Biodiesel has grabbed its fair share of headlines in recent years, but despite the coverage, it is often misunderstood. Biodiesel is NOT vegetable oil. It is made from vegetable oil that has been modified by a chemical process. 100 persent biodiesel (B100) can be used in any stock diesel engine. No significant modification to the engine is required. In contrast, straight vegetable oil (SVO) requires modifications to the fuel delivery system in the vehicle and in some systems, mods to the engine itself. In short, biodiesel fueling requires you to modify the vegetable oil; straight vegetable oil fueling requires you to modify the vehicle instead.
B100 has its positives. Biodiesel is renewable since it's derived from plant sources. It is predominantly a domestic rather than an imported product. It burns cleaner than regular diesel and has higher cetane rating and better lubricity. It is said to have an exemplary energy balance returning about 3.2 units for energy for every unit consumed in its production (ethanol is about 1.2-1.6 depending upon what study you believe). It is also biodegradable. Like ethanol, biodiesel is typically blended with a traditional fuel. B100 is blended with no. 2 petroleum diesel to form blends like B20 (20 percent biodiesel and 80 percent diesel), B5 or B99. Unlike E85, biodiesel blends from B2 to B20 deliver equivalent fuel mileage in comparison to traditional fossil fuels.
I'm a big biodiesel fan. Even made a few thousand gallons myself. The chemistry is not grad school level stuff, but it is risky. The popular method I employed made use of methanol (highly flammable) and sodium hydroxide (highly corrosive) mixed together to form a sodium methoxide catalyst (highly nasty - use rubber aprons and full respirator) for the reaction. I ran my homebrew in a 1981 VW diesel pickup truck and it was a willing volunteer for my chemistry experiments. The truck never missed a beat, even on my early substandard biodiesel batches.
Let me clue you in on the big secret: biodiesel ain't free. In fact, it's ain't even cheap. This is true of the home brewer and the commercial producer. Fans of B100 tend to minimize the expense of the materials, equipment and labor required to make a decent batch of biodiesel. Back in the day, I had about $800 in equipment. When I quit making biodiesel about two years ago, methanol was pushing $4/gallon and I needed to use 20 gallons per 100 gallon batch of biodiesel. Add in the time spent gathering used cooking oil, filtering, preparing the catalyst solution, mixing, settling, drawing off glycerin, washing the raw biodiesel, disposing of the glycerin and final filtering of the B100 and you have a sizable chunk of somebody's time. I ultimately decided I didn't want that somebody to be me. It was fun while it lasted.
The availability of commercial biodiesel is improving. Happily, biodiesel can be moved through our existing fuel infrastructure. If you're not interested in making your own, you can use the retail variety. Depending upon tax incentives in your area, you might pay a smidge less than regular diesel for your biodiesel blend. Nationally, biodiesel blend prices hover close to those of petroleum diesel.
Check the final tally. Biodiesel has an impressive less of assets. It's made in the USA, it's biodegradable, renewable, burns clean, doesn't increase your fuel consumption, costs about the same as regular diesel and you can make it in your garage if you don't burn it down in the process.
On the negative side, higher concentrations of biodiesel (above B20) are associated with an increase in NOx emissions. Biodiesel is a good solvent. Good for cleaning up oil spills and the like, bad for rubber hoses and gaskets. Viton hoses and seals are recommended to make your system completely biodiesel compatible if it's a vehicle built before 1996. The quality of homemade biodiesel can vary from batch to batch. Even biodiesel made to the ASTM D-6751 standard is accepted in only a limited way by diesel vehicle and equipment manufacturers. Generally, B5 is OK and B20 is not. Homebrew biodiesel is decidedly verboten. Finally, availability of biodiesel at the retail pump, like that of E85, is spotty at best.
No, we're not talking gasoline-electric hybrids. Pure kilowatts. That's the ticket. Most sources of electricity to power electric vehicles involve burning other fuels like coal, natural gas or diesel fuel. Yes, there are certainly "clean" sources such as hydroelectric, biogas, wind and solar. However, there are still in the minority. Let's not ignore nuclear power either, even though it has its own unique set of problems (begone, flame wars!).
Where the rubber meets the road, electricity kicks butt. There's no fuel burning in the vehicle, hence zero pollution. Critics are quick to point out the pollution created at the electric powerplant itself. Advocates emphasize it's easier to apply and maintain pollution controls to a single location (i.e. the powerplant) than to thousands of locations (i.e. the vehicles).
Similar to CNG, storage is an issue for electricity. Current battery technology can only store the energy equivalent of a couple of gallons of gasoline. An ideal battery that would allow dense energy storage, fast charging, long service life and weigh less than today's lead acid battery has yet to hit the streets. Fuel cells? Still too expensive and the ideal fuel cell fuel (i.e. hydrogen) requires bulky tanks and high pressures for onboard storage. The maddening fact is that electricity is the cheapest of the five fuels in this competition. It can be derived from many sources and several of those are renewable and domestically produced. At the vehicle, electricity is absolutely the cleanest fuel because there's no burning involved. Pollutants can be controlled to a large extent at the source. Electric motors make killer torque and they do it at zero rpms. Big advantage overcoming inertia. Translation? Quick getaways. Electric motors are quiet and vibration free.
