Automobile unit 5 alternate energy sources

Prepared By:K.Rajesh, AP/Mech,RMKCET

TOPICS TO BE COVERED
 Use of Natural Gas
 Liquefied Petroleum Gas
 Bio-diesel and Bio-ethanol
 Engine modification required
 Gasohol as fuel
 Hydrogen as fuel
 Electric and Hybrid Vehicles
 Fuel Cells

NEED FOR ALTERNATIVE FUELS
 ❖Depletion of fossil fuels
 ❖High crude prices
 ❖Stringent environmental regulation
 ❖Emergence of natural gas
 ❖Sustainable energy source- Bio fuels
 ❖Rural economy & employments
 ❖Import bill

PRESENT SCENARIO….
1 1 0
1 0 0
9 0
8 0
7 0
6 0
5 0
4 0
3 0
2 0
1 0
0
1 9 6 0 1 9 7 0 1 9 8 0 1 9 9 0
Y E A R
2 0 0 0 2 0 1 0 2 0 2 0
MILLIONSOFBARRELS/
DAYOFOIL
EQUIPMENT
De s ir e d d e m a n d
P o te n tia l s u p p ly
❖About 20% of the world’s energy consumption is taken
by the automobiles. This acts as a predominant source of
emissions.
❖To meet this demand we should shift to a fuel that is
renewable and less polluting one.

TRENDS IN WORLD ENERGY USAGE

PETROLEUM PRODUCTS –
UTILIZATION SHARE
Transport
51%
Commercial
13%
Industry
14%
Domestic
18%
Agriculture
4%
Utilization Share

EMISSIONS FROM VEHICLES
Regulated emissions
Unregulated emissions
Green house gases
- CO, HC, NOx, PM, SMOKE
- ALDEHYDES
- CH4, N2O, CO2

ALTERNATE FUELS
❖Alternate fuels are Non-Conventional fuels.
❖Material or Substance that can be used as fuel
❖Biodiesel, Bio-alcohol, Stored Electricity, Hydrogen
and other bio mass sources

ALTERNATE FUEL VEHICLE
❖ It is a vehicle that runs on a fuel other than
“traditional” petroleum fuels.
❖ Electric car,
powered, Bioalcohol,
Petrol-electric hybrid, Solar
oil, Biodiesel,Vegetable
CNG, Hydrogen & LPG.

EMERGING ALTERNATIVE
FUELS &
TECHNOLOGIES
❖ Alternate fuels currently in use
❖CNG
❖LPG
❖Alcohol
❖ Emerging Fuels & EngineTechnologies
❖Bio-fuels (Bio-diesel)
❖Electric vehicles
❖Hydrogen fueled IC engines
❖Fuel cells

❖ Bio-fuels will ensure energy security of the country
❖ Bio-fuels production will generate employment
opportunities for rural masses
❖ Greening of waste lands by plantation
❖ Bio-fuels will promote integrated holistic rural
development
BIO-FUELS IN INDIAN PERSPECTIVE

BIO - DIESEL

Biodiesel is monoalkyl ester
of long chain fatty acids
produced from the Trans-
esterification reaction of
vegetable oil with alcohol in
the presence of catalyst & can
be used as fuel
BIO-DIESEL

In 1911 Dr.Rudolph Diesel stated as:
“The diesel engine can be fed with vegetable oils and
would help considerably in the development of agriculture
of the countries which use it.”
In 1912 he stated as:
“The use of vegetable oils for engine fuels may seem
insignificant today. But such oils may become in course of time
as important as petroleum and the coal tar products of the
present time.”

SOURCE OF BIODIESEL

EDIBLE OILS
 Palm oil
 Cotton seed oil
 Coconut oil
 Rape seed oil
• Sunflower oil
• Soybean oil
• Peanut oil
• Groundnut oil

NON EDIBLE OILS
 Jatropha curcus
 Pongamia pinnata
 Rubber seeds
 Madhuca indica
 Neem oil

17
BIODIESEL
 TheAmerican Society for Testing and Materials
(ASTM) defines biodiesel fuel as
“mono alkyl esters of long-chain fatty acids derived from a
renewable lipid feed stocks, such as vegetable oils or animal
fats, for use in diesel engines”

WHY VEGETABLE OIL?
• Decreasing reserves, unstable supplies
Industries
from Petroleum
• Vegetable oils are renewable from inexhaustible sources of
energy
• Easily produced in rural areas
• Country like India has strong agricultural base and possible
to produce massively at cheaper cost
• To clean environment
• Vegetable oil properties are comparable to diesel

