   #copyright

Biodiesel

2007 Schools Wikipedia Selection. Related subjects: Engineering; Environment

     Plant oils
           Types
   Vegetable fats  (list)
   Essential oil   (list)
   Macerated      ( list)
           Uses
   Drying oil - Oil paint
   Cooking oil
   Fuel - Biodiesel
   Aromatherapy
        Components
   Saturated fat
   Monounsaturated fat
   Polyunsaturated fat
   Trans fat

   Biodiesel refers to a diesel-equivalent, processed fuel derived from
   biological sources. Though derived from biological sources, it is a
   processed fuel that can be readily used in diesel-engined vehicles,
   which distinguishes biodiesel from the straight vegetable oils (SVO) or
   waste vegetable oils (WVO) used as fuels in some modified diesel
   vehicles.

   In this article's context, biodiesel refers to alkyl esters made from
   the transesterification of both vegetable oils and/or animal fats.
   Biodiesel is biodegradable and non- toxic, and has significantly fewer
   emissions than petroleum-based diesel when burned. There is much debate
   about the extent to which biodiesel can safely be used in conventional
   diesel engines without modification. Using biodiesel in unmodified
   engines can lead to problems, particularly blocked injectors, which in
   turn can lead to serious engine damage. The majority of vehicle
   manufacturers say using 100% biodiesel can damage their engines. In the
   UK, for example, most manufactuers only maintain their engine
   warranties for use with maximum 5% biodiesel - blended in with 95%
   conventional diesel - although this position is generally considered to
   be overly cautious. Peugeot and Citroen are an exception in that they
   have both recently announced that their HDI diesel engine can run on
   30% biodiesel. Scania are another exception as they allow most of their
   engines to operate on 100% biodiesel.

   Biodiesel can also be used as a heating fuel in domestic and commercial
   boilers. A technical research paper No.7 published in the UK by the
   institute of plumbing and heating entitled "Biodiesel Heating,
   Sustainable Heating for the Future" by Andrew J. Robertson describes
   laboratory research and field trials project using pure biodiesel and
   biodiesel blends as a heating fuel in oil fired boilers. During the
   Biodiesel Expo 2006 in the UK, Andrew J. Robertson presented his
   biodiesel heating oil research from his technical paper and suggested
   that B20 biodiesel could reduce UK household CO[2] emissions by 1.5
   million tonnes per year and would only require around 330,000 hectares
   of arable land for the required biodiesel for the UK heating oil
   sector. The paper also suggests that existing oil boilers can easily
   and cheaply be converted to biodiesel if B20 biodiesel is used.

   Biodiesel can be distributed using today's infrastructure, and its use
   and production are increasing rapidly. Fuel stations are beginning to
   make biodiesel available to consumers, and a growing number of
   transport fleets use it as an additive in their fuel. Biodiesel is
   generally more expensive to purchase than petroleum diesel but this
   differential may diminish due to economies of scale, the rising cost of
   petroleum and government tax subsidies.

Description

   Biodiesel is a light to dark yellow liquid. It is practically
   immiscible with water, has a high boiling point and low vapor pressure.
   Typical methyl ester biodiesel has a flash point of ~ 150 °C (300 °F),
   making it rather non-flammable. Biodiesel has a density of ~ 0.86
   g/cm³, less than that of water. Biodiesel uncontaminated with starting
   material can be regarded as non-toxic.

   Biodiesel has a viscosity similar to petrodiesel, the industry term for
   diesel produced from petroleum. It can be used as an additive in
   formulations of diesel to increase the lubricity of pure Ultra-Low
   Sulfur Diesel (ULSD) fuel, although care must be taken to ensure that
   the biodiesel used does not increase the sulfur content of the mixture
   above 15 ppm. Much of the world uses a system known as the "B" factor
   to state the amount of biodiesel in any fuel mix, in contrast to the
   "BA" or "E" system used for ethanol mixes. For example, fuel containing
   20% biodiesel is labeled B20. Pure biodiesel is referred to as B100.

