Scottish Government

2| CO ₂ sources

In this section, the principal industrial sources of CO ₂ (power generation and industrial plant) in Scotland and NE England are identified, and the levels of output for sources in Scotland during 2006 are quantified. Likely levels of CO ₂ output are then estimated for 2020, 2030 and 2040 by considering various energy generation mixes. This information is used to quantify CO ₂ storage and transport requirements and to plan a network infrastructure that will respond to these requirements.

Figure 3
Relative proportions of CO ₂ emitted by source in 2006 in the UK.

Scotland's total CO ₂ emissions in 2006 were estimated to be 44 Mt, around 8% of the total UK emissions of approximately 557 Mt. The majority of the large fixed sources of CO ₂ are power generation plants, which give rise to 33% (~184 Mt) of the UK total; integrated steel plants and the larger oil refinery/petrochemical complexes are further significant sources. Of the remaining sources of emissions, the largest single contribution was from transport (23.5%) (Figure 3).

All the major energy generators and industrial point sources of CO ₂ in England, Wales and Scotland that emit more than 10, 000 tonnes of CO ₂ per year report this output to the National Atmospheric Emissions Inventory ( NAEI) and the Scottish Environmental Protection Agency ( SEPA) (Figure 4).

Figure 4
Location of industrial sources of CO ₂ emissions in Scotland and NE England that emitted more than 100, 000 tonnes per year in 2006.

In 2006, approximately 18 Mt of CO ₂ (around 41% of Scotland's total carbon emissions) was produced by Scotland's three largest power stations. The output of Longannet alone is approximately 10 Mt. A combined total of 71 Mt of CO ₂ (~24% of total UK fixed industrial) was produced by the top ten sites in Scotland and NE England (Figures 4 and 5).

Figure 5
Top ten CO ₂ sources in Scotland and northern England in 2006.

For Scotland, the amount of CO ₂ produced in the future will largely depend upon the method of energy generation and the relative proportions of types of energy supplied. Likely levels of CO ₂ production were considered for 2010, 2020, 2030 and 2040. For 2010, it was assumed there would be little change in output from figures provided for 2006 (Figure 5). A range of scenarios for CO ₂ production in 2020, 2030 and 2040 is summarised below (Figures 6, 7 and 8). For each of these years, different energy mixes were analysed, with no judgement as to which scenario was more likely, and a range of possibilities presented. (Tables 1, 2 and 3). The scenarios yield high, medium or low CO ₂ output reflecting the different energy mixes. The examples shown in Figures 6, 7 and 8 assume that carbon capture technology is not installed. Note that if carbon capture equipment were installed, gross (prior to capture and storage) CO ₂ output would be higher, by between approximately 12% ( CCS mature) and 25% ( CCS immature) reflecting the additional energy required to extract the CO ₂ and purify it. However, the extra CO ₂ produced by the carbon capture process will, by definition, be captured as part of this process and should not result in additional CO ₂ being released into the atmosphere.

Figure 6
CO ₂ output at 2020 for 11 Scottish scenarios.

Table 1
Proportions of different energy generation methods for each of the 11 scenarios possible for 2020.

Figure 7
CO ₂ output at 2030 for 6 Scottish scenarios.

For 2030, CO ₂ production was calculated on the basis of electricity demand as at present. Calculations assuming a year on year 1% increase of electricity demand from 2020
to 2030 were also carried out but did not change the ranking of energy mix scenarios.

Table 2
Proportions of different energy generation methods for each of the 6 scenarios possible for 2030.

Figure 8
CO ₂ output at 2040 for 12 Scottish scenarios.

For 2040, CO ₂ production was calculated on the basis of electricity demand as at present. Calculations assuming a year on year 1% increase in electricity demand from 2030 to 2040 were also carried out but did not change the ranking of energy mix scenarios.

Table 3
Proportions of different energy generation methods for each of the 12 scenarios possible for 2040.

CO ₂ Sources-key conclusions

For Scotland over a 40-year period from 2010 to 2050, total output from electricity generation alone will produce CO ₂ outputs of:

• ~ 700 Mt or 17.5 Mt/year under a high CO ₂-output scenario;
• ~ 320 Mt or 8 Mt/year under a low CO ₂-output scenario assuming no nuclear power.

Additional major sources in NE England produced ~50 Mt CO ₂ in 2006. Thus, if outputs from both regions are included, over the period to 2050, up to 3000 Mt CO ₂ is potentially available for capture and storage. This is equivalent to 75 Mt CO ₂ per year taking this high-case scenario.