Inside a Fuel Cell

1. Inside a Fuel Cell The red Hs represent hydrogen molecules (H2) from a hydrogen storage tank. The orange H+ represents a hydrogen ion after its electron is removed. The yellow e- represents an electron moving through a circuit to do work (like lighting a light bulb or powering a car). The green Os represent an oxygen molecule (O2) from the air. The blue drops at the end are for pure water--the only byproduct of hydrogen power.

2. Types of Fuel Cells-Alkaline- • Operate on compressed hydrogen and oxygen. • Uses an alkaline electrolyte such as potassium hydroxide. • Efficiency is about 70 percent, cell output being 300 watts-5 kW • Originally used by NASA on space missions, specifically in Apollo to provide electricity and drinking water. • It is now finding applications in hydrogen-powered vehicles.

3. Molten Carbonate • The molten carbonate fuel cell uses a molten carbonate salt as the electrolyte. It has the potential to be fueled with coal-derived fuel gases or natural gas. • Efficiency ranges from 60-80 percent with an output of 2 MW. • They operate at around 1,200 degrees Fahrenheit, making them too hot for home use.

4. Phosphoric Acid • A phosphoric acid fuel cell (PAFC) consists of an anode and a cathode made of a finely dispersed platinum catalyst on carbon paper, and a silicon carbide matrix that holds the phosphoric acid electrolyte. • This is the most commercially developed type of fuel cell and is being used in hotels, hospitals, and office buildings. The phosphoric acid fuel cell can also be used in large vehicles, such as buses. • Efficiency is 40-80 percent with outputs of 200kW

5. Proton Exchange Membrane • The proton-exchange membrane (PEM) fuel cell uses a fluorocarbon ion exchange with a polymeric membrane as the electrolyte. • The PEM cell appears to be more adaptable to automobile use than the PAFC type of cell. These cells operate at relatively low temperatures and can vary their output to meet shifting power demands. • Efficiency is about 40 to 50 percent with outputs generally ranging from 50 to 250 kW

6. Solid Oxide • Solid oxide fuel cells (SOFC) currently under development use a thin layer of zirconium oxide as a solid ceramic electrolyte, and include a lanthanum manganate cathode and a nickel-zirconia anode. • This is a promising option for high-powered applications, such as industrial uses or central electricity generating stations. • Efficiency is about 60 percent with outputs of 100kW

7. What do you get when you cross a fuel cell, an ear of a corn and a fuel injector from a stray jalopy?

8. Ethanol as a Fuel Source • Ethanol is produced by converting biomass like cornstarch, sugarcane, sugar beets, and some trees and grasses to sugar, then fermenting it. • In the United States each year, approximately 2 billion gallons are added to gasoline to increase octane and improve the emissions quality of gasoline It's not cheaper than natural gas or coal... but it's cleaner, and renewable -Lanny Schmidt

9. Ethanol and Fuel Cells • Though hydrogen is the most abundant element on Earth, most of it is locked up with other elements in forms such as hydrocarbons and water. It takes a lot of energy to get significant quantities of hydrogen from water alone, so the most practical sources from which to liberate hydrogen are fossil fuels such as natural gas, diesel fuel or gasoline. But using fossil fuels as a hydrogen source removes some of the “green” appeal of fuel cells. • University of Minnesota’s Lanny Schmidt was able to produce hydrogen from ethanol after two simple adjustments to a process already used to get hydrogen from methane, natural gas and gasoline. • Ethanol is fairly flammable, and the process of extracting hydrogen from ethanol destroys • the catalyst traditionally used to extract hydrogen from hydrocarbons like oil. • The first step was to use an automotive fuel injector to vaporize an ethanol-water mix. • The second required altering the composition of the reactor’s ceramic catalyst material, • a combination of the elements rhodium and cerium, for the vaporized ethanol to pass • through and be converted

10. Why Ethanol is better… • Conversion of biomass materials such as ethanol into hydrogen is a more cost-efficient method to power fuel cells. • “Ethanol in car engines is burned at 20% efficiency because you have to remove the water first. But if you use ethanol to produce hydrogen, the efficiency is 50 to 60% because you don’t need to remove the water. Hydrogen comes from the ethanol and the water.” • Ethanol is relatively easy to make, transport and store, and it's renewable. • Ethanol reduces our dependence on foreign oil because it can be produced domestically. • Ethanol is low in reactivity and high in oxygen content, making it an effective tool in reducing ozone pollution.

11. Why it hasn’t happened yet… • “We’re not going to be switching tomorrow, because there’s not enough corn out there. If you took it all, you could replace maybe 40 percent of our petroleum needs." • The energy that goes into raising corn and making ethanol makes it less attractive than natural gas as a source for hydrogen. (It's only if you make the ethanol from a cellulosic material with not much energy going into it that it becomes even plausible as an option for hydrogen) • The potential for the new reactor, in its current form, is also restricted by an existing fossil-fuel dependent infrastructure.