By now, most of us have had some exposure to the idea that hydrogen is the fuel of the future. From the President's State of the Union address, to numerous articles in technical and business journals, we are told that hydrogen-powered fuel cell vehicles may someday replace internal combustion engines that we have long relied upon to propel our personal cars, trucks and SUVs. The resulting, somewhat idealistic scenario is a transportation system based upon a pollution-free, renewable, abundant fuel that is not dependent upon politically unreliable foreign governments. While we continue to wait for that happy day to arrive; government, nonprofit organizations and commercial companies are searching for ways to turn the promise of hydrogen into a hydrogen reality. These efforts are leading to some unexpected conclusions regarding the first commercial applications for hydrogen technology that could very well include the GSE industry.
Most of the media attention on hydrogen has focused on passenger vehicle applications. Indeed, all of the major auto manufacturers have announced and/or demonstrated prototype fuel cell vehicles. Many of them have been featured on TV news shows and in national magazines. While passenger cars receive most of the attention from news sources, off-road vehicles such as industrial/warehouse trucks and ground service equipment vehicles are leading contenders for early fuel cell vehicle applications due to predictable duty cycles and favorable cost comparisons with battery-electric alternatives. Also, technical challenges with hydrogen storage and fueling infrastructure - huge issues for passenger vehicles - are more easily solved in a GSE application.
Hydrogen, the most common element in the universe, exists on earth only in combination with other elements, such as oxygen to form water or carbon to form hydrocarbons such as coal, oil and natural gas. To become a usable fuel, it must be separated from these other elements. By far, the most common method to obtain hydrogen today is via "steam reformation" whereby steam is combined with heat and natural gas to yield hydrogen. Hydrogen has the highest energy content per unit of weight of any fuel (making it a good choice for space missions.) However its energy density per unit of volume is very low - which means it must be compressed or liquefied when it is stored. As a fuel, hydrogen can be used in a fuel cell to generate electricity or it can be used in a conventional combustion engine. Either way, it is very clean, with almost no emissions.
A fuel cell is an energy conversion device that combines hydrogen with oxygen from the air to yield heat, water and electricity. While there are different types of fuel cells, a Proton Exchange Membrane (PEM) fuel cell is the most promising for vehicles. The PEM fuel cell allows hydrogen to chemically combine with oxygen in the presence of a catalyst and generate electricity in the process (see figure 1.)
Fuel cells are approximately twice as efficient as internal combustion engines in providing usable energy to a vehicle. They have the added benefit of generating no emissions in the process. A 50-kilowatt fuel cell that would be about the size needed for a tow tractor is about as large as a two-drawer file cabinet - the type that fits under a desk.
Hydrogen Technologies are at a Transition Point
Hydrogen technologies are in the late development or early commercialization stage. For power generation, fuel cells are already being used for back-up and on-site electric generation. For vehicles however, there are still a few years to go. In fact, the US Dept. of Energy (DOE) has identified 2015 as its target year for the transportation industry to make commercialization decisions regarding mass deployment of fuel cell and hydrogen vehicles. What, then happens in the meantime?