Technical standards

   The common international standard for biodiesel is EN 14214.

   There are additional national specifications. ASTM D 6751 is the most
   common standard referenced in the United States. In Germany, the
   requirements for biodiesel is fixed in the DIN EN 14214 standard. There
   are standards for three different varieties of biodiesel, which are
   made of different oils:
     * RME ( rapeseed methyl ester, according to DIN E 51606)
     * PME (vegetable methyl ester, purely vegetable products, according
       to DIN E 51606)
     * FME (fat methyl ester, vegetable and animal products, according to
       DIN V 51606)

   The standards ensure that the following important factors in the fuel
   production process are satisfied:
     * Complete reaction.
     * Removal of glycerin.
     * Removal of catalyst.
     * Removal of alcohol.
     * Absence of free fatty acids.
     * Low sulfur content.

   Basic industrial tests to determine whether the products conform to the
   standards typically include gas chromatography, a test that verifies
   only the more important of the variables above. More complete tests are
   more expensive. Fuel meeting the quality standards is very non-toxic,
   with a toxicity rating ( LD50) of greater than 50 mL/kg.
   Biodiesel sample
   Enlarge
   Biodiesel sample

Applications

   Biodiesel can be used in pure form (B100) or may be blended with
   petroleum diesel at any concentration in most modern diesel engines.
   Biodiesel will degrade natural rubber gaskets and hoses in vehicles
   (mostly found in vehicles manufactured before 1992), although these
   tend to wear out naturally and most likely will have already been
   replaced with Viton which is nonreactive to biodiesel. Biodiesel's
   higher lubricity index compared to petrodiesel is an advantage and can
   contribute to longer fuel injector life. Biodiesel is a better solvent
   than petrodiesel and has been known to break down deposits of residue
   in the fuel lines of vehicles that have previously been run on
   petrodiesel. Fuel filters may become clogged with particulates if a
   quick transition to pure biodiesel is made, as biodiesel “cleans” the
   engine in the process. It is, therefore, recommended to change the fuel
   filter within 600-800 miles after first switching to a biodiesel blend.

Use

   In warm climates, pure unblended biodiesel can be poured straight into
   the tank of any diesel vehicle. Some older diesel engines still have
   natural rubber parts which will be affected by biodiesel, but in
   practice these rubber parts should have been replaced long ago.
   Biodiesel has been noted to be linked to premature injection pump
   failures. While many vehicles have been using biodiesel for many years
   without ill effect, the uncanny correlation between several cases of
   pump failure and biodiesel cannot be dismissed. Pure biodiesel produced
   'at home' is in use by thousands of drivers who have not experienced
   failure, however. The fact remains that biodiesel is a very new subject
   and will carry some risk until it is fully researched. Biodiesel sold
   publicly is held to high standards set by the ASTM.

Gelling

   The temperature at which pure (B100) biodiesel starts to gel varies
   significantly and depends upon the mix of esters and therefore the
   feedstock oil used to produce the biodiesel. For example, biodiesel
   produced from low erucic acid varieties of canola seed (RME) starts to
   gel at approximately -10 °C. Biodiesel produced from tallow tends to
   gel at around +16 °C. As of 2006, there are a very limited number of
   products that will significantly lower the gel point of straight
   biodiesel. One such product, Wintron XC30, has been shown to reduce the
   gel point of pure biodiesel fuels. Wintron XC30 is a blend of styrene
   copolymer esters in a toluene base. It reduces the tendency of the
   viscosity of biodiesel to increase as it is cooled. This is a key step
   in cold temperature crystallisation. In this way it acts to decrease
   both the temperature at which the crystals formed become large enough
   to block the pores of a fuel filter (cold filter plugging point or
   CFPP) and the lowest temperature at which the fuel will still flow
   (pour point). A number of studies have shown that winter operation is
   possible with biodiesel blended with other fuel oils including #2 low
   sulfur diesel fuel and #1 diesel / kerosene. The exact blend depends on
   the operating environment: successful operations have run using a 65%
   LS #2, 30% K #1, and 5 % bio blend. Other areas have run a 70 % Low
   Sulfur #2, 20 % Kerosene #1, and 10% bio blend or a 80% K#1, and 20 %
   biodiesel blend. According to the National Biodiesel Board (NBB), B20
   (20 % biodiesel, 80 % petrodiesel) does not need any treatment in
   addition to what is already taken with petrodiesel.

