COMMONLY ASKED QUESTIONS
What is biodiesel?
Biodiesel is the name of a clean burning alternative fuel produced from domestic,
renewable resources. Biodiesel contains no petroleum, but it can be blended at any
level with petroleum diesel to create a biodiesel blend. It can be used in compression-
ignition (diesel) engines with no major modifications. Biodiesel is simple to use,
biodegradable, nontoxic, and essentially free of sulfur and aromatics.
Biodiesel is the first fuel commercially produced nationwide that meets US EPA’s
definition of an advanced biofuel.
Technical Definition: Biodiesel, n—a fuel composed of mono-alkyl esters of long chain
fatty acids derived from vegetable oils or animal fats, designated B100, and meeting
the requirements of ASTM (American Society for Testing & Materials) D 6751.
Is biodiesel used as a pure fuel or is it blended with petroleum diesel?
Biodiesel can be used as a pure fuel or blended with petroleum in any percentage.
B20 (a blend of 20 percent biodiesel with 80 percent petroleum diesel) has
demonstrated significant environmental benefits with a minimum increase in cost for
fleet operations and other consumers.
Is it approved for use in the U.S.?
Biodiesel is registered as a fuel and fuel additive with the Environmental Protection
Agency (EPA) and meets clean diesel standards established by the California Air
Resources Board (CARB). Neat (100 percent) biodiesel has been designated as an
alternative fuel by the Department of Energy (DOE) and the U.S. Department of
Transportation (DOT).
How do biodiesel emissions compare to petroleum diesel?
Biodiesel is the only alternative fuel to have fully completed the health effects testing
requirements of the Clean Air Act. The use of biodiesel in a conventional diesel engine
results in a substantial reduction of unburned hydrocarbons, carbon monoxide, and
particulate matter compared to emissions from diesel fuel. In addition, the exhaust
emissions of sulfur oxides and sulfates (major components of acid rain) from biodiesel
are essentially eliminated compared to diesel.
Of the major exhaust pollutants, both unburned hydrocarbons and nitrogen oxides are
ozone or smog forming precursors. The use of biodiesel results in a substantial reduction
of unburned hydrocarbons. Emissions of nitrogen oxides are either slightly reduced or
slightly increased depending on the duty cycle of the engine and testing methods
used. Based on engine testing, using the most stringent emissions testing protocols
required by EPA for certification of fuels or fuel additives in the U.S., the overall ozone
(smog) forming potential of the hydrocarbon exhaust emissions from biodiesel is nearly
50 percent less than that measured for diesel fuel.
Can I use biodiesel in my existing diesel engine?
Biodiesel blends of up to 20 percent work in any diesel engine with no modifications to
the engine or the fuel system. Biodiesel has a cleansing effect that may release
deposits accumulated on tank walls and pipes from previous diesel fuel usage. The
release of deposits may end up in fuel filters initially, so fuel filters should be checked
more frequently at first. Ensure that only fuel meeting the biodiesel specification (D
6751) is used.
Can biodiesel help mitigate “global warming”?
Biodiesel is the best greenhouse gas mitigation strategy for today’s medium and heavy
duty vehicles. A 1998 biodiesel lifecycle study, jointly sponsored by the U.S. Department
of Energy and the U.S. Department of Agriculture, concluded biodiesel reduces net
carbon dioxide emissions by 78 percent compared to petroleum diesel. This is due to
biodiesel’s closed carbon cycle. The CO² released into the atmosphere when
biodiesel is burned is recycled by growing plants, which are later processed into fuel.
Does biodiesel take more energy to make than it gives back?
No. Biodiesel has one of the highest “energy balance” of any liquid fuel. For every unit
of fossil energy it takes to make biodiesel, 5.5 units of energy are gained. This takes into
account the planting, harvesting, fuel production and fuel transportation to the end
user.
Is biodiesel better for human health than petroleum diesel?
Scientific research confirms that biodiesel exhaust has a less harmful impact on human
health than petroleum diesel fuel. Pure biodiesel emissions have decreased levels of
polycyclic aromatic hydrocarbons (PAH) and nitrited PAH compounds that have been
identified as potential cancer causing compounds. Also, particulate matter, an
emission linked to asthma and other diseases, is reduced by about 47 percent, and
carbon monoxide, a poisonous gas, is reduced by about 48 percent.
Do I need special storage facilities?
In general, the standard storage and handling procedures used for petroleum diesel
can be used for biodiesel. The fuel should be stored in a clean, dry, dark environment.
Acceptable storage tank materials include aluminum, steel, fluorinated polyethylene,
fluorinated polypropylene and teflon. Copper, brass, lead, tin, and zinc should be
avoided.
Where can I purchase biodiesel?
Biodiesel can be made available anywhere in the U.S. The National Biodiesel Board
(NBB) maintains a list of member fuel producers as well as petroleum distributors and
retail fueling sites. A current list is available on the biodiesel web site at
www.biodiesel.org under the “Using Biodiesel” tab.
04/2012
