The Science of Hydrogen Fuel Cells

Bush pledges $1.2 billion in subsidies

In the State of the Union Address in January, President Bush promised an additional $1.2 billion in subsidies for hydrogen fuel cell research. Since then the number has increased to $1.7 billion, and President Bush has agreed with European Union leaders to work jointly on a five-year effort to bring hydrogen fuel cells, particularly for vehicles, closer to commercial reality.

Would that be money well spent? Or would federal hydrogen research subsidies be a waste of taxpayer money? The answers to those questions depend on several variables, almost all of which are beyond the control of the federal government. Because of the risks associated with such research, both economic and political, federal research subsidy efforts should proceed with caution.

And public opinion on these questions should be grounded in a firm understanding of the science of hydrogen fuel cells, and how they really work. Several recent articles have done a good job of summarizing the challenges in moving toward hydrogen as an energy source, including this Gregg Easterbrook article in The New Republic, and this International Energy Agency white paper entitled “Moving to a Hydrogen Economy: Dreams and Realities.” These analyses highlight some important aspects of hydrogen, and of fuel cell technology, to bear in mind.

1. Pure hydrogen does not exist on Earth. Given existing and foreseeable technology, as well as the fact that pure hydrogen does not exist in isolation on Earth, hydrogen on Earth is an energy medium, not an energy source. Because hydrogen on Earth occurs in molecules that also contain either carbon or oxygen, isolating pure hydrogen involves “reforming” existing hydrocarbon molecules.

2. Isolating hydrogen still requires fossil fuels as inputs. Reformation of hydrogen still means using hydrocarbons such as natural gas as a source of hydrogen, because the primary potential sources of hydrogen on Earth are hydrocarbons and water. Both hydrocarbons and water are in scarce supply. Furthermore, this use of hydrocarbons to isolate hydrogen offsets some of the optimistic predictions about the emissions reductions we could expect from using hydrogen fuel cells.

3. Converting either water or hydrocarbons to hydrogen requires the expenditure of energy. Breaking hydrogen free from hydrocarbon molecules requires an expenditure of energy. Furthermore, depending on the process used, the reaction could actually use more energy than the electrolysis process itself actually produces. In other words, to figure out how much energy has actually been created, we have to subtract out the energy expended in getting to the point where we can separate out the hydrogens in the first place.

The most developed form of hydrogen isolation through electrolysis requires electricity to separate the hydrogens from the carbons in the hydrocarbon molecule, and within that reaction the net energy produced is positive. However, the electrolysis reaction also uses a catalyst to increase the energy release in the process. The catalyst typically used in hydrogen electrolysis is platinum. Mining and processing platinum is incredibly energy intensive, using fossil fuels such as coal to drive machinery that makes platinum available for the electrolysis.

Given the existing electrolysis technologies and platinum mining technologies, the platinum catalyst has to continue to work in the fuel cell without being damaged for almost three decades to get positive energy payback from the fuel cell. Put another way, it takes almost thirty years for the energy production of the fuel cell to equal the amount of energy that went into manufacturing the fuel cell and making the fuel available to it for the electrolysis reaction. So in energy terms, to pay for the fuel cell and start getting a net benefit from it, it has to run for at least three decades.

Furthermore, platinum is a very expensive metal, and its expense lengthens the financial payback period of the fuel cell as well as the energy payback period. Research on other catalysts is crucial for making fuel cells commercially viable, and private companies are actively engaged in undertaking such research.

4. Hydrogen is less intense than fossil fuels. For a given input, hydrogen production and fuel cell technologies generate less energy output (measured in BTUs) than traditional hydrocarbons. Recent estimates by the International Energy Agency suggest that replacing all of the transportation fuel currently used in France with hydrogen would require generating four times the electricity, which would in turn require either covering 6% of France’s surface with wind turbines, or 1% of it with photovoltaic solar panels.

Thus replacing fossil fuel systems with hydrogen fuel cell systems will mean an increase in the space required for the production, transport, and use of hydrogen relative to an equivalent amount of potential energy from hydrocarbons. This fact mirrors the energy intensity issue with solar power, in which to generate a given amount of energy, a system of photovoltaic panels would have to cover a much, much larger surface area than generating the same amount of energy using hydrocarbons. Again, though, note that private companies are actively engaged in and investing in research to make hydrogen production, transportation and storage more compact.

5. Handling hydrogen can be dangerous. Remember the Hindenberg. Pure hydrogen is unstable and oxidizes easily, which makes it extremely combustible. Thus long-distance transport of hydrogen, say, to fill hydrogen fueling stations, is potentially dangerous.

Lynne Kiesling is director of economic policy at Reason Foundation and senior lecturer in economics at Northwestern University.

This is part 1 of Reason’s 5-part Let the Hydrogen Economy Evolve series:

Part 1: The Science of Hydrogen Fuel Cells
Part 2: The Economics of Hydrogen: Innovation in Mature and New Technologies
Part 3: Are Hydrogen Fueling Station Subsidies Necessary?
Part 4: Hydrogen-Powered Buildings
Part 5: Can the Government Pick Technology Winners? Can Anyone?