Contamination by water

   Biodiesel, although hydrophobic, may contain small but problematic
   quantities of water. Some of the water present is residual to
   processing, and some comes from storage tank condensation.

   The presence of water is a problem because:
     * Water reduces the heat of combustion of the bulk fuel. This means
       more smoke, harder starting, less power.
     * Water causes corrosion of vital fuel system components: fuel pumps,
       injector pumps, fuel lines, etc.
     * Water freezes to form ice crystals near 0 °C (32 °F). These
       crystals provide sites for nucleation and accelerate the gelling of
       the residual fuel.
     * Water accelerates the growth of microbe colonies which can plug up
       a fuel system. Biodiesel users who have heated fuel tanks therefore
       face a year-round microbe problem.

   Previously, the amount of water contaminating biodiesel has been
   difficult to measure by taking samples, since water and oil separate.
   However it is now possible to measure the water content using water in
   oil sensors.

Availability

Production

   Chemically, transesterified biodiesel comprises a mix of mono- alkyl
   esters of long chain fatty acids. The most common form uses methanol to
   produce methyl esters as it is the cheapest alcohol available, though
   ethanol can be used to produce an ethyl ester biodiesel and higher
   alcohols such as isopropanol and butanol have also been used. Using
   alcohols of higher molecular weights improves the cold flow properties
   of the resulting ester, at the cost of a less efficient
   transesterification reaction. A byproduct of the transesterification
   process is the production of glycerol. A lipid transesterification
   production process is used to convert the base oil to the desired
   esters. Any Free fatty acids (FFAs) in the base oil are either
   converted to soap and removed from the process, or they are esterified
   (yielding more biodiesel) using an acidic catalyst. After this
   processing, unlike straight vegetable oil, biodiesel has combustion
   properties very similar to those of petroleum diesel, and can replace
   it in most current uses.

Biodiesel feedstock

   Soybeans are used as a source of biodiesel
   Enlarge
   Soybeans are used as a source of biodiesel

   A variety of oils can be used to produce biodiesel. These include:
     * Virgin oil feedstock; rapeseed and soybean oils are most commonly
       used, though other crops such as mustard, palm oil, hemp, jatropha,
       and even algae show promise (see List of vegetable oils for a more
       complete list);
     * Waste vegetable oil (WVO);
     * Animal fats including tallow, lard, yellow grease, and the
       by-products of the production of Omega-3 fatty acids from fish oil.
     * Sewage. A company in New Zealand have successfully developed a
       system for using sewage waste as a substrate for algae and then
       producing bio-diesel.

   Worldwide production of vegetable oil and animal fat is not yet
   sufficient to replace liquid fossil fuel use. Furthermore, some
   environmental groups object to the vast amount of farming and the
   resulting over-fertilization, pesticide use, and land use conversion
   that they say would be needed to produce the additional vegetable oil.

   Many advocates suggest that waste vegetable oil is the best source of
   oil to produce biodiesel. However, the available supply is drastically
   less than the amount of petroleum-based fuel that is burned for
   transportation and home heating in the world. According to the United
   States Environmental Protection Agency (EPA), restaurants in the US
   produce about 300 million US gallons (1,000,000 m³) of waste cooking
   oil annually. Although it is economically profitable to use WVO to
   produce biodiesel, it is even more profitable to convert WVO into other
   products such as soap. Therefore, most WVO that is not dumped into
   landfills is used for these other purposes. Animal fats are similarly
   limited in supply, and it would not be efficient to raise animals
   simply for their fat. However, producing biodiesel with animal fat that
   would have otherwise been discarded could replace a small percentage of
   petroleum diesel usage.

