Bio-fuels have been around as long as vehicles have, but for decades gasoline and diesel were kept at low prices probably because it was readily available. To-days rising oil prices, and the need for energy security have made these fuels increasingly popular. Derived from Biomass they are mostly used for liquid form transportation fuels, although some are also used to produce electricity and heat in solid form.
Two of the most common fuels used for vehicles are Ethanol and Bio-diesel, made through conversion processes such as biochemical and thermo-chemical. The biochemical process involves pretreatment and hydrolysis, obtained via enzymes and microbes of plant-based feed-stocks such as corn and wheat grains. The goal is to release the biomass derived sugars, and then convert these to Ethanol through fermentation.
The thermo-chemical process, uses cellulosic feed-stocks such as wood and forest products that are rapidly heated to temperatures between 400-900C in the absence of oxygen to produce a syn-gas which is then converted to bio-alcohols, then separated and purified to produce Ethanol, Methanol, and other useful products.
Some other Bio-fuels are Green Diesel, Bio-fuel Gasoline, Vegetable Oil, Bio-Ether, Bio-gas, and Solid Bio-fuels. Wood Char which is derived from solid Bio-fuels and made from agricultural waste, can be substituted for wood charcoal as a good alternative especially as wood stocks are becoming scarce.
Solid Bio-fuels include wood, sawdust, grass trimmings, charcoal, agricultural waste, nonfood energy crops, and dried manure. These solid fuels ( such as firewood), can be used directly in a stove, or furnace in their natural form to produce heat or steam.
When the raw biomass is in the form of sawdust, wood chips, grass, waste-wood and agricultural residues, a process is used that includes grinding the raw biomass to a suitable size which is then concentrated into fuel products in the form of wood pellets, cubes, or pucks. The wood pellets are used directly in pellet stoves for heat.
What is Ethanol? It is a clear colorless liquid alcohol used as a gasoline additive to increase octane which prevents engine knocking and improves vehicle emissions, also is extremely important (in engines that operate at a higher compression ratio) in generating more power.
As an alternative fuel, Ethanol as a (5-10% blend with gasoline) will work in any vehicle without engine modification to boost octane. E-10 is widely available at gas stations in most parts of the U.S., and E-85 containing 51% to 83% Ethanol, (depending on location and season) can be used in flexible fuel vehicles (with some minor engine modification) that can withstand high Ethanol content, and can operate normally under very cold conditions.
There are currently more than 7 million vehicles on the roads today that uses alternative fuels, according to the U.S. Department of Energy's Bio-energy Technologies Office.
Second generation (advanced) Bio-fuels are under development such as Cellulosic Ethanol and Algae Fuels. Cellulosic Ethanol has the potential of reducing green house gas emissions by 86%. Even the U.S. Department of Energy studies show that corn Ethanol results has 19% fewer GHG compared to Petroleum.
Produced from oils, fats, restaurant greases, and processed into a liquid fuel, Bio-diesel can be used in any diesel engine if mixed with mineral diesel. Because it is non-toxic and biodegradable, it is safe to handle and to transport, and the air quality and green house gas benefits are usually in proportion to the blend.
The most common Bio-diesel blend used in the U.S. is B20 which is Bio-diesel blended with 20% petroleum diesel, it is used by vehicle fleets. Individual consumers, using diesel vehicles can use B20 along with nearly all diesel storage and distribution equipment.
Bio-fuels production and use have been debated in the news and scientific journals with many of the issues being their adverse impacts on the environment, on food security, on land use, also on the effect of moderating oil prices, impact on water resources, and on energy balance and efficiency.
Fuels of the future such as the ones made from cellulosic feed-stocks and algae, and production processes using progressively more clean, renewable energy sources, greenhouse gas emissions will decrease dramatically.
The U.S. Department of Energy's Bio-energy Technologies Office are addressing environmental, social, and economic issues along the entire bio-energy supply chain. With laboratory-based research, computer modeling, and advanced analysis, the Office investigates life-cycle impacts of bio-energy production on greenhouse gas emissions, cleaner air, soil and enhanced water quality, and the use of marginal croplands.
The Energy Department is focused on forming cost-sharing partnerships with key stakeholders for the production of advanced fuels. The benefits are a more secure, sustainable, and economical future. Jobs in the U.S. bio-fuel industry represent the creation of thousands of direct jobs, and ten of thousands of indirect jobs, and is expected to continue growing. Another benefit of Bio-fuels is our dependence on imported oil is being greatly reduced.
For more information see alternative energies
Also see Biomass