20 February 2015 19
PROPERTIES OF VEGETABLE OILS
❖ Density slightly higher
❖ Calorific value slightly lower
❖ Viscosity at room temperature is much higher
❖ CN slightly higher
❖ Flash point is very high
❖ Volatility is quite low
❖ Carbon residue is very high

PHYSICOCHEMICAL PROPERTIES OF
BIODIESEL BLENDS
PROPERTIES BIS
Spec.
HSD B20 PPME B20 JCME B20 PPEE
Cetane Index,
min
46 48.8 50.3 50 52
Lubricity, WSD
microns
460 430 260 260 250
Flash point, °C
min.
35 49 70 70 71
K. V.,cSt at
37.8°C
2.0 to
5.0
3.000 3.534 3.284 3.430
Sulphur, %
ppm., max
2500 /
500
330 270 235 235
CFPP °C, max 6°C/18°C - 4 Zero - 2 Zero

20 February 2015 21
DIFFICULTIES - VEGETABLE OILS AS
C. I. ENGINE FUELS
❖ High viscosity
- Difficult to atomize and Cold starting
❖ Poor volatility
-Difficult to vaporize and ignite, leads to
smoke and carbon deposit

METHODS USED FOR VEGETABLE OILS
IN DIESEL ENGINE
❖ Heating
❖ Thermal cracking (breakdown the heavy
molecules of oils into lighter one)
❖ Pyrolysis
❖ Transesterification
- Lower viscosity (nearer to diesel)
- Lower density
- Lower carbon residues and cloud points
- Higher cetane number
- Heating value slightly reduced
- improves the volatility

TRANSESTERIFICATION
❖Trans-esterification is to make glycerol
esters into alcohol esters in presence of
catalyst.
❖Finally alcohol ester (bio-diesel) and
pure glycerin (by-product used in soaps
and other products) are obtained.

BASIC CHEMICAL
REACTION
CH2COOR’
|
CHCOOR”
|
CH2COOR”’
3 ROH Catalyst CH2OH
|
CHOH
|
CH2OH
R'COOR
+
R''COOR
+
R'''COOR
1000 ml 200 ml
Metha
nol
(Alcohol )
12gm
KOH
(Catalyst)
50 ml
Glycerin
(By
product)
950 ml
yield
Biodiesel

ALCOHOL FUELS

INDIAN EXPERIENCE- ALCOHOL
1979- The Ministry of Petroleum, Chemicals and Fertilizers,
constituted an Inter- Departmental Committee to
examine the use of alcohol as fuel in admixture with
gasoline.
1980- Trials were conducted on 15 passenger cars in
collaboration with IIP, Dehradun. Trials were also
conducted scooters, motor- cycles and three wheelers.
1991 - Project sponsored by MNES.
- Recommendation by the committee for development
of Alternate fuels for surface transport.
Fuels - Blends containing 5 to 10% of ethanol in gasoline.
Vehicles - Fleet of 93 vehicles of Delhi Administration.

32
NEED FOR ALCOHOL
❖ Availability of Ethanol
❖ Reduction of NOx and smoke emissions
❖ Foreign exchange savings
❖ Renewable made from plants

ALCOHOL FUELS
 ❖Both Ethanol & Methanol can be used as an
 alternate automotive fuel.
 ❖Ethanol is better than Methanol, since it can
be obtained from sugar/starch in crops.
 ❖It can also be produced from sugarcane
and sugar beets.
 ❖Even Butanol can be used.
 ❖Obtained from fermentation of plants.

PROPERTIES OF ALCOHOL
❖ High latent heat
❖ High volumetric efficiency
❖ Better oxidation
❖ Lower cetane number (< 10)
❖ High octane number (>100)
❖ Low flash and fire point
❖ Lower heating value (CH3OH ≈19 MJ/kg,C2H5OH ≈ 27 MJ/kg)

Properties of Ethanol gasoline BlendsProperties BIS Spec. Com.
Gasoline
Gasoline +
5% Ethanol
Gasoline + 10%
Ethanol
Distillation
E 70 10-45 30.0 36.5 45.0
RON 88 89.2 90.5 92.6
Potential
Gum, g/m3
50 40 140*
180*
RVP, kPa 35-60 55.9 63.3 63.0
VLI 750 / 950 769 885 945
* Need for control by additives Prepared By:K.Rajesh, AP/Mech,RMKCET