   The estimated transportation fuel and home heating oil used in the
   United States is about 230 billion US gallons (0.87 km³) (Briggs,
   2004). Waste vegetable oil and animal fats would not be enough to meet
   this demand. In the United States, estimated production of vegetable
   oil for all uses is about 24 billion pounds (11 million tons) or 3
   billion US gallons (0.011 km³), and estimated production of animal fat
   is 12 billion pounds (5.3 million tons). (Van Gerpen, 2004)

   Biodiesel feedstock plants utilize photosynthesis to convert solar
   energy into chemical energy. The stored chemical energy is released
   when it is burned, therefore plants can offer a sustainable oil source
   for biodiesel production. Most of the carbon dioxide emitted when
   burning biodiesel is simply recycling that which was absorbed during
   plant growth, so the net production of greenhouse gasses is small.

   Feedstock yield efficiency per acre affects the feasibility of ramping
   up production to the huge industrial levels required to power a
   signifcant percentage of national or world vehicles. The highest yield
   feedstock for biodiesel is algae, which can produce 250 times the
   amount of oil per acre as soybeans..
   Feedstock US Gallons/acre Litres/hectare
   Soybean                40            375
   Rapeseed              110          1,000
   Mustard               140          1,300
   Jatropha              175          1,590
   Palm oil              650          5,800
   Algae              10,000         95,000

Efficiency and economic arguments

   According to a study written by Drs. Van Dyne and Raymer for the
   Tennessee Valley Authority, the average US farm consumes fuel at the
   rate of 82 liters per hectare (8.75 US gallons per acre) of land to
   produce one crop. However, average crops of rapeseed produce oil at an
   average rate of 1,029 L/ha (110 US gal/acre), and high-yield rapeseed
   fields produce about 1,356 L/ha (145 US gal/acre). The ratio of input
   to output in these cases is roughly 1:12.5 and 1:16.5. Photosynthesis
   is known to have an efficiency rate of about 16 % and if the entire
   mass of a crop is utilized for energy production, the overall
   efficiency of this chain is known to be about 1 %. This does not
   compare favorably to solar cells combined with an electric drive train.
   Biodiesel out-competes solar cells in cost and ease of deployment.
   However, these statistics by themselves are not enough to show whether
   such a change makes economic sense. Additional factors must be taken
   into account, such as: the fuel equivalent of the energy required for
   processing, the yield of fuel from raw oil, the return on cultivating
   food, and the relative cost of biodiesel versus petrodiesel. A 1998
   joint study by the U.S. Department of Energy (DOE) and the U.S.
   Department of Agriculture (USDA) traced many of the various costs
   involved in the production of biodiesel and found that overall, it
   yields 3.2 units of fuel product energy for every unit of fossil fuel
   energy consumed. That measure is referred to as the energy yield. A
   comparison to petroleum diesel, petroleum gasoline and bioethanol using
   the USDA numbers can be found at the Minnesota Department of
   Agriculture website In the comparison petroleum diesel fuel is found to
   have a 0.843 energy yield, along with 0.805 for petroleum gasoline, and
   1.34 for bioethanol. The 1998 study used soybean oil primarily as the
   base oil to calculate the energy yields. Furthermore, due to the higher
   energy density of biodiesel, combined with the higher efficiency of the
   diesel engine, a gallon of biodiesel produces the effective energy of
   2.25 gallons of ethanol. Also, higher oil yielding crops could increase
   the energy yield of biodiesel.

