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Thursday, 18 July 2013

ALTERNATIVE FUELS by mosesdhilip kumar

                                                  ALTERNATIVE FUELS
                          The fuels play an important role in human life for example petroleum, gasoline use to operate automobile engines, produce power, to operate power turbine and more. But this fuel is non renewable energy because they take millions of years to form and Conventional. This fuels include: fossil fuels (petroleum (oil), coal, propane, and natural gas), and nuclear materials such as uranium. The production and use of fossil fuels raise environmental concerns. The burning of fossil fuels produces around 21.3 billion tonnes (21.3 gigatonnes) of carbon dioxide (CO2) per year, but it is estimated that natural processes can only absorb about half of that amount, so there is a net increase of 10.65 billion tonnes of atmospheric carbon dioxide per year (one tonne of n 90% of greenhouse gas emissions come from the combustion of fossil fuels.
                                This fossil fuel has high cost, environmental concerns. So we desired to introduce about Alternative fuels and encouraged to use this fuel because this have more advantage than fossil fuels and less cost. By using the Alternative fuels we can reduce the greenhouse gases then more suitable for IC engines to increase the engine efficiency to considerable range. There are many types and it can be used as petrol, diesel. These Alternative fuels can be used in IC engine. Most important Alternative fuels are alcohol.
INTRODUCTION: 
                                  Alternative fuels, also known as non-conventional or advanced fuels, are any materials or substances that can be used as fuels, other than conventional fuels. Some well known alternative fuels include biodiesel, bioalcohol (methanol, ethanol, butanol), chemically stored electricity (batteries and fuel cells), [GreenNH3] non fossil, hydrogen, non-fossil methane, non-fossil natural gas, vegetable oil, and other biomass sources. Methanol fuel has been proposed as a future biofuel. methanol for racing purposes has largely been based on methanol produced from syngas derived from natural gas and therefore this methanol would not be considered a biofuel. These Alternative fuels are more economical so many countries are interested to produce this Alternative fuels and also used wide range in most countries in the world as fuels in automobiles.
                      Brazil was until recently the largest producer of alcohol fuel in the world, typically fermenting ethanol from sugarcane. The country produces a total of 18 billion liters (4.8 billion gallons) annually, of which 3.5 billion liters are exported, 2 billion of them to the U.S.
                       Russia has reduced its dependency on oil by using methanol made from the destructive pyrolysis of eucalyptus wood and fibre. However, this system is less likely to be emulated elsewhere, due to the disadvantages of methanol fuel.
                         Although alcohol used as alternative fuel they have main some demerits i.e. may cause blindness or death. So we desired to reduce the demerits due to mix the methanal with compressed air.
                          Let we see the types, composition, application, advantages, demerits and solution for that demerits.
BIOFUEL:
                    Alternative fuels dispensers at a regular gasoline station in Arlington, Virginia.B20 biodiesel at the left and E85 ethanol at the right. Biofuels are also considered a renewable source. Although renewable energy is used mostly to generate electricity, it is often assumed that some form of renewable energy or at least it is used to create alternative fuels.
ALCOHOL FUELS:
                          Methanol and Ethanol fuel are typically primary sources of energy; they are convenient fuels for storing and transporting energy. These alcohols can be used in "internal combustion engine as alternative fuels", with butanol also having known advantages, such as being the only alcohol-based motor fuel that can be transported readily by existing petroleum-Product pipeline networks, instead of only by tanker trucks and railroad cars

 HYDROGEN:

Hydrogen is an emissionless fuel. The by product is pure water which is harmless to our earth.
AMMONIA:
                     Ammonia can be used as fuel. A small machine can be set up to create the fuel and it is used where it is made. Benefits of ammonia include, no more need for oil wars, zero emissions, and distributed production reducing transport and related pollution.
Hydrogen is an emissionless fuel. The by product is pure water which is harmless to our earth.

HCNG:

HCNG (or H2CNG) is a mixture of compressed natural gas and 4-9 percent hydrogen by energy.

COMPRESSED AIR:

The air engine is an emission-free piston engine using compressed air as fuel. Unlike hydrogen, compressed air is about one-tenth as expensive as fossil oil, making it an economically attractive alternative fuel.