36
ALCOHOL IN GASOLINE ENGINE

Brake Thermal Efficiency Vs Engine Speed

CO vs Engine Speed

CO2 vs Engine Speed Figure 4

HC vs Engine Speed

NOx vs Engine Speed

O2 vs Engine Speed

PROBLEMS ON ALCOHOL
 Quality of anhydrous ethanol - phase separation problems
 Effect on fuel system components of vehicles
 Storage, handling and distribution
 Slowly decompose certain rubber compounds.
 Difficult to start the engine using Higher percentage of
ethanol.
 Electrically conductive –problem foe electric fuel pump.
 Corrosion of magnesium & Aluminium parts.

NATURAL GAS

PROPERTIES OF NATURAL GAS

20 February 2015 72
COMPOSITION OF CNG
Methane - 91.9 %
Ethane - 3.7 %
Propane
1-butane
- 1.2 %
- 0.4 %
CO2 - 2.0 %

20 February 2015 73
PROPERTIES OF CNG
❖High ignition temperature (540 °C)
❖Good knock resistance
❖Octane number is >100
❖High CR in S.I engines

20 February 2015 74
CNG IN SI ENGINE
❖ Bi-fuel system (petrol/CNG)
• CNG storage tank (200 bar)
• Pressure regulator
• Fuel selection switch (petrol or gas)
• Gas carburetor
• Gas filling valve / Petrol solenoid

20 February 2015 75
CNG IN CI ENGINE
❖Duel fuel mode (Diesel and Natural gas)
-Starts with diesel and automatically switches to dual fuel mode
1. Mixed fuel system (Diesel sub is 50-70%)
2. Pilot injection system (Diesel sub is 90%)
❖Full gas mode
• Conversion to spark ignition engine

CNG-DIESEL DUAL FUEL
ENGINE
Schematic layout of CNG-diesel dual fuel engine test set up

Actual image of CNG-Diesel dual fuel engine test set up.

Schematic representation of a typical CNG fuel-storage system

Typical under-floor bus installation of Type-1 steel cylinders in a fuel cylinder pod,
strap-mounted with manual shut-off valves with integrated burst-disc pressure-relief
devices

Schematics of a roof-mounted system assembly
A general schematic showing location of lightweight composite cylinders on a
low-floor bus

a typical Luxfer Gas Cylinders system consisting of 4 x 320-litre cylinders that provide a
total storage volume of 315 Specific Cubic metres of gas at 200 bar—equivalent to 340
litres of gasoline

Cylinder Type Selection
Four types of cylinders are used in CNG vehicles
➢ Type-1: Constructed completely from metal only, typically steel
➢ Type-2: Metal liner (aluminium or steel) hoop-wrapped with
composite material, typically carbon
➢ Type-3: Metal liner (aluminium or steel) fully wrapped in
composite material, typically carbon, often with a glass-fiber
over wrap to offer additional wear resistance
➢ Type-4: Polymer liner fully wrapped in composite material,
generally a combination of carbon and glass fiber

Type-2 aluminium-lined, composite hoop-wrapped CNG cylinder

Type-3 aluminium-lined fully wrapped composite CNG cylinder.

Brake thermal efficiency with engine load for pure diesel and
dual fuel mode

Brake specific fuel combustion with load for pure
diesel and dual fuel modes

CO Emission with load applied for pure diesel and dual
fuel modes

Hydrocarbon (ppm) emissions for diesel and dual fuel
modes

CO2 Emissions for diesel and dual fuel mode of operation

NOX Emission as a function of engine load for diesel
and dual fuel modes

Smoke opacity analysis for diesel and dual fuel modes

Liquefied Petroleum
Gas(LPG)

➢ High octane number
➢ Wide flammability limits
➢ Better Performance
➢ Lesser Pollution
LPG as SI engine Fuel

Properties of LPG

➢ LPG has been used as a fuel for vehicles as early as 1912 but only at a
limited scale.
➢ The fuel became more popular in the 1970s and the 1980s when
territories such as the US and Canada tried to reduce their dependence
on crude oil.
➢ In the 1990s, the increased demand of the fuel is driven by rising
environmental concerns
➢ Although LPG is mainly used in passenger cars such as taxis, the fuel is
also applicable to other types of vehicles such as vans, trucks and buses.

