GREEN TECHNOLOGY AS AN ALTERNATIVE FUEL IN I.C. ENGINES SEMINAR REPORT

“GREEN TECHNOLOGY AS AN ALTERNATIVE FUEL IN I.C. ENGINES”

TABLE OF CONTENTS

TOPIC                                                                                                                   PAGES

Acknowledgement                                                                                                   2

Preface 3

Certificate                                                                                    4

CHAPTER 1: INTRODUCTION                                                                                            7

CHAPTER 2: MANUFACTURE OF METHANOL                                                              8

          2.1: METHANOL FROM COAL                                                                                8

          2.2: METHANOL FROM MUNICIPAL SOLID WASTES                                     8-9

CHAPTER 3: MANUFACTURE OF ETHANOL                                                                        10-12

          3.1: ETHANOL FROM GRAINS                                                                              10

          3.2: ETHANOL FROM SUGARCANE                                                                         11-12

CHAPTER 4: ALCOHOL V/S GASOLINE FUEL                                                                    13-15

          4.1: COMPARISON OF PROPERTIES OF DIFFERENT FUELS                           13

       4.1.1: AIR FUEL RATIO                                                                                               13

       4.1.2: CHEMISTRY OF COMBUSTION                                                                       13

       4.1.3: CALORIFIC VALUE                                                                                             13

       4.1.4: LATENT HEAT OF VAPORIZATION                                                                 13

       4.1.5: VOLATILITY                                                                                                         13

       4.1.6: VAPOR PRESSURE                                                                                               14

       4.1.7: OCTANE QUALITY                                                                                               14

       4.1.8: WATER TOLERANCE OF ALCOHOL BLENDS                                                14

       4.1.9: EFFECT IN PRESENCE OF GUMS 15

CHAPTER 5: ALCOHOL AS DIESEL FUEL                                                                               16

CHAPTER 6: ANOTHER ADVANCE ALTERNATIVE FUEL FOR I.C. ENGINE       16-19

     6.1 HYDROGEN       16-17

     6.2 PROPANE 17

     6.3 BIODIESEL 18

      6.4 ELECTRICITY 19

CONCLUSION                                                                                                                  20

REFERENCE                                                                                                                         21

LIST OF FIGURES

DESCRIPTION                                                                                                              PAGE

1.1 ALTERNATIVE FUEL 9

2.1 METHANOL PRODUCTION FROM MUNICIPAL SOLID WASTES 13

2.2 ALTERNATIVE FUEL 13

3.1ETHANOL PRODUCTION FROM GRAINS                                                14

3.2 ETHANOL PRODUCTION FROM SUGARCANE            16

3.3   ENERGY BALANCE OF ETHANOL 18

6.1 HYDROGEN ATOM STRUCTURE             23

6.1(B) FUEL CELL BUS             24

6.2 PROPANE OR L.P.G.             25

6.3 ATOMIC STRUCTURE OF PROPANE            25

6.4 ATOMIC STRUCTURE OF BIODIESEL            27

6.5 CORN PRODUCES ALTERNATIVE FUEL            28

CHAPTER 1

INTRODUCTION

The rapid depletion of petroleum fuels and their ever increasing costs have led to an intensive search for alternative fuels. The most promising substitute for petroleum fuels are the alcohols – mainly methanol and ethanol. These alcohols can be readily made from a number of non-petroleum sources. Methanol or methyl alcohol (CH3OH) can be produced from coal, a relatively abundant fossil fuel. Ethanol or ethyl alcohol (C2H5OH) can be produced by fermentation of carbohydrates which occur naturally and abundantly in some plants like sugarcane and from starchy materials like corn and potatoes. Hence these fuels can be from highly reliable and long lasting raw material sources.A non- conventional fuel or advanced fuel are any substance that can be used as fuel other than conventional fuels as fossil fuels as well as nuclear materials like U & Th.  

