The Railfreight Energy and Emissions Calculator (REEC) was developed by the University of Hull Logistics Institute in partnership with Aether, Carrickarory and the University of Derby. Freightliner supported the project with data, operations advice and as an early adopter. Funding was provided by the Department for Transport, through Innovate UK. REEC is the first tool for the UK that can calculate, to a high level of granularity and accuracy, the energy usage and resulting emissions (of CO2, NOx and particulate matter) for a specified freight train configuration travelling on specified routes on the Great Britain rail network.
The Challenge
The UK target for net-zero greenhouse gas emissions by 2050 and the DfT target for "no diesel-only trains" by 2040 are challenging for the GB rail industry. The limited electrification of the existing network and the requirement for freight trains to have ‘go-anywhere’ capability, along with the energy requirements to move heavy freight trains, means that this challenge is more acute for freight operating companies. These companies are actively pursuing ways to decarbonise diesel trains. This includes exploring the use of alternative bio-fuels, and assessing the technological feasibility of a hybrid diesel-electric combination or an electric-battery combination.
The challenge to decarbonise is amplified by the fact that only 44% of the GB rail network is electrified and full electrification remains several decades away. Today, less than 10% of rail freight is moved using electric locomotives. Freight operating companies are asking questions such as "how much battery power will be needed on specific lines to bridge the gaps in electrification" and "what are the resulting impact on emissions (CO2, NOx and PM)" of different mitigation measures. Answering these questions requires knowledge of train energy usage (of different locomotive and wagon combinations), speed restrictions, and timetabling constraints.
A detailed energy and emission profile calculator, performing on-the-fly computation for any path for any realistic trainload and all major locomotive classes, simply did not exist before REEC. Although the broad methodology is known, no single database contained all the necessary information gathered from on-train telematic equipment and train performance data (e.g. the tractive effort, braking performance), and network infrastructure constraints (e.g. line speed and gradients). Before REEC was created, it required months of data gathering and experienced experts to perform detailed analysis for a single route and scenario. Furthermore, previous calculations were based on broad rail industry averages, rather than for a specific combination of locomotive, train (type of wagons and cargo), route characteristics and typical driver behaviour.
Freightliner, a major rail freight operating company, presented the University of Hull-led team with a number of specific challenges to use as test cases in the development of the calculator:
- How much energy will be required to bridge the non-electrified gap on the route from Felixstowe to Crewe via Peterborough?
- How do the two routes between Felixstowe and Trafford Park, one via London and the other via Peterborough, compare from an energy usage and emissions perspective?
- What would the energy and emissions savings per freight tonne be if longer trains could be run on certain routes?
- What would the energy and emissions savings per freight tonne be if we manage to remove some schedule stops or low speed restrictions from certain routes?
- How do emissions compare between electric and diesel haulage on selected routes?
The Solution
The University of Hull Logistics Institute embarked on a project to create the Railfreight Energy and Emissions Calculator (REEC or /rɛk/) with its partners, Aether, Carrickarory and the University of Derby. Funding was awarded by the Department for Transport’s (DfT), through the “First of a Kind” (2021) competition, run by Innovate UK. Freightliner agreed to provide rail freight expertise and train telematic data to support the project. The project was initiated in July 2021 and completed in March 2022. From April 2022 the tool is now being actively used by Freightliner to analyse some of their considered decarbonisation initiatives and investments and to consider the pathing of their services to reduce emissions.
REEC is deployed on the existing NR+ platform used for rail planning. This platform was developed by the University of Hull Logistics Institute in 2019 and contains a unique set of data that include the UK rail network track geometry, gaging, length and weight constraints, line electrification, current and historic rail schedules and actual movements of all trains, as well as enabling the scalable performance of the computationally intensive calculations. The calculations in REEC use the established Davis Equation that balances the net accelerative and decelerative forces on a train at any point on its journey to determine the energy required to achieve the desired speed. From this the required notch (or power-setting) for the locomotive can be determined. Underlying inputs, such as tractive effort curves, were derived through the filtering, processing and analysis of a large on-train monitoring recorder (OTMR) dataset and associated train consist data, while factors for emissions by notch for CO2, NOx and particulate matter are based on the recent RSSB T1187 project. The OTMR data was also used to calibrate and validate the model, helping to ensure calculations were within the observed variance in driver behaviour.
