Encyclopedia
Biofuel is any
fuel that is derived from
biomass — recently living
organisms or their metabolic byproducts, such as manure from cows. It is a
renewable energy source, unlike other
natural resources such as
petroleum,
coal and
nuclear fuels.
One definition of
biofuel is any fuel with an 80% minimum content by volume of materials derived from living organisms harvested within the ten years preceding its manufacture.
Like
coal and
petroleum, biomass is a form of stored
solar energy. The energy of the sun is "captured" through the process of
photosynthesis in growing
plants.
One advantage of biofuel in comparison to most other fuel types is it is biodegradable, and thus relatively harmless to the environment if spilled.
Agricultural products specifically grown for use as biofuels include
corn and
soybeans, primarily in the
United States; as well as
flaxseed and
rapeseed, primarily in
Europe;
sugar cane in
Brazil and
palm oil in South-East Asia. Biodegradable outputs from industry,
agriculture,
forestry, and households can also be used to produce bioenergy; examples include
straw,
timber,
manure,
rice husks, sewage,
biodegradable waste and food leftovers. These feedstocks are converted into
biogas through
anaerobic digestion. Biomass used as fuel often consists of types, like chaff and animal waste.
Much research is currently in progress into the utilization of
microalgae as an energy source, with applications being developed for biodiesel, ethanol, methanol, methane, and even hydrogen. On the rise is use of
hemp, although politics currently restrains this technology.
Paradoxically, in some industrialized countries like
Germany, food is cheaper than fuel compared by price per joule . Central heating units supplied by food grade
wheat or
maize are available.
Biofuel can be used both for central- and decentralized production of electricity and heat. As of 2005, bioenergy covers approximately 15% of the world's energy consumption. Most bioenergy is consumed in developing countries and is used for direct heating, as opposed to
electricity production. However,
Sweden and
Finland supply 17% and 19% respectively, of their energy needs with bioenergy, a high figure for industrialized countries.
The production of biofuels to replace oil and natural gas is in active development, focusing on the use of cheap organic matter in the efficient production of liquid and gas biofuels which yield high net energy gain. The
carbon in biofuels was recently extracted from atmospheric
carbon dioxide by growing plants, so burning it does not result in a net increase of carbon dioxide in the
Earth's atmosphere. As a result, biofuels are seen by many as a way to reduce the amount of carbon dioxide released into the atmosphere by using them to replace non-renewable sources of energy.
Noticeable is the fact that the quality of timber or grassy biomass does not have a direct impact on its value as an energy-source.
and are two other companies that have received United States government Department of Energy funding for research into reducing the cost of cellulase, a key enzyme in the production cellulosic ethanol by enzymatic hydrolysis.
Other enzyme companies, such as , have been using fungi to develop and manufacture cellulases in 150,000 liter industrial fermenters.
Dried compressed
peat is also sometimes considered a biofuel. However, it does not meet the criteria of being a renewable form of energy, or of the carbon being recently absorbed from atmospheric carbon dioxide by growing plants. Though more recent than
petroleum or
coal, on the time scale of human industrialisation, peat is a fossil fuel and burning it does contribute to atmospheric CO
2.
History
Biofuel was used since the early days of the car industry. Nikolaus August Otto, the German inventor of the combustion engine, conceived his invention to run on ethanol. While
Rudolf Diesel, the German inventor of the
Diesel engine, conceived it to run on peanut oil. The Ford Model T, a car produced between 1903 and 1926 used ethanol. However, when crude oil began being cheaply extracted from deeper in the soil , cars began using fuels from oil.
Nevertheless, before World War II, biofuels were seen as providing an alternative to imported oil in countries such as Germany, which sold a blend of gasoline with alcohol fermented from potatoes under the name
Reichskraftsprit. In Britain, grain alcohol was blended with petrol by the Distillers Company Ltd under the name
Discol and marketed through
Esso's affiliate Cleveland.
After the War cheap Middle Eastern Oil lessened interest in biofuels. Then with the oil shocks of 1973 and 1979, there was an increase in interests from governments and academics in biofuels. However, interest decreased with the counter-shock of 1986 that made oil prices cheaper again. But since about 2000 with rising oil prices, concerns over the potential
oil peak, greenhouse gas emissions , and stability in the Middle East are pushing renewed interest in biofuels. Government officials have made statements and given aid in favour of biofuels. For example, U.S. president
George Bush said in his 2006 State of Union speech, that he wants for the United States, by 2025, to replace 75% of the oil coming from the Middle East.