Steadily escalating gasoline prices, increased environmental concerns, and poor international politics have sparked new interests for alternatively fueled vehicles. There are numerous alternative fuel technologies including gasoline-hybrids, diesels, full electrics, as well as hydrogen and ethanol. These technologies are changing rapidly and consumers are having difficulty trying to decipher which type of vehicle is the most worthy investment. This study provides a simple breakdown of the pros and cons of the alternative fuel technologies as well as a statistical review of the total ownership costs of the vehicle up to 100,000 miles.

It has been known since the invention of the internal combustion engines that alcohol could be used as a motor fuel. Alcohols were used in vehicles in the early part of this century, until low cost gasoline nearly forced them off the market. Since World War II the use of alcohol as a motor fuel has been reduced to less than one-tenth of the pre-World War II levels except in countries like Brazil, Cuba and Philippines where there is large supply of sugar-cane. Racing cars have always preferred and continue to prefer methanol as a fuel because of the increased power obtainable from the same engine over gasoline. We use these fuels because of these advance properties as

• As the cost of conventional fuels increase by the time.
• Alternative fuels are more environment friendly.
• Some alternative fuels are more energy efficient.

Increased gas prices as well as greater environmental concerns, have led many Americans to search for better alternatives to the conventional gasoline-powered automobiles. Due to misconception, confusion, and biased public opinion, consumers have been apprehensive towards alternatives such as diesel, gas-electric hybrids, all electric, as well as hydrogen and ethanol. With gasoline prices rising to record highs nation-wide, there has been increased interest in these vehicles. It is evident that clear and unbiased information on this topic is difficult to come by.

Through in-depth research including overall life-cycle cost, comparisons, and the analysis of other studies on the matter, the inquiries will be of importance to anyone who owns or is planning to own a passenger or sport utility vehicle. The results will include life costs, cost-to-benefit ratios, vehicle comparisons, and performance statistics. The analysis will be divided into three groups; 20 % city – 80 % highway, and 80% city –20% highway. These figures will be based off of these assumptions; 100,000 mile life span over a ten-year period, every vehicle will be bought new at the MSRP (Manufacturer’s Suggested Retail Price) including shipping and receiving, they will be driven in an equivalent manner, recommended factory service maintenance intervals will be followed, and lastly, fuel prices will be calculated from the peak prices as of July 17th, 2008. The outcome of this research is to enlighten the general public of the financial and environmental concerns on the alternatives to gasoline.

The study focused on the incentives necessary to increase the use of alternative fuels in public transit vehicles, including buses, fixed guideway vehicles and ferries, and considered the following aspects of alternative fuels:

1. Environmental benefits of increased use of alternative fuels in transit vehicles;

2. Opportunities currently available to transit system operators that encourage the purchase of alternative fuels for transit vehicle operation;

3. Existing barriers to transit system operators that discourage the purchase of alternative fuels for transit vehicle operation, including situations where alternative fuels that do not require capital improvements to transit vehicles are disadvantaged over fuels that do require such improvements.

4. Levels and types of support necessary to encourage additional use of alternative fuels for transit vehicle operation.

Figure 1.1 ALTERNATIVE FUEL

ALTERNATIVE DIESEL is the name for a variety of non-petroleum fuels and petroleum diesel blends that can be used in diesel engines. Some examples include biodiesel, Fischer-Tropsch diesel, and ethanol/diesel blends. Each promises emissions benefits compared to neat petroleum diesel. Petroleum diesel blends, though they contain alternative fuels, are not considered alternative fuels according to the Energy Policy Act definitions above.

• BIODIESEL is a fuel derived from vegetable oils or animal fats. It is typically blended with petroleum diesel at a concentration of 20 percent biodiesel (known as B20) as this blend represents a good balance of emission benefits, cost and risk of field problems. B20 is commonly used in diesel engines with no modifications.

• FISCHER-TROPSCH DIESEL is a synthetic diesel fuel made from coal, natural gas, or biomass feedstock via the Fischer-Tropsch process. The fuel has the same properties regardless of the feedstock. No engine modifications are required to use Fischer-Tropsch diesel, whether alone or blended with petroleum diesel.