Modes of operation
Dual-fuel
- vehicles have two separate fuel systems, with only one
fuel being used at a time.
flexi-fuel
- vehicles have one fuel system operating on a mixture of
fuels.

Emissions of Passenger Cars on LPG and Petrol
(grams per km)

Relative Efficiency and Performance of LPG, Petrol and
Diesel
+ : better than LPG
0 : more or less equal to LPG
- : worse than LPG

Safety
➢ LPG tends to be more inflammable than both petrol and diesel
because it has a wider flammability limit
➢ Accidents involving LPG sometimes result in fire or in explosion.
➢ The characteristics of LPG have implications on the design of
fuel tanks, storage tanks and refuelling stations
➢ It evaporates quickly and expands 270 times its volume in liquid
state

HYDROGEN FUELS

Properties of Hydrogen
 ➢Lower Ignition Energy
 ➢Small Quenching Distance
 ➢High Auto Ignition temp
 ➢High flame speed
 ➢High diffusivity
 ➢Lower density

HYDROGEN
 Easy to convert existing engine to work with h2
 Has excellent properties as a SI engine fuel.
 Wide flammability limits of H2 ,make the engine to
work without throttle.
 Thus reduces pumping losses, hence causes an
increase in the thermal efficiency.
 High burning velocity leads to almost constant
volume combustion.
 High self ignition temperature, thus allows to work
with high compression ratio.i.e increase in thermal
efficiency.
 H2 is a clean burning fuel, steam is the only
product of combustion.

CHALLENGES
FACED
❖Due to low ignition energy ,it is more prone to
backfire,
But this can overcome by adopting EGR or
water injection in the manifold.
❖H2 is odour less & has an invisible flame. Hence
safety problems have to be overcome if H2 is
used as an alternate fuel.

PROPERTIES OF HYDROGEN
Property Hydrogen Gasoline
Limits of inflammability
( % fuel in air )
4 to 75 1.1 to 3.3
Stoichiometric laminar burning
velocity ( cm/sec )
265 37
Auto-Ignition Temperature ( °C ) 580 340
Minimum Ignition energy ( mj ) 0.02 0.24
stoichiometric mixture
mass ratio ( Kg air / Kg fuel )
34.4 14.7
Lower enthalpy of combustion
in ( KJ / KgK )
119930 45000
Higher enthalpy of combustion
in ( KJ / KgK )
141860 48000

H2 PRODUCTION METHOD
❖Thermal Processes
▪ Natural Gas Reforming
➢Methane reacts with the steam in presence of a catalyst
to produce hydrogen
▪ Gasification
➢synthesis gas which reacts with steam to produce more
hydrogen
▪ Renewable Liquid Reforming
▪ Ethanol or bio-oil, are reacted with high-
temperature steam to produce hydrogen

H2 PRODUCTION METHOD (CONT..)
❖Electrolyte Processes
➢Electrolytic processes use an electric current to
split water into hydrogen and oxygen
❖Photolytic Processes
➢Uses light energy to split water into hydrogen and
oxygen

ADVANTAGES
❖ The wide flammability limits as indicated hydrogen as an
excellent fuel for SI engines.
❖ Hydrogen engine output can be changed by varying the
equivalence ratio while keeping the throttle wide open.
❖ This will reduce throttling losses.
❖ The high flame speed of hydrogen will lead to near constant
volume combustion and good thermal efficiency.
❖ Wide flammability and flame velocity lead to low cycle by
cycle variations

CHALLENGES
❖Hydrogen can become a viable automotive fuel.
❖back flash and pre-ignition.
❖hydrogen occupies more
substantial amount of air and
volume, it displaces a
thus reduces the
power developed by the engine.
❖Also, the higher burning rate of hydrogen results in
high peak cylinder gas temperature and aids the
formation of NOx.

