Biofuels are fuels generated from living organisms. Biofuels are solid biomass biofuels, liquid biofuels and various biogases. Biofuels are low cost alternative fuel energy sources for vehicles. Many cheaper biofuels increase vehicle engine safety and life. Biofuels are gaining increased public and scientific attention, driven by factors such as oil price spikes, the need for increased energy security, and concern over greenhouse gas emissions from fossil fuels.

Most transportation fuels are liquids, because vehicles usually require high energy density, as occurs in liquids and solids. High power density can be provided most inexpensively by an internal combustion engine; these engines require clean burning fuels, to keep the engine clean and minimize air pollution. The fuels that are easiest to burn cleanly are typically liquids and gases.

Key Points on Different Types of BioFuels

  • Bioethanol is an alcohol made by fermenting the sugar components of plant materials and it is made mostly from sugar and starch crops. With advanced technology being developed, cellulosic biomass, such as trees and grasses, are also used as feedstocks for ethanol production. Ethanol can be used as a fuel for vehicles in its pure form, but it is usually used as a gasoline additive to increase octane and improve vehicle emissions. Bioethanol is widely used in the USA and in Brazil.
  • Biodiesel is made from vegetable oils, animal fats or recycled greases. Biodiesel can be used as a fuel for vehicles in its pure form, but it is usually used as a diesel additive to reduce levels of particulates, carbon monoxide, and hydrocarbons from diesel-powered vehicles. Biodiesel is produced from oils or fats using transesterification and is the most common biofuel in Europe.
  • Bioalcohol is an Alcohol fuel. Biologically produced alcohols, most commonly bioethanol, and less commonly biopropanol and biobutanol, are produced by the action of microorganisms and enzymes through the fermentation of sugars or starche, or cellulose.
  • Biobutanol (also called biogasoline) is often claimed to provide a direct replacement for gasoline, because it can be used directly in a gasoline engine (in a similar way to biodiesel in diesel engines).
  • 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.
  • Bioethers (also referred to as fuel ethers or oxygenated fuels) 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.
  • Biogas is methane produced by the process of anaerobic digestion of organic material by anaerobes. Biogas can be recovered from mechanical biological treatment waste processing systems. Farmers can produce biogas from manure from their cows by using an anaerobic digester (AD).
  • 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.
  • Solid biofuels are wood, sawdust, grass cuttings, domestic refuse, charcoal, agricultural waste, non-food energy crops, and dried manure.
  • 2G Biofuels are cellulosic biofuels, biohydrogen, biomethanol, DMF, BioDME, Fischer-Tropsch diesel, biohydrogen diesel, mixed alcohols and wood diesel. 2G biofuels are generated use biomass to liquid technology with the raw biomass materials include waste biomass, the stalks of wheat, corn, wood, and special-energy-or-biomass crops (e.g. Miscanthus).
  • Algae fuel, also called oilgae or third generation (3G) biofuel, is a biofuel from algae. Algae are low-input, high-yield feedstocks to produce biofuels. 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.
  • Ethanol from living algae: Most biofuel production comes from harvesting organic matter and then converting it to fuel but 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.
  • Fourth generation (4G) biofuels: 4G biofuels are “bio-chemical” and “thermo-chemical” processes that produce “drop in” fuels like “green gasoline,” “green diesel,” and “green aviation fuel”. Hydrocarbon plants or petroleum plants are plants which produce terpenoids as secondary metabolites that can be converted to gasoline-like fuels. If biocatalytic cracking and traditional fractional distillation are used to process properly prepared algal biomass i.e. biocrude, then as a result we receive the following distillates: jet fuel, gasoline, diesel, etc.. Hence, we may call them third generation or green fuels.