• DIESEL/ALCOHOL BLENDS, also called diesohol or oxygenated diesel, are petroleum diesel blends containing up to 15 percent ethanol or methanol. These fuels are marketed under names such as O2Diesel™ and E-Diesel™. Diesel blends with low concentrations of ethanol can be used in existing engines without modifications.

ETHANOL is also known as ethyl alcohol or grain alcohol. It is primarily fermented from grains, such as corn or other agricultural products. The form of ethanol typically used in transportation is known as E85 and contains 15 percent gasoline. All flex-fuel light-duty vehicles are designed to use E85. During the 1990s, the Los Angeles County Metropolitan Transportation Authority operated an ethanol bus fleet.

METHANOL, also called methyl alcohol, is a clear, odorless liquid typically made from natural gas, though it can also be made from coal, wood or various grains. In heavy-duty vehicles, methanol is typically used unblended, though it is also sold as M85, which contains 15 percent gasoline. Methanol powered transit vehicles were used in significant numbers in the 1990s, when the Los Angeles County Metropolitan Transportation Authority operated more than 300 of them.

LIQUEFIED PETROLEUM GAS, also called propane or LPG, is a by-product of petroleum refining and natural gas processing. In the U.S., most propane comes from natural gas processing plants. Propane is gaseous at room temperature and atmospheric pressure but liquefies easily at moderate pressure (120 psig).

P-SERIES one of the alternative fuels designated by Department of Energy, is a proprietary gasoline substitute derived from approximately 70% renewable biomass for use in light and medium-duty vehicles. Since it is not a fuel suitable for the heavy-duty engines used in most transit vehicles, it was not considered further in this study.

NATURAL GAS comes in two forms: compressed (CNG) and liquefied (LNG). If the gas is compressed, it typically comes through a utility pipeline. If the gas is liquefied, it is typically delivered by tanker truck.

HYDROGEN is a developmental fuel. Like natural gas, it may be compressed or liquefied. Its use has been restricted to research and demonstration projects of buses with hydrogen internal combustion or fuel cell engines. A test fuel made of a hydrogen/natural gas blend is undergoing evaluation, and Section 1823 of the 2005 EPAct requires a DOE report to Congress regarding commercialization of Hythane, a proprietary mixture of hydrogen and natural gas. Fuel cell buses may be powered by hydrogen derived from fuels such as methanol if the bus is equipped with an on-board hydrogen reformer is delivered in one of two ways: directly, through a catenary wire or third rail, or indirectly, through a battery that must be charged offline or filled with chemicals that create an electric potential when combined. Electric-drive hybrid vehicles use batteries, but they are not purely electric vehicles. In electric-drive hybrid propulsion systems, diesel, gasoline or an alternative e fuel is used by an engine or fuel cell to generate electricity to drive the wheels. The electricity is stored in a battery, and regenerative braking is typically used to capture kinetic energy otherwise lost in stop-and-go urban driving. The engine or fuel cell may also provide a direct mechanical drive.

CHAPTER 2

MANUFACTURE OF METHANOL

Methanol can be produced from a wide range of abundantly available raw materials lignite or coal, municipal solid wastes and waste or specifically grown biomass. Of course methanol can also be produced from natural gas but there is no point in it because the basic objective is to conserve petroleum gases or liquids.

1. METHANOL FROM LIGNITE OR COAL:

A schematic diagram of a plant for producing methanol from lignite or coal is shown in the following figure:

Pulverized lignite or coal is fed to steam/oxygen-blown gasifiers (partial combustors) to produce a synthesis gas consisting of CO and H2.

