Biofuels have been around as long as cars have. At the start of the 20th century, Henry Ford planned to fuel his Model Ts with ethanol, and early diesel engines were shown to run on peanut oil. But discoveries of huge petroleum deposits kept gasoline and diesel cheap for decades, and biofuels were largely forgotten. However, with the recent rise in oil prices, along with growing concern about global warming caused by carbon dioxide emissions, biofuels have been regaining popularity.
Gasoline and diesel are known as fossil fuels because they are made from decomposed plants and animals that have been buried in the ground for millions of years. Biofuels are similar, except that they're made from plants grown today.
Biofuels are produced from living organisms or from metabolic by-products (organic or food waste products). In order to be considered a biofuel the fuel must contain over 80 percent renewable materials. There are various ways of making biofuels, but they generally use chemical reactions, fermentation, and heat to break down the starches, sugars, and other molecules in plants. The leftover products are then refined to produce a fuel.
Countries around the world are using various kinds of biofuels. For decades, Brazil has turned sugarcane into ethanol, and some cars there can run on pure ethanol rather than as additive to fossil fuels. And biodiesel—a diesel-like fuel commonly made from palm oil—is generally available in Europe.
On the face of it, biofuels look like a great solution. Cars are a major source of atmospheric carbon dioxide, the main greenhouse gas that causes global warming. But since plants absorb carbon dioxide as they grow, crops grown for biofuels should suck up about as much carbon dioxide as comes out of the tailpipes of cars that burn these fuels. And unlike underground oil reserves, biofuels are a renewable resource since we can always grow more crops to turn into fuel.
First Generation Biofuels
First Generation Biofuels
'First-generation biofuels' are biofuels made from sugar, starch, and vegetable oil.
Bioethanol is an alcohol made by fermenting the sugar components of plant materials mostly from sugar and starch crops. The bioethanol production methods used are enzyme digestion (to release sugars from stored starches), fermentation of the sugars, distillation and drying. With advanced technology being developed, cellulosic biomass, such as trees and grasses, are also used as feedstocks for ethanol production. Ethanol can be used in petrol engines as a replacement for gasoline; it can be mixed with gasoline to any percentage. Most existing car petrol engines can run on blends of up to 15% bioethanol with petroleum/gasoline. Bioethanol is widely used in the USA and in Brazil.
Green diesel, also known as renewable diesel, is a form of diesel fuel which is derived from renewable feedstock rather than the fossil feedstock used in most diesel fuels. Green diesel feedstock can be sourced from a variety of oils including canola, algae, jatropha and salicornia in addition to tallow. Green diesel uses traditional fractional distillation to process the oils.
Biodiesel is the most common biofuel in Europe. It is produced from oils or fats using transesterification and is a liquid similar in composition to fossil/mineral diesel. Biodiesel can be used in any diesel engine when mixed with mineral diesel to reduce levels of particulates, carbon monoxide, and hydrocarbons from diesel-powered vehicles. Pure biodiesel (B100) is the lowest emission diesel fuel.
Second Generation Biofuels
Second-generation biofuel implemented from non-food crops include waste biomass, the stalks of wheat, corn, wood, and special-energy-or-biomass crops. Second generation biofuels use biomass to liquid technology, including cellulosic biofuels. Many second generation biofuels are under development such as biomethanol, DMF, BioDME, Fischer-Tropsch diesel, mixed alcohols and wood diesel.
Second-generation biofuel implemented from non-food crops include waste biomass, the stalks of wheat, corn, wood, and special-energy-or-biomass crops. Second generation biofuels use biomass to liquid technology, including cellulosic biofuels. Many second generation biofuels are under development such as biomethanol, DMF, BioDME, Fischer-Tropsch diesel, mixed alcohols and wood diesel.
Third Generation Biofuels
Algae fuel, also called third generation biofuel, is a biofuel from algae. Based on laboratory experiments, it is claimed that algae can produce up to 30 times more energy per acre than land crops such as soybeans, but these yields have yet to be produced commercially. One advantage of algae fuels over most other fuel types is that they are biodegradable, and so relatively harmless to the environment if spilled.
Second and third generation biofuels are also called advanced biofuels.
Unfortunately, it's not so simple. The process of growing the crops, making fertilizers and pesticides, and processing the plants into fuel consumes a lot of energy. It's so much energy that there is debate about whether ethanol from corn actually provides more energy than is required to grow and process it. Also, because much of the energy used in production comes from coal and natural gas, biofuels don't replace as much oil as they use.
For the future, many think a better way of making biofuels will be from grasses and saplings, which contain more cellulose. Cellulose is the tough material that makes up plants' cell walls, and most of the weight of a plant is cellulose. If cellulose can be turned into biofuel, it could be more efficient than current biofuels, and emit less carbon dioxide.
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