   The debate over the energy balance of biodiesel is ongoing, however.
   Transitioning fully to biofuels could require immense tracts of land if
   traditional crops are used. The problem is especially severe for
   nations with large economies, since energy consumption scales with
   economic output. If using only traditional plants, most such nations do
   not have sufficient arable land to produce biofuel for the nation's
   vehicles. Nations with smaller economies (hence less energy
   consumption) and more arable land may be in better situations, although
   many regions cannot afford to divert land away from food production.
   For third world countries, biodiesel sources that use marginal land
   could make more sense, e.g. honge oil nuts grown along roads or
   jatropha grown along rail lines. More recent studies using a species of
   algae with up to 50 % oil content have concluded that only 28,000 km²
   or 0.3 % of the land area of the US could be utilized to produce enough
   biodiesel to replace all transportation fuel the country currently
   utilizes. Furthermore, otherwise unused desert land (which receives
   high solar radiation) could be most effective for growing the algae,
   and the algae could utilize farm waste and excess CO[2] from factories
   to help speed the growth of the algae. The direct source of the energy
   content of biodiesel is solar energy captured by plants during
   photosynthesis. The website biodiesel.co.ukdiscusses the positive
   energy balance of biodiesel:

          When straw was left in the field, biodiesel production was
          strongly energy positive, yielding 1 GJ biodiesel for every
          0.561 GJ of energy input (a yield/cost ratio of 1.78).
          When straw was burned as fuel and oilseed rapemeal was used as a
          fertilizer, the yield/cost ratio for biodiesel production was
          even better (3.71). In other words, for every unit of energy
          input to produce biodiesel, the output was 3.71 units (the
          difference of 2.71 units would be from solar energy).

   Biodiesel is becoming of interest to companies interested in commercial
   scale production as well as the more usual home brew biodiesel user and
   the user of straight vegetable oil or waste vegetable oil in diesel
   engines. Homemade biodiesel processors are many and varied. The success
   of biodiesel homebrewing, and micro-economy-of-scale operations,
   continues to shatter the conventional business myth that large
   economy-of-scale operations are the most efficient and profitable. It
   is becoming increasingly apparent that small-scale, localized,
   low-impact energy keeps more resources and revenue within communities,
   reduces damage to the environment, and requires less waste management.

Environmental benefits

   Environmental benefits in comparison to petroleum based fuels include:
     * Biodiesel reduces emissions of carbon monoxide (CO) by
       approximately 50 % and carbon dioxide by 78 % on a net lifecycle
       basis because the carbon in biodiesel emissions is recycled from
       carbon that was already in the atmosphere, rather than being new
       carbon from petroleum that was sequestered in the earth's crust.
       (Sheehan, 1998)
     * Biodiesel contains fewer aromatic hydrocarbons: benzofluoranthene:
       56 % reduction; Benzopyrenes: 71 % reduction.
     * Biodiesel can reduce by as much as 20 % the direct (tailpipe)
       emission of particulates, small particles of solid combustion
       products, on vehicles with particulate filters, compared with
       low-sulfur (<50 ppm) diesel. Particulate emissions as the result of
       production are reduced by around 50 %, compared with fossil-sourced
       diesel. (Beer et al, 2004).
     * Biodiesel produces between 10 % and 25 % more nitrogen oxide NO[x]
       tailpipe-emissions than petrodiesel. As biodiesel has a low sulphur
       content, NO[x] emissions can be reduced through the use of
       catalytic converters to less than the NO[x] emissions from
       conventional diesel engines. Nonetheless, the NO[x] tailpipe
       emissions of biodiesel after the use of a catalytic converter will
       remain greater than the equivalent emissions from petrodiesel. As
       biodiesel contains no nitrogen, the increase in NO[x] emissions may
       be due to the higher cetane rating of biodiesel and higher oxygen
       content, which allows it to convert nitrogen from the atmosphere
       into NO[x] more rapidly. Debate continues over NO[x] emissions. In
       February 2006 a Navy biodiesel expert claimed NO[x] emissions in
       practice were actually lower than baseline. Further research is
       needed.
     * Biodiesel has higher cetane rating than petrodiesel, which is
       insignificant in terms of emissions and performance.
     * Biodiesel is biodegradable and non-toxic - the U.S. Department of
       Energy confirms that biodiesel is less toxic than table salt and
       biodegrades as quickly as sugar. (See Biodiesel handling and use
       guidelines)
     * In the United States, biodiesel is the only alternative fuel to
       have successfully completed the Health Effects Testing requirements
       (Tier I and Tier II) of the Clean Air Act (1990).