H2O + C → CO + H

Gasification also produces acidic contaminations such as H2S and CO2. All H2S and most of the CO2 are removed by scrubbing the synthesis gas with an amine solution. The H2S is later recovered as elemental sulfur. Subsequently, part of the clean synthesis gas undergoes a CO shift conversion to adjust the H2|CO|CO2 ratios to the necessary values. This conversion produces additional CO2, which is partly removed by amine scrubbing, and then the shifted gas is mixed with the remainder of the synthesis gas. Methanol synthesis, via the low pressure process with a Cu/Zn/Cr catalyst, is the final step. The theoretical reaction is

CO + 2H2 → CH3OH

The raw material is then purified to remove water. Currently, aldehydes and higher alcohols are also removed after methanol synthesis, but this is not necessary for methanol to be used as a motor fuel.

2. METHANOL FROM MUNICIPAL SOLID WASTE:

The waste can be converted to methanol. The wastes are first shredded and then passed under a magnet to remove ferrous materials. The iron free wastes are then gasified with oxygen. The product synthesis gas is cleaned by water scrubbing and other means to remove any particulates, entrained oils, H2S and CO2. CO-shift conversions for H2|CO|CO2 ratio adjustment, methanol synthesis, and methanol purification are accomplished in a manner similar to that for lignite feed.

Fig 2.1 Methanol production from municipal solid wastes.

Figure 2.2 Alternative fuels

CHAPTER 3

MANUFACTURE OF ETHANOL

The process of production of ethanol from sugarcane or grain is well known. It does not require extreme temperature and pressure and thus very small units are possible. Basically, the starch in grain is converted to sugar by means of enzymes and then sugar is fermented with yeast to produce a dilute alcohol solution. Distillation is used to separate and purify the alcohol solution. Distillation is used to separate and purify the alcohol to a maximum of about 190 proof. If 200 proof (anhydrous) is required an additional operation usually distillation with benzene is required.

3.1 ETHANOL FROM GRAINS: Ethanol can be manufactured from any feed stock containing carbohydrates such as corn, wheat, maize, sugar beets, potatoes, sugarcane and other grains.Production of ethanol from grains such as corn is shown schematically in the given figure. The grain is first ground and cooked with water to convert the starch to sugar with the enzyme analyses. The sugar is then fermented with yeast to produce raw ethanol and a high protein material commonly known as distillers dried grain (DDG). The raw ethanol is distilled to remove impurities such as higher alcohols and to remove most of the water. Ethanol forms an azeotrope with 5 percent water, and the last step in producing anhydrous ethanol is an extractive distillation with benzene. The DDG is dried and recovered for sale as a cattle feed. The optimum capacity of an ethanol fermentation plant is small because of the difficulties in controlling and storing raw materials and typically would be about 1.4 million barrel per stream day.

Fig. 3.1 Ethanol production from grain

3.2 ETHANOL FROM SUGARCANE:

Production of ethanol from sugarcane requires only simple, well established processes since the fermentable sugar is obtained directly from the sugarcane. The cane is first cut and ground, and the cane juice is extracted by maceration. After clarification by filtration and concentration through evaporation, the juice is fermented with yeast to yield raw ethanol. A series of distillation steps, including a final extractive distillation with benzene are used to obtain anhydrous ethanol.Ethanol is produced by fermentation of carbohydrates by the Gay Lusaac relation:

C6H12O6→2C2H5OH+2CO

In this process 180 gm. of carbohydrate are converted to liquid fuel ethanol weighing only 92 gm with almost no loss of energy. About 1.5 kg of sugar yields a liter of ethanol. Following figure shows conversion of sugarcane to ethanol in a sugar factory via the molasses route and next figure by direct fermentation of cane juice. Molasses contain a large percentage of sugar, 30% or higher and most of the nutrient content that was in cane such as nitrogen, potassium and phosphorous. The normal yield of ethanol is about 8.73 liters of alcohol per tone of cane processed in a sugar factory. Even taking yield to be as low as 4 liters per ton the potential of ethanol production in India is about 475 million liters per year.

