In this article we will discuss about:- 1. Introduction to Fuel Cell Vehicles 2. History of Fuel Cells 3. How Fuel Cells Work? 4. Working 5. Types 6. Fuels for Fuel Cell Vehicles 7. Advantages 8. Cost Economics and Future Trends 9. Status 10. Indian Status.
Contents:
- Introduction to Fuel Cell Vehicles
- History of Fuel Cells
- How Fuel Cells Work?
- Working of a Fuel Cell
- Types of Fuel Cells
- Fuels for Fuel Cell Vehicles
- Advantages of Fuel Cell Vehicles
- Cost Economics and Future Trends of Fuel Cells in Vehicles
- Status of Fuel Cell Vehicles
- Indian Status of Fuel Cells
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1. Introduction to
Fuel Cell Vehicles:
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“In this century, the greatest environmental progress will come about… through technology and innovation. Tonight, I am proposing $1.2 billion in research funding so that America can lead the world in developing clean, hydrogen- powered automobiles… With a new national commitment, our scientists and engineers will overcome obstacles to taking these cars from laboratory to showroom, so that the first car driven by a child born today could be powered by hydrogen, and pollution-free”
— President George W. Bush, State of the Union Address, January 28, 2003.
Fuel cells are starting to hit the roads, in demonstration and validation projects around the world. Most auto makers feel they can bring fuel cell vehicles to the public by 2010.
Fuel cell engines use chemistry to generate power and do not burn the fuel. This means fuel cells produce no waste gases or other pollution. The only emissions from fuel cell vehicles are heat and pure water.
Fuel cell engines are two to three times more efficient than today’s motor vehicle engines. That means energy saving for the consumer, energy security for the nation and a cleaner environment. Fuel cells have many other benefits that today’s car engines cannot match. They can generate pollution free electricity while the car is parked, electricity to power a home or even a neighbour’s home through the electric grid. They can even supply supplemental energy back to the grid during peak hours and getting paid for it.
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According to William C. Ford Jr. of Ford motors, “I believe fuel cell vehicles will finally end the hundred year reign of the internal combustion engine as the dominant source of power for personal transportation. It’s going to be a winning situation all the way around-consumers will get an efficient power source, communities will get zero emissions, and automakers will get another major business opportunity-a growth opportunity”
According to K. Ataken Ozbek of Allied Energy Intelligence, “by the second decade of the century, mass production of automobile fuel cells will result in a glut in the world oil supply and then in a total rejection of oil as a vehicle fuel”. Allied Business Intelligence estimates that “U.S market penetration in 2010 could rise as high as 1.2 million vehicles representing 7.6 per cent of U.S. market”.
Fuel cells have the power to change our future. Fuel cells will power the car of tomorrow-quieter, cleaner and more energy efficient, with equivalent range of performance. The benefits will be extra ordinary, in national energy security, cleaner air and economic opportunity.
About 25% of all human-generated greenhouse gases come from transportation. Because fuel cells significantly reduce greenhouse gases and other pollutant emissions, it is an important strategy/technology in the fight against global warming and other pollution problems.
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2. History of Fuel Cells
:
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In 1839, Sir William Robert Grove discovered that hydrogen and oxygen could be combined to produce water and electric current. The technology developed slowly through the years, with scientists building and improving on earlier research. In 1932, Francis Bacon developed the first successful fuel cell device, a hydrogen oxygen cell using alkaline electrolytes and nickel electrodes.
NASA scientists took advantage of this discovery in the 1950s, developing fuel cells to power space exploration vehicles and produced drinking water for the crew. Today, fuel cell technology is being developed to power cars and buses, office buildings and homes, cellular phones and laptop computers and everything in between.
For transportation, “PEM” fuel cells were developed in 1991. In April 1994 Mercedes Benz developed and demonstrated the first fuel cell Bus.
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3. How Fuel Cells Work
?
