Can we use vegetable oil as fuel in our cars and in electrical generators? The short answer is yes. The longer answer is, well, yes, with a good number of qualifications.
First of all, all biofuels are essentially vegetable oil before they are refined into ethanol, biodiesel, or the class of biofuels falling under the unwieldy but technically accurate label of fuels that are chemically identical to gasoline but not derived from petroleum.
The technical, environmental and social concerns about large-scale biofuel production would take entire books to fully document (and those books exist) or a whole archive of blog posts on the subject (like TreeHugger has done, nudge, nudge…).
Suffice it to say for now that switching over all of our cars, trucks, ships, and airplanes to run on liquid fuels derived from plants and not petrol is a monumental undertaking, rife with environmental problems. It’s also perfectly possible to generate electricity on a commercial scale from biofuels. A number of studies have shown it’s actually more efficient to generate electricity from biofuels and then power electric cars than burning the fuel directly in internal combustion engines. The same issues apply here though.
That said, on a more limited scale and on the individual level, it is entirely possible, and not overly complicated, to convert diesel cars to run on waste vegetable oil.
Running a diesel car on vegetable oil requires fuel system modifications that run about $2,000 for parts and labor, and different driving practices: A driver must purge the fuel lines of vegetable oil during the last moments of a trip to avoid congealing, that purge function can only be run for 20 seconds or so before diesel fuel will run back into the vegetable oil tank and possibly cause an overflow, and s/he must keep an extra vegetable oil filter on hand, as it requires changing as soon as its served its useful life.
And importantly, as GreaseCar.com points out, straight vegetable oil is not biodiesel.
The fundamental difference between SVO and biodiesel is that SVO requires modification to the engine to operate, while biodiesel requires modification to the vegetable oil itself. SVO will always be cheaper to produce than biodiesel because SVO only needs to be filtered and dewatered before it is ready to be used in any vehicle that has an SVO conversion kit. Biodiesel on the other hand, then needs to go through an additional dangerous process which uses caustic chemicals to make the vegetable oil less viscous and slightly more flammable, this process is called transesterification.
Note however, as How Stuff Works (another Discovery site) reminds us, running your car on straight vegetable oil (remember, not biodiesel made from waste vegetable oil, which exists) is a bit of a legal grey area, though no one has actually been fined yet for doing so:
The problem with vegetable oil is that it’s not approved by the Environmental Protection Agency (EPA) for use as fuel. It’s not exactly illegal — it won’t land you in jail — but it could get you fined. Other biofuels, like ethanol and biodiesel, are EPA-approved. They’ve been researched and tested heavily by the EPA and are government regulated like any other fuel source. In terms of EPA approval, this means that the ethanol or biodiesel you can buy from a commercial seller is in compliance with the Clean Air Act.
Not deterred? Even more excited to convert your car? How Stuff Works has all the info you need to get started. Check out: Can any car be converted into a grease car?
As for electrical generation on the home level, remember that the original diesel engine, built by Rudolf Diesel in 1893 was designed to be run on a variety of oils. Consequently it’s no surprise than you can buy diesel generators today perfectly capable of making electricity from vegetable oil.