PROTON EXCHANGE MEMBRANE FUEL CELL (PEMFC)

Among the six types of fuel cells are known at this time, the hydrogen fuel cell electrolyte membrane (PEMFC) most of the attention throughout the country because it has advantages compared with conventional engines and other fuel cells. This cell uses the so-called solid electrolyte (Proton Exchange Membrane, PEM) so easy to make, energy efficiency is almost doubled compared with the efficiency of conventional engines. Results of electrochemical reaction only water (zero emission), modular, no corrosion problems, the life of 11.000 hours, no sounds and can be applied to a moving tool and tools that is not easy to move.

Anodes in PEMFC fuel cell as a negative pole of an electrode that will drain off electrons from hydrogen molecules. These electrons can be used outside the circuit. At the anode material are channels that hydrogen gas can spread to the entire surface of the catalyst.

PEMFC cathode in a fuel cell pole positive electrode has a channel that will spread to the entire surface of the catalyst oxygen. Cathode also plays a role in the flow of electrons from the external circuit into the circuit. Electrons from the external circuit (load) combine with hydrogen ions and oxygen to form water to the entire surface of the catalyst.

Electrolyte PEMFC is a proton exchange membrane (proton exchange membrane / PEM). Shaped electrolyte material such as plastic wrapping which can only drain the positively charged ions. Electrons are negatively charged will not be through this membrane (membrane would hold electrons).

The catalyst in PEMFC is used to facilitate the reaction of oxygen and hydrogen. Catalysts made ​​of a sheet of carbon paper by a thin layer of platinum powder. The catalyst surface is always porous and rough so that the entire surface area of the platinum can be achieved hydrogen and oxygen. Platinum catalyst layer directly adjacent to the positive ion exchange membrane. 

Figure 1.

PEMFC Structure

Working Principle of PEMFC

-      Hydrogen gas that has a certain pressure enters the fuel cell at the anode.

-      The hydrogen gas will react with the catalyst to boost the pressure.

-      When the H₂ molecule contacts with the platinum catalyst, the molecules will separate into two H⁺ ions and two electrons (e^-)^.

-      Electrons will flow through the anode, the electrons will make a point outside the circuit of fuel cell and perform electrical work, and then flows back to the cathode in a fuel cell.

-      On the other hand, on the cathode fuel cell, oxygen gas (O₂) is driven style press then reacts with a catalyst to form two oxygen atoms.

-      Each oxygen atom has a very large negative charge. This will attract the negative charge two H⁺ ions out of the membrane PEM,

-      These ions combine with one atom of oxygen and electrons from the external circuit to form a water molecule (H₂O).

APPLICATION OF FUEL CELL

In many developed countries, the technology of fuel cell has not new anymore. Countries like the United States (US), Japan, Germany or the UK have developed this technology for a long time. In this country that triggered the use of hydrogen as a vehicle fuel is environmental issues and energy conservation. Vehicle manufacturers such as General Motors (GM) for example has released a prototype hydrogen-fueled cars. The car is scheduled commercially in 2010 using fuel cell-shaped wafer that serves to separate the hydrogen atoms into protons and electrons. By using electrons as electric current, coupled protons with oxygen from the air, so that the side only water vapor. To generate the necessary driving power car series consisting of 372 cells wafer. Although already able to apply these technologies, it does not mean everything went smoothly. GM claims that driving over a tank of compressed hydrogen is very uncomfortable compared with the above the gas tank. The car that was exhibited in the arena Alberto Fujimori American International Auto Show can cover a distance of almost 500 kilometers before having to recharge the fuel. In addition there are obstacles in the areas of comfort, hydrogen cars are relatively expensive, which is about 700.000 dollars.

Canadian company launched the generator fuel cell model of E8 Portable Power module containing two fuel cell PowerStack MC250. This portable power station has a capacity of 2,4 kW with voltage of 48 VDC at 50 A current and an electrical efficiency of over 50 percent. This plant is intended for stationary application such as backing up to Curacao response for commercial and military users.

Not only motor vehicles are considered to be feasible utilizing the fuel cell, but also information technology (IT). Manufacturers of portable computer from Japan, for example, to develop this technology on a number of products. Not all fuel cell can be used for a portable electronic device, only fuel cell from direct methanol (direct methanol fuel cell) which includes alkaline fuel cell  who can. If mass-produced, the price of the fuel cell can compete with Lithium-ion batteries are now widely used. Energy density can even be 5-10 times greater Lithium-ion battery.

A well-known manufacturer of electronic equipment in the United States, during the 1960s to produce electric power-based fuel cell to power NASA space shuttle as that Gemini and Apollo. Fuel cell system used in these tools based on Bacon cell. Until now, the energy used in the spacecraft still use fuel cell because the fuel cell energy used is not too complicated such as a battery or nuclear power are quite risky. In terms of technology research fuel cell, NASA has funded more than 200 research.

Not only that, the technology fuel cell that is found also be varied, such as the discovery of fuel cells are more efficient at generating hydrogen gas by increasing number doubled. This technology involves even by microbial fermentation processes that were previously impossible once in fuel production.

Obstacles still restrict the use of fuel cell, among others:

1.    If the use of hydrogen fuel, it takes a thick-walled safety tank and has a safety valve. Also required compressor to enter into the tank.

2.    If that is taken is liquid hydrogen, then there will be trouble of having to be maintained at a temperature of -253,15 °C at a pressure of 10⁵ Pa.

3.    If the use of methanol instead of hydrogen, then the required reformer. But efficiency is lowered.

4.    The temperature is quite high when operating between 60 °C -120 °C