GLOBAL WARMING

~HOW FUEL CELLS CAN HELP SOLVE THE PROBLEM~

ABSTRACT

Energy has been the life-blood for continuing progress of human civilization. Since the beginning of industrial revolution around two hundred years ago, the global energy consumption has increased dramatically to accelerate our living standard, particularly in the industrialized nations of the world. Today, the major portion of world’s electrical energy is generated by fossil fuel and nuclear power plants.

Besides, burning of fossil fuels, it creates environmental pollution that causes global warming. Global warming causes sea level rise due to melting of glaciers and polar ice caps that inundates low-lying areas of the world. Besides, it creates adverse effect on world climate. The nuclear energy is free from environmental pollution, but it has safety and serious waste disposal problems.

Increasing emphasis on renewable energy sources, to some extent, will solve the above problems. Fuel cell is now destined to play a key role in the global energy conservation scenario.

The presentation will start with broad introduction about global warming, its causes and consequences, environmental pollution problems by fossil fuels. The important role of fuel cells as an alternate source of energy will be emphasized. The role of fuel cells in transportation systems and portable electronic devices will be discussed.

INTRODUCTION

Global warming is the increase in the average temperature of the Earth's near-surface air and the oceans. The Intergovernmental Panel on Climate Change (IPCC) concludes that anthropogenic greenhouse gases are responsible for most of the observed temperature increase since the middle of the twentieth century, and that natural phenomena such as solar variation and volcanoes probably had a small warming effect from pre-industrial times to 1950 and a small cooling effect afterward.

Global mean surface temperature anomaly relative to 1961–1990

CAUSES

GREEN HOUSE GASES

The excessive emission of green house gases are the major cause of global warming. The green house gases like carbon dioxide, methane, and nitrous oxide are playing hazards in the present times. These green house gases trap heat in earth’s atmosphere and thus result in increasing the temperature of earth.

The major source of carbon dioxide is the power plants. These power plants emit large amounts of carbon dioxide produced from burning of fossil fuels for the purpose of electricity generation. Coal is the major fuel that is burnt in these power plants. The coal gives out eighty percent more carbon per unit of energy as compared to natural gas. Another major source of carbon dioxide in the atmosphere is the emission from automobiles. About twenty percent of carbon

dioxide emitted in the atmosphere comes from burning of gasoline in the engines of the vehicles.

The second major greenhouse gas after carbon dioxide is Methane. Methane is more than 20 times as effectual as CO2 at entrapping heat in the atmosphere. Methane is obtained from resources such as rice paddy fields. When these fields are flooded, anaerobic situation build up and the organic matter in the soil decays, releasing methane to the atmosphere.

Nitrous oxide, which is a colorless gas with a sweet odour, is another green house gas. The main sources of nitrous oxide include nylon and nitric acid production, the use of fertilizers in agriculture and the burning of organic matter.

DEFORESTATION

Another major cause of global warming is deforestation. Trees collect the CO2 that we breathe out and they give back oxygen that we breathe in. Thus, cutting of trees is leading to greater concentration of carbon dioxide in the atmosphere. Greater urbanization, requirement of land for factories and buildings, requirement of timber are all reasons that are leading to deforestation.

CONSEQUENCES

An increase in global temperatures may in turn cause broader changes in the environment. Changes in the amount and pattern of precipitation may result in flooding and drought. There may also be extreme weather events. These changes are not likely to be reversible on timescales shorter than a thousand years. Other effects may include changes in agricultural yields, addition of new trade routes, reduced summer stream flows, species extinctions, and increases in the range of disease vectors.

A 2001 report by the IPCC suggests that glacier retreat, ice shelf disruption, sea level rise, changes in rainfall patterns, are attributable in part to global warming. Other expected effects include water scarcity in some regions, an expanse of the subtropical desert regions, changes in mountain snow pack, and adverse health effects from warmer temperatures.

FOSSIL FUEL AND IT'S IMPACT ON THE ENVIRONMENT

Fossil fuel can be defined as "incompletely oxidized and decayed animal and vegetable materials, specifically coal, peat, lignite, petroleum and natural gas". We retrieve these fossil fuels from the ground and under the sea and have them converted into electricity. Approximately 90% of the world's electricity demand is generated from the use of fossil fuels.

Combustion of these fossil fuels is considered to be the largest contributing factor to the release of greenhouse gases into the atmosphere. The harmful outcomes of converting fossil fuels to energy are air pollution, water pollution and accumulation of solid waste.

Air pollution is another problem arising from the use of fossil fuels, and can result in the formation of smog. Other than causing human illness, smog can also affect the sustainability of crops.

