Cost-effectiveness of controls on

sulphur emissions from ships

A review of CONCAWE data in the context of recent developments.

Recent discussions within the International Maritime Organization (IMO) and European Parliament continue to focus attention on the emission of sulphur oxides (SOx) from ships and the cost-effectiveness of reducing sulphur contents in bunker fuels. Some years ago, CONCAWE published a series of reports relating to this issue but there continues to be some confusion concerning the validity of the CONCAWE information in the light of recent publications by different authors. This article confirms the validity of the CONCAWE studies and provides an overview of the main findings in relation to these other studies.

Ship Emissions of Sulphur Oxides

Up until recently, EMEP1 used Marintek2 data as the basis for its ship emission estimates. Marintek data related to international trade and therefore did not include the contribution from ferries or national shipping.
CONCAWE expressed its reservations about the Marintek data in its 1994 report (CONCAWE Report 2/94) and chose to base its modelling work on Lloyds Register data instead. The comparison made by CONCAWE at the time suggested that the emission estimates used by EMEP at that time were probably underestimating emissions from ships at sea by some 30-50 per cent. This has been born out by the revisions made by EMEP and reported in their 1997 report.
It is generally agreed that the Lloyds Register emission estimates are the most reliable estimates currently available and we are pleased that the validity of the CONCAWE emission assumptions is confirmed. Table 1 on the following page provides a comparison between the estimated SOx emissions between different studies.
1: Cooperative Programme for Monitoring and Evaluation of the Long-Range Transmission of Air Pollutants in Europe
2: Norwegian Marine Technology Research Institute

Recent EMEP modelling results

The 1997 EMEP report on 'The contribution of ship emissions from the North Sea and the north-eastern Atlantic Ocean to acidification in Europe' examined contributions from the NE Atlantic and North Sea to sulphur depositions on land in 1990 and 1995. It also examined emissions from 50- and 100-nautical-mile zones. The EMEP report states that a zone in the North Sea of approximately 50 nautical miles from the coastline and including the Channel accounts for around 90 per cent of the total shipping emissions from the North Sea. If the contribution to deposition on land from ships in this 50-nautical-mile area is assessed, then there is very little difference in the deposition maps derived from data for the whole of the North Sea and Channel areas. The new EMEP results had not been incorporated into the RAINS3 model at the time when the EU Acidification Strategy was drawn up.
3: Regional Air Pollution Information and Simulation Model

Comparison of emission estimates for the study area

Study | Area | SO2(kt) | Comments

Marintek (1990)
Year 1990

English Channel

74

International shipping only Year: 1990 Ports
not included

North Sea

104

Emission rates estimated from literature etc.
150 km x 150 km resolution

NE Atlantic**

316

3.0% (S) Bunker Fuel Oil and 1.0% (S)
Marine Diesel Oil

CONCAWE (1994)
Year: 1992

English Channel
and southern
North Sea

152*

International and national shipping, ports
included (55 kt SO2)
Estimates attributed directly to shipping lanes
Emission ratesestimated from literature etc.
2.82% (S) Bunker Fuel Oil and 1.18% (S)
Marine Diesel Oil

Lloyd's (1995)
Year: 1990

English Channel
and southern
North Sea

162

International and national shipping, ports not
included
50 km x 50 km resolution

NE Atlantic

1371

Emission rates measured for various
vessels/engines
2.7% (S) Bunker Fuel Oil and 0.5% (S)
Marine Diesel Oil

* For comparison, port emissions are not included **Barret and Sealand,1995
Table 1 : The Lloyds Register emission estimates are generally considered to be the most reliable estimates currently available: they confirm the validity of CONCAWE's emission assumptions.

CONCAWE modelling Results

The CONCAWE study modelled emissions at a much finer spatial resolution than in the recent EMEP work but for a smaller area, namely the Channel and southern North Sea. CONCAWE clearly identified in-port emissions as a significant source of ship emissions in the study area, with ships in ports contributing some 26 per cent of the total emissions from ships. It was also found that ships within territorial waters (12-nautical-mile limit) could be significant contributors to deposition on land in certain sensitive grid squares. However, the study concluded that the cost-effectiveness of ship emission controls declined rapidly with distance from the shore, with controls outside territorial waters being least cost-effective.

