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Emissions Clampdown - But will cleaner engines be forgotten?

Europe is poised to decide how to deal with NOx, but will the authorities take into account advances in engine technology?

Measures to deal with the additional climate impact caused by nitrogen oxides have yet to be proposed within the European Union emissions trading scheme.

But a decision on the preferred mechanism is close, especially after a compromise deal was struck on 8 July between the European Parliament and the Council of Ministers on the precise way carbon trading will be imposed on aviation.

In addition, if the original schedule is to be honoured, the mechanism must be decided this summer, allowing for the necessary impact assessment and further rounds of consultation that would lead to an eventual legislative proposal by mid-December.

 © Mark Wagner/

The issue of NOx has come under great political pressure with the greenest of MEPs on the Parliament's environment committee demanding that the value of carbon credits bought by airlines from 2012 are doubled in the absence of specific new legislation. That multiplier mechanism did not feature in the compromise deal, but has not disappeared as an option and could yet have an influence on NOx measures.

In January, the European Commission set about identifying and evaluating European measures to limit or reduce NOx emissions. That study, which is due to be completed this summer, sought opinion from industry stakeholders including engine manufacturers and airframers, airlines and airports. An initial stakeholder meeting held in February produced a long list of possible options presented by consultancy CE Delft for the EC, which subsequently whittled that list down to four options for further study. They were:

  • A landing/take-off NOx charge, possibly coupled with a distance factor.
  • A NOx en route charge.
  • Landing/take-off NOx emission standards, either issued by the EU or by the International Civil Aviation Organisation following concerted EU action.
  • A multiplier on aviation CO2 emissions in the EU emissions trading scheme as a reference.

Ruled out at this early stage, however, were specific cruise NOx measures, a phase-out of dirty engines, climate-optimised air traffic management and inclusion of a NOx criterion in slot allocation rules at airports.

A group of European airline associations in a joint submission expressed the concern of many in the industry that implementing the Single European Sky (SES) or research funding into low NOx technology such as the Clean Sky Joint Technology Initiative should feature in any assessment and quantification of standalone measures to achieve reduction in NOx levels.

"These two elements represent the potential for the greatest savings in aircraft emissions, including NOx. While estimates have been made for CO2 savings arising from the SES, none exist in respect of NOx. In the absence of such estimates, the need for or scale of any additional regulatory measures cannot be logically justified," the airline associations say.

Moreover, they claim, manufacturers are on track to meet the ACARE-defined NOx reduction objective of 80% in 2020 compared with 2000.

The associations say: "As an illustration, one can notice that the currently delivered A320 with new CFM56-5B/3 engines incorporating the new Tech56 technology emit 20% less NOx than the same A320 with previous engines. The TAPS technology to come and then, dual chamber combustor technology, will deliver additional NOx reductions in line with ACARE objectives and timescale."

With ICAO reviewing NOx standards, European airlines are also urging the Commission to get actively involved at this level to influence the outcome or else risk placing a disproportionate discriminatory burden on EU operators.

"It would be laughable to expect the world's manufacturing industry to produce products to meet only EU requirements. Likewise, it would not be legally feasible to impose a production ban on non-EU manufacturers," they say.

They add that as an accurate global warming potential assessment for aviation NOx is probably still up to five years away, so CE Delft's proposal to use global warming potential as a charging basis is scientifically unsupported.

In conclusion, they say the way in which the study has been structured and undertaken not only creates more questions than answers, but simultaneously underlines the need for realistic timescales.

"The options being considered cannot be assessed objectively in the proposed timescales: there is simply too much research required, particularly if the Commission meets its own obligations with respect to the production of a 'thorough' impact analysis," they say.

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