Clean Snowmobiles: Background and Overview
Essential Links:
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Clean Snowmobile Facts
Presents objective and balanced information about all aspects of the debate over snowmobile emission...
How Two-Stroke Engines Work
Explains how two-stroke engines operate and their advantages and disadvantages.
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Snowmobiling is a popular winter sport and basic mode of transportation in remote areas.
The economic impact of the industry is $20 billion per year. In 2004, there were 109,750
snowmobiles sold in the U.S. The average suggested retail price of a new snowmobile sold
in 2004 was $6,550. There are more than 1.7 million registered snowmobiles in the U.S.
and more than 225,000 miles of groomed and marked snowmobile
trails. The average snomobiler rides 990 miles per year.
Source:
International Snowmobile Manufacturer's
Association
Twenty-six states in the U.S. have active state snowmobile associations:
Alaska, Arizona,
California, Colorado, Idaho, Illinois, Indiana, Iowa, Massachusetts,
Michigan, Minnesota, Montana, Nebraska, New Hampshire, New York, North
Dakota, Ohio, Oregon, Pennsylvania, South Dakota, Utah, Vermont, Virginia,
Washington, Wisconsin, and Wyoming.
Source: American Council of Snowmobile
Associations
Do snowmobiles
emit significant amounts of pollution?
Some Do, and Some Do Not!
A final EPA regulation of snowmobiles was published in September
2002, utilizing 2000 baseline data developed from 23 different snowmobile
machines. Starting in model year 2004, these regulations will reduce fleet-wide
hydrocarbons (HC) and carbon monoxide (CO) snowmobile emissions by 30 percent
by 2006, by 50 percent by 2010, and by 70 percent by 2012. The reduction is
a fleet average for each manufacturer depending on the number and type of engines
used each year. The regulations have allowances for minor producers and special
use (racing) snowmobiles. The first regulation deadline incorporates some emissions
credits for manufacturers fielding cleaner 4-stroke snowmobiles used in Yellowstone
and other environmentally sensitive areas. These cleaner, quieter snowmobiles
have reduced audible noise by about half, reduced CO and HC by more than 80
percent, as measured using the EPA 5-mode emissions test protocol. The emissions
are similar to those of small engine requirements in California on a mass of
pollutant per unit of power basis.
The EPA regulation does not cover particulate matter, although
the 2012 emissions level will require a change of technology such as the use
of 4-strokes or direct-fuel-injection two-stroke engines. This type of two-stroke
engine was measured as emitting less HC and CO than four-stroke equivalents.
- Current (2004) production snowmobiles use cleaner versions of two-stroke
engines or four-stroke engines. The two-stroke engines produce amounts of
unburned HC and CO similar to that produced by automobiles before the 1970
Clean Air Act. These two-stroke engines still produce significant amounts
of fine (PM-2.5) particulate matter emissions due to the method of scavenging,
leaving the exhaust and fuel inport ports open at the same time.
- The best estimates available comparing snowmobile emissions to average automobile
emissions conclude that a traditional snowmobile produces ten to 70 times
more CO and between 45 and 89 times more unburned HC than an average car (see
the National Park Service revised 2001 report on Impacts of Snowmobiles in
National Parks.)
| Two-stroke engines used in snowmobiles are sometimes
the same engines used in personal water craft (PWC) like jet skis, with
modified air and exhaust systems to adapt for water use. However, the way
these engines are used in PWC is considerably different, and these operational
differences change the emissions and emission content. Temperature difference
is one large variable. PWC seldom operate at temperatures below freezing
(0° C) where snowmobiles typically operate at colder temperatures when
all engines want to run rich. Colder temperatures favor the production of
carbon monoxide and warmer temperatures favor the production of unburned
hydrocarbons. |
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