Types of high volume industrial biomass on Earth
Certain types of biomass have attracted research and industrial attention. Many of these are considered to be potentially useful for energy or for the production of bio-based products. Most of these are available in very large quantities and have low market value.
Examples of biofuels
Biologically produced alcohols
Biologically produced
alcohols, most commonly
ethanol and
methanol, and less commonly
propanol and
butanol produced by the action of bacteria — see
alcohol fuel.
- Methanol, which is currently produced from natural gas, can also be produced from biomass — although this is not economically viable at present. The methanol economy is an interesting alternative to the hydrogen economy.
- Biomass to liquid, synthetic fuels produced from syngas. Syngas in turn, is produced from biomass by gasification.
- Ethanol fuel produced from sugar cane
...
is being used as
automotive fuel in
Brazil. Ethanol produced from
corn is being used mostly as a
gasoline additive in the
United States, but direct use as fuel is growing. Cellulosic ethanol is being manufactured from
straw by Iogen Corporation of Ontario, Canada; and other companies are attempting to do the same.
ETBE containing 47% Ethanol is currently the biggest biofuel contributor in Europe.
- Butanol is formed by A.B.E. fermentation and experimental modifications of the ABE process show potentially high net energy gains with butanol being the only liquid product. Butanol can be burned "straight" in existing gasoline engines , produces more energy and is less corrosive and less water soluble than ethanol, and can be distributed via existing infrastructures.
- Mixed Alcohols , obtained either by biomass-to-liquid technology or by the MixAlco process.
- GTL or BTL both produce synthetic fuels out of biomass in the so called Fischer Tropsch process. The synthetic biofuel containing oxygen is used as additive in high quality diesel and petrol.
Biologically produced gases
Biogas is produced by the process of
anaerobic digestion of organic material by anaerobes. Biogas can be produced either from
biodegradable waste materials or by the use of energy crops fed into
anaerobic digesters to supplement gas yields. The solid ouput,
digestate, can also be used as a biofuel.
Biogas contains
methane and can be recovered in industrial
anaerobic digesters and
mechanical biological treatment systems. Landfill gas is a less clean form of biogas which is produced in
landfills through naturally occurring anaerobic digestion. Paradoxically if this gas is allowed to escape into the atmosphere it is a potent
greenhouse gas.
Biologically produced gases from wastes
Biologically produced oils and gases can be produced from various wastes:
- Thermal depolymerization of waste can extract methane and other oils similar to petroleum.
- Pyrolysis oil may be produced out of biomass, wood waste etc. using heat only in the flash pyrolysis
- Woodgas [i] ...
process. The oil has to be treated before using in conventional fuel systems or internal combustion engines . - One company, GreenFuel Technologies Corporation, has developed a patented bioreactor system that utilizes nontoxic photosynthetic algae to take in smokestacks flue gases and produce biofuels such as biodiesel, biogas and a dry fuel comparable to coal .
Biologically produced oils
Biologically produced oils can be used in
diesel engines:
Applications of biofuels
One widespread use of biofuels is in home cooking and heating. Typical fuels for this are wood, charcoal or dried dung. The biofuel may be burned on an open fireplace or in a special
stove. The efficiency of this process may vary widely, from 10% for a well made fire up to 40% for a custom designed charcoal stove
1. Inefficient use of fuel may be a minor cause of
deforestation but more importantly it means that more work has to be put into gathering fuel, thus the quality of cooking stoves has a direct influence on the viability of biofuels.
"American homeowners are turning to burning corn in special stoves to reduce their energy bills. Sales of corn-burning stoves have tripled this year [...] Corn-generated heat costs less than a fifth of the current rate for propane and about a third of electrical heat" .
Direct electricity generation
The
methane in
biogas is often pure enough to pass directly through gas engines to generate green energy.
Anaerobic digesters or
biogas powerplants convert this renewable energy source into electricity. This can either be used commercially or on a local scale.
Use on farms
In Germany small scale use of biofuel is still a domain of agricultural farms. It is an official aim of the German government to use the entire potential of 200,000 farms for the production of biofuel and bioenergy.
