TransForum Vol. 6, No. 1

Two Hydrogen Economies Needed to Address World Energy Challenges

Hydrogen is a compelling replacement for fossil fuels used in transportation for its clean, efficient propulsion of cars and light trucks using fuel cells whose only exhaust is ordinary water. A hydrogen economy that meets all our transportation fuel needs would greatly reduce emissions of pollutants that are harmful to human health and greenhouse gases associated with climate change. It would also save energy in the process.

In fact, George Crabtree, Argonne Senior Scientist and Director, Materials Science Division, contends that two hydrogen economies actually are needed to adequately address these challenges and provide the greatest advantages.

First, a near-term, incremental hydrogen economy will be established using technology within commercial reach. "The incremental economy will make hydrogen from fossil fuels as we do now, store hydrogen as liquid or compressed gas, and burn hydrogen in internal-combustion engines or turbines for generating electricity. The energy impact will be minimal. It will use the same amount of fossil fuels, have little impact on efficiency, and provide the same CO₂ output. However, it rolls out the hydrogen economy, establishing an infrastructure and teaching us how to use it," he says.

"But to get the full energy benefits, we need a mature hydrogen economy, as opposed to an incremental one," Crabtree explains. "To develop it, we need basic research to learn how to produce hydrogen by splitting water renewably, store hydrogen in solid compounds, and react it in fuel cells. This second economy is independent of fossil fuels. Hydrogen fuel cells will offer twice the efficiency of internal-combustion engines."

Crabtree notes that Argonne is currently working on the technology advances needed to achieve the incremental hydrogen economy as well as the basic research breakthroughs needed for the mature hydrogen economy. Before the two hydrogen economies can become a reality, however, scientists face research challenges in catalysis, membranes, nanoscale architectures, bio-inspired production, in situ experiments, and theory/simulation.

Advances being explored to promote the incremental economy include new and improved ways of reforming fossil fuel (see related article on pp. 5-6), storing hydrogen as a gas or liquid, and enhancing combustion in heat engines. New basic research initiatives are laying the foundation for the mature hydrogen economy. For example, Argonne scientists have discovered a route to significantly enhance the catalytic activity of platinum (Pt) in hydrogen fuel cells. They found that alloys like platinum cobalt (Pt₃Co) are more active than pure Pt for reacting hydrogen and oxygen to produce water at the fuel cell cathode. Alloying tunes the strength of the oxygen bonds and thus the catalytic activity through a volcano-shaped peak. The catalytic activity at the peak for Pt₃Co is a factor of two larger than for Pt without alloying.

Ultimately, the success of the two hydrogen economies depends on whether emerging hydrogen technology will provide more value than today's fossil fuels. While the market will ultimately decide the fate of the hydrogen economies, government can play a critical role in introducing hydrogen technology. The large R&D investments, the uncertain outcome for new approaches, and the long timeline to payoff often deter market investment. As a result, early government investments in setting goals, offering research support, and sharing risk are essential to cultivating viable, market-driven incremental and mature hydrogen economies.

The Two Hydrogen Economies

September 9, 2006