The
basic feed stocks for the production of first generation biofuels are often
seeds or grains such as wheat, which yields starch that is fermented into
bioethanol, or sunflower seeds, which are pressed to yield vegetable oil that
can be used in biodiesel.
(i) Vegetable oil
—Edible vegetable oil is generally not
used as fuel, but lower quality oil can be used for this purpose.
Used vegetable oil is increasingly being
processed into biodiesel, or (more rarely) cleaned of water and particulates
and used as a fuel.
(ii) Biodiesel
— Biodiesel is the most common bio fuel in
Europe.
—It is produced from oils or fats using
trans-esterification and is a liquid similar in composition to fossil/mineral
diesel.
biodiesel include animal fats, vegetable
oils, soy, rapeseed, jatropha, mahua, mustard, flax, sunflower, palm oil,
hemp, field pennycress, pongamia pinata and algae.
(iii) Bioalcohol
—Biologically produced alcohols, most
commonly ethanol, and less commonly propanol and butanol, are produced by the action of
microorganisms and enzymes through the fermentation of sugars or starches
(easiest), or cellulose (which is more difficult).
(iv) Bioethers
Bio ethers are cost-effective compounds
that act as octane rating enhancers.—They also enhance engine performance,
whilst significantly reducing engine wear and toxic exhaust emissions.Greatly reducing the amount of
ground-level ozone, they contribute to the quality of the air we breathe.
(v) Biogas
- Biogas is produced by the process of
anaerobic digestion of organic material by anaerobes.
- —It can be produced either from
biodegradable waste materials or by the use of energy crops fed into anaerobic
digesters to supplement gas yields.
- Landfill gas is a less clean form of
biogas which is produced in landfills through naturally Occurring anaerobic
digestion. If it escapes into the atmosphere it is a potent greenhouse gas.
(vi) Syngas
Syngas, a mixture of carbon monoxide and
hydrogen, is produced by partial combustion of biomass, that is, combustion
with an amount of oxygen that is not sufficient to convert the biomass
completely to carbon dioxide and water.
(vii) Solid biofuels
Examples include wood, sawdust, grass
cuttings, domestic refuse, charcoal, agricultural waste, non-food energy crops
and dried manure. It can burn directly in a stove or
furnace to provide heat or raise steam.
Second Generation biofuels
- Second
generation (2G) biofuels use biomass to liquid technology, including
cellulosic biofuels from non food crops.
- Many second generation biofuels are under
development such as biohydrogen, biomethanol, Fischer-Tropsch diesel, bio hydrogen diesel, mixed
alcohols and wood diesel.
Third Generation biofuels
- Algae fuel, also called oilgae or
third generation biofuel, is a biofuel from algae. Algae are low-input, high-yield feedstock
to produce biofuels.
- Based on laboratory experiments, it
claimed that Algae can produces up to 30 times more energy per acre than land
crops such as soybeans
.
Ethanol from Living Algae
- An
alternative approach relies on the fact that some algae naturally produce
ethanol and this can be collected without killing the algae.
- — The
ethanol evaporates and then can be condensed and collected.
Helioculture
- Helioculture is a newly developed Technology which is
claimed to be able to produce 20,000 gallons of fuel per acre per year, and
which removes carbon dioxide from the air as a feedstock for the fuel.
- The process of Helioculture can develop many different fuels and
petroleum-derived chemicals all while not using any fresh water or agriculture.
Advantages of Bio fuels
1. Bio-fuels lessen the burden on gradually-vanishing fossil fuels
As fossil energy resources are in decline and the need to become less reliant on energy imports is becoming more and more relevant and alternative energy sources are needed. —Biofuels are one possible replacement for fossil fuels. Although biofuels still cost more than fossil fuels, their share in terms of use is increasing worldwide. The global production of biofuels is now estimated to be about 5 billion litres per year.
2. Bio-fuels are environment-friendly. They help reduce carbon emissions into the atmosphere
Fossil fuels generate huge amounts of pollution. Bio-fuels are comparatively safer. Bio Fuel contribute to climate protection. As bio fuels are usually considered to be CO neutral, their use helps to reduce greenhouse gas emissions. Fossil fuels, on the other hand, are a major source of CO
3. Fossil fuels are created over millions of years while biofuels can be made very quickly.
—Because of their regeneration time, biofuels are considered much more ‘renewable’.
4. The use of biofuels as transport fuels
Biofuels are usually used for transport fuels, but they are also applicable for electricity and heat generation. In relation to reducing dependency on fossil fuel imports, bio fuel is particularly effective.
Biodiesel can be used in pure form (B100) or may be blended with petroleum diesel at any concentration in most modern diesel engines.Bio diesel is widely used for:
As a heating oil
Aircraft
Railway usage
5. Cost Effectiveness
Bio-fuels, especially, bio-diesel prove to be very cost-effective for consumers.
Are Bio fuels Cost Competitive?
In 2005, neither biofuel was cost-competitive with petroleum – but as petroleum prices increased the gap closed.
Ethanol:
Estimated ethanol production cost in 2005 was $0.46 per gasoline
energy equivalent Wholesale gasoline prices averaged $0.44/L in 2005
Soy biodiesel
Estimated soybean biodiesel production cost in 2005 was $0.55 per
diesel EEL, Diesel wholesale prices averaged $0.46/L in 2005
Recent price effects unfavorable for biofuels:
Lower fossil-fuel price Higher corn prices
6.Invasive crop species can be used in Bio fuel making to reduce their impact on other food crops.
Disadvantages relating to biofuels
1."Food vs. fuel" debate
Regarding the risk of diverting farmland or crops for biofuel production in detriment of the food supply on a global scale.
Biofuel production has increased in recent years. Some commodities like maize, sugar cane or vegetable oil can be used either as food, feed or to make biofuels.
This result in higher food prices.
Efforts are currently being put into the production of second generation biofuels from non-food crops, crop residues and waste.
2.Emission of hazardous gases
- Can contribute as much or more to global warming by nitrous oxide emissions.
- Crops with higher requirements for nitrogen fertilizers, are highly responsible for these emissions.
- Burning biodiesel also emits aldehydes and other potentially hazardous aromatic compounds which are not regulated in emissions laws.
3. Indirect land use change impacts of bio fuel
- — Release more CO2 when farmers elsewhere in the world clear rainforests and other pristine lands to grow grain to produce ethanol, translating in a net increase in CO2 emissions.
- —“Biofuel carbon debt” -Biofuel release 17 to 420 times more CO2 than the annual greenhouse gas (GHG) reductions, these biofuels provide by displacing fossil fuels. (mostly corn based ethanol)
4.Soil erosion, deforestation, and biodiversity
- —Demand for biofuel has led to clearing land for Palm Oil plantations.
- Large-scale deforestation contributes to un-sustainable global warming, atmospheric greenhouse gas level increment, loss of habitat, and a reduction of valuable biodiversity.
- —A portion of the biomass should be retained onsite to support the soil resource.
5.Impact on water resources
— Increased use of biofuels puts increasing pressure on water resources in at least two ways:
1.water use for the irrigation of crops used as feedstocks for biodiesel production;
2. water use in the production of biofuels in refineries, mostly for boiling and cooling
6.Biofuels and solar energy efficiency
Photovoltaics are 100 times more efficient than corn ethanol and 10 times more efficient than the best biofuel.
FOR YOU TO THINK……….
Biofuels are not the answer to sustainable energy, but biofuels may be part of the answer .
Biofuels may offer advantages over fossil fuels, but the magnitude of these advantages
depends on how a biofuel crop is grown and converted into a usable fuel.
Some examples for bioreactors 
