Biodiesel
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[edit] History
Rudolf Diesel intended his motor to run on peanut oil. (From the Wikipedia biography: "Diesel was interested in using coal dust or vegetable oil as fuel, and his engine in fact ran on peanut oil.")
[edit] Terms
The term "biodiesel" is also often used to refer to Straight Vegetable Oil (SVO) and Waste Vegetable Oil (WVO).
- SVO is simply vegetable oil (peanut, soybean, palm, etc.). Modern vehicles that run on this fuel should be converted for cold weather operation, as vegetable oils "gel" or "wax" at low temperatures. (Fossil diesel fuel also gels at low temperatures, but is sold with additives to prevent this happening.) Work is also being done to obtain fuel from algae.
- WVO is vegetable oil that has been recycled for use as a fuel. Grease is collected from restaurants, then filtered for use in vehicles. As with vehicles running on SVO, the fuel system must be modified to prevent waxing at low temperatures.
- Biodiesel is a refined fuel made from SVO or WVO. The oil is cleaned further with methanol, with glycerine (the basis of many soap products, and useful as a weedkiller) the waste product. The fuel is often treated with additives to reduce waxing at low temperatures.
Biodiesel is often mixed with fossil diesel to produce different grades. "B10", "B20", "B80", "B99" are what you'd expect them to be: 10%, 20%, 80% and 99% biofuel, with the remainder as fossil diesel. B5 is actually 5% biofuel, but with the twist that regular diesel from the pump has 5% vegetable oil added! This replaces the sulfur that was present in LSD (low sulfur diesel), but is lacking in ULSD (ultra-low sulfur diesel): it's a lubricant.
- So if you're paying extra for B5 biodiesel, either go to regular diesel (which is the same, or better, fuel), or switch up to B20, where at least you'll be making a marginal difference!
- "B100" is sometimes really B99, but sometimes B100. The difference being that B99 has more additives to prevent waxing.
- The EPA seems to think that there's also such a thing available as "B2": 2% biodiesel[1].
[edit] Conversions
The conversion for SVO/WVO vehicles usually involves adding a second fuel tank, a heated fuel line, and a changeover valve hooked to a switch on the dash. The car is started up and shut down on fossil diesel, and run on vegetable oil for the most part. Automated switching systems are available, as are single-tank systems where the veg. oil is the only fuel in the system. Kits and conversion services are available.
[edit] Advantages
- Political
- Some people run vegetable oil in the vehicle to make a political statement: domestically grown crops (or algae) mean we do not depend on oil-producing nations for our motive power.
- Environmental
- Others run the fuel for environmental reasons: it is almost carbon neutral, in that fuel burnt today was grown last year or the year before; meaning that the carbon dioxide released today was absorbed by the crops grown a year or two ago.
- Efficiency
- While biofuels do not have quite so high an energy density as fossil fuels (they're about 2-5% lower), the overall fuel economy is pretty much unchanged compared to fossil fuels. This is due to the fact that vegetable oils are lubricants, which allow the motor to run more freely; whereas fossil fuels must have lubricants added in the form of sulfur (equivalent to the lead in gasoline), or ironically, biofuels.
[edit] Controversy
Critics have argued that using vegetable oil for fuel reduces the availability of crops for food: either the crop is used for fuel, or a fuel-crop is grown instead of a food crop. This is a specious argument, as the uptake of biofuels is far lower than the uptake of meat-based diets in the developing world. (Raising animals for meat takes around 100 times the land for an equivalent nutritional amount of vegetable food.) However, if biofuels were to be more rapidly taken up, land use might then become an issue.
[edit] Fuel from algae
Certain types of algae can be grown to produce oils suitable for use as the basis of biodiesel. (With genetic engineering, the final processing could be done by the algae too.) The two great advantages of this method are:
- land use would not become an issue, because algae can be grown in the dark, and in inhospitable environments such as the exhaust of fossil fuel power plants
- the "wax point" -- the temperature at which a liquid begins to solidify -- is far lower for algae-derived oils than for even refined fossil diesel fuel
[edit] External links
- Wikipedia's biodiesel article
- National Biodiesel Board's retailer map (U.S. only)
- U.S. Department of Energy's retailer map (U.S. only, includes government and private refuelling stations)
