In an engine-switching locomotive, multiple smaller efficient engines provide power on demand instead of one conventional large engine. Automatic adjustments are made to the number of engines used at any given time to conserve fuel while providing the power and torque required. By switching the required number of engines on, each one is able to be run at its most efficient speed (compared with one larger engine having to be throttled up and down to adjust power and torque).

As a concept, this technology is broadly comparable to ‘variable cylinder management’, which enables road vehicles to run on six, four or three cylinders depending on speed and load conditions.

Application relevance

The applicability of this concept in Australia is limited. Experience suggests that benefits may be accessible only at low throttle levels as there may be some sacrifice of power compared to a conventional single diesel. This may restrict application to switching/shunting locomotives which move cars within a rail yard terminal. This limitation is supported by a general lack of linehaul applications to date.

An additional point for context is that the use of gensets in North America has been largely driven by US Environmental Protection Agency regulations to reduce harmful pollutants affecting urban areas in close proximity to rail yards. Similar regulations do not apply in Australia.

If they were to be adopted in Australia, new locomotives from US and Canadian-based suppliers would need to be re-engineered for Australian conditions and gain certification to operate on local track. Some rebuilds from older engines in the US use off-the-shelf components but there is a lack of Australian technology providers and installers.

Potential benefits

Case studies indicate expected fuel savings of between 37% and 49% compared with a conventional switching/shunting locomotive. The upper end of estimated savings are achieved when combined with hybrid regenerative braking technology. The ability to achieve fuel savings when compared to a conventional diesel will be attributed to the power requirements dictated by the locomotive’s duty cycle.

Key implementation considerations

Switcher locomotives cost from US$1.3m to US$1.4m each. However, rebuilt switcher locomotives are 30–40% less expensive but still up to six times more expensive than regular locomotives. No information is available with regards to the capital cost for linehaul applications.

Payback information is very limited. It is worth noting that many US rail operators have only considered genset investment decisions with the assistance of government funding (up to 80% contribution from federal and state programs) due to the additional air quality benefits.

Examples of implementation

Union Pacific website

This website outlines environmental management initiatives such as the development of the first prototype genset switcher in 2005, purchase of the world’s largest genset fleet of over 160 locomotives, and testing of a genset for intermediate linehaul service.

CSX Corporation website

This website details the purchase of 8 gensets in 2009. Although capital cost information is provided there is no information on fuel saving performance.

Railway Age media release

This media release on the Brookville Equipment Corp identifies performance improvements of using genset switchers (up to 49% achieved to date) .

For the full report, see Fuel for Thought – Identifying potential energy efficiency opportunities in the Australian road and rail sectors (opens in a new window) PDF 1.5 MB.