Unlike truck or automobile engines, locomotive engines cannot
use antifreeze in their cooling systems for technical reasons
related to reactions of antifreeze chemicals on internal engine
parts. Therefore, during cold weather, a locomotive engine must
either be working to transport freight or idling to prevent
freezing. A freeze-damaged locomotive engine can cost upwards of
$200,000 to repair.
Recognizing the need to continuously reduce fuel consumption and
exhaust emissions, the railroad industry and its suppliers
developed the Auxiliary Power Unit, or APU, which is a small diesel
engine that automatically operates via computer control whenever
the main locomotive engine is shut down and ambient temperatures
are close to or below freezing. Heat from the small engine is
transferred to the larger engine via fluid transfer connections to
prevent freezing. The APU keeps the main engine warm, reducing fuel
consumption and emissions while the main engine is shut down.
While a typical locomotive main engine burns five gallons of diesel
fuel per hour while idling, the APU consumes only one gallon. When
GWI monitored data for a 15-month period from one of its Canada
Region locomotives equipped with an APU, fuel savings averaged more
than 20 gallons per day. Over a typical year, the APU can reduce
emissions from one locomotive by more than 80 tons of nitrogen
oxides, 12 tons of carbon monoxide and three tons of particulate
matter.
GWI has installed APUs on 20 locomotives in its colder operating
regions, with more scheduled in 2009.
Next:
"GenSet" Locomotives