Alternative Fuels for SI Engines

By K C KARTHIK2nd sem, M.Tech(A.E)

The increase in energy consumption particularly in the past several decades has raised fears of exhausting vital natural resources

Rapid industrialization and massive growth in population has increased the dependence and use of natural fuels

Approximately 90% of our energy requirement are met by fossil fuels

Ethanol

Hydrogen

Natural Gas

Propane

Methanol

• Ethanol is an alcohol-based alternative fuel produced by fermenting and distilling starch crops that have been converted into simple sugars. Feedstock for this fuel include corn, barley, and wheat.

• Ethanol can also be produced from "cellulosic biomass" such as trees and grasses and is called bioethanol. Ethanol is most commonly used to increase octane and improve the emissions quality of gasoline.

• High octane (100+); enhances octane properties of gasoline and used as oxygenate to reduce CO emissions.

• 27% - 36% less energy content than gasoline. Also 15% - 30% decrease in mileage.

• E85 vehicles demonstrate a 25% reduction in ozone-forming emissions compared to gasoline.

• As an alternative fuel, most commonly used in a blend of 85% ethanol and 15% gasoline (E85).

A mixture of 85% Ethanol and 15% Gasoline (E85)Pros

Higher Octane Rating 100-105Reduces dependence on fossil fuelsReduces tailpipe emissionsUsually cheaper than 87 octane gasoline

ConsProduction process does add extra green house gases to

atmosphereUse of corn crop for fuel instead of foodLower energy content than gasolineLimited distribution network

Hydrogen

• It is the simplest and lightest fuel with atomic no. 1.

• Hydrogen burns more efficiently and creates energy more than gasoline.

• Hydrogen is extremely reactive with oxygen and makes it highly flammable

• Hydrogen mixed with natural gas can be used in internal combustion engine.

• Hydrogen is the perfect fuel to run fuel cells cause pure hydrogen reacts only with oxygen releasing water thus no emissions.

Properties

Does not occur to any significant extent on earth in its free, elemental form.

Found in chemical compositions such as water and hydrocarbons, and dry coal.

Pure hydrogen contains no carbon thus burns to form water with no CO2 or CO emissions.

One kg of hydrogen contains roughly equivalent energy to one gallon of gasoline.

Can be stored as compressed hydrogen at 5,000 – 10,000 psi or liquid hydrogen (cooled to -4230F, -2520C).

There are two types of Hydrogen engineHydrogen IC engineHydrogen fuel cell engine

Hydrogen IC engine emits zero CO2 and minimal Nox when compared to other engines. The SI engine can be used for it.

Generation of Hydrogen – Electrolysis of waterH2OH2 + ½ O2

Supply Hydrogen gas to intake valve of SI engineVary voltage of DC supply to control electrolysis process.

HydrogenPros

Much lower emissions than PetrolHuge supply of hydrogenReduce consumption of PetrolMore energy per weight than gasolineHigher thermal efficiency than gasoline engine

ConsMost common production method burns fossil fuelsLower volumetric density than gasolineExpensive to produceNo distribution networkDifficulties in transportation and storage

• Natural gas is a mixture of hydrocarbons, mainly methane, and is produced either from gas wells or in conjunction with crude oil production.

• Natural gas is consumed in the residential, commercial, industrial, and utility markets.

• Natural gas can either be stored onboard a vehicle as compressed natural gas (CNG) or as liquefied natural gas (LNG). Natural gas can also be blended with hydrogen.

Natural Gas

CNGIn India CNG costs are at Rs. 40/kg much

cheaper than petrol at Rs. 70/ltr.The cost saving is immense along with

reduced emissions and environment friendly.The use of CNG is mandatory for public

transport in New Delhi as well as for Ahmedabad.

The Delhi Transport Corporation operates the world’s largest fleet of CNG buses.

Natural GasPros• Lower emissions• Lower smog producing gases (60-90% Light-Duty use, 90% in Mid to Heavy-duty use)• Can be used to make hydrogen to power the future fuel cell technology

Future of natural gas• Natural gas is now being installed in 1 out of 5 transit buses today • Fueling systems are being installed in home or public facilities• Gradually the automobiles shift to natural gas fuel.

Propane

• Propane is a liquefied gas made up of propylene, butane, and butylene from petro chemicals.

• By-product of natural gas processing and crude oil refining.

What are the benefits?• A 98% reduction in toxic emissions in light-duty bi-fuel

vehicles• In the quantities needed it costs less than gasoline• Very accessible compared to other alternative fuels.

Propane Properties• HD5, the automotive propane standard, a mixture of 90%

propane and other hydrocarbons(proplyene).

• Contains 33% - 41% less energy content per gallon than gasoline.

• Vehicles can demonstrate a 60% reduction in ozone-forming emissions compared to gasoline.

• High octane properties (~104) allow vehicles to operate with higher compression ratios; leads to higher efficiency/fuel economy

• Used in light- and medium-duty vehicles, heavy-duty trucks and buses.

• Many propane vehicles are converted gasoline vehicles.

(Conversion kits include regulator/vaporizer, air/fuel mixer, oxygen-monitoring closed-loop feedback system, and special fuel tank.)

Propane

Propane

Future

• Currently 200,000 vehicles in the US use propane (mostly fleet vehicles like taxis and police cars)

• Since the current infrastructure can easily be converted to dispense propane it makes for a cost effective solution to gasoline by using the current fuel dispensing system

• Methanol is wood alcohol, which can be made from natural gas, coal, or wood.

• Methanol is produced from natural gas in production plants with 60% total energy efficiency.

• Methanol can be made with any renewable resource containing carbon such as seaweed, waste wood and garbage.

• Methanol fuel cells will greatly reduce carbon dioxide emissions for vehicles and virtually eliminate smog and particulate pollution.

Methanol

Methanol

Pros

• Lower emissions• Higher performance• Lower risk of flammability• Methanol can be used to easily make hydrogen

Cons

• The biggest is the lack of vehicles to use it, manufactures have stopped making vehicles to run on Methanol

ConclusionAlternative fuels generally lower emissions making

them appealing for environmental concerns. Many

of these fuels are renewable and would lessen the

need for petroleum products. A lot of these fuels

are going to be used with the developing fuel cell

technology. With making the public aware of these

alternatives it could hasten the development of

these fuels and the technologies to run them