Emissions from the petroleum sector

The oil and gas industry results in heavy emissions of GHGs, both during production and mostly during product combustion. In 2015, GHG emissions from oil and gas extraction on the NCS were 15.1 million tonnes CO2-equivalents (MtCO2e), of which 14.1 million tonnes were CO2 emissions (NEA 2016; SSB 2016). The offshore oil and gas extraction emitted around 11 million tonnes CO2 on the NCS (SSB 2016). The UKCS emitted 14.7 MtCO2e GHG emissions in 2015 from the petroleum industry, of which 13.2 million tonnes were CO2 emissions (Oil and Gas UK 2016). Thus, the UKCS have more of other GHGs from their petroleum activity relative to NCS.

Most of the Norwegian CO2 emissions come from the petroleum industry, which constitute slightly less than one third of their total CO2 emissions. Most Norwegian electricity comes from hydropower. Other countries use electricity mostly generated on fossil fuels associated with CO2 emissions. This contributes to the Norwegian petroleum activity’s high share as an emission source compared to other petroleum producers around the Northern Sea area (NOG 2010a). On the UKCS, 3 % of UK’s total CO2 emissions are from the petroleum sector (Oil and Gas UK 2016). As UK still uses coal and fossil fuels for electricity generation, this contributes to the UK petroleum activity’s low share as an emission source. But also because UK is a larger country with higher emissions relative to Norway, where national CO2 emissions in 2015 was 405 MtCO2e in UK (DECC 2016), while Norway’s national CO2 was 44.7 MtCO2e (SSB 2016). In addition, the oil sector on the UKCS is smaller than on the NCS.

From Figure 3, we see that CO2 emissions from oil and gas production increased slightly from 2014 to 2015 on both the NCS and UKCS, which is because of increased production in 2015 (Oil and Gas UK 2016). GHGs from oil and gas industry have increased significantly since 1997 on NCS since several new installations have started producing and many fields are approaching the last stage of production (declining phase), which is more energy intensive. While on the UKCS, the CO2 emissions have steadily decreased as the production is gradually falling due to maturing fields.

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The CO2 emissions in Figure 3 are based on the reported emissions received from BEIS and NEA. The Norwegian emissions from the offshore oil and gas extraction, was around 11.9 MtCO2e in 2015, compared to the 14.2 MtCO2e from the petroleum industry, which includes onshore fields and terminals.

It is uncertain why the emission data from UK are so different (13.2 MtCO2 compared to nearly 4 MtCO2

in Figure 3). The amount of 13.2 MtCO2 most likely include emissions from both onshore fields and terminals. The emissions from UKCS in Figure 3 are received from BEIS. Further, BEIS have been contacted about this significant difference, and been asked about which kinds of emissions sources the reported emission figures cover. But we are still waiting on the reply.

Figure 3. Overall production and CO2 emissions from offshore oil and gas extraction.

Source: Based on data from NPD, OGA & BEIS.

2.3.2 Emission sources

Emissions from the petroleum industry mainly come from combustion of natural gas and diesel in turbines to generate power and heat on installations when producing oil and gas offshore. Other sources are gas flaring³ engines, boilers, venting, storing and transporting oil and gas. According to data from NPD, turbines caused 81 % of the CO2 emissions from petroleum activities on the NCS in 2015. On the UKCS 75 % of the CO2 emissions were due to fuel combustion to provide electrical power to run oil pumps, heating, etc., and to drive compressors to convert gas into liquid form for gas export (Oil and Gas UK 2016). Both on the NCS and the UKCS is gas flaring the second largest emission source.

3Gas flaring is post combustion to get rid of excess gas and oil by petroleum production, and involves disadvantages such as loss of resources and large CO2 emissions (NOG 2016).

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Total production from oil and gas fields (NCS) Total production from oil and gas fields (UKCS)

CO2 emissions (NCS) CO2 emissions (UKCS)

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CO2 emissions from the petroleum industry are largely based on each field and installations energy demand, but also on how energy efficient the installation is. Energy, i.e., power and heat, is needed to extract oil and gas. While gas flaring on the NCS mainly is maintained due to safety considerations in case of failures in the process (Devold 2013; NOG 2010a). According to the World Bank (2017), the UKCS flared 1 321 mSm³ gas in 2015, while NCS flared 336 mSm³ gas, which is considerably lower.

This is equivalent to a flare intensity of 0.014 Sm³gas per Sm³oe produced and 0.0014 Sm³ gas per Sm³oe produced, respectively. The flare intensity was around 13.6 tonnes of gas per thousand tonnes of hydrocarbon produced for the world average in 2015 (IOPG 2016).

On the NCS, gas flaring is limited according to regulations in the Petroleum Act 1996 (NOG 2016). On the UKCS, the regulation for flaring is strict and is subject to the Petroleum Act 1998. A consent is needed to flare, but the flaring regulation is somewhat “looser” than for the NCS. Still, gas flaring mainly is conducted due to safety reasons. However, the UKCS have several mature fields that are over 30 years old. These fields are designed to flare higher level of gas since the infrastructure to transport gas is lacking (Oil and Gas UK 2016).

Figure 4. CO₂ emissions from petroleum activities in 2015, by source (in thousand tonnes).

Source: Based on data from Norwegian Petroleum Directorate.

Turbines 81.1 % Engines

7.1 % Boilers

1.7 %

Flaring 9.7 %

Well testing 0.2 %

Other sources

0.3 %

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