Fig. 3.2 Conversion of sugarcane to alcohol. (Top schematic shows the indirect route where alcohol is a byproduct of sugar. Direct conversion is shown in bottom schematic)

FIGURE 3.3   ENERGY BALANCE OF ETHANOL

CHAPTER 4

ALCOHOL v/s GASOLINE FUELS

4.1 COMPARISON OF PROPERTIES OF ALCOHOLS AND GASOLINE AS ENGINE FUELS:

All the alcohols have a common feature. Their molecular structure includes an OH, or hydroxyl radical, which give them certain characteristics, high solubility in water. Their water-like characteristics are most apparent in the alcohols of low molecular weight, methanol and ethanol, because the OH radical predominates over their short hydrocarbons chains. They are least apparent in the alcohols of high molecular weight, tertiary butyl or heavier alcohols, because their longer hydrocarbon chains predominate over the OH radical.

The properties of a typical gasoline used as I.C. Engine fuel and two alcohols, namely methanol and ethanol, are given in the following table:

1. AIR FUEL RATIO:

Because of the fixed oxygen the quantity of air required for a stoichiometric combustion of the alcohols is considerably lower than that required for petrol.

2. CHEMISTRY OF COMBUSTION:

When the fuel and air react in an engine cylinder to produce products of combustion, the product is different than the number of moles of reactant. The ratio of moles of products to reactants for gasoline and alcohols is as follows:

OCTANE

1.058 C8H18 + 12.5 O2 → 8 CO2 + 9 H2O + 47 N2‬‬‬‬‬

  (60.5 moles)                     (64.0 moles)

METHANOL

1.061 CH3OH + 1.5 O2 + 5.65 N2 → CO2 + 2 H2O + 5.65 N3

  (8.15 moles)                                            (8.65 moles)     

ETHANOL

1.065 C2H5OH + 3 O2 + 11.3 N2 → 2 CO2 + 3 H2O + 11.3 N2

    (15.3 moles)                                           (16.3 moles)  

3. CALORIFIC VALUE:

Because of its chemical structure, the alcohol molecule contains fixed oxygen. This results in a lower calorific value than that of petrol. To generate equal amount of energy (43960/19680) = 2.2 or more than double the weight of methanol compared to gasoline is required, and (43960/26800) = 1.64 or approximately 64% greater weight of ethanol compared to gasoline is required.

4. LATENT HEAT OF VAPORIZATION:

In comparison with gasoline, the alcohols have a very high latent heat of vaporization. For methanol it is 3.77 times and for ethanol it is 2.91 times that of gasoline in a stoichiometric mixture of liquid gasoline and air results in an air temperature reduction of approximately 4.5ºC. For the alcohols temperature drop will be greater, increasing the volumetric efficiency and the power output. This is the reason for the popularity of methanol as a straight factor blending constituent for racing cars.

5. VOLATILITY:

Gasoline is composed of mixture of large number of hydrocarbons having boiling points ranging from approximately 30ºC to 225ºC. Alcohols, in contrast, have a single boiling point as shown in figure below. The alcohols lack the light ends with the boiling points near 38ºC (110ºF) which are essential for cold starting of S.I.ENGINES.

6. VAPOUR PRESSURE:

Alcohols have lower vapor pressure than gasoline. Vapor pressure of all fuels diminishes as the temperature declines. It determines the cold start behavior of an engine. Following figure shows the vapor pressure of different fuels.The low vapor pressure and the boiling point behavior together with high latent heat of evaporation make vaporization of fuel more difficult and thus put higher demands on the mixture formation system, both in cold starting and warm running conditions.

7. OCTANE QUALITY:

The octane number of methanol and ethanol is higher than gasoline. Hence higher compression ratios can be used with alcohols resulting in higher thermal efficiency. The difference between the research and motor octane number is commonly taken as an indication of fuel sensitivity. By these measures alcohols are sensitive to charges in engine conditions. Methanol displays a tendency to backfire which is an indication of preignition.