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Hydrogen fuel-from a storage tank or produced on-board the vehicle (from a variety- of fuels), is fed through channels in one bipolar plate. Oxygen (drawn from the air) enters the fuel cell through another bipolar plate.
A platinum catalyst starts a reaction which strips an electron from the hydrogen. These electrons create a current that flows to an electric motor that drives the wheels. The positive hydrogen ions pass through the electrolyte membrane.
The electric current coming back from the motor joins with positively charged hydrogen ions and oxygen at another platinum catalyst, where the two elements combine. Water and heat are the only “emissions”. Hydrogen is fed into the “anode” of the fuel cell.
4. Working of a Fuel Cell
:
The following reactions occur in a fuel cell:
Anode Reaction:
2H2 = 4 H + + 4e–
4H + 4 e– + O2 = 2H2O.
H2 is a hydrogen molecule
O2 is an oxygen molecule
H2O is a water molecule and
H+ is ionized hydrogen (proton)
e– is an electron.
Hydrogen can be supplied directly from the storage tanks on the vehicle or by extracting it on board from hydrogen rich fuels like methanol. This process is known as “fuel reforming”. Many developments have taken place in fuel reforming technology to expand the fuels that can be processed on-board to generate hydrogen.
Arthur D. Little, a US company has developed a flexible fuel reformer, which can reform ethanol, methanol, natural gas and gasoline through a technique known as “partial oxidation”. Arco and Exon are also working on gasoline to hydrogen reforming techniques.
5. Types of Fuel Cells
:
Based on the electrolyte used, there are various types of fuel cells with different operating temperatures, power densities and applications. Phosphoric acid, Proton Exchange Membrane (PEM), molten carbonate, solid oxide and alkaline types of fuel cells have been developed in the recent years.
Both phosphoric acid and proton-exchange membrane fuel cells are being used in vehicles. However proton exchange membrane (PEM) fuel cells are the preferred choice due to their higher power density, lower operating temperatures, and simplicity of operation.
Phosphoric Acid Fuel Cells (PAFC) are the most mature fuel cell technology. This type of fuel cell is commercially available today. Existing PAFC’s have outputs upto 200kw, and 1 mw units are under commercial trials. PAFC’s generates electricity at 40% efficiency — and nearly 85% of the steam this fuel cell generates is used for co-generation.
Operating temperatures of this fuel cell are in the range of 150-200 degrees centigrade. The electrolyte is liquid phosphoric acid. One of the main advantages of this type of fuel cell is that it can use impure hydrogen as fuel. The major disadvantage is that it has a large size and weight.
Proton exchange membrane (PEM) fuel cells operate at relatively low temperatures (about 80°C), have high power density, can vary their output quickly to meet shifts in power demand and are suited for applications-such as in automobiles-where quick start up is required. The proton exchange membrane is a thin plastic sheet that allows hydrogen ions to pass through it.
The membrane is coated on both sides with highly dispersed metal alloy particles (mostly platinum) that are active catalysts. The electrolyte used is a solid organic polymer, poly-perflouro sulfonic acid. The solid electrolyte is an advantage because it reduces corrosion and management problems. Hydrogen is fed to the anode side of the fuel cell where the catalyst encourages the hydrogen atoms to release electrons and become hydrogen ions (protons).
The electrons travel in the form of an electric current that can be utilised before it returns to the cathode side of the fuel cell where oxygen has been fed. At the same time, protons diffuse through the membrane (electrolyte) to the cathode, when the hydrogen atom is recombined and reacted with oxygen to produce water, thus completing the overall process. This type of fuel cell is, however sensitive to fuel impurities. Cell outputs generally range from 50 to 250 kw.
6. Fuels for Fuel Cell Vehicles
:
Fuel cells need hydrogen gas to generate electricity. In fuel cell vehicles, this is provided by storing hydrogen in the vehicle or using other fuels such as methanol, ethanol, natural gas and gasoline which are converted to hydrogen on board the vehicle through a process called reforming.
When hydrogen is used directly as a fuel, it has to be stored either in the form of a cryogenic liquid or as compressed gas. Other options for hydrogen storage include metal hydride.
