The Transportation Energy Center at the University of Michigan: Fuels for the Future

bridges vol. 10, June 2006 / Feature Articles
by Johannes Schwank

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Clean air and water, and enough food are the three things absolutely crucial for sustaining the growing world population on this planet. All three of these depend on access to sufficient energy. Today, the major portion of this energy comes from fossil fuels. In the 1970s, when the first true energy crisis hit, we first became painfully aware of how precarious our energy supply was. In the years to follow, however, the memory of waiting in long lines at gas stations quickly faded, as did the sense of urgency to find alternative energy sources.

{access view=guest}Access to the full article is free, but requires you to register. Registration is simple and quick - all we need is your name and a valid e-mail address. We appreciate your interest in bridges.{/access} {access view=!guest}To help find solutions to the many open questions and challenges in the transportation energy sector, the University of Michigan in Ann Arbor has established the Transportation Energy Research Center (TEC). The mission of the center is to evaluate and develop technology options for a transition to sustainable transportation energy. One of the major research initiatives in this center is to discover and develop fuels for the future, including clean-burning synthetic fuels. The center is also developing advanced energy harvesting, conversion, and storage concepts. Another major research thrust is the generation of hydrogen from a variety of sources. This is a smaller scale, more practical approach for supplying hydrogen to fuel cell auxiliary power systems, small stationary fuel cell systems, and electric microgrids. This research explores the interface between mobile and stationary energy conversion systems.

tec_schwank_research_groupTEC is a strategic resource not only for the university but also for the automotive, petroleum, chemical, and utility industries. The TEC research model is based upon establishing close ties with industry through research partnerships. The goal is to accelerate the development of technologies and processes for transitioning from petroleum-based fossil fuels to flexible fuel options drawing from a variety of sources, including biomass, synthetic fuels from coal, and hydrogen. The scientists and graduate students working in TEC see their role as that of an "honest broker," objectively evaluating the pros and cons of energy options.

In the US, there has been for quite some time a growing imbalance between domestic production and consumption of petroleum, forcing a steady increase in petroleum imports. The situation is aggravated by the rapidly growing demand for oil in China and India. At the same time, there is strong evidence that production of "cheap" oil will peak in the not too distant future. We may be headed towards a perfect storm where increased competition among nations for scarce oil resources collides with decreasing oil production. In addition, we will have to cope with the environmental consequences of fossil fuel-generated emissions. President Bush, in his 2006 State of the Union Address, remarked: "Keeping America competitive requires affordable energy. And here we have a serious problem: America is addicted to oil, which is often imported from unstable parts of the world." At a recent Senate Foreign Relations Committee hearing in Washington, DC, former Federal Reserve Chairman Alan Greenspan warned that the balance of world oil supply and demand "has become so precarious that even small acts of sabotage or local insurrection have a significant impact on oil prices." With the price of oil driven high, and national security concerns so grave, "we are seeing the gradual disengagement of the United States from petroleum."

By the year 2050, the world population will have grown to 9-10 billion people. To provide these billions of people with enough food and clean water, and to power the homes, industries, and transportation systems, will require 30-50 terawatts of energy. Unless an economical and sustainable supply of energy is found, the world may be headed towards major conflicts over access to energy sources. Over the last few years, a new sense of urgency has been building. Some have started to voice the need to launch a "Manhattan project" for energy. Others, driven by concern over greenhouse gas emissions, have started to call for a worldwide shift from a fossil fuel economy to a hydrogen economy. To bring such major transitions about will require significant technical advances and enormous investments in new materials, processes, and infrastructure. This may be one of the greatest scientific, technical, and economic challenges our world faces in the coming decades.

tec_schwank_synthetic_fuel Economic growth in modern societies goes hand in hand with increased mobility. About one-third of our energy consumption is related to transportation. Nowhere is our dependence on petroleum more critical than in the transportation sector. While we have more flexibility in supplying energy to homes and factories, the options for powering cars and trucks are much fewer. In a vehicle, we have to carry the fuel supply on board. Therefore, the weight and volume of the fuel become an important issue. Since gasoline and diesel contain a lot of energy per unit volume, they have become the fuels of choice for transportation. There is also a worldwide distribution infrastructure in place. But gasoline and diesel are made from petroleum. And this puts us squarely into the path of the "perfect storm"!