8. WATER TOLERENCE OF ALCOHOL BLENDS:

Until about 1920 industrial alcohols did not exceed about 190 proof, the remaining 5% being water 4=u74200 proof is anhydrous). The earlier difficulty of producing the water free alcohols explains why the older tests were carried out with alcohol containing some water. In recent years, it has become practical to produce alcohol with less than 0.1% water.Gasoline and water-free alcohols are miscible in all proportions over a wide range of temperatures. However, even small addition of water to this blended fuel causes separation of the alcohols and the gasoline. The separation of alcohols and gasoline in presence of water can be one of the most difficult problems attending the use of these blends as motor fuels. The condensation of the moisture from the air is vented and partially filled tanks and the accidental addition of water to gasoline storage tanks are well known. The difficulties due to water separation have commonly led to the use of either20-25% of blends of alcohols alone or 10-15% alcohol and 10-15% benzol to reduce preparation troubles.

CHAPTER 5

ALCOHOLS AS DIESEL FUEL

While S.I. engines can use alcohol fuel with minimal modification to their fuel delivering systems, the diesel engine has not been a good candidate for alcohols. Basically alcohols are unsuitable as diesel fuels for the following reasons:

1. The cetane number of alcohol fuels is very low (of the order of zero to eight), which prevents their ignition by compression.
2. Alcohol fuels have low lubricating qualities causing trouble in injection pumps and nozzles.
3. There are material problems caused by the harsh reaction of methanol towards various plastics and metals.

Because of very low compression ignition quality, alcohols cannot be used alone as fuels for diesel engines without some incylinder assistance like sparkplug, glow plug or other heated surface. Chemical ignition accelerators (usually organic nitrates) may be added to alcohol fuels to give acceptable ignition quality (i.e. increase the cetane number). 5 to 20 percent additives are required for knock free operations. But additives are expensive and because they contain nitrogen they also increase the NOx emission

Another method of use of alcohols is in conjunction with conventional diesel oil pure ethanol is completely miscible with diesel fuel at temperatures in excess of about 30ºC. At lower temperatures, or when the ethanol contains water, miscibility is limited Co. solvents, such as ethyl acetate, may be added to increase the range of miscibility. Methanol, even when dry, is almost completely immiscible with diesel fuels. The ignition properties of fuel mixtures containing more than about 25% of light alcohol are not generally found to be adequate.

Another method of using alcohol in diesel engines is by dual injection. The alcohol can be injected into the cylinder by a second high pressure system, or into the inlet manifold by a low pressure system; in either case a charge of diesel fuel is used to initiate the combustion process. However the onset of misfire limits the use of alcohol to about 20% on energy basis.

CHAPTER 6

ANOTHER ADVANCE ALTERNATIVE FUELS FOR I.C. ENGINE

6.1 HYDROGEN-

Depleting fossil fuel reserves and increasing vehicular emissions have forced the attention of various petroleum industries to find the alternate fuel that will power the vehicle in future, based on the present day internal design as the deposits of crude oil is expected to last for another 50 years at minimum utilization level. The resulting alternative fuel can be biodiesel, waste cooking oil, biogas, compressed nitrogen gas etc. But we are discussing another most efficient and simple technology fuel i.e. HYDROGEN. Hydrogen combines the properties of higher calorific value, higher velocity of flame propagation, no toxicity as well as lowest possible emissions level that don’t affect the balance of water of the hydrospace. Fuel cell vehicles represent one of the most emerging technologies of the innovation age. An efficient, combustion-less, virtually pollution free, free power source, capable of being sited down town urban areas or in remote regions, that runs almost silently and has few moving parts. Fuel cells are one of the cleanest and most efficient technologies for generating electricity. Moreover, the by-products of combustion are devoid of carbon monoxide, carbon-dioxide, which is the main advantage of fuel cell powered vehicles. The technology is extremely intersecting to people in all walks of life because it offers a mean of making power more efficient without pollution and with the performance that users expect. Another name for fuel cell based vehicles is zero-emissions vehicles. When the fuel cells are fuelled with pure hydrogen they are considered to be zero-emissions vehicles. Fuel cells have been used on spacecraft for many years to power electrical equipment. These are fuelled with liquid hydrogen from on spacecraft’s rocket fuel tank.

