VOLUME 12, NUMBER 1
JANUARY/FEBRUARY 1998
© Copyright 1998 American Chemical Society
Special Section on Hydrogen Hydrogen, the Once and Future Fuel Catherine E. Gregoire-Padro´ Hydrogen Program Manager, National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, Colorado 80401 Hydrogen currently plays a significant role in the U.S. energy economy, but, almost exclusively, this role is indirect and obscureswe rarely use hydrogen as hydrogen. NASA is the notable exception. The use of hydrogen as a fuel in the utility and transportation sectors faces hurdles that would have to be overcome. These hurdles have been faced by other fuels such as methanol, ethanol, and natural gas; some hurdles have been overcome, while others remain as significant challenges. There is an interesting and somewhat perplexing dichotomy when considering hydrogen as a fuel or energy carrier. We have a significant database of experience and knowledge about hydrogen. It is easy to make inexpensive hydrogen from steam reforming of natural gasswe produce approximately 1 billion standard cubic feet of hydrogen every day for use in the petroleum, food, and chemicals industry. NASA uses hydrogen as a launch fuel and to power orbiting spacecraft. Fuel cells, invented before the turn of the 20th century, are used commercially to generate power and can be found in transit buses in several cities in the U.S. and Canada, and around the world. Hydrogen is transported safely in dedicated pipelines in the southeastern U.S., and in liquid form over several hundreds of miles every day throughout the U.S. With this experience and knowledge base, it seems logical to expect that an accelerated demonstration program could provide the needed stimulus to bridge the gap. For hydrogen, this gap is not small. We are blessed with abundant resources of fossil fuels, our economy is addicted to cheap energy, and our transportation infrastructure is based almost exclusively on liquid fuels. Even considering the environmental benefits that hydrogen use would engender, arguments have been made that the advances made in clean power generation and the design of high-efficiency automobiles will provide
us with most of these benefits with little or no disruption in our economy or our existing infrastructure. It has also been suggested that hydrogen will play an integral role in greenhouse gas reduction scenarios. Proposed systems include large-scale steam reforming of natural gas with recovery of hydrogen and carbon dioxide as pure streams. In this concept, CO2 would be sequestered in abandoned natural gas or oil wells, deep aquifers, or in the ocean. The hydrogen would be used as a transportation fuel, or to generate electricity or heat. Although elegant in theory, this concept would require an extensive distribution network for hydrogen that does not exist and would be expensive to implement. Beyond the difficulty in distribution, there are insufficient end users of hydrogen to justify widespread implementation of this as a major sequestration option in the near- or mid-term. Again, arguments have been made that the advances in clean power systems and increased use of renewable electricity and fuels will provide significant greenhouse gas reductions without major disruptions. An intellectual exercise conducted by Hydrogen Program managers at several national labs to define the “Hydrogen Future” resulted in some interesting revelations. The widespread use of petroleum in the transportation sector has been well noted and has served as one of the major drivers for the Program. The potential for hydrogen as a storage medium for intermittent renewable energy systems is also well recognized. Of note, the prevalence of chemicals and plastics derived from petroleum in every sector of the economy was not previously considered as a major driver for the Program. Assuming fossil fuels will be depleted or their use restricted by limits on greenhouse gas emissions, new sources of organic feedstocks will be required, and hydrogen will be needed as a chemical feed in the production process. In addition, the use of fossil fuels
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2 Energy & Fuels, Vol. 12, No. 1, 1998
for industrial process heat is significant. Nearly every phase of the economy would be significantly affected, particularly the industrial sector. In order to be in a position to provide enormous quantities of hydrogen from renewable or sustainable resources, substantial progress must be made in long-term, high-risk research in renewable production, high-efficiency storage, lowcost distribution, and efficient and safe use of hydrogen. The research supported by the DOE Hydrogen Program has focused primarily on the exploration of longterm, high-risk concepts that have the potential to address these future needs. While production of hydrogen from renewables has dominated the portfolio, storage is recognized as an important component of any renewable system, including transportation, utility, and industrial applications. Efforts in the development of efficient end-use applications include hydrogen burners, PEM fuel cells, and reversible fuel cells. In support of hydrogen systems, research is also conducted on safety and detection. Hydrogen can be produced directly from sunlight and water by biological organisms and using semiconductorbased systems similar to photovoltaics. Because all renewables are ultimately generated by the sun, other systems that rely on renewable resources for the production of hydrogen include PV/electrolysis, wind/ electrolysis, and thermal conversion of biomass. These production technologies have the potential to produce essentially unlimited quantities of hydrogen in a sustainable manner. Storage of hydrogen is an important area for research, particularly when considering transportation as a major user of the fuel, and an increase in intermittent renewable electricity generation. Although compressed gas and liquid hydrogen storage systems have been demonstrated in numerous vehicle demonstrations, the issues of safety and energy consumption have resulted in a broadening of the storage possibilities to include systems such as metal hydrides, glass microspheres, and
Editorials
carbon nanostructures. Stationary storage systems that are high efficiency with quick response times will be important for incorporating intermittent PV and wind into the electric grid as base load power. Bulk storage of large quantities of hydrogen may also be an appropriate area for research, especially when considering industrial energy requirements, and seasonal electricity storage from renewables. In addition to the extensive fuel cell development programs in DOE’s Office of Fossil Energy and Office of Transportation Technologies, the Hydrogen Program conducts fuel cell research that is focused on the development of inexpensive, easy-to-manufacture membrane electrode assemblies, and the development of reversible fuel cells for stationary applications. Perhaps the largest hurdle for the expanded use of hydrogen is public perception. Although the industrial hydrogen safety record is relatively good, two spectacular and very public hydrogen accidents have provided the Program with its greatest challenge. The Hindenburg and Challenger explosions present an extraordinary education opportunity, as well as the absolute requirement that safety be intrinsic to all processes and systems. The development of codes and standards for the safe use of hydrogen is an important aspect of the Program, as is the development of reliable, low-cost hydrogen sensors. Hydrogen will play an ever-increasing role in our energy future. We, as scientists and engineers, must continue to conduct novel and innovative research in sustainable energy production, storage, and end use to revolutionize our energy system for future generations. This special issue of Energy & Fuels contains reports on a sampling of the innovative R&D that is supported by the DOE Hydrogen Program. The future begins now. EF970197P