ALTERNATIVE FOSSIL FUELS:

Compressed natural gas (CNG) is a cleaner burning alternative to conventional petroleum automobile fuels. The energy efficiency is generally equal to that of gasoline engines, but lower compared with modern diesel engines. CNG vehicles require a greater amount of space for fuel storage than conventional gasoline power vehicles because CNG takes up more space for each GGE (Gallon of Gas Equivalent). Almost any existing gasoline car can be turned into a bi-fuel (gasoline/CNG) car. However, natural gas is a finite resource like all fossil fuels, and production is expected to peak gas soon after.
METHANOL AND ETHANOL:
                                           Methanol and ethanol can both be derived from fossil fuels, biomass, or perhaps most simply, from carbon dioxide and water. Ethanol has most commonly been produced through fermentation of sugars, and methanol has most commonly been produced from synthesis gas, but there are more modern ways to obtain these fuels. Enzymes can be used instead of fermentation. Methanol is the simpler molecule, and ethanol can be made from methanol. Methanol can be produced industrially from nearly any biomass, including animal waste, or from carbon dioxide and water or steam by first converting the biomass to synthesis gas in a gasifier. It can also be produced in a laboratory using electrolysis or enzymes.
As a fuel, methanol and ethanol both have advantages and disadvantages over fuels such as petrol (gasoline) and diesel fuel. In spark ignition engines, both alcohols can run at a much higher exhaust gas recirculation rates and with higher compression ratios. Both alcohols have a high octane rating, with ethanol at 109 RON (Research Octane Number), 90 MON (Motor Octane Number), (which equates to 99.5 AKI) and methanol at 109 RON, 89 MON (which equates to 99 AKI). Note that AKI refers to 'Anti-Knock Index' which averages the RON and MON ratings (RON+MON)/2, and is used on U.S. gas station pumps. Ordinary European petrol is typically 95 RON, 85 MON, equal to 90 AKI. As a compression ignition engine fuel, both alcohols create very little particulates, but their low cetane number means that an ignition improver like glycol must be mixed into the fuel with approx. 5%.
This include both fuel system compatibility and lambda compensation of fuel delivery with fuel injection engines featuring closed loop lambda control. In some engines ethanol may degrade some compositions of plastic or rubber fuel delivery components designed for conventional petrol, and also be unable to lambda compensate the fuel properly.
Methanol combustion is: 2CH3OH + 3O2 → 2CO2 + 4H2O + heat
Ethanol combustion is: C2H5OH + 3O2 → 2CO2 + 3H2O + heat
BUTANOL AND PROPANOL:
                                        Propanol and butanol are considerably less toxic and less volatile than methanol. In particular, butanol has a high flashpoint of 35 °C, which is a benefit for fire safety, but may be a difficulty for starting engines in cold weather. The concept of flash point is however not directly applicable to engines as the compression of the air in the cylinder means that the temperature is several hundred degrees Celsius before ignition takes place.
                   The fermentation processes to produce propanol and butanol from cellulose are fairly tricky to execute, and the Weizmann organism (Clostridium acetobutylicum) currently used to perform these conversions produces an extremely unpleasant smell, and this must be taken into consideration when designing and locating a fermentation plant. This organism also dies when the butanol content of whatever it is fermenting rises to 7%. For comparison, yeast dies when the ethanol content of its feedstock hits 14%. Specialized strains can tolerate even greater ethanol concentrations - so-called turbo yeast can withstand up to 16% ethanol. However, if ordinary Saccharomyces yeast can be modified to improve its ethanol resistance, scientists may yet one day produce a strain of the Weizmann organism with a butanol resistance higher than the natural boundary of 7%. This would be useful because butanol has a higher energy density than ethanol, and because waste fibre left over from sugar crops used to make ethanol could be made into butanol, raising the alcohol yield of fuel crops without there being a need for more crops to be plant.
 METHANOL:
                   Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with formula CH3OH (often abbreviated MeOH). It is the simplest alcohol, and is a light, volatile, colorless, flammable, liquid with a distinctive odor that is very similar to but slightly sweeter than ethanol (drinking alcohol). At room temperature it is a polar liquid and is used as an antifreeze, solvent, fuel, and as a denaturant for ethanol. It is also used for producing biodiesel via transesterification reaction.
Methanol is produced naturally in the anaerobic metabolism of many varieties of bacteria, and is ubiquitous in the environment. As a result, there is a small fraction of methanol vapor in the atmosphere. Over the course of several days, atmospheric methanol is oxidized with the help of sunlight to carbon dioxide and water.
Methanol burns in air forming carbon dioxide and water:
2 CH3OH + 3 O2 → 2 CO2 + 4 H2O
A methanol flame is almost colorless in bright sunlight.
Because of its toxic properties, methanol is frequently used as a denaturant additive for ethanol manufactured for industrial uses — this addition of methanol exempts industrial ethanol from liquor excise taxation. Methanol is often called wood alcohol because it was once produced chiefly as a byproduct of the destructive distillation of wood.
Today synthesis gas is most commonly produced from the methane component in natural gas rather than from coal. Three processes are commercially practiced. At moderate pressures of 4 MPa (40 atm) and high temperatures (around 850 °C), methane reacts with steam on a nickel catalyst to produce syngas according to the chemical equation:
CH4 + H2O → CO + 3 H2
This reaction, commonly called steam-methane reforming or SMR, is endothermic and the heat transfer limitations place limits on the size of and pressure in the catalytic reactors used. Methane can also undergo partial oxidation with molecular oxygen to produce syngas, as the following equation shows:
2 CH4 + O2 → 2 CO + 4 H2
This reaction is exothermic and the heat given off can be used in-situ to drive the steam-methane reforming reaction. When the two processes are combined, it is referred to as autothermal reforming. The ratio of CO and H2 can be adjusted to some extent by the water-gas shift reaction,
CO + H2O → CO2 + H2,
to provide the appropriate stoichiometry for methanol synthesis.
It is worth noting that the production of synthesis gas from methane produces 3 moles of hydrogen gas for every mole of carbon monoxide, while the methanol synthesis consumes only 2 moles of hydrogen gas for every mole of carbon monoxide. One way of dealing with the excess hydrogen is to inject carbon dioxide into the methanol synthesis reactor, where it, too, reacts to form methanol according to the equation:
CO2 + 3 H2 → CH3OH + H2O
Although natural gas is the most economical and widely used feedstock for methanol production, many other feedstocks can be used to produce syngas via steam reforming.