The advantages of using hydrogen in a fuel cell are:
1. The vehicle will be a zero emission vehicle with only water vapour as the emission.
2. The design is simpler and
3. The energy efficiency is higher.
The major disadvantage is that the necessary infrastructure for refilling hydrogen is expensive and needs to be developed.
Among the other fuels, methanol is the leading contender due to the ease of reforming as well as the ease of storage and refueling, since it is a liquid at room temperature. The development of infrastructure is, therefore, relatively easier. Methanol is commonly produced from natural gas. Methanol can also be produced from bio mass which is renewable.
Flexible fuel processors that convert fuels like methanol, natural gas, gasoline and ethanol to hydrogen on board the vehicle have recently been developed. These are advantageous since necessary infrastructure for natural gas and gasoline is already in place.
The disadvantage of using these fuels is that the vehicle would not be a zero emission vehicle since traces of carbon dioxide (CO2) and hydrocarbons (HC) are released during the reforming process. These would be significantly lower than the emissions from conventional vehicles.
7. Advantages of Fuel Cell Vehicles
:
In addition to zero or low emissions, fuel cells have various advantages, which make them attractive compared to the conventional internal combustion engines.
Their major features and advantages are summarised as follows:
1. Fuel cell vehicles produce very little emissions compared to conventional vehicles. If hydrogen is used as the fuel, the only emission is water vapour and the vehicle is a zero emission vehicle. If other hydro carbons are used, there will be trace emissions of CO2 and HC.
2. In fuel cell vehicles, since chemical energy is directly converted to electricity, no energy is lost to heat. In addition, since there are fewer moving parts, the efficiency is increased further. As a result, they are twice as efficient as gasoline internal combustion engine vehicles, where considerable energy is lost to waste heat and friction. While current gasoline engines have efficiency in the range of 20%, the fuel cell efficiency is generally around 40%.
3. Compared to battery operated electric vehicles, fuel cells are more practical to use. The fuel is continuously fed to the cell and is refueled as in a gasoline engine. In a battery powered vehicle, recharging the battery is a time consuming process and reduces the range of the vehicles. The fuel cell vehicles can attain the same range as vehicles fitted with internal combustion engines.
4. Fuel cells are modular and can be configured into a relatively wide array of shapes to fit available on-board space.
5. With practically no moving parts, fuel cell vehicles require no oil for lubrication and general maintenance.
6. Fuel cell vehicles will be more comfortable than conventional vehicles since there is no transmission and no noise.
8. Cost Economics and Future Trends of Fuel Cells in Vehicles
:
For vehicle application, proton exchange membrane fuel cell appears to be the most mature technology. However the key to adaptation of any technology by the consumers is the price. Present cost of internal combustion engines is about U.S $50 per kw. whereas fuel cell costs today work out to be about U.S $5000 per kw. Therefore various measures of cost cutting are to be adopted in the major segments of fuel cell stack, reformer cost and other components.
Once the cost cutting is achieved, fuel cells will power the two wheelers, cars and buses of tomorrow. The benefits of increased share of fuel cell vehicles results in national energy security, cleaner air and economic opportunity.
9. Status of Fuel Cell Vehicles
:
Fuel cells are modular, scalable and fuel flexible, characteristics that make them excellent candidates for a wide range of applications in vehicles. Buses, vans, cars, bicycles and scooters with on-board electrical outlets are under extensive trials in different countries. Many of the major vehicle manufacturers have significant research, development and demonstration projects going. Some of the oil companies are also involved in these projects.
Ballard power systems, Canada demonstrated the first hydrogen – powered, proton exchange membrane technology (PEM) fuel cell bus in 1993. In 1997, Diamler Benz formed a joint venture with Ballard power systems, Canada to develop fuel cell cars and buses. Their fuel cell bus reached the level of commercial prototype and matches the performance of a conventional diesel bus.
