Energy and CO2 emissions

The global railway sector is working extremely hard to maintain its environmental advantage by improving its energy efficiency and reducing its CO2 emissions. For example, 28 European UIC members have collectively committed to reducing CO2 emissions per passenger-kilometre and per tonne-kilometre by 50% by 2030, and are well on track to meet this target.

Improving energy efficiency is the most important aspect of the rail sector’s strategies to reduce CO2 emissions and, of course, offers significant business benefits as well as reducing costs.

Railway companies use a combination of technical and non-technical means to improve energy efficiency. Technical measures include using more modern rolling stock with lower energy consumption, or innovative technologies such as regenerative braking – a system that harnesses the energy produced during braking, transferring it back into the rail system so that other trains can use it. Non-technical measures include energy-efficient driving techniques, which focus on developing train drivers’ expertise to save energy or diesel fuel costs. Linked to both of these points is the installation of energy metering on trains so that operators can monitor their energy consumption and assess which approaches save the most energy.

Energy and CO2 Emissions Expert Network

The UIC Energy Expert Network provides strategy, guidance and leadership across UIC, and the rail sector in general, on projects and issues related to energy efficiency and renewable energy in the railway sector. It also provides a forum for information-sharing on good practice. It consults and advises on energy efficiency-related UIC projects led by other platforms and working groups and provides expert positions on current issues (pending legislation, media enquiries, etc.) at UIC’s request. The UIC Energy Expert Network deals with all aspects of energy efficiency and CO2 emissions. More specifically, it is committed to publishing information on progress against the targets set by international organisations and coalitions using the data collected via the Environment Strategy Reporting System (ESRS) and CO2 database. The network organises many different workshops every year on new IRSs, energy infrastructure, efficient driving, etc.


  • Management of the Environmental Strategy Reporting System (ESRS) database and data collection
  • Publication of “The Future of Rail” in partnership with the IEA
  • SFERA (IRS 90940) project management on standardisation of DAS (Driving Advisory Systems) languages for broader implementation, reduced costs and exchange of data for traffic management systems
  • UIC Leaflet 930 (IRS 90930): project management in relation to measurement, exchange, validation and billing of traction energy for cross-border traffic
  • Organisation of best practice workshops on energy efficiency (two per year)
  • Contribution to the Sustainable Mobility 4 All (World Bank) report to integrate the rail sector’s work on sustainable development
  • Contribution to the SLoCaT Transport and Climate Change 2018 Global Status Report
  • Contribution to the deliverables for optimisation of energy usage in rail innovation within the scope of the OPEUS European project
  • Maintenance and improvement of the EcoPassenger online tool

Energy efficiency best practice workshops

Energy efficiency offers huge potential for cost savings - a 1% improvement in energy efficiency will save several million euro per year for most railways - and is also the most direct way to reduce CO2 emissions and secure strong environmental performance in support of the UIC-CER Sustainability Strategy. In recent years, many successfully concluded projects have delivered promising results in terms of energy efficiency (Railenergy, CleanER-D, Energy Consumption, Parked Trains, MERLIN, etc.), and further important projects such as Shift2Rail are underway.

The workshops on best practice in energy efficiency aim to support practical implementation and optimisation in the field. They bring together experts from railway undertakings, infrastructure managers and manufacturers to share experience, develop solutions and overcome obstacles.

Environment Strategy Reporting System (ESRS)

In December 2010, with a view to taking a unified approach to environmental and sustainability issues in the European railway sector, UIC and CER voted on the document “Moving towards Sustainable Mobility: Rail Sector Strategy 2030 and beyond – Europe (UIC-CER 2010)”:

The strategy outlined in the document describes how the rail sector should be performing in environmental terms in 2030 and 2050 and focuses on four key environmental topics: climate protection, energy efficiency, exhaust emissions and noise. It sets out specific objectives to be met by 2030 and, because predictions for 2050 more somewhat more difficult, outlines a more general vision for 2050.

In 2015, during COP 21, the objectives to be met by 2030 were revised and leaders of UIC member companies were invited to make a pledge of commitment to climate-friendly policies and to report to UIC in this respect.

More information is available at

The relevant data has been collected on a regular basis since 2007 and is stored at

This tool also feeds data to the “Ecopassenger” and “EcoTransit” eco-calculators developed by UIC on an annual basis.