ALTERNATIVES TO PETROLEUM-BASED VEHICLE FUELS:

  •                                                                  Alternative fuels used in standard or modified internal combustion engines (i.e. biofuels or combustion hydrogen).
  • propulsion systems not based on internal combustion, such as those based on electricity (for example, all-electric or hybrid vehicles), compressed air, or fuel cells (i.e. hydrogen fuel cells).
Currently, cars can be classified into the following groups:
  • Internal combustion engine cars, which may use
    • petrol, fuel and/or biofuels (e.g. alcohol, biodiesel and biobutanol)
    • compressed natural gas used by natural gas vehicles
    • Hydrogen in hydrogen vehicles.
  • Advanced technology cars such as hybrid vehicles which use petroleum and/or biofuels, albeit far more efficiently.
  • Plug-in hybrids, that can store and use externally produced electricity in addition to petroleum.
  • electric cars
ALTERNATIVES TO BURNING PETROLEUM FOR ELECTRICITY:
                       In oil producing countries with little refinery capacity, oil is sometimes burned to produce electricity. Renewable energy technologies such as solar power, wind power, micro hydro, biomass and biofuels might someday be used to replace some of these generators, but today the primary alternatives remain large scale hydroelectricity, nuclear and coal-fired generation.
FUEL FOR VEHICLES:
                     Methanol is used on a limited basis to fuel internal combustion engines. Pure methanol is required by rule to be used in Champcars, Monster Trucks, USAC sprint cars (as well as midgets, modifieds, etc.), and other dirt track series such as World of Outlaws, and Motorcycle Speedway. Methanol is also used, as the primary fuel ingredient since the late 1940s, in the powerplants for radio control, control line and free flight airplanes (as methanol is required in the "glow-plug" engines that primarily power them), cars and trucks, from such an engine's use of a platinum filament glow plug being able to ignite the methanol vapor through a catalytic reaction. Drag racers and mud racers also use methanol as their primary fuel source. Methanol is required with a supercharged engine in a Top Alcohol Dragster.
CONCLUSION:
                             These are the types, properties, applications, advantages and demerits of Alternative fuels. The demerits of some of Alternative fuels are reduce by mixing of two or more Alternative fuels to get desired properties of Alternative fuels. We can say strictly the Alternative fuels will have important role in human life.


 


   




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