SOLUTIONS
❖ Fuel metering system can be a gas carburetor or an
injection system with fuel being admitted into the manifold
or cylinder directly.
❖ These need electronic controls and can avoid the problem
of backfiring.
❖ The spark timing also has to be closely controlled to avoid
rapid pressure rises.
❖ The valve timing has to be altered so that overlap can be
minimized.
❖ The gases that leak into the crank case have to be properly
ventilated so that crank case explosions can be avoided

HYDROGEN
STORAGE
 Compressed state(140 bar)
 Liquid hydrogen
 Metal hydride system

HYDROGEN IN INTERNAL
COMBUSTION ENGINES
 Hydrogen can be used in various
systems as given
 below :
❖Neat mode in S.I. engine
system
❖In dual fuel mode in S.I.
and C.I. engine system
❖ In fuel cell systems

HYDROGEN IN S.I. ENGINE
❖ Manifold introduction
❖ Direct injection of Hydrogen
❖ Supplementation to gasoline

HYDROGEN IN C.I. ENGINE
❖ Duel fuel mode
Introducing with air – spray of diesel
❖Surface ignition
Injecting hydrogen in to the cylinder – part of
hydrogen is impinge on hot glow

PERFORMANCE AND EMISSION
CHARACTERISTICS
❖ Low volumetric efficiency.
❖ Less Power output compared to gasoline.
❖ Higher NOx emission compared to diesel.
❖ Compared to gasoline less thermal efficiency. By
supercharging we can improve the thermal efficiency.

Auto-ignition of the hydrogen jet
Ignition delay of hydrogen fuel

Engine Performance
Diesel DI Dual fuel
(diesel + H2)
H2 HCCI H2 DI
Shaft output [%] 27.9 33.9 48.0 42.8
Shaft power [W] 9000 8950 7076 10280

Cylinder Pressure

Oxides of Nitrogen Emission.

HYBRID AND BATTERY
VEHICLE

BATTERY ELECTRIC VEHICLES
❖BEVs are Electric vehicles which use chemical
energy of batteries.
❖Theses vehicles are zero emission vehicles.
❖Common batteries: Lead-acid, NiCd, Nickel
metal hydride, Li-ion, Li-poly & Zinc-air
batteries.

❖Battery powered cars primarily use lead-acid
batteries & NiMH batteries.
❖ Lead-acid batteries recharge capacity is reduced if
discharged beyond 75% -hence less than ideal
solution.
❖NiMH batteries are better choice.
❖More Expensive.
❖ Li-ion battery powered vehicles show excellent
performance and range but very expensive.
BATTERY ELECTRIC VEHICLES (CONT..)

Layout of Electric Vehicle

C: Clutch
D: Differential
FG: Fixed gearing
GB: Gearbox
M: Electric motor
(a) conventional driveline with multi gear transmission and clutch,
(b) single-gear transmission without need of a clutch,
(c) integrated fixed gearing and differential,
(d) two separate motors and fixed gearing with their driveshaft,
(e) direct drive with two separate motors and fixed gearing, and
(f) two separate in-wheel motor drives.1
POSSIBLE ELECTRIC VEHICLE CONFIGURATION

HYBRID VEHICLES
Disadvantages of IC Engine
(1) Depends on fossil fuel
(2) Environmental pollution
(3) mismatch of engine fuel efficiency characteristics with the real
operation requirement
(4) dissipation of vehicle kinetic energy during braking, especially
while operating in urban areas
(5) low efficiency of hydraulic transmission in current automobiles in
stop-and-go driving patterns
Disadvantages of electric Vehicles
1. The performance, especially the operation range per battery
charge, is far less competitive than IC engine vehicles,
2. Much lower energy density of the batteries than that of gasoline
fuels.
Hybrid Vehicles - uses two power sources(a primary power source and
a secondary power source), have the advantages of both IC engine
and Electric vehicles and overcome their disadvantages

Concept of Hybrid DriveTrains
1.Power train 1 alone delivers its power to the load.
2. Power train 2 alone delivers its power to the load.
3.Both power train 1 and power train 2 deliver their power to the load
simultaneously.
4. Power train 2 obtains power from the load (regenerative braking).
5. Power train 2 obtains power from power train 1.
6.Power train 2 obtains power from power train 1 and the load
simultaneously.
7.Power train 1 delivers power to the load and to power train 2
simultaneously.

Classifications of hybrid Vehicles
(a) Series (electrically coupling),
(b) parallel (mechanical coupling),
(c) series–parallel (mechanical and electrical coupling)

Series Hybrid electric vehicle

Parallel Hybrid electric vehicle

Series parallel hybrid

BATTERY ELECTRIC VEHICLES (CONT..)
❖A solar car is also an electric vehicle.
❖Powered by solar energy obtained from solar panels
on the car.
❖Not practical form of transportation.
❖Insufficient power falls on the roof of the car.
❖It does not provide adequate performance
❖Hence only research interest.