Methods of inducing hydrogen in si engines

Hydrogen can be used in SI engines by 3 methods:

Figure 6.1 Hydrogen atom structure

BY MANIFOLD INDUCTION.

In the manifold introduction of hydrogen, cold hydrogen is introduced through a valve controlled passage into the manifold. This helps to reduce the risk of back flash. The power output of the engine is limited by 2 factors, preignition and back flash. Also the energy content of air hydrogen mixture is lower than that of liquid hydrocarbon fuels.

BY DIRECT INTRODUCTION OF HYDROGEN INTO THE CYLINDER.

In the direct introduction of hydrogen in the cylinder, hydrogen is stored in the liquid form in a cryogenic cylinder. A pump, pumps this liquid through a small heat exchanger where it is converted into cold hydrogen gas. The metering of hydrogen is also done in this unit. The cold hydrogen helps to prevent preignition and also reduces NOx formation.

BY SUPPLEMENTING GASOLINE.

Hydrogen can also be used as a supplementary fuel to gasoline in SI engines. In this system, hydrogen is inducted along with gasoline, compressed and ignited by a spark.

Figure 6.1(B) Fuel Cell Bus

6.1.1 METHODS OF INDUCING HYDROGEN IN CI ENGINES:

There are 2 methods by which hydrogen can be used in diesel engines:

By introducing hydrogen with air and using a spray of diesel oil to ignite the mixture that is by the dual fuel mode. The limiting conditions are when the diesel quantity is too small to produce effective ignition, that is failure of ignition and when the hydrogen air mixture is so rich that the combustion becomes unacceptably violent. In between these limits, a wide range of diesel to hydrogen proportion can be tolerated. Investigations show that beyond a certain range (30 to 50% substitution of diesel fuel by hydrogen) leads to violent pressure rise.

By introducing hydrogen directly into the cylinder at the end of compression. Since the self-ignition temperature of hydrogen is very high, the gas spray is made to impinge on a hot glow plug in the combustion chamber i.e. by surface ignition. It is also possible to feed a very lean hydrogen air mixture during the intake into an engine and then inject the bulk of the hydrogen towards the end of compression stroke.

6.1.2 ADVANTAGES OF USING HYDROGEN

Hydrogen has extremely wide ignition limits. This allows a SI engine to operate on hydrogen with very little throttling, a decided advantage. Stoichiometric hydrogen air mixture burns seven times as fast as the corresponding gasoline air mixture. This too is a great advantage in IC engines, leading to higher engine speeds and grater thermal efficiency. All are the cleanest and the most abundant source of energy.

6.1.3 DISADVANTAGES OF USING HYDROGEN

Hydrogen has a very low density both as gas and as liquid. Hence, in spite of its high calorific value on mass basis its energy density as a liquid is only one fourth than that of gasoline. As gas it has less than one tenth the density of air and its heating value per unit volume is less than one third that of methane. This is one of its chief disadvantages.

Hydrogen has to be stored as compressed gas, as liquid (in cryogenic containers) or in absorbed form (as metal hydrides), none of which is as convenient as gasoline storage.

Hydrogen has a high self- ignition temperature but requires very less energy to ignite it. Hence, it is highly prone to preignition and back flash in SI engines.

2. PROPANE-

Propane or liquefied petroleum gas (LPG) is a popular alternative fuel choice for vehicles because there is already an infrastructure of pipelines and storage for its efficient distribution. LPG produces fewer vehicle emissions than gasoline.

Propane is produced as a by-product of natural gas processing and crude oil refining.The cost of a gasoline-gallon equivalent of propane is generally less than that of gasoline, so driving a propane vehicle can save money.

Figure 6.2 Propane or L.P.G.