Updated CONCAWE Cost Estimates
CONCAWE confirms the conclusions expressed in CONCAWE report 1/93 concerning the costs associated with the production of low sulphur bunker fuels using Residue Desulphurization (RDS), Residue Conversion and Flue Gas Desulphurization (FGD). Table 2 presents these costs updated to 1997 and expressed in ECU instead of US dollars.

Updated CONCAWE cost estimates for limited volume of low sulphur bunker fuel

Bunker sulphur content

Additional cost of producing low sulphur
bunker fuel compared with current high
sulphur bunker fuels (1997 ECU/tonne)

Cost of SO2 removed (1997 ECU/kg of SO2)

2 % mass

35-50

3.0

1.5 % mass

45-70

3.0

2.0 % mass

55-85

2.9

N.B. Cost figures are based upon the supply of up to 8 million tonnes per annum, for selective use of low sulphur bunker fuel. The original data is based on a bunker sulphur content of 3.4% mass; these costs (when expressed per kg SO2 removed) also apply at the current average of around 3% mass. The 1991 data have been increased by 15% to update them to 1997 costs (this represents the low end of the inflation figures given for a number of countries in Europe).

Table 2 : CONCAWE has updated its estimates of the costs associated with the production of low sulphur bunker fuel. Note that the costs are now expressed in ECU.

SOx Emission Control Areas

The concept of introducing special areas for SOx emission control has been debated for many years within IMO. At the end of 1997, there was a decision to designate the Baltic Sea as one such area. Criteria and procedures for designating other SOx Emission Control Areas were also established. The procedures clearly state that 'In assessing the proposal the Organization [IMO] shall take into account ... the relative costs of reducing sulphur depositions from ships when compared with land-based controls'. The possibility to designate SOx Emission Control Areas in coastal zones provides the means, particularly in the Scandinavian countries, to protect sensitive ecosystems on land from any relevant ship emissions.

Cost-Effectiveness of Controls
The European Commission has urged EU Member States to press for the North Sea and Channel to be designated as a SOx Emission Control Area. They base their position upon the IIASA RAINS cost-effective analysis undertaken in relation to the Acidification Strategy.
The marginal cost curve used in the RAINS optimizer examines the marginal cost-effectiveness of moving from one step to the next, not the overall cost-effectiveness of each measure. This means that the cost-effectiveness of controls for a particular source can be very dependent upon the number of slices the 'cake' is cut into. In the case of bunker fuels, the cost-effectiveness of controls not only vary according to the sulphur content of the bunkers used but also according to the ship's distance upwind of sensitive ecosystems. Having one cost-effectiveness category for all ships means that the (better) cost-effectiveness of using lower sulphur bunkers close to these ecosystems is lumped in with the (poorer) cost-effectiveness of using the same bunkers far from these ecosystems. This means that the cost-effectiveness is under-estimated for 'nearby ships' and over-estimated for 'far away ships'. Figure 1 illustrates this point.

Figure 1
The relative cost-effectiveness of control measures can vary according to the ship's distance from the sensitive ecosystem.

Whilst CONCAWE supports the underlying cost-effectiveness approach adopted by in the IIASA model, it is unfortunate that the models and data that RAINS depends upon are not yet able to deal with ship emissions at the required spatial resolutions. It is CONCAWE's view that, so far, the evidence to support ship emission controls as being more cost-effective than land-based controls is of insufficient rigour and should not be judged as meeting the criteria that IMO will apply in assessing proposals for new SOx Emission Control Areas. CONCAWE urges that the relative cost-effectiveness of controls in ports, territorial waters and at sea be examined at both the EU and IMO levels, and that the Lloyds Register estimates of ship emissions be used.

|

|

|
|