The Scottish Energy Study is the first major study of energy supply and demand to be conducted in Scotland for over a decade.
The purpose of the study is to inform Scottish Executive decision-making in areas such as improving energy efficiency, the development of renewable energy, the Scottish Climate Change Programme and sustainable development. The aim is to supply the Scottish Executive with an understanding of current energy supply and demand, together with the factors driving these. This will be used to develop an appreciation of the opportunities open to Scotland and the barriers to sustainable energy use that must be addressed. The study focuses on initiatives that will succeed at the Scottish level, and so can capitalise on, and develop, Scotland's natural resources, its industrial capability and the skills of its workforce.
This report describes Scotland's current energy supply, energy consumption and energy-related CO 2 emissions during 2002, and provides background information on how this picture was developed.
The approach taken to estimating energy use
Two parallel approaches were used to derive an understanding of energy supply and demand:
- 'Top-down' supply of fuels, whether directly or to generate electricity
- 'Bottom-up' use of each fuel in the domestic, industry, services and transport sectors.
Where possible, bottom-up and top-down totals were compared and contrasted for all fuels, including consumption for electricity generation. Data are more readily available for some sectors than others but, in general, the top-down and bottom-up figures agreed within ± 3% or better.
In 2002, Scotland consumed approximately 175 TWh1 (628 PJ) of delivered energy, 164 TWh consumed by demand sectors and 10.6 TWh in refineries, emitting 45 Mt of CO 2 (or 12 Mt of Carbon) 2 . Total primary energy consumed is estimated to be 221 TWh. In addition, Scotland generated a further 8.0 TWh of electricity, which was exported to England and Northern Ireland.
Supply and demand
Sankey flow diagrams are one means of representing energy supply and demand. Figure S1 shows, reading from left to right, the supply of fuels, their transformation to generate electricity, and their final use in demand sectors. The width of the lines is proportional to the energy consumed.
Figure S1: Summary Sankey energy flow diagram ( TWh)
Figure S2 shows the relative input contributions of fuels, firstly to overall primary energy supply, then as electricity generated and energy delivered, and finally showing losses associated with electricity generation and transmission, and from energy use in refineries. The areas of the pie charts in Figures S2, S4 and S6 are scaled to the relative amounts of fuel use in each sector.
Figure S2: Summary energy supply and demand
As the above diagrams show, natural gas, oil (especially for transport) and electricity are the predominant forms of energy delivered to end-users. However, coal and nuclear fuel also make significant contributions via electricity generation.
Combustion of fossil fuels gives rise to CO 2 emissions. Figure S3 illustrates the main contributions to CO 2 emissions by fuel. The largest single contribution arises from oil, predominantly used in transport. Close behind is electricity. Although electricity contributes only about 21% of delivered energy it contributes 30% to CO 2 emissions, because there are substantial losses in the electricity generation and distribution process.
This arises even though almost 40% of Scottish electricity was generated using nuclear fuel which does not give rise to CO 2 emissions.
Figure S3: CO 2 generation by secondary energy source
The emissions of CO 2 by sector are shown in Figure S4 below.
Figure S4: CO 2 generation by demand sector and to generate electricity
Whilst calculating CO 2 emissions from combustion is straightforward, it is possible to take different approaches to estimating the CO 2 associated with electricity generation, depending on whether a UK-wide or Scottish view of the fuels used for generation is taken. Options are discussed within the body of the report. In general, the UK generating 'basket' figure of 0.432 kg CO 2/kWh has been used, to reflect the integrated nature of power generation in the UK.
Considering each fuel in turn:
Solid fuel - predominantly coal - is mainly used to generate electricity, with little direct use by demand sectors. The majority of solid fuel consumption in Scotland is for electricity generation at Scotland's two coal-powered electricity generators.
Scotland mines and exports much of its coal to England, Northern Ireland and elsewhere. Overall, net exports outweigh imports by about 10 TWh.
Oil - about 1,150 TWh (100 Mtoe) of oil is produced by Scotland, most of which is exported as crude oil, although nearly 10% is refined at the Grangemouth oil refinery. The majority of oil product use in Scotland is for transport, especially road transport, which has grown steadily over the past 10-20 years. Oil is also used for process heating in industry, and space/water heating in the industry, domestic and service sectors.
Gas - in 2002 nearly 400 TWh of gas was extracted and transported through Scotland - mostly to England, but also to Northern Ireland and the Republic of Ireland. Gas is used directly for heating in domestic, industry and service sectors, and also used to generate electricity at Peterhead power station. Gas consumption has grown over the past 10-20 years because of its availability, low cost, versatility and low levels of emissions. This has occurred despite the fact that gas is not available in sizeable areas of Scotland, particularly in the north and north-west.
Renewables - the main sources of renewable energy are from hydroelectric generators built in the mid-20 th century, together with increasing contributions from wind, newer small-scale hydro schemes and thermal sources. There is also direct consumption of renewable energy sources, although given the dispersed nature of the fuel ( e.g. wood from fallen trees, waste pallets, etc), it is difficult to determine an accurate figure.
Nuclear fuel - is used solely to generate electricity at three power stations 3.
Electricity - in 2002, the majority of power was generated from nuclear fission, coal and, to a lesser extent, gas combustion. Scotland had six major power plants ( MPPs): three nuclear, two coal and one gas. Scotland also had several large (and many small) hydro schemes, a pumped-hydro storage facility, many small-scale generators/ CHP schemes, and wind and thermal renewable facilities.
Scotland exported about 20% of its electricity to England, Northern Ireland and the Republic of Ireland. Many of the large MPPs are, however, expected to stop generation in 10-20 years.
The main end-use sectors are, in decreasing order of energy consumption: domestic, transport, industry and services:
Figure S5: Energy use in demand sectors
Figure S6 shows fuel use by end demand sector, with that for electricity, for comparison:
Figure S6: CO 2 emissions by demand sectors
To consider each demand sector in turn:
The domestic sector is the largest energy consumer. This has grown in recent years, as average household sizes have decreased, and use of electrical appliances has grown. In general, energy demand in Scotland is greater on average than in the UK, mainly because of the harsher climate.
Transport Transport energy use grows year-on-year, particularly due to rising levels of road transport (the largest sub-sector) and air transport.
Industrial consumption has seen a significant decline in recent years, with moves from manufacturing to service provision. Energy use by industrial sector is shown in Figure S7.
Figure S7: Scottish industry - main sectors
Services Energy consumption is in this sector includes: the public sector, tourism and related activities, retail, commerce and the agriculture sector. Although the smallest end-use sector in Scotland, the average consumption is greater than the UK average.
Non-energy and process CO 2
Whilst the prime purpose of this study is to examine energy consumption and CO 2 emissions, it is recognised that Scotland is a major emitter of non-energy CO 2, particularly from soil, as shown in Table S1 and Figure S8:
Table S1: Scottish non-energy CO 2 emissions
Land use change and forestry - emissions
Carbon sink - forest growth
Scottish soils emitted some 5.0 Mt of CO 2 in 2002. Much comes from disturbances to the peaty soil found in large areas of Scotland.
The contribution from land use is becomes a net sink if the CO 2 absorbed by forest growth is credited but, unless the carbon is permanently sequestered, it will eventually return to the carbon cycle, through burning or decomposition. This is shown below, where CO 2 arising for energy use is compared to that from land use change and forestry.
Figure S8: Scottish CO 2 contributions in perspective (Mt CO 2/annum)
Finally, fugitive emissions from oil, gas and industry processing (cement, glass and primary aluminium) were nearly 1.6 Mt CO 2 in 2002.
The overall CO 2 picture
Geographical representations have also been developed to show distribution of CO 2 sources for 2003 4. Maps were developed from the NAEI dataset to show CO 2 emissions from energy use alone, and from all sources (including industrial processes and land use), for both Scotland and the UK. These maps do not include the impacts of CO 2 sinks. The maps for Scotland are shown in Figure S9.
Figure S9: Scottish CO 2 distribution - total CO 2 and energy CO 2
The maps illustrate the concentration of high emissions, which are mainly in urban areas where houses, businesses and factories are located, together with Lanarkshire, the Ayrshire coast, around Grangemouth, around Dunfermline and the South Fife coast. The effects of transport are also visible, in terms of both road links and marine transport.
Energy consumption in Scotland compared to the rest of the UK
Overall, Scotland has slightly greater energy consumption per head than the average for the UK as a whole: consuming 9.1% of UK energy with 8.5% of the UK population. Considering this by sector:
Figure S10: Comparison of Scottish versus UK per capita energy consumption
Scotland consumes more energy in each sector, apart from transport. This arises in part from a slightly higher use of energy for heating and greater than average oil refining, which more than offsets the slightly below average consumption by transport. The fuel split is not dissimilar to the UK average, with a slightly lower demand for solid fuels, but higher consumption of gas and electricity.
In 2002, Scotland's energy was fuelled directly by gas and oil and also using electricity, generated predominantly from nuclear fuel and coal, with a lesser contribution from gas. The main demand was in the domestic sector, as energy was for space and water heating in homes, then for transport, especially road transport: these two sectors use over 60% of Scotland's delivered energy. This represents a considerable change in recent years and is explored in more depth in Volume 2 of the study.