Lately, there has been great interest in hydrogen as energy carrier, as an alternative to liquid fuels. Hydrogen could directly power fuel cell cars, or be burned in advanced internal combustion engines. However, the worldwide hydrogen production capacity is barely sufficient to supply all the hydrogen needed to make ammonia for fertilizer, petroleum refining, and chemical production. We would have to increase hydrogen production capacity at least tenfold if all our cars were fuel cell or hydrogen-burning vehicles. On the other hand, should we decide to go the route of hydrogen-fueled vehicles, we will be faced with an enormous investment in an entirely new distribution and storage infrastructure.

The first question is: "How do we secure an adequate hydrogen supply?" Pure hydrogen does not occur naturally and must be generated from other substances, for example natural gas, petroleum, coal, biomass, or water. This requires up-front investment of energy. In the near future, most of the hydrogen will be generated from natural gas. To convert natural gas into hydrogen pure enough for fuel cells requires elaborate chemical processes involving catalysts; and as long as we produce hydrogen from fossil fuels, we are still emitting carbon dioxide into the environment. In essence, we are simply shifting the environmental pollution problem to a different location without really solving it. One possible solution to this problem could come from research into carbon dioxide capture and sequestration, which becomes a more realistic option in larger-scale, centralized fuel processing and hydrogen production facilities.

The alternative is making hydrogen from water. You may remember your high school teacher doing an experiment called "electrolysis," where electricity is used to split water into hydrogen and oxygen. To split water requires the expenditure of large amounts of energy and, currently, is not economical on a large scale. Water splitting could be achieved by harnessing solar, wind, nuclear, or geothermal energy. However, major advances in technology will be needed to make this process more economically attractive. It seems prudent to start now, while we can still count on fossil fuel supplies, on a large-scale research and development program for water-based hydrogen generation. Water, most likely, may become our long-term source for large-scale hydrogen production.

tec_schwank_catalyst Once an abundant supply of hydrogen from water is available, many technical options open up. For example, coal could be converted to liquid transportation fuels through the Fischer-Tropsch process. This process was developed during the second World War in Germany, and is practiced today on a large scale in South Africa. Synthetic fuels made from coal and hydrogen are compatible with the already existing fuel distribution infrastructure, from oil refineries to pipelines to local gas stations. The coal reserves in the US and other parts of the world would be large enough to secure our transportation energy needs for several hundred years.

Another intriguing possibility is to use hydrogen for recycling carbon dioxide generated in coal- or gas-fired electric power plants and converting it back into methane, the main ingredient of natural gas. Currently, it would be difficult to economically justify this process, and better ways would have to be developed to separate carbon dioxide from the smokestacks. However, should carbon dioxide emissions become subject to increasing carbon taxes, the economics could quickly change.

Ethanol made from biomass as a gasoline replacement has also received lots of attention recently. Ethanol made from corn can, at best, be a supplement to the gasoline supply, as there is not enough arable land available to grow the quantities of corn required to replace gasoline. More promising is the production of cellulosic ethanol from wood, grasses, and agricultural wastes, but more research and development are needed to improve the process and reduce the cost.

At this point, the verdict is still out as to which of the many energy technology options (gasoline, diesel, or hydrogen-fueled internal combustion engines, fuel cells, batteries, or hybrids) will dominate future transportation energy systems. But there is no longer any question that sustainable substitutes for America's oil addiction are urgently needed.

The author, Johannes Schwank, is full professor of chemical engineering and director of the Transportation Energy Center at the University of Michigan.




Related Sources:
DiPardo, Joseph. "Outlook for Biomass Ethanol Production and Demand." Energy Information Administration, 2006.

Hirsch, Robert L. Peaking of World Oil Production: Impacts, Mitigation, and Risk Management. US Department of Energy, February 2005.

Lavelle, Marianne. "The New Oil Rush." US News & World Report, 24 April 2006.

Mader, Jerry. "The U.S. Petroleum Addiction: Is It Hopeless?" The University of Michigan, 17 May 2006.

Mufson, Steven, "Greenspan Testifies on Oil Dependence, and Few Pay Attention." The Washington Post, 8 June 2006.

"State of the Union Address by the President." 31 January 2006.{/access}