Blending low levels of alternative fuel with conventional
fuel is an important option for reducing petroleum consumption.
Examples of low-level fuel blends include E10 (10%
ethanol/90% gasoline), B5 (5% biodiesel/95% diesel), and B2 (2% biodiesel/98%
diesel). Blends can also consist of two types of alternative fuels, such
as hydrogen and compressed natural gas (HCNG), which can be a combination
of 20% hydrogen/80% CNG. Many fleets are starting to use alternative fuel
blends such as these in their fleet vehicles.
Low-Level Ethanol Blends
Low-level ethanol fuel blends are sold in every state. In
fact, nearly one-third of U.S. gasoline now contains up to 10% ethanol to
boost octane or meet air quality requirements. All auto manufacturers
approve the use of low-level ethanol blends because these fuels work well
in gasoline engines and have no noticeable difference in vehicle
performance.
The Clean Air Act Amendment of 1990 (and subsequent laws)
mandated the sale of oxygenated fuels in areas with unhealthy levels of
carbon monoxide. This kicked off the modern U.S. ethanol industry growth.
Problems with groundwater contamination from the use of methyl tertiary
butyl ether (MTBE)—the only other available oxygenate and principal octane
booster—accelerated the use of ethanol in low-level blends.
The Energy Policy Act of 2005 established a nationwide
renewable fuels standard requiring the use of 4 billion gallons of
renewable fuel in 2006 and increasing to 7.5 billion gallons in 2012. The
new standard gives fuel blenders flexibility to use ethanol or other
renewable fuels and eliminates the previous 2% oxygen (5.7% ethanol)
requirement for reformulated gasoline. Ethanol production was already well
ahead of the new standard at the time of its enactment, with 2006
production of 4.9 billion gallons and use of 5.4 billion gallons.
Low-Level Biodiesel Blends
When biodiesel is blended with petroleum diesel, it produces a fuel that
is compatible with diesel engines, displaces imported petroleum, and
reduces harmful emissions. Blends like B2 (2% biodiesel and 98% diesel)
and B5 (5% biodiesel and 95% diesel) are becoming increasingly common as
drivers become more aware of the many benefits. Higher-level biodiesel
blends, such as B20, are also becoming more widely available and can
qualify for credits under the Energy Policy Act of 1992.
Benefits
As of 2006, most U.S.
highway diesel fuel is limited to 15-ppm sulfur, down from a 500-ppm
limit. This new ultra-low sulfur diesel fuel (ULSD) might have reduced
lubricating properties before additives. Adding as little as 0.25%
biodiesel, which is very low in sulfur, can significantly increase fuel
lubricity. B2 and B5 are becoming increasingly popular for this reason.
Another reason for using B2 or B5 is to introduce a large quantity of
renewable fuel into the diesel fuel market with no noticeable impact on
users or fuel properties. Using 100 gallons of B5 brings roughly the same
air-quality and alternative fuel use benefits as using 25 gallons of B20
or 5 gallons of B100. Minnesota adopted a statewide requirement for B2 use
in 2005. After some problems from out-of-specification fuel the first
winter, the program is working well. Louisiana, Maryland, and Washington
have enacted similar programs contingent on state biodiesel production
reaching certain levels.
What types of vehicles can run on biodiesel
blends
As long as the biodiesel used for blending meets ASTM D6751 standards(U.S.),
low-level biodiesel blends such as B2 and B5 can be used safely in any
compression-ignition engine designed to be operated on diesel fuel. This
can include light-duty and heavy-duty diesel cars and trucks, tractors,
boats, and electrical generators
Resources
DRIVERS
- 
