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How its Made

Biodiesel is generally made from new or used vegetable oils, animal fats, oil produced by algae, or oil from microbes. There are a few different ways to produce biodiesel, but most involve a process called transesterification. This process involves adding an alcohol, usually methanol, but sometimes ethanol, to the fat or oil in the presence of a catalyst such as potassium hydroxide or sodium hydroxide. The fat (triacylglycerol) is transformed into esters and glycerol. The esters are what we refer to as biodiesel, and the glycerol can be used in the pharmaceutical, cosmetics, or other industries. http://www.afdc.energy.gov/afdc/fuels/biodiesel.html has a flow chart of this process. While it is very possible to create biodiesel at home, there is the risk of causing damage to an engine if it doesn't meet the rigorous ASTM D6751-07b specifications. Still, for the adventurous types, we have included a couple of links to biodiesel tutorials:

• http://journeytoforever.org/biodiesel_make.html
• http://www.biodieselcommunity.org/gettingstarted/

Advantages

Some advantages of biodiesel are that it is:

• Domestically produced from non-petroluem, renewable resources
• Can be used in most diesel engines, especially newer ones
• Less air pollutants (other than nitrogen oxides) and greenhouse gases
• Biodegradable
• Non-toxic
• Safer to handle

It also has an excellent energy balance: biodiesel contains 3.2 times the amount of energy it takes to produce it.

Domestically Produced

Biodiesel in the US is produced mostly from soybean oil, which is a major domestic crop. This could reduce the demand for imported fossil fuels in the future.

Usable in Most Diesel Engines

Most diesel engines produced after 1992 can handle biodiesel with little or no alteration. Biodiesel actually can help increase engine life by increasing fuel lubricity by as much as 65% with only a 1% blend of biodiesel and by not leaving any deposits of its own. Biodiesel acts as a solvent, which helps to loosen deposits left there from petroleum diesel usage.

Less Pollutants

There is a graph at http://www.afdc.energy.gov/afdc/fuels/biodiesel_benefits.html that shows the air pollutants in a number of different blends in biodiesel. As you can see, all blends have reductions in a number of pollutants, including unburned hydrocarbons, carbon monoxide, sulfates, polycyclic aromatic hydrocarbons, nitrated polycyclic aromatic hydrocarbons, and particulate matter. In addition, there are reductions in greenhouse gas emissions, with CO2 being reduced about 78% in B100 and 15% in B20. B100 can also reduce the carcinogenic properties of biofuel by 94%. Biodiesel is the only biofuel to have successfully completed testing in accordance with the Clean Air Act. http://auto.howstuffworks.com/biodiesel3.htm also has emissions chart for B100 and B20. Although biodiesel does slightly increase nitrous oxide emissions, which lead to smog production, it decreases the unburned hydrocarbons emitted, which also contribute to smog production. Taken together, biodiesel reduces ozone forming potential of diesel fuel by nearly 50% compared to petroleum diesel fuel.

Biodegradable

If spilled, biodiesel will naturally degrade at a rate four times faster than petroleum diesel.

Non-toxic

If spilled, biodiesel will not have any major toxic effects. It is about 10 times less toxic than table salt.

Safer to Handle

Biodiesel has a much higher flashpoint than petroleum diesel, higher than 150°C compared to about 52°C for petroleum diesel. This means that it is less likely to catch fire when being stored or transported.

Disadvantages

Some disadvantages of biodiesel are: • Use of blends above B5 not yet warrantied by auto makers • Lower fuel economy and power • Currently more expensive • More nitrogen oxide emissions • B100 generally not suitable for use in low temperatures • Concerns about B100's impact on engine durability • Problems with water • Food vs. Fuel concerns

Automaker Warranties

Most engine makers warranty their components for up to a B5 blend, but higher blends may void warranties.

Lower Fuel Economy

There is about a 10% reduction in energy output of a gallon of biodiesel compared to petroleum diesel, lowering the range on a single tank of fuel. For B20, this can mean a 1-2% difference.

Cost

Pure biodiesel can cost anywhere from $1.95-$3.00 per gallon, while B20 blends average about 30-40 cents higher per gallon, although this obviously varies. One of the major factors affecting price is the availability in a particular area. Biodiesel is typically not pumped through pipelines, so tends to be sold close to the point of production.

NOx Emissions

As described above, biodiesel has a slight increase in nitrous oxide emissions compared to petroleum diesel, although the smog-factor of this increase is offset in reductions in unburned hydrocarbon emissions.

Temperature Problems

The point at which biodiesel begins to gel is referred to as its cloud point. It varies widely depending on the particular mix of esters found in the fuel and so the feedstock used to produce the fuel. However, there are some feedstocks that have cloud points as high as 60°F. While they are not all this high, it brings up the fact that B100 may not act well under cold conditions and that the fuel must either be heated or not used year-round in cold climates.

Engine Durability

While beneficial to engine wear in newer engines, older vehicles, such as those made before 1992, can experience clogging due to a large amount of debris loosened by biodiesel entering the fuel filter. Biodiesel also wears down natural rubber and so may break down older fuel lines and pump seals. This is not usually a problem with newer engines.

Water Interactions

Although hydrophobic, biodiesel does sometimes attract small amounts of water if the reaction used to create the fuel was not fully completed. There are a number of concerns with water mixing with biofuels:

• Water reduces the heat of combustion, creating more smoke, harder starting, and less power
• Water causes the corrosion of fuel system components
• Water freezes, creating ice crystals and accelerating the gelling of the fuel
• Water accelerates the growth of microbe colonies that can grow in biodiesel tanks. This is especially a problem with heated fuel tanks.
• Water can cause pitting in the pistons on a diesel engine

Food vs. Fuel

All biofuels have come under some criticism for food vs. fuel debates. The reasoning goes that burning something that can be used for food causes food for the poor to be replaced by fuel for the rich. Even if direct food isn't used for fuel, any agricultural crop used for food could cause pressure for farmers to take up that crop instead of a normal food product. Therefore, only non-food fuels grown on marginal lands are going to be exempt from this controversy.

Future Research

Mustard

Specially bred mustard varieties can produce reasonably high oil yields and are also useful in crop rotation with cereals. In addition, the meal leftover after the oil has been pressed out can act as an effective and biodegradable pesticide.

Algae

From 1978 to 1996, the US National Renewable Energy Laboratory experimented with using algae for biodiesel in the \"Aquatic Species Program\". The advantages with algae are that there are some species that contain over 50% oil and they can be grown on ponds at wastewater treatment plants, eliminating food vs. fuel concerns. There are a number of companies currently working towards producing biodiesel from algae on a commercial level.

Bacteria

The US Army is using 7 test sites to try to turn biodegradable waste into diesel fuel via bacteria.

Fungus

In September 2008, a group at the Russian Academy of Sciences in Moscow published a paper stating that they could isolate large amounts of lipids from a single-celled fungi, C. japonica, and others to produce biodiesel. There has been a recent discovery of a variant of the fungus Gliocladium roseum that produces myco-diesel from cellulose. It has the ability to turn cellulose into medium length hydrocarbons typically found in diesel fuel.