manner as 0.8 atoms of hydrogen per atom of carbon in bituminous coal. Its gasification reaction may be represented by the (unbalanced) reaction equation:

    CH0.8 + O2 + H2O → CO + CO2 + H2 + other species

  • An advantage of this technology is that carbon dioxide can be separated more easily from the syngas and captured instead of being released into the atmosphere. If carbon dioxide can be successfully sequestered, hydrogen can be produced from coal gasification with near-zero greenhouse gas emissions. Learn more about carbon capture and sequestration.

  • Coal gasification can also be used to produce electricity by routing the syngas to a turbine to generate electricity. Coal gasification technology could be used to generate both electricity and hydrogen in one integrated plant operation. DOE's FutureGen is a $1 billion, 10-year initiative to demonstrate the world's first coal-based, zero-emissions power plant.

  • Coal gasification technology is most appropriate for large-scale, centralized hydrogen production. This readiness is due to the nature of handling large amounts of coal and the carbon capture and sequestration technologies that must accompany the process.

Why Is This Technology Being Considered for the Hydrogen Economy?

Coal is an abundant and inexpensive domestic resource. The United States has more proven coal reserves than any other country in the world. About half of the electricity produced in the United States is generated from coal. Today, electricity is generated from coal in a combustion process, which releases carbon dioxide and other emissions. Coal gasification research, development, and demonstration activities seek to ensure that coal can provide a clean, affordable, reliable, and efficient way to produce electricity—and hydrogen—in the future, without releasing carbon dioxide and other emissions into the atmosphere.

It Is Important to Note...

DOE's strategy is to produce hydrogen directly by coal gasification (not to use coal-produced electricity as an intermediate). The DOE strategy includes coal with sequestration, never without.

Research Focuses on Overcoming Challenges

There are several challenges to using coal gasification to produce hydrogen at target costs and with near zero greenhouse gas emissions. Additional R&D is needed to:

  • Develop carbon capture and sequestration technologies that ensure no carbon dioxide is released in the production process

  • Develop new membrane technologies that can replace the cryogenic process currently used to separate the required oxygen from air

  • Develop new membrane technologies to separate and purify the hydrogen from the gas stream.