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Action on CO2

Growth in emissions from the transport sector may mean that Europe misses its Kyoto targets on climate change. Research initiatives are already underway to reduce greenhouse gas emissions from all segments of the transport sector and other actions to reduce or eliminate carbon dioxide pollution are envisaged.

Heavy road traffic
© Peter Gutierrez

Under the Kyoto Protocol, Europe has committed to reduce its overall emissions of greenhouse gases (GHG) during the period 2008 - 2012 by 8% compared to the level of emissions in 1990.

Over the 20th century the mean temperature in Europe increased by more than 0.9ºC and globally the 10 warmest years on record all occurred after 1991. The overwhelming scientific consensus is that this climate change is due to increased GHG emissions resulting from human activity. Predictions indicate an average temperature increase in Europe (compared to 1990) of between 2.0 and 6.3ºC by 2100 with significant effects on weather, seal levels agricultural and general economic production. Climate change must be slowed and halted and this requires action on GHG emissions.

Kyoto represented an important first step forward in tackling climate change as it included binding, quantified objectives for reducing GHG. Since Kyoto the evidence for accelerating climate change due to GHG emissions from human activity has grown and more ambitious targets may be anticipated for future, post-Kyoto global climate change agreements.

The protocol covers six GHG of which carbon dioxide (CO2) is the most important in terms of the volume of emissions and therefore its potential contribution to climate change. The other gases are methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulphur hexafluoride.

A key transport issue

In many sectors, for example in industrial processes and power generation, significant reductions in the level of carbon dioxide emissions have been achieved. However, in contrast, the total volume of CO2 emissions from the European transport sector has increased since 1990 and it is becoming a more significant contributor to GHG emissions as overall traffic volumes rise (see figure).

At present transport accounts for 32% of European energy consumption and 28% of total CO2 emissions. However the sector is expected to account for some 90% of the increase in emissions between 1990 and 2010 and could become the primary reason for the EU missing its Kyoto target. For example passenger transport on European roads is forecast to increase by 19% while freight haulage on the roads is set to increase by 50%.

This massive rise has renewed research efforts to find new vehicle technologies that will reduce or eliminate CO2 emitted by the various transport segments. For the new European Research Framework programme (FP7) one of its overall objectives is to develop integrated, “greener” and smarter transport systems. The budget for Commission funded research in Transport for the period 2007 – 2013 is over €4 100 million. This builds on considerable research investment in previous research programmes.


Aircraft usually operate at cruising altitudes of 8 to 13 km, where they release several gases and particles which alter the composition of the atmosphere and contribute to climate change. This includes CO2, nitrogen oxides (NOx), water vapour (contrails), soot and particles. Currently in the EU the direct GHG emissions from aviation correspond to about 3% of the total. However from 1990 to 2003, the EU’s GHG emissions from international aviation increased by 73%, or 4.3% per year. If growth continues at this rate it would offset more than a quarter of the emission reductions the EU15 is required to make under the Kyoto Protocol on climate change.

Reducing the environmental impact of air transport with regard to emissions and noise is therefore an important element in achieving the overall goals of European aeronautics research. The research community has set itself a number of goals in this area.

An important goal is reducing CO2 emissions (and fuel consumption) for commercial aircraft by 50% per passenger-kilometre in the long-term. This can be achieved through improved engine efficiency as well as improved efficiency of aircraft operation. A reduction of 80% in NOx emissions in the landing and take-off cycle, and reducing other gaseous and particulate emissions such as unburnt hydrocarbons are also envisaged.

The environmental impact of the manufacture and maintenance of aircraft and their components will also be addressed. The Advisory Council for Aeronautical Research in Europe (ACARE) has produced a Strategic Research Agenda that includes an Ultra Green High Level Target Concept that embraces the global issue of climate change as well as the local issues of noise and air quality.

To achieve its aims the ACARE agenda highlights new green engine technologies, alternative fuels, novel aircraft/ engine configurations, intelligent low-weight structures, improved aerodynamic efficiency, more efficient airport operations and air traffic management together with better manufacturing and recycling processes.

The proposed ‘Clean Sky’ Joint Technology Initiative will bring together European R&D stakeholders to develop such “green” air vehicle design, engines and systems.

In addition, exploitation of efficiency improvements in Air Traffic Management, including more direct flight routes, less queuing of aircraft etc., should be exploited in line with the aims of the SESAR (formally known as SESAME) programme, one of the measures for implementing the Single European Sky initiative.

