This post is out of date! See the new version at Gas 2.0: Biodiesel Mythbuster 2.0: Twenty-Two Biodiesel Myths Dispelled (Apr. 2008)

Editor’s note: Our first installment of Green Myth-Busting comes from GO’s resident biofuels expert Clayton Bodie Cornell. As I’ve come to expect from Clayton, he’s covered the subject very thoroughly!

The poster-child for biofuels, biodiesel, is easily the most popular alternative fuel available. Despite the best efforts of biodiesel enthusiasts, the fuel is still engulfed in a morass of misinformation. This Myth-Buster is intended to dispel some of the most common myths associated with using biodiesel - the myths that may keep you from using the fuel.

In case you’re new to the topic, biodiesel is a renewable fuel made from plant oils and occasionally animal fat. It can be made from both used and unused sources of oil, such as freshly-pressed soybean oil, or oil left-over from the deep fryer at your local burger joint. Biodiesel can only be used in diesel engines - no gasoline engines allowed. Biodiesel can be blended into regular diesel in any amount, such as 20% biodiesel/80% diesel (B20), or used pure 100% (B100, aka ‘neat’). As a disclaimer, this post does not address homemade biodiesel (aka homebrew), which usually does not meet the quality standards of ASTM-certified biodiesel.

MYTH: Biodiesel is ethanol (or vice versa).
FACT: Ethanol and Biodiesel are completely different. Ethanol is a fermentation product, primarily made from corn grain and sugarcane. Biodiesel is chemically-converted fat or oil. Ethanol is blended into gasoline. Biodiesel is blended into diesel fuel.

MYTH: Ethanol is better than biodiesel.
FACT: We shouldn’t bicker over this - biodiesel has clear environmental, energetic, and sustainability advantages over corn-grain ethanol. Read on.

MYTH: You must convert your vehicle to run biodiesel.
FACT: Let me describe the conversion process: Drive to the nearest biodiesel pump, put the spout in the side of the car, and pump the biodiesel into your fuel tank (provided it’s diesel). That’s it. You can use biodiesel in any diesel engine without modification. In fact, if you own a diesel vehicle you can fill it up today with 100% biodiesel (B100) and should experience no problems whatsoever. Let me repeat this: you can use ANY amount of biodiesel, from B2 to B100, in a diesel engine with NO modification to the engine. This myth is commonly perpetuated by the hypothetical possibility that biodiesel will clean out diesel sludge that has accumulated in older fuel lines. If you drive an old diesel vehicle, this hypothetically could happen and your fuel filter could subsequently clog. I’ve never actually heard of this happening and can easily be avoided by switching out the fuel filter after a few tanks of biodiesel (take it to your local Jiffy Lube). My 25 year old Datsun pickup truck did just fine when I switched to B100.

MYTH: You have to be a diesel mechanic to use biodiesel.
FACT: No, all you have to do fill up with a different fuel, just like switching between regular and premium.

MYTH: Biodiesel will wreck your engine.
FACT: Nope. This is completely false. There have been reports of biodiesel damaging gasoline engines, and that’s why some mechanics rail against using the fuel - they’ve had to deal with these hapless folks, but we already covered that. Engine manufacturers are especially cautious about new fuels, but some of biggest names in the diesel world (like Cummings) have cleared B20 from doing any harm. Biodiesel and diesel fuel are similar in chemical structure and have similar properties, so they burn similarly in diesel engines. But biodiesel has some specific advantages. Biodiesel adds significant lubricity to the fuel (something that sulfur formally did in diesel fuel, but has since been reduced, hence low-sulfur diesel), reducing engine wear and reportedly extending engine life. Biodiesel has a higher cetane number (higher ignitability) and combusts more completely. Biodiesel is also a good solvent and will clean out diesel fuel residue left in the fuel tank and lines. Over time, because it’s such a good solvent, biodiesel can degrade rubber fuel lines and gaskets. Most post-1990 vehicles don’t have rubber lines and gaskets, but some older vehicles do. I have driven for a year now on B100 and B50 with no visible deterioration of my rubber fuel lines.