FUEL CELLS

Introduction
A fuel cell configuration
Principle, construction and working
Types of fuel cell
Advantages, disadvantages and applications

✓ Every fuel cell also has an electrolyte, which carries
electrically charged particles from one electrode to the
other, and a catalyst, which speeds the reactions at the
electrodes.
✓ In all types of fuel cell, hydrogen is used as fuel and can
be obtained from any source of hydrocarbon.
✓ The fuel cell transform hydrogen and oxygen into
electric power, emitting water as their only waste
product.
What is fuel cell?
A Fuel cell is a electrochemical device that converts
chemical energy into electrical energy
1. Introduction

➢COMPONENTS INVOLVED:
•ELECTRODES(ANODE&CATHODE)
•ELELCTROLYTE
•CATALYSTS
•BACKING LAYERS
•FLOW FIELDS
• CURRENT COLLECTORS
2. A fuel cell configuration
TO ENHANCE DIFFUSION AND CONDUCTION OF
FUEL CELLS

1. Every fuel cell also has an electrolyte, which carries
electrically charged particles from one electrode to the
other, and a catalyst, which speeds the reactions at the
electrodes.
2. The DC current produced by fuel cell is later converted
into AC current using an inverter for practical application.
3. The voltage developed in a single fuel cell various from
0.7 to 1.4 volt.
4. In practice, many fuel cells are usually assembled into a
stack. Cell or stack, the principles are the same.
5. Therefore, electricity power ranging from 1 kW to 200 kW
can be obtained for domestic as well as industrial
application.

Hydrogen
Oxygen
Electrical power production by fuel cell
Rotating shaft connected to generator for electricity production

WORKING
The electrolyte plays a key role. It must permit only the
appropriate ions to pass between the anode and cathode. If
free electrons or other substances could travel through the
electrolyte, they would disrupt the chemical reaction.

1) Hydrogen atoms enter a fuel cell at the anode
where a chemical reaction strips them of their
electrons.
2) The hydrogen atoms are now "ionized," and
carry a positive electrical charge.
3) The negatively charged electrons provide the
current through wires to do work.
4) Oxygen enters the fuel cell at the cathode and
picks up electrons and then travels through the
electrolyte to the anode, where it combines
with hydrogen ions to form water .

3. Types of fuel cells
There are different types of fuel cells, differentiated by the
type of electrolyte separating the hydrogen from the oxygen
.The types of fuel cells are:
• Alkaline fuel cells (AFC)
• Direct methanol fuel cells (DMFC)
• Molten carbonate fuel cell (MFFC)
• Phosphoric acid fuel cells (PAFC)
• Polymer electrolyte membrane fuel cells (PEMFC)
• Solid oxide fuel cells (SOFC)
• Regenerative fuel cells

COMBINED CELL DIAGRAMS

Fuel cell type Op.
Temp.
(oC)
Transport
ed ion
Membrane
used
Power
density
mW/cm2
Fuel cell
efficiency
Polymer electrolyte
membrane fuel cell
(PEMFC)
50-80 H+ Polymeric
membrane
350 45-60
Alkaline fuel cell
(AFC)
60-90 OH- Aqueous
alkaline
solution
100-200 40-60
Phosphoric acid
fuel cell (AFC)
150-200 H+ Molten
phosphoric
acid
200 55
Molten carbonate
fuel cell (MCFC)
600-700 CO3
2- Molten alkaline
carbonate
100 60-65
Solid oxide fuel cell
(SOFC)
800-
1000
O2- Ceramics 240 55-65
COMBONED FUEL CELLS (SPECIFICATIONS)

1) Operate on compressed hydrogen and oxygen.
2) Electrolyte: potassium hydroxide (chemically, KOH) in
water.
3) Efficiency is about 70 percent
4) operating temperature is 100to 250degrees C.
5) Cell output ranges from 300 watts (W) to 5 kilowatts
(kW).
6) DOES NOT REQUIRE PRECIOUS METAL CATALYSTS
Used in Apollo spacecraft to provide both
electricity and drinking water.
✓DISADVANTAGES:
✓Require pure hydrogen fuel.
✓ Platinum electrode catalysts are expensive.
✓Leakage is possible.
ALKALI FUEL CELLS

