10 Edible Biofuels

        Auto | Biofuels

5
Cottonseed Oil
Cottonseed oil begins to solidify in chilly weather, making it impractical for cold climates.
Cottonseed oil begins to solidify in chilly weather, making it impractical for cold climates.
iStockphoto/Thinkstock

Cotton doesn't come to many people's minds as a food product. The main use of cotton in the modern world, after all, is as a fiber for cloth. But the oil from cotton seeds is a light, neutral-flavored vegetable oil that has been used for cooking in America since the 1860s [source: NCPA]. Cottonseed has also been used as animal feed, although using too much of it can lead to nutritional problems with livestock [source: Osborne].

Cottonseed oil's use as a biofuel makes sense: According to some analysts, there's more oil available per acre from cotton than from corn or soy, two of the most popular biofuel sources [source: Journey]. But cottonseed oil does have one drawback that, as with many other biofuels, presents a nagging engineering challenge.

Cottonseed oil begins to solidify in cold temperatures. A vehicle run on pure cottonseed oil would be unusable in winter unless it contained some type of oil-heating system that kept the biofuel above its gel point. More popular biofuels, such as soy biodiesel, encounter this problem, too. But while soy biodiesel gels at about -16 degrees Celsius, cottonseed oil gels at only -1 degree Celsius. Much of the world encounters colder temperatures on a regular basis, making pure cottonseed oil less than optimal for widespread use as a biofuel.