A broad definition of biofuel is any fuel derived from biomass. According to this definition, biofuel includes liquid and gaseous fuels derived from: agricultural products, animal wastes, organic wastes from industries, forestory and domestic sectors or other organic sources. Landfill gas and biogas generated in the sewage treatment process can also be classified as biofuel but they are separately discussed in the Energy-from-Waste section.
This section focuses on liquid fuels produced biologically as a substitute for fossil fuel for automotive applications, mainly bioethanol and biodiesel. Both bioethanol and biodiesel can be used in pure form or blended with petrol or conventional diesel as automotive fuel.
Bioethanol can be produced from biomass materials that contain sugar, starch or cellulose. Feedstocks can be agricultural crops like sugar cane, wheat, barley, potatoes, corn or waste paper, sawdust and straw.
- Sugary or starchy crops like wheat can be fermented and distilled into bioethanol.
- To produce ethanol from cellulosic biomass, steam is applied to break down and decompose the biomass into glucose, and followed by hydrolysis. The glucose then converts into alcohol by fermentation. After fermentation, distillation is required to remove water and other impurities in the alcohol-containing mixture. The production of bioethanol from cellulosic biomass is still under research.
Simplified Bioethanol Process Flow Diagram
Ethanol can be applied in pure form or blended with petrol as automotive fuel. Due to its volatile property, ethanol is very suitable to be used in direct-injection petrol engines as a substitute for petrol. Generally speaking, no engine modification is required if less than 10% by volume of ethanol is blended with petrol and used as fuel. Fuel with higher concentration of ethanol will require engine modifications.
Flexible-fuel vehicles are cars and trucks that are capable of running on petrol or petrol blended with any level of ethanol up to 85 percent. They are built with special fuel system components designed to be compatible with higher ethanol concentrations.
The term biodiesel refers to long-chain fatty acid alkyl esters made from vegetable oils, recycled cooking oils, or animal fats. It is most commonly produced by chemically altering an organic oil with methanol, by the use of a catalyst through a process called esterification. In the esterification process, the glycerine portion of the oil molecules is replaced by alcohol and is eventually removed from the mixture in the washing and drying process. Biodiesel is then formed.
(Source for above: This web page has hyperlinks which may transfer you to third-party website.http://www1.eere.energy.gov/biomass/pdfs/renewable_fuel.pdf)
Simplified Biodiesel Reaction (the no. in the original formula represent no. of units of ingredients and products)
Oil or Fat + Alcohol ----(catalyst)---> Glycerin + Biodiesel
The feedstock for biodiesel production is mainly vegetable oil, i.e. oil of rapeseed, sunflower or soybeans. To produce biodiesel, vegetable oil is firstly extracted from the oil-bearing seeds and then goes through the esterification process. Used oil, such as cooking oil and fat can be another source of biodiesel. However, when such kind of oil is used, purification treatment is needed before the esterification process. Nowadays, rapeseed is the principal feedstock for biodiesel production in the European Union, soybeans are mainly used in the USA, and the use of sunflower and palm oil is mainly found in warm/hot climate regions.
Apart from replacing a portion of the fossil fuels used in the transport sector, biofuels also bring about other benefits:
- The amount of carbon dioxide released in the utilization process is close to the amount of carbon dioxide absorbed when growing the crops. (Note that energy is required for the farming, processing, refining and transportation steps.)
- Biofuels are biodegradable and nontoxic, and hence cause less soil and groundwater contamination.
- Biofuel utilization produces lower emissions of greenhouse gases, sulphur dioxide and particulates than the converntional automotive fuels.
- Biofuels produced from organic wastes also offer waste management benefits as an alternative for solid waste treatment.
- Biofuels are found to improve engine performance. Ethanol has higher octane number than petrol, making it a very knock-proof fuel. Besides, biodiesel has the ability to dissolve diesel residues in diesel engines.
- The production of biofuels from suitable feedstock can create socio-economic benefits by increasing employment, reducing fossil fuel import and opening up potential export markets.
Nowadays, Brazil and the USA are the leading bioethanol producing countries in the world.