When coal is burned, it releases nitrous oxide. Unfortunately this is kept in the atmosphere for very long time. The harmful impact of this chemical could take up to a couple of hundred years to make itself known. Nearly 50% of the nitrogen oxide in the atmosphere and 70% of sulfur dioxide are direct result of emissions released when coal is burned.

Converting fossil fuels may also result in the accumulation of solid waste. This type of accumulation has a devastating impact on the environment. This type of waste also increases the risk of toxic runoff which can poison surface and groundwater sources for many miles. Toxic runoff also endangers surrounding vegetation, wildlife, and marine life.

We have become a very energy greedy generation and our demands for electricity are very high. As far as reducing these harmful effects, we must first reduce our demand and also find an alternate source of energy like fuel cells, tapping non conventional energy resources that least harms the environment with a very effectual usage.

FUEL CELLS

A fuel cell is an electrochemical conversion device. It converts energy of fuels directly into electricity without combustion. It produces electricity from fuel (on the anode side) and an oxidant (on the cathode side), which react in the presence of an electrolyte. The reactants flow into the cell, and the reaction products flow out of it, while the electrolyte remains within it. Many combinations of fuel and oxidant are possible. A hydrogen cell uses hydrogen as fuel and oxygen (usually from air) as oxidant. Other fuels include hydrocarbons and alcohols, propane-oxygen fuel cells.

The general reaction is

Fuel + Oxygen Oxidation product + Energy

HISTORY OF FUEL CELLS

The principle of the fuel cell was discovered by German scientist Christian Friedrich Schönbein in 1838. Based on this work, the first fuel cell was demonstrated by Welsh scientist Sir William Robert Grove in the February 1839. The fuel cell he made used similar materials to today's phosphoric-acid fuel cell.

In 1955, W. Thomas Grubb, a chemist working for the General Electric Company (GE), further modified the original fuel cell design by using a sulphonated polystyrene ion-exchange membrane as the electrolyte.

Sketch of William Grove's 1839 fuel cell

United Technologies Corporation's UTC Power subsidiary was the first company to manufacture and commercialize a large, stationary fuel cell system for use as a co-generation power plant in hospitals, universities and large office buildings.

WORKING OF FUEL CELL (H2 – O2 FUEL CELL)

The hydrogen–oxygen fuel cell consists of two porous electrodes anode and cathode. Hydrogen (the fuel) is bubbled through the anode compartment, where it is oxidized. The oxygen (oxidizer) is bubbled through the cathode compartment, where it is reduced.

AT CATHODE:

The electrons produced at the anode pass through the external wire to the cathode, where it is absorbed by oxygen and water to produce hydroxide ions.

O2 + 2H2O + 4e- 4OH-

AT ANODE:

Hydrogen molecules are oxidized at the anode with the liberation of electrons, which then combine with hydroxide ions to form water.

2H2 + 4OH- 4H2O + 4e-

OVERALL CELL REACTION:

2H2 + 2O2 2H2O

ADVANTAGES OF FUEL CELLS

1. Reduced carbon footprint

When fuelled by pure hydrogen the only by-product is water. The inherent higher efficiency of a well integrated fuel cell installation can significantly reduce your carbon footprint.

2. Highly efficient

Electrochemical conversion of the fuel is more efficient than combustion and it produces more electricity per kilowatt of input fuel.

3. Virtually silent and vibration free

The electrochemical process used by fuel cells means there are no moving parts to generate noise or vibration.

4. Highly reliable

The lack of moving parts means fuel cells can be an incredibly reliable source of energy.

5. High quality power

Fuel cells provide a virtually perfect sine wave for sensitive electronic equipment.

6. Continuous source of energy

The fuel is continuously supplied to produce power.

7. Pollution free working

There are no objectionable by–products and therefore, they do not cause pollution problems.

FUEL CELLS IN REDUCING GLOBAL WARMING

In traditional methods of generating electricity, the fuel and air are burned, generating a high-temperature gas. In the case of a coal-burning power plant, heat is transferred from this hot gas to high pressure liquid water that is boiled. In the case of, diesel engine, the hot gas itself is at high pressure. The high-pressure hot gas is expanded in a mechanical device (e.g. turbine) and ultimately turns on an electrical generator.

In a fuel cell, the same basic chemical reactions occur, but generate electricity directly as an electrochemical device and therefore, never go through the step of being a high-temperature gas through normal burning. This direct conversion of chemical energy to electrical energy is more efficient and generates much less pollutants than do traditional methods that rely on combustion. The direct conversion of fuel and air to electricity is much more efficient than internal combustion engines and other methods of generating electricity. Therefore, fuel cells can generate more electricity from the same amount of fuel.

