In our current universe of planetary heating, clime alteration, fuel insecurity, and high energy demand and ingestion from developing states, it is perfectly necessary we started looking into how to bring forth the power of the hereafter. Through research, development, and promotion of engineering, several beginnings of alternate, clean renewable energy have been identified. One of the alternate beginnings of energy for the hereafter is “ The Fuel Cell Technology ” . This engineering ( fuel cell engineering ) has the possible to be the drift which will transform the manner in which industries of today will bring forth energy of tomorrow.
Fuel Cell can merely be describe as a power bring forthing system made up of electrochemical cell that converts the chemical energy of H into electrical energy. The electrical energy is generated from the reaction between H ( which is the fuel ) an O ( which is the oxidizer ) .
The history of fuel cells history can be dated back to 1939 when William Grove, a British scientist foremost discovered its rule. He demonstrated this by utilizing four big cells ( each incorporating H and O ) to bring forth electric power which was so used to divide the H2O ( in a smaller upper cell ) into H and O. The National Aeronautics and Space Administration ( NASA ) subsequently demonstrated their possible applications in supplying power during infinite flights. Since so, industry has been looking at the commercial viability of fuel cells engineering to bring forth energy in assorted applications in such a manner that it can vie with other sources/types of energy coevals.
There are several types of fuel cells being developed. The chief difference between fuel cells types is their electrolyte. The chief fuel cells types are listed below:
Proton Exchange Membrane Fuel Cells ( PEMFC ) :
This is besides called the Polymer Electrolyte Membrane Fuel Cell. It is the most favorable fuel cell engineering that offer alternate to the internal burning engine. The PEMFC uses a thin plastic membrane as its electrolyte. The reaction gases ( H and O ) are fed into the cell to respond with the anode and the cathode. The fuel H continuously flows to the anode. At the anode, H ions ( or protons ) and negatrons are produce from the H. Merely positively charged H ions pass through the membrane. The negatively charged negatrons flow to the electrical socket to bring forth electrical power. Oxygen continuously flow to the cathode. At the cathode the O combines with H ions and the negatrons to organize H2O which flows out of the cell.
2HA? a 4Ha?? + 4ea?» Equation for the reaction of the anode
Oa‚‚ + 4Ha?? + 4ea?» a 2Ha‚‚O Equation for the reaction at the cathode
2Ha‚‚ + Oa‚‚ a 2Ha‚‚O Overall Equation
Figure 1: How PEMFC works ( Beginning: hypertext transfer protocol: //altenergystation.com/fuel-cells.html )
The PEMFC has many advantages over all other types of fuel cell ; The PEMFC has a high power denseness and a low operating temperature ( of about 60-80 grades Celsius ) compared with other types of fuel cell. Its low operating temperature makes the fuel cell to warm up and get down bring forthing electricity within a short period of clip. Besides, the electrolyte is a solid stuff which makes it simpler to fabricate. The solid electrolyte of PEMFC makes it easier to orientate compared with other electrolytes. It is besides less caustic and has longer cell life and stack life. Other advantages of PEMFC are:
It merely requires H and O as reactant.
The by merchandise is H2O.
It can be used as an option to internal burning engine.
Although PEMFC has many benefits, it does hold some disadvantages excessively.
The operating temperature is low ( about 80A°C ) ; which is non high plenty to execute utile cogeneration.
It is an expensive signifier of electricity coevals. It cost about ?2500 – ?5000 per kilowatt.
The control of wet in the cathode and anode watercourse is of import as the electrolyte is required to be saturated with H2O to run optimally.
Direct Methanol Fuel Cells ( DMFC )
These types of fuel cells are comparable to the PEMFC except that methyl alcohol is used as fuel alternatively of H. It works by oxidising of the liquid methyl alcohol ( CHa‚?OH ) in the presence of H2O at the anode. The DMFC uses the same type of electrolyte as the PEMFC, but with thicker membranes. The chemical equation ( reaction ) of the DMFC is as follow ;
At the anode: CHa‚?OH + Ha‚‚O a COa‚‚ +6Ha?? + 6ea?»