I've owned and operated two electric cars. One was a gas vehicle converted to electric drive, the other a purpose-built electric. The convert was known as the "Lectric Leopard" (no kidding). It was a street legal Renault 5 ("Le Car" in the 1980s U.S.) with lead acid batteries and controller electronics that were primitive by today's microprocessor standards. But it did reach highway speeds....eventually. Like many early electric cars, merging into traffic required, shall we say, careful planning? Hey, you get what you pay for. I bought it cheap. Not like a $100K Tzero or Tango.
I eventually replaced that EV with a cool electric three-wheeled vehicle called the Gizmo manufactured in Oregon by NEVCO (Neighborhood Electric Vehicle Company). Kind of a cheaper NmG (see this previous AutoblogGreen article on Myers Motors NmG). Cost only $8K, easy to work on and cheap to fix, titled as a motorcycle and delivered an honest 40 miles or range for its single passenger/driver - suitable for my local travel at the time. It had the usual EV virtuous attributes of zero emissions at the vehicle level, cheap fuel, home "re-fueling" via 110V charger, silent and vibration free operation. The big downside for me was not the limited range but that it was designed to go no faster than 40 mph. Perfect for city streets. Bad if you had to do even a short distance on a highway. I eventually sold it to a guy in San Francisco. Sadly, the company has ceased production of this little gem.
Let's summarize. Besides the storage bugaboo, electricity as a vehicle fuel is a very attractive choice. It's clean, cheap, can be derived from several sources - a good portion of which are renewable and domestic - and the infrastructure to support electricity is already in place (the notable exception being a hydrogen production, storage and transfer infrastructure). Frankly, the solar power is on the EV's side of the hedge. EVs have a bright future despite the release of "Who Killed the Electric Car?" (See AutoblogGreen's recent review and interview). As evidence of this prognostication, I draw your attention to the current gas-electric hybrid rage, to the serious interest in the PHEV (Plug-in Hybrid Electric Vehicle) concept and to the commitment of major auto manufacturers to fuel cell vehicle development.
Straight Vegetable Oil
We'll keep this short. SVO is not biodiesel. Many homegrown and commercial systems have been employed to adapt diesel engines to run on straight plant oil. Most achieve their goal by applying heat to SVO carried in a separate tank on the vehicle. Does SVO burn clean? Check. Is it renewable? Check. Multiple crop sources? Check. Domestic sources? Existing infrastructure? Check. Cheap? Check check. Looking good so far.
Now we hit the snags. SVO only works as a fuel for diesel engines, not gas (i.e. spark) engines. The oil's viscosity needs to be reduced for proper engine combustion. The fuel system and, in some designs, the engine itself needs to be modified. Manufacturers frown on such shenanigans. If you use virgin oils, you're burning food. I, for one, have an itsy bitsy moral problem with that. If you use waste cooking oil (i.e. drained from restaurant fryers), that's better. However, waste oil is often a mixture of oils, especially if gathered from several establishments. The combustion behavior of oil mixtures is difficult to predict. That is, how efficiently will it burn and under what engine operating conditions?
I won't belabor the question of whether burning straight vegetable oil in a properly modified diesel engine works. It does. I've owned three vehicles adapted for SVO fuel and enjoyed many trouble-free and inexpensive miles. However, I'm compelled to note that SVO is not as clean-burning as biodiesel or diesel in ALL respects. Lacking some official emissions data on SVO as a fuel (hey, if you can find some independent data on this let me know. I gave it the old college try and came up dry), I conducted a small study of 11 diesel vehicles adapted to run on SVO. Using an official vehicle emissions testing station in Ohio, I found that burning SVO decreased NOx, CO, and CO2 compared to petroleum diesel, but increased HC and particulates. All vehicles used diesel from the same pump and highly filtered canola oil from the same batch. Of course, I wouldn't presume to generalize from this small sample. Frankly, the big problem is the absence of a standard for vegetable oil fuel. Biodiesel has its D-6751 ASTM standard, what does peanut oil have? Nada. In Europe, there is a standard based on rapeseed oil, but most of the oil in the U.S. is soybean oil so we can't apply the European standard here.
One other shortcoming of SVO burning is the lack of big-buck engineered systems to handle it. Don't take this the wrong way. There are dozens of companies producing systems for diesel engines to burn SVO. Each has its fans and detractors. The fact is, each one of these systems designs are working well for SOME customers, or else the company wouldn't still be in business. The point I want to make is that all the companies selling these systems are small businesses. They can't afford a contingent of engineers and pricey lab testing. This is reflected in the current state of the art. Good stuff, but clearly not at the level of sophistication, reliability and ease of use you might expect from a product marketed by a major corporation. What kind of SVO system would someone like Hewlett-Packard produce? I'd hope it would a world-beater.
Pick of the Litter
Don't worry. I'm not going to wimp out on picking a winner out of the five alternative fuels. It was a close contest and here's my finishing order, from best to worst: Electricity, SVO, Biodiesel, E85 and CNG.
Electricity is cheap and clean if derived from a renewable source of power. Once the storage hurdle is overcome, look out. SVO is a close second, marked down only slightly because it's limited to diesel engines and does nothing for gas engines. I put biodiesel a hair behind SVO because it's more expensive. E85 is further down the list because of its energy balance (energy out compared to energy required to produce it) is markedly lower than biodiesel and SVO. CNG I placed last because it is not renewable and getting pricey although it is a clean burning fuel and reasonably abundant in North America.
So there you have it. Yet another "who's the fairest fuel of all" alternative fuel bedtime story. I picked my winner. Feel free to pick yours. No matter which of these beauties get your vote, I know we'll all breathe a little easier for it.
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