Home use
Different combustion-engines are being produced for very low prices lately . They allow the private house-owner to utilize low amounts of "weak" compression of methane to generate electrical and thermal power sufficient for a well insulated residential home.
Rolling Network
Although decentralised biofuel production is possible the so called island operation bears problems with capacity and load balancing. In case vehicles for commuting and social or procurement trips may be used to transport energy we have a so called rolling network. We expect a higher efficiency with wood based biogas which may be purified in a home filling station and released into the natural gas network at work or special receiving gas stations. This kind of business is not bound to constant delivery amounts but very flexible in both directions. Ie. also gas refilling is possible if the wood gas production is low at the moment or the distance travelled was high.
With so called plug in hybrid electric vehicles in theory it would be also possible to carry energy produced underway to work or to home and feed it into the grid. But this is less efficient and also less probable.
Problems and solutions
Unfortunately, much cooking with biofuels is done indoors, without efficient ventilation, and using fuels such as dung causes airborne pollution. This can be a serious health hazard; 1.5 million deaths were attributed to this cause by the
World Health Organisation as of 2000 2. There are various responses to this, such as improved stoves, including those with inbuilt flues and switching to alternative fuel sources. Most of these responses have difficulties. One is that fuels are expensive and easily damaged. Another is that alternative fuels tend to be more expensive, but the people who rely on biofuels often do so precisely because they cannot afford alternatives.
3 Organisations such as
Intermediate Technology Development Group work to make improved facilities for biofuel use and better alternatives accessible to those who cannot currently get them. This work is done through improving ventilation, switching to different uses of biomass such as the creation of biogas from solid biomatter, or switching to other alternatives such as micro-hydro power. Many environmentalists are concerned that first growth forest may be felled in countries such as Indonesia to make way for Palm Oil plantations, driven by rising demand for diesel in SE Asia and Europe.
Direct biofuel
Direct biofuels are biofuels that can be used in existing unmodified
petroleum engines. Because engine technology changes all the time, exactly what a direct biofuel is can be hard to define; a fuel that works without problem in one unmodified engine may not work in another engine. In general, newer engines are more sensitive to fuel than older engines, but new engines are also likely to be designed with some amount of biofuel in mind.
Straight vegetable oil can be used in some diesel engines. Only in the warmest climates can it be used without engine modifications, so it is of limited use in colder climates. Most commonly it is turned into biodiesel. No engine manufacturer explicitly allows any use of vegetable oil in their engines.
Biodiesel can be a direct biofuel. However, no current manufacturer covers their engine under warranty for 100% biodiesel . Many people have run thousands of miles on biodiesel without problem, and many studies have been made on 100% biodiesel.
Butanol is often claimed as a direct replacement for gasoline. It is not in wide spread production at this time, and engine manufacturers have not made statements about its use. While on paper it appears that butanol has sufficiently similar characteristics with gasoline such that it should work without problem in any gasoline engine, no widespread experience exists.
Ethanol is the most common biofuel, and over the years many engines have been designed to run on it. Many of these could not run on regular gasoline. It is open to debate if ethanol is a direct replacement in these engines though - they cannot run on anything else. In the late 1990's engines started appearing that by design can use either fuel. Ethanol is a direct replacement in these engines, but it is debatable if these engines are unmodified, or factory modified for ethanol.
Small amounts of biofuel are often blended with traditional fuels. The biofuel portion of these fuels is a direct replacement for the fuel they offset, but the total offset is small. For biodiesel, 5% or 20% are commonly approved by various engine manufacturers. See
Common ethanol fuel mixtures for information on ethanol.
International efforts
On the other hand, recognizing the importance of bioenergy and its implementation, there are international organizations such as , established in 1978 by the International Energy Agency , with the aim of improving cooperation and information exchange between countries that have national programs in bioenergy research, development and deployment.
Energy content of biofuel
For a comprehensive chart of energy contents from different biofuels please see Energy content of Biofuel
See also
References
- , Simon Ekless, , retrieved 1 January 2005 from http://www.itdg.org/docs/technical_information_service/biomass.pdf.
- , , 19 March 2004, retrieved 1 January 2005 from http://www.itdg.org/?id=smoke_report_1
- , , 19 March 2004, retrieved 1 January 2005 from http://www.itdg.org/?id=smoke_report_3
External links
