Fuel cells are electrochemical devices that convert the energy of a chemical reaction directly into electricity, with heat as a by-product. The fuel and oxidant (oxygen or air) are supplied externally, enabling them to continue operating as long as they are fed. So, unlike batteries, they never “run out”.
The effort to develop alternative fuel automobiles is now a large public and private effort around the world. Government are appropriating funds for research and development. In 2003 alone worldwide government support exceeded $825 million. Private companies are spending money as well, bringing annual investment in fuel cell technology to well over a billion dollars to advance this effort.
Platinum and palladium play a large role in the technology. Platinum is the medium used to convert hydrogen and oxygen to heat, water and electricity. Palladium will likely also play a role in the fuel cell, as well, but it is unknown yet how big. What is currently known is palladium as a hydride can absorb 800 to 900 times its own volume of hydrogen at room temperature and atmospheric pressure.
Norilsk Nickel recently announced it would invest in developing hydrogen fuel cell technologies to create a new market for palladium. The allocated budget is up to $40 million per year in the initial stages of the project, which at this point has no defined length of time.
Meanwhile palladium has several integral roles in a hydrogen economy. Palladium can be used to generate hydrogen, to purify hydrogen, to store hydrogen and to detect hydrogen. Since the fuel cell is dependent on hydrogen, palladium will be important to this technology. If, as some say, that the world’s oil supply peaks in the year 2010 then this technology is not that far off.
How does a fuel cell work?
A fuel cell consists of two electrodes sandwiched around an electrolyte. Oxygen passes over one electrode and hydrogen over the other, generating electricity, water and heat. At the anode, H2 is separated into hydrogen ions and electrons, a process assisted by a catalyst often comprising platinum group metals.
The electrons travel through an external circuit, generating the required power. The ions pass through the electrolyte to the cathode where, assisted by another catalyst, they join with oxygen atoms to produce water.
Oxygen is sourced through the air. Hydrogen is sourced from either:
- a number of conventional hydrocarbon fuels such as natural gas, methanol/methane, gasoline, etc.
- or from renewable energy sources such as solar, wind, electrolysis of water, biomass, etc.
A fuel cell system including a “fuel reformer” to extract hydrogen from a hydrocarbon produces minimal NOx and less CO2 than conventional combustion technology due to increased efficiency.
If hydrogen from renewable sources is used then there is no carbon in the chain and harmful emissions are practically zero.
The only exhaust of a fuel cell is water - pure water. The US National Aeronautics Space Administration (NASA) has for years used hydrogen fuel cells to power its systems onboard and to provide drinking water for the crew.