Hydrogen is produced from coal by first gasifying the coal to form synthesis gas or syngas, a mixture of hydrogen, carbon monoxide, and carbon dioxide, cleaning the syngas, then processing the syngas further to increase the hydrogen content, and removing other components to produce a pure hydrogen stream. Once the syngas is cleaned to remove ash, slag, and sulfur, it becomes a source of useful and valuable clean fuels and chemicals. Alternatively, the syngas can be burned directly in a gas turbine to make electricity either instead of, or in addition to, other clean fuels production. Carbon dioxide from gasification can be captured in a highly concentrated form that is amenable to sequestration or storage.

CLICK ON IMAGE TO SEE LARGER VIEW

The Hydrogen and Clean Fuels program addresses hydrogen from coal pathways and RD&D activities related to those pathways. From clean syngas, there are many routes to clean energy, as shown schematically in the figure at right.

Pure hydrogen can be made from syngas for use in stationary fuel cells or fuel cell vehicles, as shown on the lower right side of the figure. There are two key steps in this process; increasing the percentage of hydrogen in the syngas using the shift reaction, and separating the pure hydrogen from the other gases. Carbon dioxide remaining in the syngas can be captured at this point and transported for sequestration or storage. The option of producing hydrogen directly is called the Central Production Pathway.

Alternatively, liquid hydrocarbon fuels such as diesel fuel or gasoline can be made via Fischer-Tropsch chemistry, or, with different catalysts, methanol or other alcohols can be produced for use as transportation fuels, or substitute natural gas (SNG) can be produced. These options are shown on the left side of the illustration above. Carbon dioxide can be captured for sequestration in either case. Either liquid fuels or SNG could be used as hydrogen carriers for fuel cell vehicles, by being produced in central plants, transported to local facilities, and reformed into hydrogen. These options are collectively called the Alternate Production Pathway.

CLICK ON IMAGE TO SEE LARGER VIEW

The figure at right shows the main R&D elements of the program. In the Primary Production Pathway, as illustrated on the left side of the figure, R&D needs to reduce costs of central station hydrogen production are addressed. Key R&D topics include hydrogen separation, membrane reactors that combine the shift reaction with other functions, and advanced concepts to simplify processes. The Alternate Production Pathway, shown at right in the figure, can enable use of the current infrastructure to move hydrogen-containing fuels nearer to the markets. Key R&D topics for this pathway include catalysts and reactor systems to improve efficiency and reduce cost of liquid fuel and SNG production, and better systems to reform the carrier materials into hydrogen near the site of utilization.

The program also supports R&D thrusts in the areas of hydrogen storage, delivery, and utilization in advanced engines, as shown at the bottom of the figure.

• Utilization R&D is addressing operation of advanced reciprocating engines to efficiently use hydrogen and hydrogen-natural gas mixtures and to minimize emissions.
• Activities in hydrogen storage addressing high-affinity advanced materials such as metal-organic frameworks are scheduled for completion by 2009.
• Work on delivery of hydrogen, hydrogen-natural gas mixtures, and synthesis is being concluded by 2009.
• Advanced computational sciences such as computational chemistry make possible exploration of new concepts for processes, catalysts, and membranes at low cost.

Systems analyses are conducted to guide the program and assist in prioritization of R&D efforts.

The Hydrogen & Clean Fuels Technology R&D program is subdivided into four areas, shown below. Click the links for more information on each program area.

• Central Hydrogen Production
• Alternate Hydrogen Production
• Utilization
• Systems Studies