In parallel the Commission has concluded that the most cost-efficient and environmentally effective option for driving change in the market would be to include emissions from aviation in the EU Greenhouse Gas Emissions Trading Scheme. The EU Emissions Trading Scheme started in 2005 and covers almost 11,500 industrial installations which together are responsible for nearly half of all EU CO2 emissions. Including the aviation sector in the Emissions Trading Scheme would expand the market covered by an overall emissions cap. Aircraft operators would be allocated emission allowances, thus giving them a permanent incentive to reduce their climate impact, but they would also have the flexibility to buy or sell allowances as necessary.

On the road

Over the next eight years road passenger transport in Europe is forecast to increase by 19% while the amount of freight carried by road is set to go up 50%. To stabilise or reduce GHG emissions will require the development of cleaner, greener vehicles.

The European Road Transport Research Advisory Council (ERTRAC) was launched in 2003 and delivered a Strategic Research Agenda in January 2005. Environment, energy and resources is a major topic and the agenda includes targets to improve vehicle efficiency to deliver reductions in CO2 emissions of up to 40% for passenger cars and 10% for heavy duty vehicles by 2020. Improvements are envisaged to fuel, new high-efficiency power trains will be developed and novel light-weight, high strength smart materials put into production. It also proposes that improve vehicle maintenance and driving targeted at maximising fuel efficiency could reduce fuel consumption and CO2 emissions by at least 10% for cars.

Improvements in the road transport infrastructure, better information technology, higher passenger occupancy and freight loading could lead to further fuel consumption reductions of 10 – 20% and reductions in carbon emissions associated with fuel prosecution will be achieved.

By 2020 vehicles that are compliant with Euro-5 and Euro-6 emission standards will be well established in the European fleet. These European standards imply near zero emission levels at minimum additional cost. This is likely to be achieved by using hybrid vehicles, low carbon fuels and intelligent energy management systems. Vehicle fuels derived from renewable bio-mass will also play an increasing role in the overall fuel mix.

Rail and marine

Increasing the capacity and use of rail transport in Europe can also help to reduce the burden of road and air use and therefore emissions. Rail transport is already by far the most environmentally friendly form of surface transport and therefore rail’s most effective contribution to the overall “greening” of European transport is to encourage a modal shift from road and air to rail.

The European Rail Research Advisory Council (ERRAC) research agenda outlines the challenges to be tackled in order to provide a rail sector that can handle three times its current freight and passenger volumes by 2020. The overriding goal of the research agenda is to provide integrated high-speed passenger and freight rail services that are have even better environmental credentials and give a boost to public transport use. Improved energy efficiency and minimised emissions are a key theme.

Similarly in the maritime sector since 2005 waterborne transport stakeholders have been involved in the WATERBORNE Technology platform that is showing the way to more effective transport research.

In terms of CO2 emissions transporting one tonne of cargo on a fully loaded ship produces only a fraction of the pollution in comparison with other freight transport. However research is still needed to improve energy efficiency and capture harmful emissions. Fuel consumption can be reduced by improving hull design to reduce drag and making efficiency gains in on-board power generation and management. Improved fuel treatment and better exhaust gas scrubbing combined with robust exhaust gas monitoring equipment will optimise engine performance and emissions. In the longer term research on new forms of power generation, such as use of liquefied natural gas, will further improve environmental performance.

Hydrogen future?

Hydrogen is seen as one long-term solution to transport energy issues. Hydrogen is one of the most abundant elements on Earth. It is high in energy and when burnt in a conventional engine or converted into electricity via fuel cell technology produces almost no pollution - its main ‘waste’ component being water. Research on hydrogen has been, and continues, to be a major topic for European Research programmes.

Hydrogen can be sourced from conventional fossil fuels or other chemical sources, produced by electrolysis of water, or possibly using solar or nuclear technologies. Hydrogen could replace fossil fuels in future surface transport applications and also in aviation.

Automotive manufacturers have already invested billions of Euros in developing hydrogen-powered cars and, in particular, research to provide small high power fuel cell systems that can deliver the performance drivers expect from conventional vehicles.

Testing of hydrogen-based fuel cells for ship propulsion is also a major challenge for the future and such technology will probably not become a regular feature of merchant vessels for another decade.

In the air, an FP5 project (CRYOPLANE) has already carried out a comprehensive system analysis of a liquid hydrogen-fuelled aircraft. The project assessed a range of aircraft types and concluded that there were clear technical barriers to the implementation of hydrogen as an aviation fuel.

Hydrogen, in tandem with clean electricity production, could replace fossil fuels as the principal energy vectors to produce a new global energy economy that has close to zero CO2 emissions. This future scenario will require considerable infrastructure investment and is very much a long-term ambition. The challenge for energy and transport research is to provide viable solutions in the short to medium term that minimise our dependence on fossil fuels and reduce CO2 pollution.