MYTH: Biodiesel will cause a noticeable power decrease.
FACT: Biodiesel contains about 8% less energy per gallon than petroleum diesel. For someone using B20, this means a 1-2% loss in power, torque, and fuel efficiency. To put things into perspective, that’s about a 2 mph difference on the freeway at 55. Millions of miles of onroad tests (aka trucking) have shown that B20 and diesel are practically indistinguishable. B100 users may notice a slight drop in fuel mileage, but torque and power are usually comparable. I have noticed a 1-3 mpg drop in fuel efficiency running B100. As an FYI, biodiesel has the highest BTU (energy) content of any alternative fuel (falling somewhere between diesel #1 and #2).

MYTH: Biodiesel use will void your warranty.
FACT: Some manufacturers have approached biodiesel cautiously, but now almost everyone recognizes B20 as a viable fuel, and it should not void warranties. According to the National Biodiesel Board (NBB), “The use of biodiesel in existing diesel engines does not void parts and materials workmanship warranties of any major US engine manufacturer.” Apparently, Federal law prohibits the voiding of a warranty just because biodiesel was used - it must be the cause of the damage. Warranties generally don’t cover problems caused by external sources, i.e. bad fuel, but can’t be voided if the problem was unrelated (see NREL’s Biodiesel Handling and Use Guidelines p. 53). Most manufacturers support B5 or B20, but that doesn’t mean they prohibit higher blends. Double-check with your manufacturer. I know some manufacturers haveexplicitly stated they won’t support higher biodiesel blends.

MYTH: Biodiesel doesn’t work in cold weather.
FACT: Ok, so maybe you read my personal experience with biodiesel in cold weather [post] - let me reiterate that operator error led to the breakdown. It’s true that biodiesel clouds up (starts to freeze) at higher temperatures when compared to regular diesel, and therefore it’s important to use a lower blend of biodiesel in the winter. B100 can be used down to about 40 degrees F, B50 between 20-40 degrees F, and B20 below that. Remember that the cold-flow properties (as they’re called) vary depending on what the biodiesel is made from (feedstocks with more saturated fat, like coconut oil or animal fat tend to freeze earlier). Local producers should be able to give you more information about this, though most biodiesel you will find is going to be good ol’ soy biodiesel. I typically use B100 between March and November, then switch to B50 for the winter, unless I plan on hitting much colder temperatures (I mean anything approaching 0 F).

MYTH: Biodiesel is hard to find.
FACT: Biodiesel is likely to be readily available in your area. The first thing is to check is if there’s a retail pumping station nearby. Try the National Biodiesel Board’s Station locator map, or search by city on the National Renewable Energy Laboratory’s website. If you can’t find a station, there may be a biodiesel cooperative in the area that resells wholesale fuel. Biodiesel is the most widely available renewable fuel and can be found in most major metropolitan areas.

MYTH: Biodiesel is too expensive.
FACT: Biodiesel generally costs around $2.80 to $3.30/gallon. Last time I checked, regular gasoline in some parts of California was $3.70/gallon! Biodiesel is nearly price competitive with premium gasoline, and certainly won’t seem that expensive in the middle of summer.

MYTH: Biodiesel requires more energy to produce than is provided by the fuel.
FACT: The vast majority of literature out there shows a positive energy balance, meaning that more energy is produced in the fuel than is used to grow the crop, press the seeds, process the oil into biodiesel, and distribute the product. The most common numbers I’ve seen say about 2-3x more energy is produced, or 1 unit of energy in equals 2-3 units of energy out. [don't leave it to me, see for yourself: (1), (2)]. Compare this to corn-grain ethanol, which optimistically produces 25% more energy than is put into it (1 unit in equals 1.25 units out).

MYTH: Biodiesel’s increases net emissions when the entire production process is taken into account (farming, distribution, etc).
FACT: According to the University of Minnesota in 2006 (1), the production and use of soybean biodiesel decreases life-cycle greenhouse gas (GHG) emissions by 41% over regular diesel, and also decreases other pollutants like Carbon monoxide, PM10, and SOx. To compare, the life-cycle of corn-grain ethanol reduces GHG emissions by 12% and actually increases emissions of five major pollutants.

