FUEL CELL TYPES

 

    
     

 

What is Renewable Energy Source?

Renewable energy is the energy that comes from natural sources that are naturally replenished.

 

What are some common forms of Renewable energy?

Renewable energy sources give us the opportunity to create “clean” or “green” electricity. Wind, Solar, hydroelectric and biomass energy are the main types of renewable energy source. Geothermal energy although is technically non renewable is also considered to be a renewable energy source because it is considered as a clean way to produce electricity. The newly introduced tidal energy conversion, ocean wave energy and ocean thermal energy conversion (OTEC), are the latest renewable energy sources.

 

What are the advantages of using Renewable Energy Sources (RES)?

  • Almost zero environmental impacts. Clean source of electricity
  • They will newer run out in comparison with coal and petroleum that they will run out in the foreseeable future
  • National Energy Dependence while every country has such forms of energy.
  • More stable in price than fossil fuels
  • Modular and portable sources of electricity

 

What about the cost of Renewable energy?

Thanks to the research and the development that is going on, the cost of renewable energy sources is continuously decreasing. According to the U.S. Department of Energy the cost for wind and solar electricity has come down by 80-90% over the past two decades and will continue to fall to levels that are competitive with conventional energy sources over the next 5-15 years.

 

What are the advantages of using fuel cells?

Fuel cells are clean, highly efficient, scalable power generators that are compatible with a variety of fuel feed stocks and can therefore be used in an assortment of power generation applications. In particular, they offer several advantages over other technologies:

  • Hydrogen has the highest energy content per unit weight of any known fuel (120.7 kJ/g)
  • Fuel cells produce electricity without combustion, which means that, unlike internal combustion engines, they generate little (if any) noise, vibration, air pollution, or greenhouse gases and operate at high efficiencies over a wide range of loads
  • In small consumer devices and for powering zero emission vehicles, fuel cells, unlike batteries, avoid the need to replace the cell or undergo a lengthy recharging cycle when its fuel is "spent". Additionally, since fuel cells store their fuel in external storage tanks, the maximum operating range of a fuel cell-powered device is limited only by the amount of fuel that can be carried
  • In distributed power generation applications, fuel cells reduce the load on the grid and also eliminate (or reduce) the need for overhead or underground transmission lines, which are expensive to install and maintain, and result in power losses/efficiency reductions
  • Since fuel cells are scalable and can be installed on site, they reduce the need for large power generation plants (and the environmental impacts of such large scale plants)

 

What are the environmental impacts of a fuel cell vehicle?

Fuel cells emit little or no pollution, can provide increased fuel efficiency compared to Ices, are compact and powerful, and provide rapid response to frequent power demands. They have the potential to be durable and easy to maintain. Very low emissions would also be obtained using gasoline and a gasoline reformer. These emissions are significantly less than those produced by today's conventional ICE vehicle. Fuel cell vehicles also have the potential to produce less - or zero - greenhouse gases because of increased energy efficiencies.

 

How does hydrogen compare with other fuels like gasoline and diesel?

Hydrogen can be totally nonpolluting and can be produced from a variety of renewable energy sources, it can help to prevent the depletion of fossil fuel reserves, it is as safe as gasoline, diesel or natural gas and it can be competitive in the close future with either gasoline or diesel. It’s a reliable source of power. In the long run it is expected to become cost-effective as fossil fuels become increasingly scarce.

 

How is hydrogen produced with a sustainable way?
 
The most sustainable way of producing Hydrogen is from renewable energy sources by the process of electrolysis. Electricity from solar, wind, or hydropower generators is supplied to an electrolyte, which splits water into its constituent elements, hydrogen and oxygen. An electrolyte uses an electric current to separate water into its components-hydrogen and oxygen. The electricity enters the water at the cathode (negatively charged electrode), passes through the water, and exists via the anode (positively charged electrode). The hydrogen is collected at the cathode and oxygen is collected at the anode. The overall process is:

Hydrogen + Oxygen + Heat → Electricity + Water

Electrolysis using renewable electricity is sustainable, efficient (generally around 75%), and does not deplete natural resources.

 

What are some of the sources of hydrogen?

Hydrogen always combined with other elements such as oxygen and carbon, so it can be generated from numerous sources – water, natural gas, propane, methanol, and ethanol. Some innovative sources include peanut shells, methane, sodium borohydride, ammonia, digester gas and using algae.

 

If we use water to obtain the hydrogen, will there be enough?

Putting aside the fact that a byproduct of fuel cells is water, there is more than enough water to sustain a hydrogen economy.

The Delft Institute for Sustainable Energy calculates:

Global energy demand: 4x1020 J/year

H2 from water: 1 GJ per 90 liters H2O

Water needed: 3.6x1021 liters

Oceans: 1.45x1021 liters

Annual rain fall: 3.63x1017 liters

 

Doesn't it take energy to create hydrogen?  