Furthermore, by skipping the combustion process that occurs in traditional power-generating methods, the generation of pollutants during the combustion process is avoided and thereby global warming is reduced.

FUEL CELL APPLICATIONS

RACE VEHICLES

Fuel cell powered race vehicles, designed and built by university students from around the world, competed in the world's first hydrogen race series called the 2008 Formula Zero Championship, in Rotterdam, the Netherlands.

Element One fuel cell vehicle

HYDROGEN FUEL CELL TRANSPORTATION

The GM 1966 Electrovan was the automotive industry's first attempt at an automobile powered by a hydrogen fuel cell. The Electrovan, which weighed more than twice as much as a normal van, could travel up to 70mph for 30 seconds.

The 2001 Chrysler Natrium used its own on-board hydrogen processor. It produces hydrogen for the fuel cell by reacting sodium borohydride fuel with Borax, both of which Chrysler claimed were naturally occurring in great quantity in the United States. The hydrogen produces electric power in the fuel cell for near-silent operation and a range of 300 miles without impinging on passenger space.

Toyota fuel cell vehicleIn 2005 the British firm Intelligent Energy produced the first ever working motorcycle which run by fuel cell, called the ENV (Emission Neutral Vehicle). The motorcycle holds enough fuel to run for four hours, and to travel 100 miles in an urban area, at a top speed of 50 miles per hour..

A hydrogen fuel cell public bus in Perth, Australia

.AIRCRAFT INDUSTRY

Boeing researchers and industry partners throughout Europe conducted experimental flight tests in 2007 of a manned airplane powered only by a fuel cell and lightweight batteries. The Fuel Cell Demonstrator Airplane research project was completed recently and thorough systems integration testing is now under way in preparation for upcoming ground and flight testing. The Boeing demonstrator uses a Proton Exchange Membrane (PEM) fuel cell/lithium-ion battery hybrid system to power an electric motor, which is coupled to a conventional propeller.

FUEL CELLS IN PORTABLE ELECTRONIC DEVICES

LAPTOPSA new scheme for creating a compact device that efficiently converts methanol into hydrogen could make it practical to incorporate fuel cells into laptop computers and other portable electronics. Such a device could allow a laptop to run for 50 hours and be recharged instantly by swapping in a small fuel pack.

OTHER ELECTRONIC DEVICES

Fuel cell is packaged into portable devices such as cellular phones, digital cameras, camcorders, and power tools. Portable devices are seen as employing up to 100 watt hours of energy, with supplemental energy available through refueling cartridges.

Examples include:

Cellular Phones (1 - 3 W) Camcorders (2 -5 W) Cordless Tools (20 - 200 W)

POWER GENERATORS

Small Portable Power Generators refer to units up to 20 pounds in weight, up to 3 - 5 KW power. Examples of applications include power for camping and other recreational activity or short-term power in an emergency.

OTHER APPLICATIONS

Base load power plants Electric and hybrid vehicles. Auxiliary power Off-grid power supply Notebook computers for applications where AC charging may not be

available for weeks at a time. Portable charging docks for small electronics (e.g. a belt clip that charges

your cell phone or PDA). Smart phones with high power consumption due to large displays and

additional features like GPS might be equipped with micro fuel cells. Energy source in space vehicles, submarines and other military

applications.

CONCLUSION

In this paper an efficient way in reducing global warming by the use of fuel cells has been emphasized. Hence it clearly reveals that fuel cell products are pollution free. There are researches and studies happening around the world to implement fuel cells in transportation and portable electronic devices in large scale in a cost effective manner. So a pollution free earth with less global warming is not far ahead.

FUTURESCOPE

There has been a concerted effort in some countries to move to less polluting forms of public transport. In India, Delhi ranks as one of the world’s worst cities for urban air pollution, banned diesel buses from its streets and plans to use hydrogen in internal combustion engines, and eventually to install fuel cells.

A survey envisages that one million hydrogen fuelled vehicles will be on Indian roads by 2020. REVA, the electric car company, manufacturer of India’s first electric car, has a fuel cell version of the REVA-EV at developmental stage.

The REVA fuel cell car

The Department of Science and Technology (DST) has established a Centre for Fuel Cell Technology (CFCT) located in Chennai with the specific objective of demonstrating and validating commercial applications of PEM fuel cells in collaboration with industries.

~ BY ~

ARJUN.R.PALANIAPPAN

CE ID: 9df8296aecafd33e60d8e4470e54e95693d3bb45