The U.S. natural gas system includes 726 natural-gas-processing plants; 410 underground gas storage fields; 254,000 miles of gas transmission lines; and 980,000 miles of local distribution pipelines (NPC, 2001). Natural gas is used extensively in homes and buildings for heating, and it is an important feedstock for chemical plants, fertilizer production, and industrial processes. Finally, its most rapidly growing use is in the production of electrical power, where it has become the fuel of choice for the majority of new electric power generation plants.
Natural gas resources are as much a cause of concern as petroleum. While much natural gas is still available in this country (especially in Alaska, if a pipeline can be built to access it), and significant new reserves may still be discovered, consumption already is rising rapidly. Furthermore, gas fields tend to deplete faster than oil fields, and advanced techniques such as enhanced oil recovery do not apply to gas. In addition, gas is more difficult to import from overseas. The main technique is liquefying it at very low temperatures, shipping it via insulated tanker ships, and reheating it at the port of entry, a technique which is also vulnerable to terrorism. Thus it is not clear that natural gas will be more than an interim source of hydrogen.
U.S. coal reserves total about 270 billion short tons, approximately 25 percent of total world reserves. Annual U.S. consumption is just over 1 billion short tons, giving a reserve life of approximately 275 years at today’s level of use. The reserves are sufficient to warrant consideration of coal as a primary feedstock for future hydrogen production.
In 2002, the top four coal-producing states were Wyoming (373 million short tons [st]), West Virginia (150 million st), Kentucky (124 million st) and Pennsylvania (68 million st) (National Mining Association, 2003). Many other states also have significant resources. Coal can be shipped long distances by train at low cost. Thus, coal can be considered as an option for primary feedstock in all regions of the United States.
In 2002, approximately 92 percent of all coal produced in the United States—that is, about 982 million st—was used