DIRECT METHANOL FUEL CELLS
Overall reaction: (1.19 V)
CH3OH + 3/2 O2 CO2 + 2H2O

DIRECT METHANOL FUEL CELLS
▪ Fuel at anode: Methanol
▪ Oxidant at cathode: Oxygen
▪ Membrane used: Proton exchange membrane (PEM)
▪ Temperature: 50-1200C
▪ Power density: 24mW/cm2
▪ Efficiency: ~60% ; Output: 0.1 – 15W
▪ BETTER THAN HYDROGEN FUEL CELLS
▪ METHANOL CAN BE EASILY STORED

Molten carbonate fuel cell
✓ ELECTROLYTE : Molten Carbonate Salts
✓ TEMPERATURE : 6500C
✓ EFFICIENCY : 60-80%(if cogenerated)
✓ Developed for NATURAL GAS AND COAL BASED power
plants.
➢ NOBLE METAL CATALYSTS ARE NOT REQUIRED
➢ FACILITATES “ INTERNAL REFORMING”
➢ LESS SENSITIVE TO IMPURITIES
 CONS:
1. Less durable
2. Corrosive electrolyte

Phosphoric acid fuel cells (PAFC)
✓ ELECTROLYTE : phosphoric acid
✓ TEMPERATURE: 150 to 200 0C
✓ EFFICIENCY: 85% (if cogenerated)
✓ Used for stationary power generation
➢ FIRST KNOWN “ MATURE FUEL CELL “
➢ COMMERCIALLLY 200 UNITS ARE BEING USED
➢ EXTREMELY TOLERENT TO IMPURITIES
 DISADVANTAGES:
1. Heavy & expensive
2. Requires noble catalyst
3. 37-42 % efficient for power generation

Polymer electrolyte membrane fuel cells
✓ ELECTROLYTE: SOLID POLYMER
✓ CATALYST : POROUS CARBONELECTRODES WITH PLATINUM
✓ TEMPERATURE : 80 0C
➢ STARTING TIME IS FAST
➢ LESS WEAR AND MORE DURABILITY
➢ USED FOR TRANSPORTATION APPLICATIONS
➢ LESS SENSITIVE TO IMPURITIES
➢ FAVOURABLE POWER TO WEIGHT RATIO
➢ DISADVANTAGES:
➢ HYDROGEN SHOULD BE STORED
➢ REQUIRES NOBLE CATALYST
➢ COSTLY
➢ EXTREMELY SENSITIVE TO (CO)

Solid oxide fuel cells
✓ ELECTROLYTE : HARD, NON-POROUS CERAMIC COMPOUND
✓ EFFICIENCY : 60 % -85% (if cogenerated)
✓ TEMPERATURE : 1000 ( VERY HIGH TEMPERATYRE )
➢ HIGH OPERATING TEMPERATURE FACILITATES “ INTERNAL
REFORMING “
➢ COST EFFICIENT
➢ RESISTANT TO SULPHUR IMPURITIES THAN ANY OTHER FUEL CELL
➢ NON POISONOUS TOWARDS (CO)
➢ CONS :
➢ SLOW STARTUP
➢ REQUIRES THERMAL SHIELDING TO RETAIN HEAT
➢ LESS DURABLE
LOW COST MATERIALS WITH HIGH DURABILITY AT CELL
OPERATING TEMPERATURES IS THE KEY CHALLENGE TODAY

REGENERATIVE FUEL CELL

• A regenerative fuel cell is one which the
product(water) is recovered into reactants (hydrogen
and oxygen)by the following methods:
✓ THERMAL
CHEMICAL
✓ PHOTOCHEMICAL
✓ ELECTRICAL
✓ RADIOCHEMICAL
I. Two stages in regenerative fuel cells are :
II. CONVERSION OF REACTANTS INTO PRODUCTS WHILE
PRODUCING CURRENT
III. RECONVERSION OF PRODUCTS BACK INTO REACTANTS

Advantages
• Zero Emissions
• High efficiency
• High power density
• Recharging is not required
Quiet operation
Disadvantages
• It is difficult to manufacture and store pure hydrogen
• It is very expense as compared to batteries
5. Advantages, disadvantages and applications

Applications
1. Portable applications
➢ small personal vehicles
➢ laptops, cell phones
➢ Backup power
➢ 2.Transportation applications
➢ Industrial , Public &Commercial transportations
➢ Marine and Military transportation
➢ 3. Power distribution applications
➢ Small power grids
➢ Power plants

Automobile unit 5 alternate energy sources

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