Morten Winther. 2008. Faglig rapport nr. 652 fra DMU. 66 s.

 

Summary

This report documents the updated 1990-2005 fuel consumption and emission inventory for navigation in <st1:place w:st="on"><st1:country-region w:st="on">Denmark</st1:country-region></st1:place>  , following the UNFCCC (United Nations Framework Convention of Climate Changes), and the UNECE CLRTAP (United Nations Economic Commission for Europe Convention of Long Range Transboundary Air Pollutants) convention rules.

 

The Danish inventory covers national sea transport, fisheries and international sea transport. For national sea transport, the new inventory distinguishes between regional ferries, local ferries (small ferries) and other national sea transport, and the fuel consumption is estimated on the basis of fleet activity data and ferry-specific technical information. For fisheries and international sea transport, the new inventory is fuel based.

 

The emission components considered are SO2, NOX, VOC (NMVOC and CH4) CO, CO2, N2O and particulates (TSP, PM10 and PM2.5). In addition a fuel consumption and emission forecast is presented from 2006-2030 based on the official Danish energy projections. The calculated results for national sea transport, fisheries and international sea transport are stored in the European Environment Agency (EEA) database system (CollectER).

 

The report explains the current fuel and emission legislation for ships, and traffic and technical data for ferries and other ships. In the report, documentation is also given for the inventory fuel consumption data and fuel consumption/emission factors, and the inventory calculation approach.

 

Fuel consumption and emission legislation

For ship engines, emission limits for NOX are agreed by the International Marine Organization (IMO) MARPOL 73/78 Annex VI, and the emission legislation is relevant for diesel engines with a power output larger than 130 kW installed on a ship constructed on or after 1th January 2000, and diesel engines with a power output larger than 130 kW which undergo major conversion on or after 1th January 2000.

 

<st1:place w:st="on">North Sea. The SECA areas are also agreed by IMO in MARPOL 73/78 Annex VI.</st1:place>

 

Activity data

Detailed traffic from Statistics Denmark, and technical data from the Danish Ferry Historical Society (DFS) are used as activity data for regional ferries. For local ferries and other national sea transport, the new inventory uses fuel consumption estimates calculated for single years, and a full fuel consumption coverage is established in a time series by means of appropriate assumptions. For fisheries and international sea transport, the new inventory uses fuel sales data from the Danish Energy Authority (DEA).

 

Fuel consumption and emission factors

Generally, the fuel consumption and emission factors are classified according to engine type (slow, medium and high speed, and gas turbines) and fuel type.

 

Fuel consumption factors come from the Danish TEMA2000 emission model, and NOx emission factors predominantly come from the engine manufacturer MAN DIESEL, as a function of engine production year. The assumed sulphur contents in marine fuels have been used to estimate the emission factors for SO2 and total particulates (PM) throughout the inventory period, and PM10 and PM2.5 size fractions are obtained from MAN DIESEL. For CO and VOC constant emission factors from TEMA2000 is used, whereas N2O emission factors and the NMVOC/CH4 split is taken from EMEP/CORINAIR (2003).

 

Calculation procedure

For regional ferries, the fuel consumption and emissions are calculated as a product of number of round trips, sailing time per round trip, engine size, engine load factor and fuel consumption/emission factor. The estimates take into account the changes in emission factors and ferry specific data during the inventory period.

 

For the remaining navigation categories, the emissions are calculated simply as a product of total fuel consumption and average emission factors. For each inventory year, this emission factor average comprises the emission factors for all present engine production years, according to engine life times.

 

Fuel consumption and emission results

International sea transport is the most important source of fuel consumption and emissions for navigation. The share of total fuel consumption for this sector is 75% of total navigation in 2005, and for CO2, N2O and VOC (NMVOC and CH4) the share is 76%. For CO the emission share is 78%, and for NOx, PM (all three fractions) and SO2 the emission shares are 80%, 95% and 96%, respectively.