The data collected has also facilitated collaboration with the IEA, with UIC providing bottom-up data from the railway sector to feed the IEA’s Mobility Model (MoMo). This in turn feeds the various analyses and overviews of energy consumption and CO2 emissions in the Railway Handbook. In 2019, these collaborative efforts gave rise to a report illustrating the prospects for a “business as usual” modal share scenario and comparing it with an alternative scenario with increased use of rail in modal share, called “The Future of Rail”. The report also provides an overview of electrification and railway development in India, which is progressing rapidly.

In 2019, the members of the Energy and CO2 Network agreed to transform the 2050 carbon neutrality vision into real targets. They also agreed to switch the baseline for emissions targets from 1990 to 2005, intensifying the efforts required to achieve the new 2030 targets.

The methodology used to collate the railway operators’ data is described in the following document :

UIC ESRS Methodological Rules - Methodology and Policy

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Traction energy settlement and data exchange

Two European Commission regulations approved in 2014 (1301 and 1302) introduce new Technical Specifications for Interoperability (TSI) that reference CENELEC standard EN 50463, with a direct impact on UIC Leaflet 930. To ensure that the leaflet is compliant with the regulations, a UIC project was initiated in 2018 with the aim of revising the leaflet as a new International Railway Solution (IRS). Posters outlining the contents of IRS 90930 were presented to relevant stakeholders at a UIC workshop held in Paris in November 2018. The IRS is expected to be published in early 2020.

UIC leaflet 930

In Europe, traction units are increasingly being equipped with metering systems that collect data on energy consumption and traction unit location. Data exchange needs to be standardised for cross-border traffic to avoid a situation whereby different metering systems are installed on the basis of varying national specifications. In this context, a project was launched in 2005 to ensure accurate settlement of energy consumption for interoperable cross-border rail traffic in Europe.

Together with the work carried out by CENELEC to standardise metering equipment, the results of the project have enabled better energy consumption allocations based on actual energy consumption.

UIC Leaflet 930, “Exchange of data for cross-border railway energy settlement”, was produced as an output of the project. The leaflet was published in November 2009.
The purpose of UIC Leaflet 930 is to:

  • describe the processes and protocols used to exchange energy consumption data between infrastructure managers which, by respecting existing national systems, contribute to an improvement in European railway interoperability
  • define the technical requirements for review and verification of data
  • allow railway undertakings to identify their actual energy consumption and pay for exactly what is consumed

UIC Leaflet 930 supporting documents

The following supporting documents to UIC Leaflet 930 were developed within the context of the Energy Billing project to support implementation of energy billing systems.

Rail transport and environment: facts and figures

Rail is one of the most energy efficient transport modes, generating significantly less CO2 emissions than other modes. Increasing the modal share of rail in line with the 2011 Transport White Paper targets would result in an estimated reduction of 238 million tonnes of CO2 a year, equivalent to 19% of EU transport emissions in 2010.

Travelling by rail is between three and ten times less CO2-intensive compared with road or air transport. Rail’s share of transport energy consumption is less than 2%, despite a market share of over 8.5%. Land use per passenger-km is about 3.5 times lower for rail than for cars. Average external costs (i.e. costs of negative effects of transport, such as air pollution, not paid by users themselves but borne by society at large) are more than four times less for rail than for road in respect of passenger services, and over six times less for freight services.

To drive continued improvement of the rail sector’s environmental footprint, CER and UIC’s European members have agreed targets up to 2030 and a vision for sustainable mobility up to 2050.

Rail Transport and Environment: Facts & Figures

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Zero-carbon railways

Reporting green electricity use

Data shows that the European railways have significantly increased renewable electricity use over the past number of years. Decarbonisation of electricity production is a key factor in CO2 emission reduction: the higher the percentage of renewable electricity used for traction, the lower the level of CO2 emitted into the atmosphere.

In this context, a transparent methodology for tracking green electricity purchasing is a top priority for the UIC Environment Strategy Reporting System.

The “Zero-Carbon Railways” report was published as the result of an intensive year’s work, which involved consulting with relevant stakeholders (IEA, EEA, DG Energy, etc.) and members of the UIC Energy Efficiency and CO2 Emissions Experts Network in order to agree a common approach for reporting on carbon performance internally and at sectoral level (ESRS).

Zero Carbon Railways - Final report (August 2014)

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