Figure 6.3 Atomic structure of Propane

6.3 BIODIESEL-

In the changing scenario the world soon will be divided into 2 parts, those who are dependent on fuels and those who are independent. For India, petroleum imports are at alarming level and will continue to rise as domestic supplies are less than that to on the edge of shrinking.

Our transportation sector relies almost exclusively on petroleum as a source of energy. In such scenario bio-diesel is emerging as a best alternative fuel. It can be produced domestically from agricultural oils and from waste fats and oils. With its ability to be used directly in existing diesel engines, bio-diesel offers the immediate potential to reduce our demand on petroleum in the transportation sector. Bio-diesel is attractive as an alternative fuel source because its emission profile is cleaner than that of diesel fuel. Bio-diesel can be used in diesel engines without modifications and can be blended with petro-diesel fuel effectively.

A blend of 20% bio-diesel and 80% diesel fuel, called B-20, is currently the most widely used form of bio-diesel. If not used as a total replacement for diesel in I.C.Engines, it got good prospect in using as an additive that improve diesel fuel properties which can be sold for a price above than that of the diesel fuel.

Figure 6.4 Atomic structure of Biodiesel

Figure 6.5 Corn produces Alternative Fuel

6.4 ELECTRICITY-

Electricity can be used as a transportation fuel to power battery electric and fuel cell vehicles. When used to power electric vehicles, electricity is stored in an energy storage device such as a battery. Batteries have a limited storage capacity and their electricity must be replenished by plugging the vehicle into an electrical source.

Batteries have lower "fuel" and maintenance costs than gasoline-powered vehicles. Vehicles that operate only on electricity require no warm-up, run almost silently and have excellent performance up to the limit of their range. Also, electric cars are cheap to "refuel." At the average price of 10 cents per kwh, it costs around 2 cents per mile. Pure electric cars still have limited range, typically no more than 100 to 120 miles.

GREEN TECHNOLOGY

ALTERNATIVE FUEL VEHICLES-

CONCLUSION

In the changing scenario the world soon will be divided into 2 parts, those who are dependent on fuels and those who are independent. For India, petroleum imports are at alarming level and will continue to rise as domestic supplies are less than that to on the edge of shrinking. Our transportation sector relies almost exclusively on petroleum as a source of energy. In such scenario alcohol fuel is emerging as a best alternative fuel. It can be produced easily from avilable substances. Alcohol offers the immediate potential to reduce our demand on petroleum in the transportation sector. Alcohol is attractive as an alternative fuel source because its emission profile is cleaner than that of petroleum fuel. Technologies soon to be common on 2007 and later model diesel buses reduce emissions of the four main criteria pollutants – NMHC, CO, NOX, and PM – to levels consistent with today’s most popular alternative fuel buses powered by CNG. To achieve this level of emissions performance, clean diesel buses must use a combination of sophisticated emission controls and ultra-low sulfur diesel known as clean diesel technology. Some buses running on alternative fuels with relatively simpler emission controls can meet the 2007 standards today. Buses, whether using diesel or alternative fuels, will require even more sophisticated emission control equipment to meet 2010 emissions standards. Alternative fuel buses will continue to appeal to a number of transit agencies due to their relatively simpler exhaust treatment and potential for even greater emissions reductions. For instance, test CNG engines equipped with exhaust gas recirculation have demonstrated emissions far below the 2010 EPA standards.17 Tailpipe emissions from hydrogen, electric, and fuel cell buses can be close to zero. Also, diesel exhaust contains relatively high amounts of mobile source air toxics, its lifecycle greenhouse gas emissions are the highest of any fuel considered, and it is more likely to cause harm to soil and groundwater if spilled or leaked than most alternative fuels. For rail vehicles, locomotives, and ferries, alternative fuels offer more pronounced emission benefits compared to diesel. The diesel engines used in these vehicles have few if any emission controls, so their use of alternative fuels is likely to offer greater emission reductions than for buses. However, no alternative fuel engines (except electric motors) are available for these vehicles in 2006.

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