 

For national sea transport, the shares of fuel consumption, CO2 and N2O (10%) are somewhat smaller than for fisheries (14%). This also the case for NOX, VOC (NMVOC and CH4) and CO; the respective emission shares are 8%, 9% and 8% for national sea transport, and 11%, 14% and 14% for fisheries. For SO2 and PM (all three fractions) the emission share for fisheries is 2%, and for national sea transport, the SO2 and PM (all three fractions) emission shares 3% and 2%, respectively.

 

The 1990-2005 emission trends follow the development in fuel consumption and emission factors. For international sea transport, the DEA reported fuel sales (and hence SO2 emissions) decrease by 14%. For CO2 and N2O the emission reductions are 15%, and for VOC and CO the emission reductions are 5%. For NOX and PM (all three size fractions) the emissions increase by 1 and 8%, respectively.

 

In the same time period fuel consumption, CO2 and N2O emissions decrease by 11% for national sea transport. Emission decreases are also calculated for VOC (2%), NMVOC (2%), CH4 (3%), CO (1%), SO2 (27%) and PM (37%, all size fractions), whereas for NOX, the emissions increase by 10%. For fisheries, the total fuel consumption, and CO2, N2O, PM (all size fractions) and SO2 emissions decrease by 17% from 1990-2005. The emissions of CO, NMVOC, CH4 and NOX change by -6%, -7%, -10% and 6%, respectively.

 

Also in the projection period, international sea transport is the most important source of fuel consumption and emissions. No change in the total fuel sales are foreseen from 2006-2030 in the DEA baseline energy forecast, and hence, zero or only smaller emission changes are expected in the same time period, except for SO2 and PM. For these two components, the expected emission reductions are 57% and 72%, respectively, mainly due to the introduction of the SECA areas from 2007. Based on the DEA baseline energy forecast, for national sea transport and fisheries the total fuel consumption decrease by 2% and 5%, respectively, from 2006-2030. As for international sea transport, the only changes of significance occur for SO2 and PM; these are -44% and -23% for national sea transport, and -52% and -12% for fisheries.

 

A cross sector comparison for Danish mobile sources from 2006-2020, show a need for more strict fuel quality and NOX emission standards for navigation, in order to gain emission improvements in line with those achieved for other mobile sources.

 

Conclusion

This project uses new information of the development of NOX emissions from ship engines, starting with production year 1949, and proceeding until the engines of today (2005). The emission data have been provided by the ship engine manufacturer MAN DIESEL, which have a 75% world market share of the ship engines produced. Emission data from this source ensures a fine representation of the emission factors used, and the inventory introduction of emission factors per engine production year is necessary for the more accurate assessments of the emission trends.

 

For national sea transport in <st1:place w:st="on"><st1:country-region w:st="on">Denmark</st1:country-region></st1:place>  , the fuel consumption estimates obtained with the new model are regarded as much more accurate than the DEA fuel sales data used in the previous model version. The large fluctuations in reported fuel sales cannot be explained by the actual development in the traffic between different national ports. The fuel discrepancies between estimated and reported sales are most likely explained by inaccurate costumer specifications made by the oil suppliers.

 

It is recommended to replace the current time series of fuel sales for national sea transport by the new bottom-up fuel consumption estimates calculated in this project. Such an updated time series for fuel consumption for national sea transport will introduce changes to the energy statistics for fisheries and industry, since the revealed differences between the sales figures and bottom-up estimates for national sea transport are balanced out by adjusting the sales figures for fisheries (for gas oil) and industry (heavy fuel oil).

 

Moreover, it would be very useful to implement a new project in which the fuel consumption and emissions for international sea transport in <st1:place w:st="on"><st1:country-region w:st="on">Denmark</st1:country-region></st1:place> are calculated based on actual vessel movements, as has already been carried out for domestic ferries. Such project results would strongly support the work made by Danish policymakers dealing with the issue of bunker emissions allocation.

 

Full report  in pdf-format (2,211 kB)