Report - DCE - Nationalt Center for Miljø og Energi

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The gas transmission company reports emissions of CH4. Calculations of the
CH4 emissions for transmission are based on registered loss in the transmission
grid and the emission from the natural gas consumption in the pressure
regulating stations. The distribution companies give data on fugitive losses,
and the CH4 emissions are estimated due to the gas quality given by Energinet.dk.
Calculations of the NMVOC emissions are based on the CH4 emission
according to the gas quality measured by Energinet.dk (equation 3.4.8).
( ( ×
( Z Z )
= FR
/ 4
4
where wNMVOC is the weight-% NMVOC and wCH4 is the weight-% CH4 according
to the gas quality of the current year.
The decrease in NMVOC emission from transmission in 2007 is caused by
the completion of a greater construction work and rerouting of a major pipeline
(Table 3.55). As the pipelines in Denmark are relatively new, most emissions
are due to construction and maintenance. There have been no significant
construction or renovation work since 2007 and therefore low emissions.
The NMVOC emission from distribution increased from 53 Mg in 2003 to 75
Mg in 2004. The increase owes to venting of the distribution network. The
reason for the decrease in 2008 is not mentioned in the environmental report
for the given company.
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Emissions of NMVOC from flaring are given in the environmental reports
for the gas storage plants (DONG Energy, 2010; DONG Energy, 2011). The
time series are shown in figure 3.108.
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The time series for the emission of NMVOC from offshore flaring fluctuates
due to the fluctuations in the fuel rate. As shown in Figure 3.108 there were
marked peaks in the amount of offshore flaring in 1997 and, especially, in
1999. The increase in 1997 was due to the new Dan field and the completion
of the Harald field. The increase in 1999 was due to the opening of three new
fields; Halfdan, Siri and South Arne.