In Brazil, the ethanol program can be dated back to 1975 due to the sharp increase of world oil price after the Arab oil embargo and a sharp decrease in sugar price. In order to reduce the need for oil imports and provide an additional market for Brazilian sugar, the government began promoting the production of ethanol for blending into gasoline (i.e. petrol) with supporting policies and market mechanisms. More than fifteen billion liters of fuel ethanol was produced in 2005, which accounted for 40% of transport fuel in Brazil.
The success of ethanol program in Brazil is a result of strong government support. The Brazilian government has required that ethanol make up a certain percentage of fuel supply since the start of the alcohol program. The blending ratio of ethanol to gasoline is set at 20% (as of 2006). The government also offers preferential tax for flexible-fuel cars. This boosts the application of flexible fuel cars from 1% of new car sales in 2001 to 53% in 2005. Since flexible-fuel car can use gasoline blended with ethanol up to 85%, this also offers the flexibility of fuel choice for car users during price swing of fuels (biofuel for transportation).
In the USA, ethanol is produced primarily from corn and wheat. It has been used as a transport fuel since the early 1980s. In the year of 2005, fifteen billion liters of fuel ethanol are produced, comprised of 3% of the total US consumption of gasoline) on volume basis in that year. Two types of ethanol fuel are available (as of 2006), i.e. E10 (ethanol is blended directly into gasoline in a mix of 10 percent ethanol and 90 percent gasoline by volume) and E85 (85% ethanol mixed with 15% gasoline by volume). All gasoline vehicles in use in the U.S. today can use E10 without engine modification. Another blend, E85 is mainly used for government fleet vehicles, flexible-fuel vehicles and urban transit buses. The 15 percent gasoline used to formulate E85 is to assure cold weather engine starting and to enhance flame luminosity in case of fire.
In the Mainland, ethanol prouduction facilities are mainly run by state-owned enterprises. Since launching of the ethanol fuel programme in the Mainland in year 2000, the ethanol production capacity in 2005 reached 1.02 million metric tons and about 0.92 million metric tons of ethanol was produced in the same year. The central government set a target to increase production capacity to 4 million metric tons by 2010. Corn and wheat are the major raw materials for the production of bioethanol. E10 is being tested in some Mainland provinces and the central government aims at replacing 15% of the country's transport fuel by biofuels by year 2020.
Current and Future Production of Ethanol in China -
|Location (Province, city)||Company Name||Principal Feedstock||Actual 2005 Production (Tonnes/Yr)||2007 Production Capacity (Tonnes/Yr) (forcasted)||Supply Location||Supply Volume (Tonnes/yr)|
|Heilongjiang, Zhaodong||China Resources Alcohol Co.||Corn||100,000||100,000||Heilongjiang||100,000|
|Jilin, Jilin||Jilin Fuel Ethanol Co.||Corn||300,000||600,000||Jilin||100,000|
|Henan, Nanyang||Henan Tian Guan Fuel-Ethanol Co.||wheat||200,000||200,000||Henan||86,842|
|Hubei ( 9 cities)||113,158|
|Hebei ( 4 cities)|
|Anhui Bengbu||Anhui BBCA Biochemical Co.||Corn||320,000||320,000||Anhui||100,000|
( 7 cities)
|Jiangsu ( 5 cities) Hebei (2 cities)|
|Guangxi||China Resources Alcohol Co.||Cassava||0||110,000||Guangxi||110,000|
|Hubei||Tian Guan Fuel Ethanol Co.||Rice||0||100,000||Hubei||100,000|
(Source of information: USDA Foreign Agriculatural Service GAIN Report No.CH6049 "China, People's Republic - Bio-fuels, An Alternative Future for Agriculature, 2006)
Global production of biodiesel nearly doubled from 2.1 billion liters in 2004 to 3.9 billion liters in 2005. In 2005, the European Union was the principal producer, with Germany accounting for half of the global production, followed by Italy and France. Outside the EU, the USA was the leading country in biodiesel production. Biodiesel production is also observed to be growing in developing countries such as Malaysia, Indonesia and the Philippines, which produce biodiesel mainly for their domestic markets.
The development of biodiesel in China is in the very early stage. Biodiesel production in China in 2005 was between between 0.1 - 0.2 million metric tons. Waste cooking oil is the major raw materials for biodiesel production and biodiesel production from Jatropha, Chinese Pistachio, rapeseed and palm oil waste are under research and testing. The government sets a target of producing 2 million metric tons of biodiesel by 2010 and 12 million metric tons by 2020.