NOx emission control in the Baltic Sea

Designating the Baltic Sea as a NOx Emission Control Area will more than halve ships’ NOx emissions by 2040

At a recent meeting in Helsinki of the Baltic Marine Environment Protection Commission (HELCOM), the Baltic Sea countries Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, the Russian Federation and Sweden discussed to propose to the International Maritime Organisation (IMO) that the Baltic Sea should be designated as a NOx Emission Control Area (NECA).

The discussions were based on a report produced by a group of experts under the lead of Finland, according to which about one quarter of the total nitrogen input to the Baltic marine environment comes from atmospheric deposition, i.e. originating from emissions of the air pollutants nitrogen oxides (NOx) and ammonia (NH₃). Shipping has its share in this deposition through large and increasing emissions of NOx, and thus adds to the eutrophication of the Baltic Sea.

The Baltic Sea suffers from a wide range of environmental problems, eutrophication (the over-supply of nutrients, primarily nitrogen and phosphorus) being the most critical one.

Emissions of NOx from shipping in the Baltic Sea are estimated to amount to some 330,000 tonnes. Under current legislation (i.e. in the absence of additional abatement measures), and assuming a two per cent annual growth in traffic, these are projected to rise to approximately 500,000 tonnes by 2040. If it is instead assumed that the Baltic Sea becomes a NECA, all new ships must comply with the stricter Tier III emission standards1 as from 2016, and ship emissions would then come down to about 160,000 tonnes by 2040.

For comparison, the NOx emissions from all land-based sources in Denmark, Finland and Sweden combined added up to some 470,000 tonnes in 2008, and are projected to be nearly halved by 2030 under current legislation.

Expected future (by 2045) impacts under a current legislation and a NECA scenario, respectively, were analysed, and three main effects considered. It was found that, as compared to current legislation, introduction of a NECA would result in:

• A noticeable reduction in depositions of oxidised nitrogen compounds, reaching tens of percentage points, to the Baltic Sea area. This difference is more significant over the coastal regions than in the open sea. Moreover, a more pronounced deposition decrease takes place in the summer period, when the sea is most susceptible to excess algae growth.
• Eutrophication – expressed as exceedance of the deposition of nutrient nitrogen over the critical limits for sensitive terrestrial ecosystems – would be reduced by up to 20-30 per cent in several regions around Baltic Sea.
• A lowering of human exposure to nitrogen oxides by up to 50-60 per cent in the coastal areas of the northern part of the Baltic proper and the Gulf of Finland. Looking specifically at harbour areas, NOx concentrations would be up to 10-20 per cent lower.

Potential improvements in human exposure to secondary fine particles (PM_2.5) or ground-level ozone were not included in the scenario analysis. Neither were reduced exceedance of the critical limits for deposition of acidification of forest and freshwater ecosystems.

Selective catalytic reduction (SCR) was seen as the only current technology that meets the Tier III reduction requirements and for which there is enough information to make cost-efficiency estimates. Abatement of one tonne of NOx by installing and operating SCR on ships was estimated to cost between 700 and 3,200 euro, depending on the type of ship and assuming an interest rate of five per cent. However, the average cost is about 1,000-1,400 euro per tonne of NOx, which equals approximately 3,400-4,500 euro per tonne of nitrogen removed.

It should be noted that these abatement costs are based on the assumption that if a ship leaves the NECA it will shut down the SCR. In practise, however, many ships operate both inside and outside of the Baltic NECA, and if the NECA were extended to cover the North Sea as well, the unit abatement costs would be lowered.

The rise in freight rates for new vessels due to the installation and operation of SCR were estimated at 2-4.6 per cent, depending on vessel type and size. It was concluded that this is a relatively small increase in freight rates, and that the potential for modal shift caused solely by the stricter NOx standards for new ships that would apply through the NECA designation, will most probably be very small, in most cases non-existent.

Emissions of sulphur dioxide (SO₂) and indirectly also emissions of particulate matter (PM) from international shipping in the Baltic Sea are already regulated through the designation of the Baltic Sea as a SOx Emission Control Area (SECA), which entered into force in May 2006 as the first SECA ever established under IMO’s MARPOL Annex VI.

A formal proposal was expected to be agreed at the March HELCOM meeting, but it was decided to postpone a final decision. The next meeting at which an agreement could be reached is in June.

Christer Ågren

Source: Report of the NECA Correspondence Group on designation of the Baltic Sea as a NOx Emission Control Area. Submitted by Finland on behalf of the NECA Correspondence Group. Discussed at the 32nd meeting of HELCOM’s Baltic Marine Environment Protection Commission on 9-10 March 2011 in Helsinki, Finland.

¹ IMO’s Tier I NOx emission standard applies globally to all marine diesel engines installed on ships built between 1 January 2000 and 31 December 2010. As from 1 January 2011 the slightly stricter Tier II standards apply, resulting in approximately 15-20 per cent lower NOx emissions. The Tier III standards are set to cut NOx emissions by about 80 per cent, as compared to Tier I, but are restricted to apply only to ships constructed after 1 January 2016 and while operating in NOx Emission Control Areas.