The document discusses various properties of alternative fuels compared to conventional fuels like petrol and diesel. It covers energy density, volatility, octane number, cetane number, heat of vaporization, flame speed, flame temperature, auto-ignition temperature, flash point and flammability limits of different alternative fuels. The production processes of natural gas, biodiesel and ethanol are also outlined. Various engine modifications required for running vehicles on alternative fuels like CNG, biodiesel, bioethanol are described. Performance characteristics of engines running on these alternative fuels are discussed and different types of fuel cells are listed along with brief descriptions.

1. UNIT - V
ALTERNATIVE ENERGY SOURCES

2. PROPERTIES OF ALTERNATIVE FUELS
1.Energy density:
petrol, diesel- higher energy densities
Ethanol, methanol also liquid
methanol- half the energy content
Ethanol- two-thirds of energy density
LPG- gas at normal temperature and
pressure is stored in a liquid form 100 psi to 300
psi.

3. 2.Volatility:
• Volatility indicates a fuels ability to vapourize
under different temperature and pressure.
• It is the property that most affects startup the
engine performance.

4. 3.Octane number:
• Octane number is a measure a fuels tendency
to knock in a SI engine.
• The self ignition occurs before the cylinder
reaches the top of its stroke thereby causing
the cylinder to push against the crank shaft.

5. 4.Cetane number:
• The combustion and ignition characteristics of
CI engine fuels are expressed in the form of
Cetane number.
• Fuels with high cetane numbers have low auto
ignition temperature and short ignition delay
times.

6. 5.Heat of vapourization:
• Heat of vapourization affects both engine
power and efficiency.
• It is the amount of heat absorbed by fuel as it
evaporates from a liquid state which occurs
when the fuel is mixed with air prior to
combustion.
• The alcohol fuels have higher heat of
vapourization than gasoline or diesel.

7. 6.Flame speed:
• The speed at which a flame front propagates
through a fuel/air mixture can affect engine
performance and emissions.
• High flame speed allows the complete
combustion and potentially lean fuel mixtures.
• Methanol –higher flame speed than gasoline.
• Natural gas- slow flame speed.
• Hydrogen – highest flame speed in alternative
fuels.

8. 7.Flame temperature and luminosity:
• For alcohol fuels, the flame temperature is
lower than gasoline and luminosity is also low
that less thermal energy is lost through
conduction or radiation.
• Low flame temperature also helps to reduce
the formation of nitrogen oxide.
• Lower luminosity is a safety issue because the
flame is essentially invisible.

9. 8.Auto –ignition temperature:
• Auto-ignition temperature is a temperatue at
which the fuel will self-ignite.
• Self ignition is a concern in the environment
where the fuel might escape and come into
contact with hot engine parts.
• Hydrogen has highest auto ignition
temperature about 1065 degree F.
• GASOLINE AND DIESEL - 495 &600 degree F.

10. 9.Flash point:
• The flash point is the lowest temperature at
which combustible mixtures of fuel vapour
and air from above the fuel.

11. 10.Flammability:
• Flammability limits the range of fuel/air
mixtures that ignite.
• Among hydrocarbon fuels, methanol has the
widest flammability limits (7.3% to 36%)
followed by ethanol.

12. PRODUCTION OF NATURAL GAS

13. PRODUCTION OF BIODIESEL

14. PRODUCTION OF ETHANOL BY DRY
MILLING PROCESS

15. FUEL ECONOMY

16. HYDROGEN FROM NATURAL GAS

17. ENGINE MODIFICATIONS REQUIRED FOR
ALTERNATIVE FUELS
1. Dual fuel engine (diesel and natural gas)
2. Bi-fuel engine (either petrol or gas)
3. Dedicated/single fuel (natural gas)

18. Engine Modification for Bio-Ethanol(Alcohol) as
Gasohol
• Fuel filters
• Cold starting
• Mechanical modifications required for
bioethanol as a fuel in SI ENGINE
(a). Reversible modifications
(b). Irreversible modifications

19. (a). Reversible modifications
i). Spark timing
ii). Vacuum advance
iii). Carburettor modifications
iv). Preheating air-fuel mixture
v). Cold start modification

20. (b). Irreversible modifications
i). Camshaft change
ii). Increasing in compression ratio
iii). Using turbochargers or superchargers

21. 4. Mechanical modifications required for
bioethanol as a fuel in CI Engine
• Converting diesel engine to a high compression
spark ignition engine.
• Modifying the diesel to tolerate straight ethanol
injection.
• Changing carburettor for the use of ethanol.
• Using dual injection of ethanol and diesel fuel.

22. Engine modification for Biodiesel
i). Rubber seals
ii). Cold starting
iii). Oil changing
iv). Engine timing
v). Engine modifications
weight of vehicle
Power and torque output in relation to braking
Strength of vehicle
Effect of steering and suspension components
The effect on vehicle handling.

23. Performance of a 4-stroke SI Engine using CNG

24. Performance of a 4-stroke SI Engine using CNG

25. Performance of SI Engine with methane,
methanol, hydrogen, propane and ethanol
gasoline fuels

26. Performance of SI Engine with methane,
methanol, hydrogen, propane and ethanol
gasoline fuels

27. Performance of SI Engine with methane,
methanol, hydrogen, propane and ethanol
gasoline fuels

28. Performance of SI Engine with methane,
methanol, hydrogen, propane and ethanol
gasoline fuels

29. Performance of CI Engine Fuelled with Biodiesel

30. Performance of CI Engine Fuelled with Biodiesel

31. Performance of soya bean oil as an alternate
fuel for CI Engine

32. Performance of soya bean oil as an alternate
fuel for CI Engine

38. FUEL CELL

39. TYPES OF FUEL CELLS
1. Hydrogen – Oxygen fuel cell
2. Polymer Electrolyte Membrane(PEM) fuel cell
3. Direct methanol fuel cell
4. Alkaline fuel cell
5. Phosphoric acid fuel cell
6. Molten carbonate fuel cell
7. Solid oxide fuel cell
8. Regenerative fuel cell

40. Low temp Cell is operated at 90 degree celsius 4 atm. Pr
High temp Cell is operated at 300 degree celsius 45 atm. Pr

41. Solid polymer-electrolyte
Porus carbon- electrode

42. Potassium hydroxide-electrolyte

43. Teflon-bonded silicon matrix and porous carbon-electrolyte

44. Molten carbonate salt mixture suspended in a porous chemically inert ceramic lithium
aluminium oxide (LiAlO2)-electrolyte