About Hydrogen Economy
Electrochemical extraction of energy from hydrogen via fuel cells is an especially clean and efficient method of meeting our power needs, and introduces the need for establishing the infrastructure for a hydrogen economy.
It must however be noted that regarding the concept of the Hydrogen vehicle, burning/combustion of hydrogen in an internal combustion engine (IC/ICE) is oftentimes confused with the electrochemical process of generating electricity via fuel cells (FC) in which there is no combustion (though there is a small byproduct of heat in the reaction).
Both processes require the establish of an hydrogen economy before they may be considered commercially viable.
Hydrogen combustion is similar to petroleum combustion (minus the emissions) and is thus limited by the Carnot efficiency, but is completely different from the hydrogen fuel cell's chemical conversion process of hydrogen to electricity and water without combustion.
Hydrogen fuel cells emit only water, while direct methane or natural gas conversions (whether IC or FC) generate carbon dioxide emissions.
Hydrogen is typically thought of as an energy carrier, and not generally as an energy source, because it is usually produced from other energy sources via petroleum combustion, wind power, or solar photovoltaic cells.
Nevertheless, hydrogen may be considered an energy source when extracted from subsurface reservoirs of hydrogen gas, methane and natural gas (Steam reforming and water gas shift reaction), coal (coal gasification) or shale oil (shale gasification).
Electrolysis, which requires electricity, and High-temperature electrolysis/Thermochemical production, which requires high temperatures (ideal for nuclear reactors), are two primary methods for extract hydrogen from water.
As of 2005, 49.7% of the electricity produced in the United States comes from coal, 19.3% comes from nuclear, 18.7% comes from natural gas, 6.5% from hydroelectricity, 3% from petroleum and the remaining 2.8% mostly coming from geothermal, solar and biomass. When hydrogen is produced through electrolysis, the energy comes from these sources. Though the fuel cell itself will only emit heat and water as waste, pollution is oftentimes produced to make the hydrogen that it runs on; unless it is either mined, or generated by solar, wind or other clean power sources.
If fusion power were to become a viable energy source then this would provide a clean method of producing abundant electricity.
Hydrogen production is only as clean as the energy sources used to produce it. Power stations always provide more energy than is consumed on the grid, especially during off-peak hours, thus hydrogen can be generated from this otherwise wasted power (rendering the pollution and costs free, because the energy would otherwise be wasted). (source: Powering the Future: The Ballard Fuel Cell and the Race to Change the World) A holistic approach has to take into consideration the impacts of an extended hydrogen scenario.
This refers to the production, the use and the disposal of infrastructure and energy converters.
Nowadays low temperature fuel cell stacks Proton exchange membrane fuel cell (PEMFC), Direct methanol fuel cell (DMFC) and Phosphoric acid fuel cell (PAFC) make extensive use of catalysts.
Impurities poison or foul the catalysts (reducing activity and efficiency), thus higher catalyst densities are required.
Limited reserves of platinum quicken the synthesis of an inorganic complex very similar to the catalytic iron-sulfur core of bacterial hydrogenase to step in.
Although platinum is seen by some as one of the major 'showstoppers' to mass market fuel cell commercialisation companies, most predictions of platinum running out and/or platinum prices soaring do not take into account effects of thrifting (reduction in catalyst loading) and recycling.
Recent research at Brookhaven National Laboratory could lead to the replacement of platinum by a gold-palladium coating which may be less susceptible to poisoning and thereby improve fuel cell lifetime considerably.
Current targets for a transport PEM fuel cells are 0.2 g/kW Pt – which is a factor of 5 decrease over current loadings – and recent comments from major OEMs indicate that this is possible. Also it is fully anticipated that recycling of fuel cells components, including platinum, will kick-in. One company, NedStack, is already stating that its units are 98% recyclable