How Does a Hydrogen Fuel Cell Work?
In 2003, President G.W. Bush announced a government plan to combat climate change and dependency on foreign oil by investing in hydrogen fuel cell technologies. But, how does a hydrogen fuel cell work?
Hydrogen is considered a fuel carrier not a fuel source, since it merely transports energy rather than creating the energy itself. By splitting up the hydrogen, this energy is released and can be utilized for power with a fuel cell. A fuel cell functions in much the same way as a battery only it does not require recharging. As long as fuel is being applied, the cell will produce energy. So, unlike batteries, fuel cells cannot run out or be depleted. However, the design is also like a battery in that one end is positively charged (the cathode) and the other end is negatively charged (the anode).
There are three basic parts to a hydrogen fuel cell: The anode in the front, the electrolyte in the middle, and the cathode in the back.
The anode is the negatively charged end of the fuel cell (think of a battery). This is where they hydrogen enters the fuel cell. Being negative, the anode attracts positively charged hydrogen ions splitting the hydrogen atom into a positive ion and negatively charged electrons. The splitting creates energy which is harnessed by the fuel cell. The positive hydrogen ion can pass through a catalyst membrane directly into the electrolyte center of the fuel cell, where as the negative electron is channeled through an external circuit creating additional electricity.
The electorlyte center of the fuel cell works as the transporter of the highly unstable positive hydrogen ion. The hydrogen ion passes from the catalyst into the electrolyte and then is contained as it continues its journey through the fuel cell. The electorlyte protects the unstable ion and thus the positive hydrogen ion does get to leave the electrolyte before it can be stabilized. Before it can get to the cathode, another catalyst layer reattaches the separated negative electron stabilizing the hydrogen atom. A Proton Exchange Membrane is sometimes used instead of this liquid electrolyte as a stabilizer. Due to the high temperature rating and the ability of the thin polymer membrane to quickly change power output. Many companies are currently working to mass produce this type of hydrogen fuel cell cost effectively.
Now that the hydrogen atom is stabilized it can pass through to the cathode. The cathode is the positively charged electrode on the other end of the fuel cell (again, think battery). Here, oxygen is joined to the newly stabilized hydrogen atom creating water and heat. These byproducts can be used along with the electricity produced by the fuel cell creating additional benefits to the technology.
In some instances an electrolyser is being used to split the hydrogen atom, storing the ions and electrons in giant tanks. By adding the ions to the anode, the electrons to the cathode, and utilizing the biproduct water to create the liquid electrode a virtually sustainable cycle is created.