   Since biodiesel is more often used in a blend with petroleum diesel,
   there are fewer formal studies about the effects on pure biodiesel in
   unmodified engines and vehicles in day-to-day use. Fuel meeting the
   standards and engine parts that can withstand the greater solvent
   properties of biodiesel is expected to--and in reported cases does--run
   without any additional problems than the use of petroleum diesel.
     * The flash point of biodiesel (>150 °C) is significantly higher than
       that of petroleum diesel (64 °C) or gasoline (−45 °C). The gel
       point of biodiesel varies depending on the proportion of different
       types of esters contained. However, most biodiesel, including that
       made from soybean oil, has a somewhat higher gel and cloud point
       than petroleum diesel. In practice this often requires the heating
       of storage tanks, especially in cooler climates.
     * Pure biodiesel (B100) can be used in any petroleum diesel engine,
       though it is more commonly used in lower concentrations. Some areas
       have mandated ultra-low sulfur petrodiesel, which reduces the
       natural viscosity and lubricity of the fuel due to the removal of
       sulfur and certain other materials. Additives are required to make
       ULSD properly flow in engines, making biodiesel one popular
       alternative. Ranges as low as 2 % (B2) have been shown to restore
       lubricity. Many municipalities have started using 5 % biodiesel
       (B5) in snow-removal equipment and other systems.

Environmental concerns

   Where the oil-producing plants are grown is of increasing concern to
   environmentalists, one of the prime worries being that countries will
   clear cut large areas of forest in order to grow such crops. This has
   already occurred in the Philippines and Indonesia, and both of these
   countries plan to increase their biodiesel production levels, which
   will lead to the deforestation of tens of millions of acres if these
   plans materialize.

   The Levington Agricultural report highlights in section 4.6 that the
   use of biodiesel has an energy footprint 25 times bigger than the use
   of Pure Plant Oil (PPO) in suitably modified engines.

   The Union of Concerned Scientists writes: "When it comes to buying a
   new car, gasoline-powered models are better than diesels on toxic soot
   and smog-forming emissions. The downside to current diesels is that
   they produce 10 to 20 times more toxic particulates than their gasoline
   counterparts, more than can be made up for with the use of biodiesel.
   Diesels fare even worse when it comes to smog-forming nitrogen oxide
   emissions, with greater than 20 times the emissions of a comparable
   gasoline vehicle."

   An indepth look at some of the worrying problems with the pursuit of
   biodiesel can be found at Biofuelwatch, a leading watch dog for the
   unsustainable growth in the biodiesel international market.

Historical background

   Transesterification of a vegetable oil was conducted as early as 1853,
   by scientists E. Duffy and J. Patrick, many years before the first
   diesel engine became functional. Rudolf Diesel's prime model, a single
   10 ft (3 m) iron cylinder with a flywheel at its base, ran on its own
   power for the first time in Augsburg, Germany on August 10, 1893. In
   remembrance of this event, August 10 has been declared International
   Biodiesel Day. Diesel later demonstrated his engine and received the
   "Grand Prix" (highest prize) at the World Fair in Paris, France in
   1900. This engine stood as an example of Diesel's vision because it was
   powered by peanut oil—a biofuel, though not strictly biodiesel, since
   it was not transesterified. He believed that the utilization of a
   biomass fuel was the real future of his engine. In a 1912 speech,
   Rudolf Diesel said "the use of vegetable oils for engine fuels may seem
   insignificant today, but such oils may become, in the course of time,
   as important as petroleum and the coal-tar products of the present
   time."

