HomeRail NewsHow optimising energy usage reduces carbon emissions

How optimising energy usage reduces carbon emissions

Legally bound by the Climate Change Act of 2008, the UK needs to reduce its greenhouse gas emissions by 80 per cent in comparison to the 1990 baseline by 2050. Resulting from initiatives across UK plc, emissions have already come down, and the challenge remains for all energy users to meet this target.

Transport is the UK’s biggest energy consumer, representing 38 per cent of the UK’s consumption, and accountable for 20 per cent of UK greenhouse gas emissions. Rail, whether electric or diesel-powered, has plenty of opportunities to clean up its act and look towards low-carbon propulsion, despite accounting for only one per cent of the transport sector’s emissions.

Added to this is the 2017 Rail Capability Delivery Plan, which sets out themed areas of development towards “optimum energy usage” and a zero-carbon railway and, more recently, Rail Minister Jo Johnson announcing the phasing-out of diesel-only trains and railway decarbonisation by 2040.

So how can this be done? The Birmingham Centre for Railway Research and Education (BCRRE) at the University of Birmingham has been asking itself the same question.


The BCRRE is Europe’s largest university-based centre for railway research and education, with more than 150 academics and researchers and around 500 taught students. It boasts a well-recognised profile within the industry and academia in the UK and overseas, engaging globally across the entire breadth of railway technology.

Research ranges from the fundamental to the applied, in partnership with over 50 companies from more than 20 countries. Projects have improved railway efficiency, capacity, safety, and energy consumption through innovations such as in-service intelligent condition monitoring, with revolutionary new algorithms now used extensively across the UK rail network to monitor points and reduce delays.

BCRRE’s aerodynamic research has informed new levels of infrastructure design and safety and its simulators have been used to evaluate billions of pounds worth of rolling stock contracts around the world, while its use of novel smart-grid strategies has already optimised energy efficiency and reduced carbon emissions on numerous UK and global rail networks.

The BCRRE is lead partner in the £92 million UK Rail Research and Innovation Network (UKRRIN), a unique collaboration between industry and academia to create three core academic Centres of Excellence and a fourth in Testing. Of these, Birmingham will house the Centre of Excellence in Digital Systems, with Huddersfield University leading the Centre of Excellence in Rolling Stock and the University of Southampton hosting the Centre of Excellence in Infrastructure.

Together with these, Birmingham will be home also to an interim Centre of Excellence in Railway Energy and Power Systems. Birmingham’s Digital Systems centre will focus on future railway operations and control, data integration and cyber security, smart sensing and autonomous systems, and introducing innovation.

The Railway Energy and Power Systems centre responds to the current policy agenda and addresses its decarbonising theme. It will build on existing capabilities in Birmingham and across UKRRIN, and will set the scene for research in future railway traction systems. One of its key academics is Dr Stuart Hillmansen, senior lecturer in electrical energy systems, who also leads BCRRE’s Power and Traction Group. Stuart researches energy efficiency and decarbonisation, exploring how to reduce the energy needed on the basis that energy used in a process creates associated emissions.

Driver behaviour and understanding energy demand

Based on the idea that small changes in the way in which a vehicle is driven can have significant impact in energy efficiency, Dr Hillmansen led a project to look at driver behaviour in light rail and tram systems.

The BCRRE team used its multi-train simulator extensively to analyse energy use and electrical losses across the MerseyRail network. Results were used to compute more accurate energy losses for that Electricity Supply Tariff Area (ESTA) which, in turn, affected the EC4T (electric current for traction) prices for that region during the last control period.

These results established an optimisation method to work out more energy-efficient train trajectories which, in turn, informed how the driver can drive the train: the group found as much as 20 per cent energy could be saved compared with standard driving by following the algorithm-based style.

Developing this further in partnership with Ricardo Rail has led to the launch of the company’s ‘SmartDrive’ product and driver training programmes. One success story already is a recent rollout with Edinburgh Trams, where the company is already seeing energy savings.

More recently, Stuart’s team undertook a short project on behalf of Association of Train Operating Companies (ATOC), now part of the Rail Delivery Group, under the leadership of the Traction Electricity Steering Group (TESG). This stakeholder group wanted a methodology for partial fleet energy measurement: ATOC proposed that it might be possible to fit electricity meters to a portion of train fleets (rather than put meters on all trains) and then to use the data recorded to extrapolate to a full-fleet energy total. The team developed a method that can achieve this within a level of accuracy acceptable to an industrial setting: it is already benefiting the Southeastern network.

The hydrogen revolution – reducing dependency on diesel

Simply put, hydrogen trains produce electricity to power the traction system by an electrolytic reaction that produces a potential difference at the anode and water at the cathode. Not only is this a clean reaction, it is combustionless, meaning zero carbon-based emissions at point of use. However, there are carbon-emissions from the production of hydrogen, whether from organic feedstocks or in operating the electrolysis process (unless powered entirely from renewable sources).

