A strategic shift on battery technology
Since the 2009 rollout of NS 999, a prototype battery switcher locomotive, Norfolk Southern has continued research into battery technology as an alternative energy source for locomotives. In 2015, the company made a strategic shift: Instead of focusing on tractive power in a full hybrid, NS now is exploring use of batteries for just the opposite – to allow locomotives to be shut down, thus reducing fuel burn and emissions from idling engines.
NS hopes to develop a “micro-hybrid” solution. The idea is to install a small battery pack on locomotives to operate critical electronic control systems, such as onboard train-handling equipment, while the locomotive is shut down. Similar to automobiles, locomotive electronics and other operating systems are run by the same battery pack that starts the engine, which requires a surge in power. As a result, locomotives often remain idling or go through an automated stop-start process when not moving freight to avoid draining the batteries while keeping those electronics running.
Economic and environmental benefits: Equipping the locomotive fleet with a micro-hybrid battery pack to reduce engine idling is much more cost-effective than building a fleet of hybrid-powered locomotives.
“We’re trying to use battery technology in a way that gives us the most fuel and emissions savings for the investment,” said Sean Woody, manager technology development and leader of the R&D effort. “Locomotives produce more emissions and are the least fuel efficient when they’re idling, so reducing idling time provides the most opportunity for improvement. We realize there’s tremendous payoff from doing that.”
Lessons learned: NS is applying lessons learned from six years of work developing the NS 999. The company’s micro-hybrid research includes looking at the best type of batteries to use, how much battery power is required, and forecasting system costs. Currently, battery technology remains too expensive and is not advanced enough to provide reliable locomotive tractive power – factors that played into NS’ strategic shift. An upgraded second-generation version of NS 999, tested in yard service during early 2015, was equipped with nearly 900 lead-carbon batteries, and maintenance was an ongoing issue.
“We still see the potential,” Woody said, “but the technology and the economics are just not there yet.”