Opinion Editorial: The
Road Not Taken
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by Rober Mauro, Technical and Policy Advisor to the NHA Board
As I look at the direction that the hydrogen program has taken, I think back to a 1994 NHA study titled “Strategy for Fuel Cells in Vehicles” that discussed the paths that could be taken to commercialize a hydrogen fuel cell vehicle. That study used much of the data from a 1992 NHA study titled “Technology Assessment of Hydrogen Vehicles.” The interesting thing about both studies was the recognition of the need for hybrid vehicles in order to lower the capacity rating of the fuel cell power plant. The “Strategy for Fuel Cells in Vehicles” study identified two directions for fuel cell development: One that the U.S. Department of Energy (DOE) and the auto industry are taking, and “The Road Not Taken.”
The road that I believe DOE and most of the hydrogen industry has taken was characterized in the 1994 study as the Fuel Cell Vehicle Development path. In 1994, it envisioned hybrids with internal combustion engines (ICE) and battery electric vehicles driven to the commercial marketplace by environmental mandates. It foresaw fuel cells requiring 45% efficiency, having 5,000 hours life, and costing no more than $250/kW before they could begin to enter the commercial marketplace. Although the study did not say, it was not anticipated that this cost would be fully reflected in the sticker price of the vehicle, and penetration was expected from most to least expensive models. The study foresaw the need for on-board reforming of a liquid fuel. Major infrastructure changes were only required if battery electric vehicles were a part of the mix. It foresaw fleets as early adopters of fuel cell vehicles. The infrastructure transition from petroleum to hydrogen was postulated to be driven by environmental regulation-mandated air quality. This is very much the road that California is on. The difficulties are with on-board reforming and the fuel cell. On-board reforming issues have to do with start-up time and complexity. While this path was a coherent and reasonable approach in 1994, it may not be today. The reason is that we are trying to make too great a leap forward. The DOE is trying to develop and design hydrogen infrastructure, a hydrogen fuel cell and the hydrogen fuel and storage system at the same time. By and large, it is trying to fit all this into a vehicle that is optimized for gasoline power.
The problem with this approach is that the change to hydrogen is not merely a substitution. It is a revolution without an immediate compelling force to justify it. There are good long-term reasons to accomplish this change to hydrogen fuel cell vehicles. The problem is that each of the technologies is evolving, and nothing is fixed to which new designs can be directed. This forces us to prematurely over-specify the systems to nail down the design fixes. I believe that this is one of the factors behind the early emphasis on codes and standards.
“The road not taken,” referred to in the 1994 study as the Hydrogen Development Path, also starts with a hybrid vehicle with an ICE gasoline engine. It initially converts to a hydrogen ICE and would use liquid hydrogen storage. One of the positive aspects of this approach is that building green field plants for hydrogen engines is not necessary.
The issue is one of retooling existing plants. Storage of liquid hydrogen requires a tank that is about 60% larger in each dimension than the existing gasoline tank to achieve the same range and efficiency. It means that a 1 x 1 x 4-foot storage volume in a vehicle has to become a 1.6 x 1.6 x 6.4-foot storage volume. The dominant car types in the U.S. today are minivans and SUVs – with higher capacity tanks, they represent a much less significant storage challenge for hydrogen than a smaller car. In addition, tanks are now available that allow the storage of liquid hydrogen, and hydrogen stored as a gas up to 5000 psi. Even if all the liquid hydrogen evaporated, at 5,000 psi you would still retain a significant portion of the hydrogen in the gaseous state. I assert that this car could be in commercial production and be affordable initially as a luxury vehicle. Such a vehicle might be filled up with high-pressure hydrogen gas for in-town driving and liquid hydrogen for longer trips. Availability of liquid hydrogen and gaseous hydrogen is similar to having two grades of gasoline.
The focus of the current DOE Hydrogen program is on infrastructure development with an emphasis on production, compression and refrigeration methods. There clearly needs to be an ongoing drive toward additional storage options, especially hydride storage. The DOE program also provides some breathing space to develop the knowledge needed for fuel cells to be reliable, long-lived, more efficient, more affordable, and reduce and ultimately eliminate the need for platinum.
The final step in the process is about substituting an affordable fuel cell for the hydrogen ICE in the vehicle when the fuel cell is ready to perform to expectations. This would be the focus of efforts to achieve an emission free vehicle. It should be noted that if storage provides acceptable range for an ICE hybrid, then storage is not an issue for a fuel cell hybrid. When the time comes, the auto industry can assist the process by reducing rolling resistance of the vehicle and drag, which will allow the use of lower capacity (cheaper) fuel cells and reduce the size of the on-board hydrogen storage container. Finally, the hybrid will evolve to using ultra capacitors instead of batteries or flywheel alternators for energy storage. I will venture to say that if fuel cells remain expensive, then in the long run they will become on-board chargers for the ultra capacitors. If that occurs then ultra capacitors might also be charged at home or while parked.
This leads to my final point. Fuel cells have a long history of yielding little or no commercial success. The principles of the fuel cell were discovered more than 30 years before the internal combustion engine was invented. Yet for almost three decades, commercialization has always been three years away. “The Road Not Taken” does not make sense if fuel cells are available in 2010; it does if fuel cells are not available at a reasonable price till 2030. I would just point out that in 1975 it was predicted that there would be orders for 26 MW stationary fuel cell power plants by 1978. From 1975 to now is a timeframe comparable to from now to 2030.
The fuel cell justifies development for the same reason that NASA resurrected it during the Gemini program – to provide pollution-free power for a period of time longer than the battery used in the Mercury program, and drinking water for astronauts in space for several days. Over the next two decades the need for drinkable water and increased power from pollution-free sources will drive the development of fuel cell technologies. In all countries, the production of several gallons a day of pure water from energy conversion will become extremely valuable over the next several decades. For islands like Bermuda which rely entirely on rainfall, renewably produced hydrogen from wind could be the first reliable source of drinking water that the island has ever had. Large regions of the world are depleting their aquifers and over the next several decades the consequences of this will be apparent. In my view, when the need for clean power and potable water is acute, fuel cells will be commercialized. They will not be the total solution, but they will make a difference in meeting the most critical needs.
Let me summarize my thoughts with the following observation. I believe that we can achieve the same goals following a different path with less risk and different challenges. A path that avoids having any single technology failure derail the entire effort. A path that does not put creating knowledge on a timetable, but uses what we know today. It makes every advance a substitution and focuses on one aspect of the system at a time. It does not try to do what cannot be done, nor do everything at once.
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