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.