BCRRE constructed the UK’s first hydrogen-powered narrow gauge locomotive in 2012 and has been investigating the use of fuel cells for railway traction for many more years.

In theory a train could be powered by hydrogen fuel cells alone. However, BCRRE studies have shown that it is more effective to combine these with batteries: the fuel cell can be operated at an optimum mid-range level, where it is most efficient, and batteries can meet variable power demand – such as starting and uphill gradients. Combining fuel cells with regenerative braking means energy can be harvested from more than just the fuel cell alone – with associated added benefits.

Funded by RSSB’s Future Railway programme, Dr Hillmansen teamed up with Hitachi Rail and Fuel Cell Systems Ltd to respond to the challenge of novel powertrain solutions for railway vehicles. The team looked at how to convert mid-life DMUs to fuel-cell hybrids, and whether a typical day’s journey could be achieved using them. Using BCRRE’s Single Train Simulator, together with operational data from RSSB, the team simulated a sample route and obtained traction energy needs.

A useful by-product was that it also provided information on how much energy could be obtained through regeneration. The team used this to develop a conceptual design for a hybrid arrangement and initial analysis indicated that a Class 156 DMU could operate and accommodate fuel sufficient for around 500 miles – ideal for many routes currently served by diesel.

Benefits of switching from diesel

Switching from diesel to a hydrogen fuel source can save up to 100 per cent of the carbon, assuming the hydrogen is sourced from a carbon-neutral supply, and potentially 100 per cent renewable. Even if using hydrogen generated from steam methane reforming, Stuart’s team calculated that roughly 30 per cent carbon saving can be achieved in comparison with a diesel engine-powered unit.

Analysis from another, similar project showed that, for a constant journey time and range, energy reductions of 34 per cent can be achieved with hydrogen-only, and 55 per cent with a hybrid fuel cell and battery arrangement. The fuel cells can be specified for the train’s average power need, not peak power, which in turn results in a more cost-effective, lighter, and more compact power train.


The traditional alternative to combustion-powered engines is electrification: from the overhead catenary or third rail. Whereas the vehicle itself becomes close to zero-carbon, the source of energy plays an important part. As the amount of electricity produced by renewables increases, correspondingly less is produced by coal and gas, which currently generates about half of the UK’s electricity generation. Thus electrification is not an entirely ‘green’ option.

However, electrically powered rail remains the most viable option on intensively used services. BCRRE researchers are actively looking at how to improve the efficiency of power transfer from the catenary through the pantograph and how to reduce OLE impedance to allow higher-power trains and/or increase the feeding distance. By modelling advanced OLE configurations using BCRRE’s multi-train simulator, they have found potential solutions to this issue.

They are also looking at discontinuous electrification: backup batteries to power the train where there is a break in electrification supply. A recent project in power electronics on static frequency converters has global relevance for new 25kV high performance railways.

Educating the next generation of railway engineers

What about the future? BCRRE’s core educational offerings – Masters in Railway Systems Engineering and Education and in Railway Safety and Control Systems – teach tomorrow’s railway business and engineering leaders. Both programmes combine a systems-thinking approach and include modules on traction and power that are informed by research.

BCRRE academics teach traction within Institute of Engineering and Technology (IET) courses in electrification and traction, and the topic is covered in the University of Birmingham’s undergraduate degrees in Civil & Railway Engineering and Electrical & Railway Engineering. Worldwide, traction and electrification is included into programmes of study in Singapore, where BCRRE delivers a bespoke PG Certificate for SMRT engineers, and in short courses offered to many international organisations.

What does this mean to the UK?

The launch of UKRRIN sets the scene for the UK to lead the world in railway research and innovation, taking advantage of policy objectives to drive the right investment in the right direction. Efficiency gains, improvements to reliability, realising savings and providing extra services are the kind of advantages where the passenger remains blissfully unaware of developments, but which are very much noticed when things go wrong.

Closely aligning research with education means the UK has a unique opportunity to drive research, development and innovation across the railway landscape, to optimise energy use across all aspects of the railway industry, and to deliver the change and value that tomorrow’s railway needs.

This article was written by Dr Jenny Illingsworth, head of operations of the Birmingham Centre for Railway Research and Education, part of the School of Engineering at the University of Birmingham. More information on the BCRRE and UKRRIN can be found at www.birmingham.ac.uk/railway and www.ukrrin.org.uk.

Read more: Why electrify?


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  1. Solar power from the grid would seem a good option for electric trains as most of the year most trains run in daylight hours. But that got me thinking, I’ve never seen a train with inbuilt solar panels, forgive my ignorance but is there a reason that it wouldn’t work for generating a small portion of a train’s power, eg internal lighting?


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