At the cathode: 3/2Oa‚‚ + 6Ha?? + 6ea?» a 3Ha‚‚O
Overall Equation: CHa‚?OH + 3/2Oa‚‚ a COa‚‚+ 2Ha‚‚O
DMFC engineering is really applicable for portable power devices like laptops, 2-way wirelesss, cell phones, PDA etc. This is due to the high energy denseness of the methyl alcohol fuel. The current DMFCs can bring forth power denseness between 300-1000mWcmA? compared to PEMFC power denseness of 300-1000mWcmA? . DMFC can run between 50A°C and 120A°C with an efficiency of approximately 40 % .
The DMFC offers a batch of benefits compared with PEMFC ; nevertheless its development is still in its early phases. Some of its advantages are ;
It uses a liquid ( methyl alcohol ) fuel for power. Methanol can incorporate efficaciously with transmittal and distribution systems that are already in being.
It does non necessitate a complicated fuel storage system, as suppose to hydrogen fuel storage for PEMFC.
It is simpler in its design, and has the possible for low-volume, lightweight packaging.
Methanol is easier to transport and provide in commercial measures utilizing current gasolene substructure.
The chief disadvantage nevertheless, is that the low oxidation of methyl alcohol to hydrogen ions and COa‚‚ requires a more active accelerator. The fuel stack requires big measures of Pt compared with the PEMFC. Due to the big measures of Pt requires, the DMFC are more expensive. Other disadvantages are ; methanol is extremely caustic and toxic, DMFC have low efficiency compared to PEMFC due to the high pervasion of methyl alcohol through the membrane.
Alkaline Fuel Cells ( AFC )
AFC were one of the first type of fuel cell engineerings developed and used in the United States infinite plan to bring forth electricity. AFC operates by utilizing a solution of K hydrated oxide ( KOH ) in H2O as the electrolyte. It can utilize a broad scope of assorted non-precious metals as a accelerator at the anode and the cathode. AFC operates at temperature between 100A°C and 250A°C, nevertheless, most recent design of AFC operate at lower temperature of approximately 23A°C to 70A°C. AFC have been proved to hold efficiency of stopping point to 60 % .
Advantages of AFC are ;
The costs of AFC are lowered compared to other signifiers of fuel cell engineerings because Alkaline engineering can work absolutely good without the usage of cherished metals.
The AFC operates at a low temperature of about 70A°C. This lower its costs because the lower the operating temperature, the lower the cost of the stuffs needed to make a working and dependable system.
AFC has the highest efficiency of all fuel cell type ( about 60 % ) .
AFC nevertheless is susceptible to taint, hence requires pure H and O. Susceptibility of AFCs to taint besides affects the cell ‘s life-time, therefore extra cost.
Phosphoric Acid Fuel Cells ( PAFC )
The PAFC is one of the modern fuel cell and the first to be used commercially. PAFC can bring forth up to 200 kilowatt of power and is chiefly used to power stationary power coevals and besides to power big vehicles like coachs. The PAFC uses liquid phosphorous acid as an electrolyte. The phosphorous acid is contained in a Teflon-bonded Si carbide matrix and porous C electrodes incorporating a Pt accelerator. The chief feature of PAFC is the impregnation of the phosphorous acid aqueous solution as the electrolyte in the matrix. The efficiency of PAFC is approximately 40 % but can be increased to over 70 % with combined heat and power. One of the chief advantages of PAFC is that they are more receptive to drosss in fossil fuels that have been reformed into H than PEMFC, which are easy poisoned by C monoxide. PAFC are besides more efficient when used for the cogeneration of electricity and heat ( about 85 % ) . Other benefit of PAFC is its first-class dependability and long-run public presentation.
The disadvantage nevertheless is that it takes longer to warm up because it operates at a higher temperature ( between 150A°C and 200A°C ) , therefore doing it unsuitable for usage in autos. It besides requires Pt as a accelerator like most other types of fuel cells, but provides low power and current. Another deficit of PAFC is its size and volume in relation to their end product compared with other types of fuel cell.