MYTH: Biodiesel causes deforestation of the rain forest.
FACT: You may have read my posts on biodiesel destroying the Brazilian and Malaysian rain forests. What’s true there is not true in the United States. The US already produces a great deal of biodiesel from domestically-grown soybeans. But don’t forget that biodiesel can be made from many other feedstocks, like rapeseed (Canola) and waste-vegetable oil (WVO). In some areas, WVO is the primary source for making biodiesel. Like any other crops, these can be grown sustainably or unsustainably.

MYTH: Biodiesel exhaust smells bad.
FACT: Well, this one is personal preference. I have had people tell me that they think the smell is disgusting (as if they would prefer diesel exhaust). I think B100 exhaust smells great. Sort of like french fries but somehow…cleaner, and not as potentially nauseating. One thing is certain: once you know what it smells like you’ll grin from ear to ear whenever you catch a whiff.

MYTH: Biodiesel exhaust produces more harmful emissions than diesel.
FACT: Biodiesel is the only alternative fuel that has completed all the testing requirements of the Clean Air Act. Biodiesel contains oxygen and burns more completely than diesel fuel, hence reduced emissions. All major pollutants are reduced dramatically in biodiesel exhaust (most of them at least 50% for B100), except one (NOx), and that’s only for blends over B20 (see my post on the subject). B20 reduces air toxics (the most damaging pollutants for human health) by 20-40%, while B100 reduces them by as much as 90%. Sulfur oxides and sulfates (major contributors to acid rain) are almost completely eliminated. The only caveat is that nitrogen oxide (NOx) emissions can increase up to 10% with B100. If you would like to evaluate this for yourself, see the National Biodiesel Board’s emissions fact sheet. New diesel technology has the potential to eliminate this problem.

MYTH: Diesel engines are more polluting than gasoline engines, so selling my car and buying a diesel is a bad idea.
FACT: It’s true that traditional diesel engines are 10-100x more polluting than their gasoline counterparts. New model diesel engines, however, are more efficient and have advanced catalytic converters allowing them to approach the emissions ofcomparable gasoline models. When combined with biodiesel newer engines should offer significant emissions reductions. Additionally, older diesels are currently in use and will continue to be used (due to long engine life). Switching these vehicles to biodiesel still provides tangible benefits. While local air pollution is an important consideration, so are greenhouse gas emissions. Biodiesel offers a significant reduction in CO2 emissions.

MYTH: Biodiesel is only used by crazy hippies and Willie Nelson.
FACT: Tell that to the Military, Department of Defense, Postal Service, National Park Service, city governments and school districts across the country, and a whole lot of truckers and farmers who all use and promote biodiesel.
That should be enough information to get you started. The first time you use biodiesel can be a thrilling experience, and I highly recommend it. Clearly, I can’t cover every issue in this post, but don’t stop here. Take a look at the following resources for more information:

Journey To Forever’s Biodiesel resources page (most comprehensive)
National Biodiesel Board (The main industry group)
National Renewable Energy Laboratory (NREL) - Non-petroleum Based Fuels
National Sustainable Agriculture Information Service - Biodiesel-A Primer

Studies:

(1) Environmental, economic, and energetic costs and benefits of biodiesel and ethanol biofuels
Jason Hill, Erik Nelson, David Tilman, Stephen Polasky, and Douglas Tiffany. PNAS published July 12, 2006, 10.1073/pnas.0604600103

(2) Sheehan et al. May 1998. A Life Cycle Inventory of Biodiesel and Petroleum Diesel for Use in an Urban Bus. NREL/SR-580-24089.

Did I forget something? Let me know and I might be able to expand this list.

Know of a green myth that needs dispelling? Heard something about green living that doesn’t seem quite right? Pass it along, and we may feature it on Green Myth-Busting.

Photo Credit: Clayton B. Cornell (That’s his truck.)