ment of a hydrogen generation appliance that can be mass-produced and operated reliably and safely in a typical fueling station with only periodic attention, with the goal of having prototype designs in 5 to 7 years. Two prototype designs, one incorporating partial oxidation (or autothermal reforming) and the other steam methane reforming, should be pursued. Funding should be adjusted to ensure that this goal is achieved. In addition, the DOE should downsize its efforts on centralized generation, pursuing only those developments that would be applicable to distributed generation.

Recommendation 8-2. The committee recommends that the Department of Energy give appropriate attention in its program to the development of an integrated fueling facility, including the generation appliance and its ancillary subsystems, to minimize cost and to improve efficiency, safety, and reliability.

HYDROGEN FROM COAL

This section presents the basics of making hydrogen from coal in large centralized plants. Appendix G presents a detailed discussion of making hydrogen from coal. Many of the issues and technologies associated with making hydrogen from coal are similar to those associated with making electric power from coal. These subjects are closely linked to one another and should be considered in concert. This is particularly the case for gasification, a clean coal technology, which will be required for making hydrogen and which also offers the best opportunity for making low-cost, high-efficiency, and low-emission power production through the integrated gasification combined cycle (IGCC) process. The lowest-cost hydrogen coal plants are likely to be ones that coproduce power and hydrogen.2

Coal is a viable option for making hydrogen in very large, centralized plants when the demand for hydrogen becomes large enough to support an associated very large distribution system. The United States has enough coal to make all of the hydrogen that the economy will need for more than 200 years, a substantial coal infrastructure already exists, commercial technologies for converting coal to hydrogen are available from several licensors, the cost of hydrogen from coal is among the lowest available, and technology improvements are identified to reach the future DOE cost targets. The major consideration is that the CO2 emissions from making hydrogen from coal are larger than those from any other way of making hydrogen. This puts an added emphasis on the need to develop carbon sequestration techniques that can handle very large amounts of CO2 before the widespread use of coal to make hydrogen is implemented.

Gasification Technology

The key to the efficient and clean manufacture of hydrogen from coal is to use gasification technology, which is a clean coal technology, as opposed to the combustion process used in conventional coal-fired power plants. Gasification systems typically involve partial oxidation of the coal with oxygen and steam in a high-temperature and elevated-pressure process. This creates a synthesis gas, a mix of predominantly carbon monoxide (CO) and H2 with some steam and CO2. This synthesis gas (syngas) can be further reacted with water to increase H2 yield. The gas can be cleaned in conventional ways to recover hydrogen and a high-concentration CO2 stream that is easily isolated and sent for disposal. Syngas produced from current gasification plants can be used in a variety of applications, often with multiple applications from a single facility. These applications include use as a feedstock for chemicals and fertilizers, use for making hydrogen for hydro-processing in refineries, or use for generating electricity by burning the syngas in a gas turbine.

Research and Development Needs

In terms of its stage of development, coal gasification is a less mature commercial process than other coal processes and other hydrogen generation processes using other fossil fuels, especially with respect to capturing CO2 and providing flexibility in both H2 and electricity production. In the committee’s analysis, the current production cost of making hydrogen from coal in central station (i.e., large, centralized) plants is estimated to be $1.03/kg. The potential for improvement through technology development is significant, as indicated below:

  • R&D for current technology should be directed at the following: capital cost reduction; standardization of plant design and execution concept; and improvements in reliability, gas cooler designs, process integration, oxygen plant optimization, and acid gas removal technology. With success in these areas, the production cost of hydrogen from coal is estimated to drop to $0.90/kg.

  • The potential also exists for new technologies to make larger improvements in the efficiency and cost of making hydrogen from coal. For new gasification technologies, the best opportunities for R&D appear to be for new reactor designs (entrained bed gasification) and improved gas separation (hot gas separation) and purification techniques (membrane purification).

These new technologies and the concept of integrating them with one another into a complete operating plant are in very early development phases and will require longer-term development to verify the true potential and to reach commercial readiness. With success, the estimated hydrogen production cost can be reduced to $0.77/kg.

2  

David Gray and Glen Tomlinson, Mitretek Systems, “Hydrogen from Coal,” presentation to the committee, April 24, 2003.



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement