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Scottish Energy Study: Volume 1: Energy in Scotland: Supply and Demand

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Footnotes

1 1 TWh = 1,000,000 MWh

2 As the mass of C is about 0.27 that of CO 2.

3 The smallest of these, Chapelcross closed in 2004.

4 This mapping of CO 2 data for Scotland is only available for 2003

5 NAEI's 'Greenhouse Gas Inventories for England, Scotland, Wales & NI, 1990-2003', published September 2005.

6 It should be noted that the NAEI emissions levels from energy use are ~5% higher than those estimated by the Scottish Energy Study. There are two main differences in methods. Firstly the NAEI attributes all CO 2 emissions associated with electricity to the point-of-generation, regardless of whether this electricity is exported or used in Scotland. Secondly emissions from domestic aviation are attributed to the UK as a whole, not to the constituent countries. When the net impact of these two differences are taken into account the figures are within 3%.

7 Degree-day figures quantify how hot or cold the weather has been for a particular region and time period. They are used to normalise the fuel used for heating.

8 See http://www.defra.gov.uk/environment/business/envrp/gas/index.htm

9 And after discussion with the Scottish Executive

10 Website = http://www.dti.gov.uk/energy/inform/energy_consumption/table.shtml

11 At time of going to press, the DTI has published additional data on domestic and small business gas and electricity use in each local authority area ( www.dti.gov.uk/energy/environment/energy_impact/seib2005ch3b.pdf).

12 DTI 'Report of Working Group on Extending the Gas Network' ( www.dti.gov.uk/energy/gas_and_electricity/trading_networks/gasnetreport.pdf)

13 Predominantly in the remoter Highland & Island communities, as well as away from major population centres. It is worth noting that across the UK, similar patterns are seen in SW England, East Anglia and Wales. Furthermore, in 2002, NI had only just introduced natural gas from mainland Britain.

14 This issue was taken up with DTI and Netcen (which produces the National Atmospheric Emissions Inventory - NAEI for UK). The anomaly has been recognised and the most recent NAEI report for England, Scotland, Wales & NI has estimated each country's consumption based on km road use times type of vehicle, rather than based on DTI's fuel sales figures. The more recent revised figures better reflect the Scottish Energy Study estimations for road transport consumption in Scotland.

15 This compares not unreasonably with NAEI's calculated figure of 9.63 Mt of CO 2 emissions. There was insufficient detail in the Regional GHG Inventory report to determine how the NAEI figure was calculated.

16 Energy consumption by air and marine transport is largely ignored by NAEI because the majority of such travel is in international airspace/waters. Estimations are made for the fuel used for aircraft landing/take-off or ships going into/out of ports.

17 The UK as a whole generates approximately 150 Mt CO 2 from transport. The vast majority of this is road, but there are 2,300 kt from tubes/trams and trains (some of which are electric) and 300 kt from pipeline transport.

18 Calculated based on CO 2 emissions from transport: www.statistics.gov.uk/downloads/theme_environment/transport_report.pdf

19 Chart 1.2 of Scottish Economic Statistics, 2004, p 61.

20 Note: this was taken as the default start position but tended to be used only for sectors with a large number (>100) of UK participants.

21 Includes DTI's statistics total of 17.5 TWh plus estimated similar additional amount of coal consumed in the coking and sintering process in the four (now three) UK integrated steelworks in England and Wales. This fuel is classified as a secondary fuel, not as an end use sector, by DTI, but omitting it from the table would skew the figures.

22 Includes coke-oven gas from integrated steelworks; not now generated or consumed in Scotland.

23 The danger of double counting this energy in the demand sectors is recognised and considered later in this report.

24 (1) Longannet is known to consume large quantities of dried sewage sludge pellets, although there was little or no contribution in 2002 and data for these have not been included in the DTI statistics. It is understood that currently, additions of around 10% are not uncommon, although their contribution to the total primary energy per tonne will be less than that of coal.
(2) Longannet also has gas over-burners which consume some natural gas, although personal communication from Scottish Power suggested that this did not start until after 2002.

25 Based on the revised DTI's Energy Trends (Jan 2005), calculated 'Electricity consumption from Public Supply' figure of 30,726 GWh is now only 396 GWh ( i.e. 1.1%) more than the 'Electricity Sales (Public Supply)' figure of 30,330 GWh. The previous figures for Scotland had a difference of 3,789 GWh that represents 11.6% unaccounted electricity, which was difficult to ignore.

26 The same is true for England, Wales and NI.

27 Considering the fact that the DTI declared figures for exports have recently been modified, it is surprising how closely the revised figures still match the bottom-up assessment. Declared exports to England and NI rose (from 6.8 to 8.04 TWh), the declared figures for autogenerators increased (from 2.6 to 4.6 TWh) and the electricity from 'other' gas and oil-fired CHP/small-scale generators changed substantially.

28 It was recognised that electricity would probably be the most significant difference between the Scottish Energy Study and NAEI model for CO 2 emissions. NAEI attributes CO 2 emissions to the point of generation, thus CO 2 emissions from electricity exported to England or NI would be effectively 'credited' to Scotland, but without Scotland actually using the generated energy.
This model also differs from other environmental studies, such as the World Wildlife Federation 'Environmental Footprint' study. The WWF study attributes all direct and intermediate (sequestered) energy to the point of final consumer, regardless of where components of the finished article were made.

29 In fact, Chapelcross closed during 2004.

30 Source: Scottish Renewables Forum.

31 However, oil refining has many more similarities to industry than electricity generation, with a relatively small proportion of the primary energy being used to generate the final product, a more tangible (storable) product, plus non-energy products. Therefore, for the purpose of the Scottish Energy Study, all the energy consumed by Scotland's refineries to create the petrol/diesel/etc has been attributed to Scotland rather than attributed to the final fuel product. It is understood that this is not consistent with the electricity model, but is similar with the way fuel transformation in primary steel production has been handled. It is believed that oil refining and electricity generation are sufficiently dissimilar to warrant this differentiation.

Secondly, this approach eliminates the need to add 5-10% to all DUKES standard emission factors to refined oil-based fuels, which would be required if the total primary energy and CO 2 emissions were to be analysed this way.

32 Plus a much smaller unit at Nynas in Dundee, which produces mostly bitumen.

33 http://www.hse.gov.uk/comah/bpgrange/summary/process.htm

34 www.sepa.org.uk

35 It is not clear if this figure is for capacity of crude oil in or refined product out. By calculation, the latter would be approximately 90-95% of the former figure.

36 Unlike other fuels, coal types vary in their composition, with important differences in sulphur content and energy value. So coals that are suitable for one consumer may not be suitable for another consumer. In addition, the CO 2 emissions vary from grade to grade.

37 Source: Coal Federation. www.scotland.gov.uk/library5/planning/oenppg16-04.asp

38 The reason that Scottish coal-powered generation is not all (or is predominantly) from Scottish coal is historical. Scottish coal has relatively low sulphur. Until the 1990s, Scottish generators were low-sulphur emitters compared with their English counterparts. However, when legislation required emission reductions, Scottish generators were obliged to change to imports of ultra-low sulphur coal. The English generators, however, could reduce their sulphur emissions by simply switching to Scottish coal.

39 The Coal Federation had estimated a smaller figure, only 300,000 tonnes. The precise figure is less important than the fact that this represents only a few TWh coal that is consumed directly, compared with the quantity consumed for generating electricity.

40 To date, it has not been possible to cross-check these figures with suppliers and importers into Scotland, nor with top-down figures from the DTI.

41 E-mail correspondence from DTI & extracted from internet site.

42 Reported in 'Energy Trends', Dec 2003. Transco uses 37 MWh/y as cut-off criterion for domestic, so some smaller business and commercial operations are likely to have been captured under Transco's criterion for domestic.

43 This issue of potential double counting has been recognised in the 'electricity data handling' section. In truth, the amount of double counting will be small.

44 E-mail correspondence between DTI & FES Scotland, plus extracts from internet: www.databydesign.co.uk/energy/ukdata/book.htm

45 The actual bottom-up figure should be 1,056 GWh, made up from 564 GWh consumed by MPP (nuclear stand-by) plus estimated 492 GWh from CHP/small-scale generator contribution to saleable electricity - see Appendix 6. The latter figure has been excluded to avoid double-counting this oil, as it will also show as direct consumption of oil in the 'industry' or 'services' demand figures.

46 http://www.dti.gov.uk/energy/inform/energy_stats/electricity/dukes5_10.xls

47 Which is nearer 20% less, although Scotland has a very high installed natural hydro capacity and thus the figures may be skewed by particularly dry or wet years.

48 That is not to say that the primary energy figure is unimportant. Clearly, it would be useful to know how much more usable energy can be obtained from primary renewable and biomass energy sources. However, addressing this issue is outside the immediate scope of the Scottish Energy Base Year Study.
It should be possible to assess the generating efficiencies of large-scale operations such as natural hydro, wind power and waste/landfill incineration. These figures would indicate how efficiently the captured energy is converted into usable electricity. They do not necessarily tell how much wind is 'spilt', how much fugitive bio-fuel escapes, etc.

49 This leads to an interesting point regarding CO 2 sequestration figures from growing wood. Currently, in the NAEI reports, 6.82 Mt CO 2 pa is 'credited' to Scotland for such activities; however, unless the carbon is permanently sequestered, it will eventually work its way back into the carbon cycle through burning or decomposition. This is a general accounting issue that, if ignored, may give a misleading picture of GHG emissions from Scotland, the UK and other Kyoto member states that 'credit' CO 2 emissions to forest growth.

50 For clarity, this contains relatively few numbers

51 Whereas electricity is consumed as a secondary fuel by all demand sectors, oil refineries self-consume fractions from crude oil refinement to generate both heat and power to operate the refinery.

52 Standard factors used for UK assessments of primary energy and CO 2 for electricity.

53 (+) This is a sign convention to indicate an energy value that has no fuel source. These values have not been included into the totals.

54 Henceforth referred to as the NAEIUKDA report.

55 These figures published in 2005 revised earlier sets of data that suggested that Scotland had a net production of CO 2 from land use and forestry.

56 This raises the question: "Should carbon sinks be counted in the GHG balance", particularly if wood burning is considered renewable energy and is attributed 0 kg CO 2/kWh? Taking the IPCC approach, one is 'crediting' Scotland with forests acting as a carbon sink but not 'debiting' Scotland (or elsewhere) when this sequestered carbon is re-released to atmosphere.

57 See http://www.aeat.co.uk/netcen/airqual/naei/annreport/annrep99/app3.html

58 For the NAEI report, all electricity CO 2 emissions are attributed to the point of generation and exports to England/ NI would not feature in its analysis.

59 It must be noted that the NAEI report was issued before the DTI Energy Trends with the special feature on electricity generation in the Devolved Administrations was published, and it may in fact be based on out-of-date fuel splits.

60 1 TWh = 1,000,000 MWh.

61 As the mass of C is about 0.27 that of C.

62 There will be small rounding errors between the individual fuels and total.

63 Extracted from this table. For the Scottish Energy Study, petrochemicals are considered as a secondary fuel and have been represented thus in the Sankey figure.

64 This has been done to accommodate Lochaber electricity (Scotland). DTI stats have 'ignored' renewable E for Lochaber and self-generated coal-fired electricity (at Lynmouth) and counted these elsewhere.

65 2002 was very untypical. Discussions with Industry SS suggest will be more gas and less coke, coke oven/ BF gas and self-generated electricity.

66 Heavily reduced - ASW in receivership.

67 Most PS/C&B will be in main towns. Estimate 85% accessibility to gas in towns, compared with UK average of 90%. Therefore, Scottish gas consumption for services will be reduced slightly, other fuels will need to be increased to compensate for the 'gap'.

68 England = 49.86, Wales = 2.94 million.

69 Plus a lot of invisible from ROI.

70 This is an opinion rather than a fact.

71 Anecdotal feedback is that there are approximately three times as many road miles per person in Scotland than England.

72 Key Transport Statistics - December 2003, Scottish Executive

73 Based on the revised DTI's Energy Trends (Jan 2005), calculated 'Electricity consumption from Public Supply' figure of 30,726 GWh is now only 396 GWh ( i.e. 1.1%) more than the 'Electricity Sales (Public Supply)' figure of 30,330 GWh. The previous figures for Scotland had a difference of 3,789 GWh that represents 11.6% unaccounted electricity, which was difficult to ignore.

74 As of 21/2/05.

75 Considering the fact that the DTI declared figures for exports have recently been modified, it is surprising how closely the revised figures still match the bottom-up assessment. Declared exports to England and NI rose (from 6.8 to 8.04 TWh), the declared figures for autogenerators increased (from 2.6 to 4.6 TWh) and the electricity from 'other' gas and oil-fired CHP/small-scale generators changed substantially.

76 Anecdotal feedback from Mike Janes ( MJ - DTI) suggests that this figure would be higher for nuclear. Both Wales and Scotland have greater than pro-rata nuclear generation and this needs to be taken into account.

77 For example, at night, nuclear plant operates at a high base load, it is not sensible to switch-off completely gas/coal for short periods, and wind is dependent on weather.

78 The January 2005 'Energy Trends' table had a total of 7,564 GWh.

79 240 GWh total for small-scale internal losses (section7) x (100-17.7)%.

80 See http://www.defra.gov.uk/environment/business/envrp/gas/index.htm

81 The solid fuel used in blast furnaces to refine iron & steel from ore is coke. However, this is generated on-site at the steelworks from coal. These coking ovens also produce coke oven gases, which are self-consumed by the coking ovens and/or used elsewhere in the integrated steelmaking process.

In theory, the coking process should be regarded as a separate 'secondary fuel' process, much the same as crude oil refining. However, nearly all coke made at the integrated steel operations is consumed downstream in steelmaking. Rather than try to separate out the coking process from the rest of the integrated steel operation, the author has assumed that all the energy from the coal going into the 'front-end' of the steelworks is eventually used somewhere within the steel operation. This eliminates the need to separately account for coke oven gas that is generated in the (secondary fuel) coking process but consumed downstream in the (industry process) steelmaking.

82 For the NAEI report, all electricity CO 2 emissions are attributed to point of generation and exports to England/ NI would not feature in its analysis.

83 It must be noted that the NAEI report was issued before the DTI Energy Trends with the special feature on electricity generation in the Devolved Administrations was published, and it may in fact be based on out-of-date fuel splits.

84 NAEI data were gathered and presented on a different basis to the Scottish Energy Study and only account for consumption of fossil fuels, not electricity.

85 Much of the analysis for electricity has been based on information extracted from DTI's Energy Trends, Dec 2003. Since writing the Scottish Energy Study Base Year report, DTI has re-assessed the 2002 UK split for electricity generation and consumption and published this in January 2005. This latter publication contained several changes to the Scottish (and other countries') electricity figures, which had a big impact on the overall electricity picture, including the primary fuels consumed to generate.
The CO 2 associated with this generation has been stripped from the above figures and attributed to the point-of-use rather than the point of generation.

86 Useful electricity = total generated electricity minus electricity self-consumed by MPP, distribution and transmission losses, and electricity used to pump water uphill for later generation as pumped hydro.