Extracting any fuel takes energy – even getting gasoline from well to pump costs the equivalent of 20% of the energy of the gasoline. It takes more energy to generate hydrogen than gasoline, but since a fuel cell is more efficient than conventional energy devices, fuel cell vehicles – even today's prototypes – offer attractive overall efficiencies, even using hydrogen.

Looking at the whole picture is important. Well-to-Wheel analyses compare the entire pathway of producing, storing, distributing and utilizing any number of fuels. They can compare efficiencies and energy needs for the many different hydrogen production methods as compared to different fuels and vehicle technologies.

 

Is hydrogen safe?

In many ways, hydrogen is a good deal safer than gasoline or diesel. Like any fuel, hydrogen stores significant amounts of energy, and handling it requires certain safety precautions. But hydrogen can be safer than gasoline if it is used properly.

Hydrogen disperses quickly. Being an extremely light molecule, hydrogen rises and spreads quickly in the atmosphere. If a leak were to occur, the hydrogen gas would quickly become so sparse that the risk of it burning would decrease just as rapidly.
Hydrogen can be stored and distributed safely. Tanks currently being used for the storage and shipment of compressed hydrogen have been through rigorous testing, completed for their certification.

 

What types of vehicles are being demonstrated?

The project is demonstrating fuel cell passenger cars and transit buses. The passenger cars include DaimlerChrysler's F-Cell, Ford's Focus FCV, GM's HydroGen 3, Honda's FCX, Hyundai's Santa Fe FCEV, Nissan's Xterra FCV, Toyota's FCHV Highlander, and Volkswagen's HyMotion. The fuel cell transit buses, all with Federal Transit Administration support, include the hydrogen-fueled ZEBus and a methanol-fueled bus developed by Georgetown University, both with Ballard fuel cell engines; and Thor's hydrogen-fueled ThunderPower bus with a fuel cell engine developed by UTC Fuel Cells.

 

What further steps are required in the commercialization of fuel cells?

Four major goals must be achieved to commercialize fuel cell engines for automobiles. The first is to prove the reliability and durability of the fuel cell. Second, the cost of building the fuel cell engine must be reduced so that it is competitive with today's internal combustion engines (ICEs). Third, depending on the choice of fuel, infrastructure investments will have to be made to support wide-scale introduction. And fourth, public acceptance must be secured in order to create demand for this technology

 

What will it cost to maintain a fuel cell vehicle?

Real-life operating data is required to determine these figures; however, because fuel cell systems have substantially fewer moving parts, it is anticipated that maintenance costs will be lower than current Ices Automakers are designing vehicles that will meet or exceed today's standards - at least 5,000 hours or 150,000 miles of on-road use. Significant operating data from these vehicle demonstrations as well as transit bus demonstration programs will help determine maintenance expectations and requirements.

 

How much will fuel cost?

The answer depends on how the hydrogen is produced and delivered. Energy companies are working to provide a fuel that is comparable in price to conventional fuels.

 

When will a typical customer be able to buy a fuel cell vehicle?

Some automotive companies are aiming at delivering vehicles to the showroom in key markets by the end of the decade.

 

How does a fuel cell generate heat?

In any process, there are inefficiencies and/or losses. In a fuel cell, the useful work is electricity; however, not all of the energy contained in the hydrogen and oxygen can be turned into electricity. Inefficiencies in the fuel cell turn some of the available energy into heat. In a fuel cell, the inefficiencies are associated with four distinct processes:

    1) Activation Losses;
    2) Fuel Crossover Losses;
    3) Ohmic or Resistance Losses;
    4) Mass Transport Losses.

Activation losses are associated with the activity of the fuel cell - i.e. its ability to dissociate hydrogen and drive the chemical reaction at low temperatures. Activation losses are governed by the temperature and pressure of the reactants, the construction of the cell, and the type and amount of catalyst used.

Fuel crossover losses are caused by leakage or diffusion of fuel between the fuel cell anode and cathode. Essentially the fuel is "short-circuiting" its normal reaction path and reacting with oxygen directly at the cathode. As the electrons participating in the reaction have not been forced to travel through an electrical circuit to complete this reaction (and do useful work), the only energy produced is in the form of heat.

Ohmic or resistance losses are the result of the electrical resistance of the cell to current.

Mass transport losses occur when the ability to maintain adequate concentrations of hydrogen and oxygen in the fuel cell is limited by high demand.

All of these losses combine to produce heat in the fuel cell.



How large or small can a fuel cell be?

Fuel cells can be manufactured as large or small as necessary for the particular power application. Presently, there are micro fuel cells that are the size of a pencil eraser and generate only a few milliwatts of power while there are others large enough to provide the electrical needs of hundreds of homes. Since an individual fuel cell may theoretically produce an open circuit voltage of approximately 1 V, their power output is fully scalable by varying the cross-sectional area of each cell to obtain the desired current and by stacking multiple cells in series to obtain the desired voltage.

 

 
   
      References

[1]   Fuel Cell Canada

[2]   Hydrogen Energy Centre

[3]   Fuel Cells 2000