Hydrogen’s proponents envision a future where end uses for energy are domestically supplied principally by hydrogen through the generation of heat and electricity. This, they argue, will complete the historical transition from a carbon-based energy economy to one based on carbon-free hydrogen. The transition from solid fuels (like wood and coal) to liquid fuels (like oil) and then to gaseous fuels (like natural gas) has decreased the amount of carbon in each unit of fuel. With hydrogen as a fuel this transformation becomes complete, providing energy to applications in transportation, stationary CHP systems, portable power systems and microelectronics without carbon. Critics charge that if fossil fuels like coal and natural gas are used to produce hydrogen, the dependence on carbon-based energy will only continue. Also, the transition from solid to gaseous fuels has never been a complete one. Even as natural gas usage has increased, coal continues to be a dominant source of electricity generation and related greenhouse emissions.

Transportation modes, from automobiles to trucks and specialty vehicles, would be powered hydrogen fuel cells. Stationary power to buildings is provided through cogeneration of electricity from fuel cells and through heat generated from hydrogen electric conversion. Heat is captured to provide additional ambient environmental control. Portable fuel cell systems would replace portable gasoline generators for various power needs. Micro-fuel cells, using a direct methanol version of a miniature PEM fuel cell, would provide power to consumer electronics such as laptops and cell phones. How hydrogen is generated and distributed in this future is the source of heated debate among hydrogen’s proponents; critics argue that alternatives to hydrogen can provide greater short-term benefits.

Diagram of Hydrogen Fuel Cell Vehicle by Honda.
Source: American Honda Motor Co., Inc.

Many hydrogen and fuel cell research, development and demonstration (RD&D) projects areaimed at creating vehicles that can be powered by fuel cells. The primary objective is to replace the current ICE with a fuel cell “stack” (multiple fuel cells bundled together to provide produce more power) to power the various systems of the vehicle. The challenges faced in achieving this goal differ depending on the type and use of the vehicle – personal vehicles or fleet applications. Personal automobiles are consumer owned, residentially stored and range from compact cars to light trucks (such as SUVs). Fleet vehicles are generally government or commercially owned, have defined routes of travel, generally are stored in a central location, and often centrally fueled as well. Examples of fl eet vehicles include taxis, buses, trucks, and delivery vehicles. While transportation often is the main focus of the debate between hydrogen proponents and its critics, there are other applications that also employ hydrogen fuel cells and may provide less controversy.

Fuel Cell Bus Demonstraion in Germany. 
Source: Ballard Power Systems 2005

Hydrogen fuel cells can be used in distributed generation (DG) systems to power buildings. Distributed generation describes small electricity generating power plants that are located near or at the site of the end user. Not all DG systems use hydrogen fuel cells, but their potential high efficiencies and low environmental impact at the point of deployment have made them attractive to DG proponents. The onsite storage, production and release of hydrogen in DG systems can be in a cogeneration confi guration where the heat generated in operating fuel cells can be used to provide climate control, thereby increasing the function, effi ciency and value to the system. In addition, portable gasoline generators used in a variety of applications can be replaced with quieter, cleaner, more effi cient hydrogen fuel cells. Furthermore, both stationary and portable fuel cells offer the potential for reduced permitting and site rules due to their low to zero emission operation.

Consumer electronics are also envisioned to be powered through the use of a fuel cell. The range of power generated from these fuel cells, which are still under development, is between 25 watts and 10 kilowatts of power. In these applications, the goal is to create a fuel cell that would provide a much longer operating life than a conventional battery, in a package of lighter or equal weight per unit of power output. Fuel cells alsohave an environmental advantage over batteries, since certain kinds of batteries require special disposal. If successfully developed, these “micro” fuel cells could deliver much higher power density, storing more power in a smaller space than current batteries.