REEC was built with a user-friendly user interface to allow users to select train configurations and routes to be analysed in an easy and flexible way. After selecting a train consist (configuration) and a route, the energy and emission calculations will be performed. The calculator breaks the route down to 10 m segments to determine the appropriate state (or “mode”) of the train at that point on the route (accelerate, coast, cruise or decelerate) by mimicking train rules, driver behaviours and train performance constraints. The calculator then determines the appropriate notch setting to achieve the strain state and the resultant energy usage and emissions.
The calculations include various factors, including the weight of the train, performance characteristics of the locomotive, traction conditions, track gradient, tunnel conditions, aerodynamic considerations and speed limits. The results are presented as summary tables, graphs and maps that users can use for their analysis. The “Compare” feature enable users to directly compare the results of two scenarios, e.g. the current baseline compared to a suggested change. The calculator results were validated by the University of Derby against several selected routes, using OTMR data from representative actual runs and several recognised calculation methodologies.
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The Results
REEC can be used to evaluate emission reduction strategies and decarbonisation investments and to rapidly compare alternatives. It can help users understand the impact on energy consumption and emissions of:
- Different locomotive types, train loadings and lengths
- Different routings and pathings
- Operational delays
- Improvements to infrastructure (e.g. linespeeds, turnout speeds)
Through more consistent and robust analysis, REEC can provide more accurate comparison to other transport modes, e.g. through derivation of accurate tonne-km factors, and so support modal shift.
REEC can be used to evaluate electrification strategies and the battery requirements for bi-mode locomotives to bridge electrification gaps. In addition to energy and emissions calculations, REEC can also be used to quickly evaluate performance characteristics, such as for which range of loadings a train will keep to time on a certain route or the benefits of single versus double-heading.
A number of potential emission reduction scenarios have been tested as use cases for REEC including:
1. Running longer multimodal trains on the route from Southampton port to Trafford Park
By increasing the train length to 832 m, CO2 emissions will be reduced by 13.6% measured in kg per tonne-km. This provides clear evidence over the benefit of train lengthening from an emissions perspective.
2. Determine the lowest emission route from Felixstowe port to Trafford Park
The London route was compared to the Peterborough route and the latter resulted in 2.5% less CO2 emissions. For the first time we can directly compare relative emissions for the train services travelling on different routes, supporting more informed decision-making on routing and pathing options.
3. Using electric rather than diesel traction on the route from Felixstowe to Trafford Park
There are several non-electrified sections on this route, totalling a distance of 148 miles (56% of the route). A total of 8,189 kWh of energy will be required to get a class 90 train across these sections, with the longest section requiring 3,723 kWh, beyond the capacity of current battery powered locomotives. Running electric locomotives on this route will reduce emissions by 46% and allow trains to complete the journey 50 minutes faster due to higher performance capabilities. With more than 8,000 freight trains scheduled to use this route in 2022, using electric traction will result in an annual CO2 emissions saving of more than 15 kilotonnes or 4% of the total rail emissions for UK rail freight.
This provides clear evidence of energy requirements to bridge gaps on non-electrified infrastructure. This will provide invaluable information supporting further research and development into new technologies to help to bridge gaps on the network. It can also be used by the infrastructure manager or by Government to inform the sequencing of future electrification programmes, in order to help narrow those gaps and bring them within the bounds of new technologies to bridge.
4. Remove a speed restriction and a scheduled stop from the Tunstead Quarry to West Thurrock depot route
Removing a 25mph speed restriction at Chinley and a scheduled stop at Toton results in a 95 kg CO2 reduction. This provides clear information of the impact of pathing on emissions and how the industry can deliver better outcomes with existing technologies on the current infrastructure.
The below video, featuring Aether's Luke Jones, further explains the functionality of the Railfreight Energy and Emissions Calculator (REEC):
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