Diamler Benz made fuel cell buses are on extensive trials with Stuttgart City Transport, Chicago Transit Authority, New York Transit Authority and in the city of Van couver, Canada. Studies indicate that most of the important parameters like power, torque, gradability and acceleration of those vehicles are satisfactory compared to the existing buses of similar capacity. The Diamler chrysler has plans to manufacture and sell 500 fuel cell buses during 2004.
Some of the major vehicle manufacturers like Honda, Toyota, Hyundai, GM, Ford, Diamler Chrysler, Volkswagen, etc. have fuel cell vehicles either in development or in commercial testing.
In the U.S, legislation requiring 10% of all vehicles sold to be zero emission vehicles in the States of California, New York, and Massachusetts provided an opportunity for large scale entry for fuel cell vehicles in U.S.A. Freedom CAR is a new cooperative research effort between the Department of Energy (DOE) and the U.S council for Automotive Research (Ford, General Motors, and Diamler Chrysler), formed to promote research into advanced automotive technologies, such as fuel cell vehicles.
In addition, the “California Fuel Cell Partnership”, an alliance of auto manufacturers, oil companies, fuel cell technology companies and the State of California, plans to develop and introduce 60 fuel cell passenger cars and buses between 2000 and 2003 for demonstration and evaluation. This is a step towards their goal of commercializing fuel cell vehicles.
Other strategic alliances such as “National Fuel cell Alliance” and “Partnership for New generation of vehicles”, comprising government agencies, auto makers, fuel cell developers and research organizations are playing a significant role in facilitating the introduction of fuel cell vehicles. In Europe, government sponsored trials and incentives are under way to introduce fuel cell technology on a large scale.
Densely populated countries like China, India, Bangkok and Japan rely heavily on two stroke two wheelers for personal transport. These vehicles (generally fitted with a two-stroke gasoline engine) actually pollute more than cars and buses and are beginning to be banned in some Asian cities. Fuel cell two wheelers may be the solution for pollution produced by these two-stroke engined vehicles.
Asia Pacific fuel cell technologies (APFCT) has developed and demonstrated a 1kw PEM fuel cell stack (for zero emission scooters) which can develop a top speed of 58kms per hour and a range of 120 kms at 30 kms/hr. The hydrogen fuel is stored in hydride canisters. Yamaha Motor Company has developed a methanol — powered fuel cell for motor cycles. It is now developing a 50 CC fuel cell scooter.
A prototype reached 40 kms per hour with an output of 500 watts. Palcan Fuel cells have integrated their 2 kw fuel cell stack system into a scooter, to be marketed in Asia and India. Palcan’s fuel cell scooter uses the company’s metal hydride hydrogen storage technology.
Aprilia/Manhatten Scientifics unveiled a fuel cell assisted bicycle in 2000. The bicycle which uses a 600 watt PEM fuel stack and is fueled by compressed hydrogen can reach 32 kms per hour speed.
10. Indian Status of Fuel Cells
:
Basic research and institutional base has been created for implementing research, development and demonstration projects in fuel cells in the country. Bharat Heavy Electricals Limited, Hyderabad has developed 50 kw fuel cell power plant. The SPIC Foundation, Chennai has developed an improved version of 5 kw fuel cell module.
Indian Institute of Technology, Chennai, in collaboration with SPIC Foundation is developing 250 watt direct methanol fuel cell stack. The Indian Institute of Chemical Technology, Hyderabad and BHEL Hyderabad have developed catalysts and reformers for reformation of methanol into hydrogen for fuel cells.
The Ministry of non-conventional Energy Sources has received funding from the United Nations Development Programmes Global Environment Facility (GEF) to carry out a feasibility study and develop a blue print for fuel cell bus introduction in India.
For effective and earlier introduction of fuel cell vehicles in India, it may be necessary to form alliances involving stake holders as in California U.S.A. Alliances can include vehicle manufacturers, fuel cell producers, research institutes and the government. Such alliances can play a crucial role and help in cost-and-risk-sharing during the initial stages.