   During the 1920s diesel engine manufacturers altered their engines to
   utilize the lower viscosity of the fossil fuel (petrodiesel) rather
   than vegetable oil, a biomass fuel. The petroleum industries were able
   to make inroads in fuel markets because their fuel was much cheaper to
   produce than the biomass alternatives. The result was, for many years,
   a near elimination of the biomass fuel production infrastructure. Only
   recently have environmental impact concerns and a decreasing cost
   differential made biomass fuels such as biodiesel a growing
   alternative.

   Research into the use of trans-esterified sunflower oil and refining it
   to diesel fuel standard was initiated in South Africa in 1979. By 1983
   the process to produce fuel quality engine-tested bio-diesel was
   completed and published internationally (SAE Technical Paper series no.
   831356. SAE International Off Highway Meeting, Milwaukee, Wisconsin,
   USA, 1983). An Austrian Company, Gaskoks, obtained the technology from
   the South African Agricultural Engineers, put up the first pilot plant
   for bio-diesel in November 1987 and the erection of the first
   industrial bio-diesel plant on 12 April 1989, with a capacity of 30 000
   tons of rapeseed per annum. Throughout the 1990s, plants were opened in
   many European countries, including the Czech Republic, France, Germany,
   Sweden. At the same time, nations in other parts of world also saw
   local production of biodiesel starting up and by 1998, the Austrian
   Biofuels Institute identified 21 countries with commercial biodiesel
   projects.

   In the 1990s, France launched the local production of biodiesel fuel
   (known locally as diester) obtained by the transesterification of
   rapeseed oil. It is mixed to the proportion of 5 % into regular diesel
   fuel, and to the proportion of 30 % into the diesel fuel used by some
   captive fleets ( public transportation). Renault, Peugeot, and other
   manufacturers have certified truck engines for use with up to this
   partial biodiesel. Experiments with 50 % biodiesel are underway.

   In September of 2005 Minnesota became the first state to require that
   all diesel fuel sold in that state contain part biodiesel. The
   Minnesota law requires at least 2% biodiesel in all diesel fuel sold.

Current research

   There is ongoing research into finding more suitable crops and
   improving oil yield. Using the current yields, vast amounts of land and
   fresh water would be needed to produce enough oil to completely replace
   fossil fuel usage. It would require twice the land area of the US to be
   devoted to soybean production, or two-thirds to be devoted to rapeseed
   production, to meet current US heating and transportation needs.

   Specially bred mustard varieties can produce reasonably high oil
   yields, and have the added benefit that the meal leftover after the oil
   has been pressed out can act as an effective and biodegradable
   pesticide.

Algaculture

   From 1978 to 1996, the U.S. National Renewable Energy Laboratory
   experimented with using algae as a biodiesel source in the " Aquatic
   Species Program". A recent paper from Michael Briggs, at the UNH
   Biodiesel Group, offers estimates for the realistic replacement of all
   vehicular fuel with biodiesel by utilizing algae that have a natural
   oil content greater than 50%, which Briggs suggests can be grown on
   algae ponds at wastewater treatment plants. This oil-rich algae can
   then be extracted from the system and processed into biodiesel, with
   the dried remainder further reprocessed to create ethanol.

   The production of algae to harvest oil for biodiesel has not yet been
   undertaken on a commercial scale, but feasibility studies have been
   conducted to arrive at the above yield estimate. In addition to its
   projected high yield, algaculture — unlike crop-based biofuels — does
   not entail a decrease in food production, since it requires neither
   farmland nor fresh water.

   On May 11, 2006 the Aquaflow Bionomic Corporation in Marlborough, New
   Zealand announced that it had produced its first sample of bio-diesel
   fuel made from algae found in sewage ponds. Unlike previous attempts,
   the algae was naturally grown in pond discharge from the Marlborough
   District Council's sewage treatment works. In November 2006, a
   commercial-scale project was announced in South Africa. Using
   American-made, closed bioreactors, it is expected to produce 900
   millions gallons a year (58 thousand barrels a day) of biodiesel within
   a couple of years.

   Retrieved from " http://en.wikipedia.org/wiki/Biodiesel"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
   Documentation License. See also our Disclaimer.
