THE TECHNOLOGY OF FUEL CELLS


WHAT IS A FUEL CELL?

A fuel cell is a device that converts the energy, without combustion, from a fuel (methane, propane, hydrogen) and oxygen into electricity, water and heat. The process consists of two electrodes, one on the left (anode catalyst), one on the right (cathode catalyst) and an electrolyte in the middle. Picture hydrogen coming in from the left, electricity coming out of the top and water coming out of the right. The hydrogen enters on the left and passes over the fuel electrode (anode catalyst). The anode catalyst assists to split the hydrogen atoms into a proton and an electron which take different routes to the cathode catalyst. The proton passes through the electrolyte. The electrons create a separate current, moving up and over the electrolyte, (they cannot penetrate the electrolyte) that can be utilized before they return to be reunited with the hydrogen proton at the cathode catalyst. Oxygen (from air) passes over the cathode catalyst and joins with the hydrogen to form a molecule of water. The above describes a typical PEMFC (proton exchange membrane fuel cell).

TYPES OF FUEL CELLS

There are several types of fuel cells in development that fulfill the same results with somewhat different technologies. They are:

  • PEMFC (proton exchange fuel cell)
  • SOFC (solid oxide fuel cell)
  • AFC (alkaline fuel cell)
  • DMFC (direct methanol fuel cell)
  • MCFC (molten carbonate fuel cell)
  • PAFC (phosphoric acid fuel cell)
  • RFC (regenerative fuel cell)

FUEL PROCESSORS

Also called Fuel Reformers, these devices are used in Fuel Cells that are designed to work with carbon based fuels such as Methane, Propane, and Gasoline. Through various methods (steam, heat) the technology "strips" the specific hydrogen molecules from the compound releasing the carbon molecule as carbon monoxide. Proper venting into the atmosphere of carbon monoxide allows it to gravitate towards oxygen molecules and form carbon dioxide, a vital chemical component in photosynthesis, the process that allows green plants to "breathe". Since a vast infrastructure already exists to deliver propane and natural gas (methane) to homes and business throughout the world, we can expect most stationary fuel cells (as opposed to fuel cells used in automotive applications) to have fuel processors.

INVERTER

The electricity produced by a fuel cell is called direct current (DC). This form of electricity is most commonly found in low voltage applications such as automotive (12-volt). However, our homes and businesses run on higher voltages (120-volts) that require alternating current (AC). In order to process the electricity for domestic and business use the fuel cell is equipped with a power inverter which transforms DC electricity to AC electricity.

HYDROGEN GENERATION

The challenge ahead is to create pure hydrogen in ample quantities to supply the demand that will be created by automotive and domestic uses of fuel cells. The immediate demand is in the automotive sector because of the lack of space onboard to house fuel processing equipment. Fortunately, the technology is nearly ready for "prime time". Through water electrolysis we can combine electricity and water to create pure hydrogen. (If you think about it, this is the exact reverse of the fuel cell's job, making this as close to a perfect "closed loop" energy supply as we can achieve, hence the environmental attractiveness.) Currently in use in California, this technology is being used to fuel buses that run daily. After the last run of the day, they are hooked up to the "bus fueler" and refilled with compressed hydrogen. Their buses look no different to the naked eye than any other buses, except for a significant detail. The only emissions they are generating are a little water vapor and heat, because hydrogen is a zero emission gas. Eventually, smaller versions of these fuelers will be sold as accessories to FCV's (fuel cell vehicles) so that we can hook them up to our garages and refill our car with fuel in the comfort of our own garage. The cost will be minimal, a small amount of electricity and some water! Exactly how much will you miss watching the price of gas go up at the pump?!

"GREEN ENERGY"

The environmental friendliness of this technology is what makes it so attractive. We can create energy from hydrogen with virtually zero emissions (water and heat). There are no moving parts that will degrade and end up in landfills. No noise. No noxious emissions as in combustion oriented power generators. Greater fuel economy through cogeneration of power and heat. No towering, buzzing electric wires running through the neighborhood. And no power outages because wires were "taken out in an ice storm"!