Digital Displacement® potential to reduce freight rail emissions

The UK rail industry is committed to the UK Government’s goal of reaching net carbon zero by 2050 – however, the route to getting there is not easy.

Whist low carbon electricity offers an obvious solution, the electrification of GB’s entire rail network is challenging, whilst other fuel solutions such as green hydrogen are not yet market ready.

A Digital Displacement® hydraulics business – has taken a different approach. Rather than looking at the energy source, they have developed a Digital Displacement® hydraulic technology which they claim can radically improve system efficiency wherever it is used – and thereby reduce energy use (and, with it, CO2).

Digital Displacement for passenger rail

They are now working closely with the University of Huddersfield and Direct Rail Services to undertake a project funded by the RSSB as part of the Intelligent Power Solutions research competition launched in October 2018.

The project – Digital Displacement for Non-Passenger Rail – is examining the possibilities provided by Digital Displacement technology as a more efficient alternative to conventional hydraulic pumps for providing traction and auxiliary power for freight locomotives, shunters and on-track plant.

  • The team is currently working on three work packages:
  • Specify the Digital Displacement pump hydrostatic cooling system for a large locomotive
  • Pursue pump swap opportunities for road-rail and track maintenance vehicles
  • Develop a modular drive system concept for small locomotives and track maintenance vehicles

According to project lead Gordon Voller, the project is going well.
“So far we have seen some very positive results for all three work packages. We found that the DDP096 pump, which is our first commercial product (available from Danfoss Power Solutions), is a good fit for many of these applications.

He continues:

“Initial calculations show that the large locomotive hydrostatic cooling system can be made significantly more efficient, providing CO2 reduction and fuel savings with a simple pump swap. For on track plant, almost all of these already use hydraulic systems, making this an ideal application area for Digital Displacement.”

This project is not the first time the team has been involved in rail. In 2018 the Edinburgh specialists completed a project with ScotRail to demonstrate using a Digital Displacement pump to replace the conventional pump powering the hotel loads in a Class 170 DMU. The successful trial of 3500 hours on an operating train indicated a fuel saving of 6.7 percent.

Gordon believes the technology could have much wider applications in rail.

“If fully integrated, Digital Displacement pumps and motors can be combined to create a hydrostatic transmission suitable for on-track machines. It would be particularly appropriate where vehicles have both transport and working modes – each at extreme ends of the speed range. It can also be used in small shunting locomotives. Hydraulic accumulators can be added to provide energy storage for power smoothing or braking energy capture, with significant performance and efficiency benefits.” Gordon concludes.

Commenting on the project, Giulia Lorenzini, Senior Grants and Partnerships Manager, RSSB, said:

“The railway remains a very low carbon form of transport for both passengers and freight. Freight, in particular, has journey characteristics which demand very high energy and power requirements, high acceleration and long periods between refuelling. Our research has shown that there are no suitable alternatives to electric and diesel traction currently available for these journey types.

Therefore, the Digital Displacement technology is a valuable transitional arrangement for rail freight, where it could be applicable to small locomotives, track maintenance vehicles and large locomotives to help reduce CO2 emissions.”

The consortium will issue their final results later in 2020.

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