Biofuel = a renewable source of energy manufactured from biomass, a biological material, either living or recently living. Various plants and plant-derived materials are used for biofuel manufacturing. Biofuel is a renewable energy source, whereas fossil fuels are limited in quantity.

Biofuel is generally carbon-neutral: the same CO2 used to grow plants is dispersed back into the atmosphere when they are used for fuel. In some cases, like algal biofuels, the manufacturing of biofuels can reduce current dioxide output from other power sources like petroleum and coal based powerplants.

Examples of Biofuels

Biowaste: municipal solid waste (city garbage), agricultural residue, farm waste
Landfills generate gas as the waste decomposes, 50% of which is methane gas.
There is a current project underway for a 1.6 megawatt landfill power plant that would capture this methane gas and put it back on the Natural Gas energy grid. This would provide 880 homes with power. This would also eliminate 3,187 tons of methane from the atmosphere and 8.76 tons of carbon dioxide, equivalent to removing 12,576 cars from the roads, or planting 15,606 trees, or not using 359 rail cars amount of coal each year.

Corn Ethanol: is ethanol produced from corn as a biofuel through industrial fermentation, chemical processing and distillation. It is primarily used in the United States as an alternative to gasoline and petroleum.
1/5 of the US corn crop is devoted to making corn ethanol
US passed a law in 2005 mandating the use of 7.5 billion gallons of fuel per year by 2012.
This has increased the value of corn, helping to stabilize our economy

Sugar Cane: ethanol produced from sugar cane crops through fermentation, chemical processing, and distillation, used to replace the use of fossil fuels for transportation.
In Brazil almost half of car transportation uses sugar cane ethanol.
The price is only $1 per gallon
Ethanol from sugar cane reduces greenhouse emissions by 90%.

Miscanthus grass: This grass can be harvested en masse to produce transportation fuel by mixing it with sugar and starch alcohol produced in large fermentation tanks.
1 acre of corn = 354 gallons of ethanol per year
1 acre of miscanthus = 1150 gallons of fuel per year
100 million acres of miscanthus, ¼ the current US cropland, would meet the entire US demand for transportation fuel

Miscanthus Grass

Interesting Facts of bio fuel in general

How to make Biodiesel:

Biodiesel is a fuel that can be used directly in any diesel engine generally without modification. It's viscosity is twice that of regular diesel fuel which means it is better at lubricating your diesel engine than regular diesel. And... emissions are cut dramatically vs using standard diesel fuel. You can buy Biodiesel already made. Your other option is to make it yourself using your own homemade equipment or by purchasing something like a Fuelmeister biodiesel processor. It costs $2995, but it comes with everything you need to make many, many gallons of biodiesel fuel. One other option is to burn straight vegetable oil (SVO) in your diesel engine. To do this, you must do three things: 1) You must pre-heat your vegetable oil including the storage tank and all feed lines, 2) You must start your engine using regular diesel or biodiesel, and 3) You must clean your system by burning only regular diesel or biodiesel before shutting the engine off. I don't recommend the SVO method because there is the possibility of carbon buildup in the long run and that may damage your engine. Here are the instructions on making your own biodiesel...

Here is a general description of how to make biodiesel fuel using methanol, lye, and used cooking oil. This process is called transesterification.You can buy methanol from your local racetrack or chemical supply store. You can buy granulated lye (sodium hydroxide) from your local grocery store or hardware store. Make sure you filter the used cooking oil before using. Fry oil filters can be purchased in any good restaurant supply store. The oil also must be warmed up so it is not solid or lumpy or thick. You can use the sun to heat the oil or some kind of water heating element or a electric or gas burner of some sort. The ideal temperature is 120° F. If you are using flames, remember that the methanol is extremely flammable and you should turn your burner off before getting the methanol mixture anywhere near it. Of course, this should all be done in a well ventilated area too.

Washing your biodiesel... after the above process is completed, you should "wash" your biodiesel fuel to remove any residual soaps suspended in your fuel. The easiest way to get rid of the unwanted soap is to simply add water. The water will emulsify with the glycerin soap and settle to the bottom. So to perform the wash, simply spray an equal amount of water on top of your biodiesel and let it settle to the bottom for 12 hours. Drain the water off the bottom of your container with a valve and then repeat the process 2-3 times until the water drained off is clear. Heat your biodiesel up to 130° F for 20 minutes to evaporate any residual water and you are literally ready to go! Remember to filter it in a 5-10 micron filter before burning it in your engine.

Other ingredients - Instead of using methanol, you can use ethanol to make biodiesel. Ethanol is less toxic than methanol and is considered a "greener" fuel than methanol. Ethanol is "grain alcohol" and is usually made from corn which makes it a renewable fuel. Methanol is highly toxic and is made from fossil fuels or it can be distilled from fermented wood. That's why it's often called "wood alcohol". Also... you can use potassium hydroxide instead of sodium hydroxide. I believe you'll have to use 1.4 times as much potassium hydroxide as sodium hydroxide though. Make sure you do your "test batch" first!
Two more things....
1) You might be wondering... what kind of engine I need to use biodiesel... basically, biodiesel will run in any diesel engine unmodified. Biodiesel is a solvent, so if you put it in an old tank or use it with a diesel engine that has been running regular diesel, it may clean and dissolve some "residues" and then the residues will clog your fuel filter. Changing the filter often when you first start using biodiesel usually fixes this problem. Usually, manufacturers warranties are not voided when biodiesel is used, but check with your manufacturer to make sure. Sometimes a blend like B20 is required (20% biodiesel). If you are running straight vegetable oil (SVO), then you need to make modifications to pre-heat the oil to increase it's viscosity.

2) The only other problem you might have is with natural rubber gaskets and hoses in vehicles made prior to 1992. The biodiesel may degrade these types of rubber and they may need replacing after a while. Newer engines have been modified (synthetic rubber) to stand up to the newer blends of diesel fuel that have been in use since 1992 and these engines will work fine with biodiesel