The technology to power railway locomotives using LNG was proven over two decades ago on switching engines in North American railyards. Today, with increased environmental concerns, the desire to be a good corporate citizen and the escalating cost of diesel, there is renewed interest in LNG from rail operators, particularly from areas where the costs and logistics of establishing an electrification infrastructure are challenging.
In November 2017, Florida East Coast Railway rolled out its line-haul fleet of 24 locomotives that had all been converted to run on LNG, making it the first North American railway to operate its entire fleet on natural gas and bringing years of industry testing and debate to a successful conclusion.
The EPA Tier-3 compliant locomotives look no different to their diesel counterparts but, under the skin, their diesel drive units have been retrofitted with GE’s NextFuel™ technology that equips them to substitute up to 80% diesel with natural gas without compromising engine performance.
As a first of its kind the project partners solved several technical challenges, including refuelling of the tender
In a throwback to the days of steam, the locomotives are fuelled from a tender hitched behind the locomotive, or in this case, between the twin locomotives. Chart’s challenge was to design and build the tender. Not only did that include the complex system for regasifying the LNG, but also to manage refuelling of the tender and meeting, or exceeding, FRA and AAR requirements.
The result is a fleet of units that each contain enough fuel for 900 miles of heavy haulage service at speeds up to 60 mph, which is sufficient for the round-trip journey with contingency for idling time and delays.
At its core the tender is a cryogenic tank and, in terms of its ability to safely store and transport cryogenic liquefied gas, little different to the technology that has been conveying industrial and hydrocarbon liquid gases, incident free, on roads, railways and waterways for many years. An inner stainless steel tank is contained within an outer carbon steel shell separated by a layer of Chart proprietary thermal insulation. Thereafter, a PLC manages supply of gas to the engines, which can be transferred via liquid pump, liquid pressure or gas pressure, for maximum flexibility.
Safety is paramount
Safety was a huge design consideration and the tender is far stronger than a traditional well car and has been extensively computer modelled to simulate worst case scenarios for derailment, puncture and impact. It will withstand side-impact from a tractor-trailer without damage and the under-carriage has no openings where track debris or other projectiles could rupture the tank, even in the event of a derailment. The cryogenic tank is secured to the rail bogey and fully protected in a rollover by a rigid steel frame. Even the specialty pipe work incorporates enhanced safety features, such as valves that detect damage and close automatically to prevent leakage.
The EPA Tier-3 compliant locomotives look no different to their diesel counterparts
Far from being a pipe dream, LNG as a rail fuel is now a reality and, as well as significantly reducing emissions, diesel substitution could reduce direct fuel costs by as much as 50%.
Authors: Paul Shields and Scott Nason with kind assistance of William C Vantuono
All images supplied courtesy of William C Vantuono/Railway Age