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Energy Storage and Management Study

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2 Stage 1: The challenge of addressing intermittency

In order to assess the challenge for energy storage and demand side management in Scotland it is necessary to develop a view of how generation and demand may evolve over the coming years. Below we outline three Scenarios of electricity supply and demand for Scotland over the period to 2020 and 2030. The Scenarios have been developed to show the challenges posed by accommodating increasing volumes of intermittent generation within the predicted mix of conventional and renewable generation. The Scenarios are used to assess the potential role energy storage and demand side management may make in helping accommodate this generation mix.

The three supply side Scenarios include:

  • Scenario 1 - a view of how renewable energy could grow in Scotland in order to meet the current 2020 renewable targets, based on known plans and developments in hand, plus a proportion of the marine energy potential (offshore wind, wave and tidal). This Scenario represents a pathway for renewable energy in Scotland that was until recently considered ambitious. However this view has been overtaken by the rapid development of proposals for marine energy and identification of longer term growth opportunities.
  • Scenarios 2 and 3: two stress test Scenarios - with more rapid growth of renewable energy capacity designed to mirror more ambitious renewable aspirations for Scotland. These Scenarios represent a more current view of the potential for increasing amounts of marine energy. These Scenarios will also act as a stress test for operation of the electricity network. One of these two Scenarios is used for more detailed assessment.

This Section provides a summary of the Scenarios, with key assumptions and key data.

2.1.1 Policy Background

Increasing the contribution from renewable energy has become an integral part of long term energy policy goals for both the UK and Scotland, driven by an increasing consensus that climate change is a significant threat and that the electricity sector will be key to reducing CO 2 emissions.

The Scottish and UK Governments have set a number of significant targets for carbon emission reductions. The Scottish Government's Climate Change Bill, passed by the Scottish Parliament in June 2009, sets a target of reducing emissions by 80 per cent by 2050. It also sets a world-leading interim target for a 42 per cent cut in greenhouse gas emissions by 2020. The key actions to achieve these reductions in emissions are set out in the Scottish Government's draft Climate Change Delivery Plan.

The UK Government has also adopted greenhouse gas reduction targets in the Climate Change Act ( CCA). The Climate Change Bill was introduced into Parliament on 14 November 2007 and became law, in the form of the Climate Change Act, on 26th November 2008. The CCA introduces a framework to set 5 year carbon budgets with legally binding emission reduction targets. In the April 2009 budget the Government presented the first three carbon budgets under the CCA, which aim to set the UK on a path to achieve the 80 per cent reduction on 1990 emissions by 2050.

Europe is also setting targets - the so called 20/20/20 targets - that aim to reduce CO 2 emissions by 20 per cent, provide 20 per cent of EU energy from renewables and improve energy efficiency by 20 per cent - all by 2020. The Renewable Energy Directive sets mandatory national targets for each Member State with the aim of achieving a 20 per cent share of renewable energy in Europe's final energy consumption by 2020. Each Member State must design long-term renewable energy measures and policies and develop detailed estimations on the contribution of renewable energy in final energy consumption - so called National Renewable Energy Action Plans. For the UK the EU renewables target translates into renewables providing 15 per cent of the UK's final energy demand by 2020 - enormously challenging given that the UK currently produces less than 2 per cent of energy from renewables. For Scotland a target of achieving 20 per cent of final energy demand from renewables has been set.

The electricity sector will be integral to achieving long term CO 2 reductions. The UK Government has suggested that, in order to meet the 2020 renewable targets then some 35 per cent of the UK's electricity must be generated from renewables by 2020. In Scotland renewable energy generation is to have an even larger role. The Scottish Government has set tougher renewable targets of at least 50 per cent of Scottish electricity 1 to be provided by renewables by 2020, with an interim target of 31 per cent by 2011.

Beyond 2020 there is the potential for significant and continued growth in renewable energy. The recent Offshore Valuation study (Offshore Valuation Group, 2010) identifies 206 GW of potential off the Scottish coastline and a total of 531 GW off UK coasts.

2.1.2 The Issues with intermittent generation

Much of the new renewable generation in Scotland over the period to 2020 and out to 2030 is likely to be wind, particularly onshore wind under Scenario 1, but with increasing contributions from offshore wind especially for the more ambitious renewable scenarios, biomass and wave and tidal energy. Incorporating increasing volumes of intermittent wind generation onto the system will be a challenge. The intermittency of wind generation is a function of wind variability and predictability. Even if the output of wind generation was entirely predictable, the variability of that output increases the difficulties of matching system supply and demand. Improvements have been made in recent years vis-à-vis forecasting the output from wind farms. In general over relatively short time frames, and with robust historic wind data for a specific site, it is possible to predict wind farm output. Such information can be used by the system operator (SO), in conjunction with a suitable forecasting error, to assist the SO in accommodating wind generation onto the system. Although the forecasting error will increase as the forecast extends further ahead in time.

However, in addition to predicting wind output is the associated issue of the variability of this output. For a SO the issue is planning for, and accommodating variability in, the output of wind generation within a system in real time. An extreme example of wind variability might occur where the output of wind generators declines as the evening demand peak is approaching. This fall might then be followed by a rise in wind output at a time when demand is falling steeply. While relatively extreme, the example serves to highlight the system management issues associated with wind generation.

The challenges associated with accommodating wind generation are, for the most part, minimised if the proportion of wind capacity is small relative to the overall size of the interconnected system. The more diverse an electricity system, the more wind generation may be more easily accommodated within the system. Diversity includes differing forms of demand and supply coupled with an interconnected transmission system. In Scotland the potential volume of wind generation that might emerge could lead to intermittent generation 2 amounting to around 50 % of installed capacity by 2020 and even greater levels post 2020. Such high levels of variable generation will pose a significant system challenge.

There are a number of potential techniques the SO might use to accommodate wind variability, these include:

  • Making use of interconnections to neighbouring systems
  • Keeping other generation operating at low output to 'make good' wind variability
  • Physically restricting the output of wind onto the system
  • Limiting the maximum rate at which the output of wind generators may change
  • Utilising energy storage and demand side management options

The primary focus of this study is the role energy storage and demand side options may play in helping accommodate increasing volumes of intermittent generation onto the system. However the other factors outlined above will also play a role.

In order to determine the ease with which increasing volumes of intermittent generation may be accommodated onto the system in Scotland and the role of the options outlined above, particularly energy storage and demand side management, we have created Scenarios that outline Scottish electricity demand growth and generation over the period to 2020 and 2030.

2.2 Scottish electricity demand growth

This section sets out the demand growth assumptions that are used. These are the same in all three Scenarios. A demand projection is required as:

  • The net flows of electricity need to be assessed - i.e. generation less demand
  • The Scottish renewable energy is set as a percentage of demand, hence total future demand need to be assessed.

Our analysis indicates that Scottish electricity demand growth will be muted over the period to 2015, a reflection of the large fall in electricity demand anticipated during 2009 due to the global economic downturn. Although demand growth begins to recover in 2010, it takes until around 2015 for electricity demand to recover to pre recession levels. Over the period 2015-2020 electricity demand growth is sustained at a moderate level of around 0.6% p.a. reflecting some increased energy efficiency drivers. Beyond 2020 a move begins towards electricity away from fossil fuels in the transport, domestic and commercial sectors and electricity demand growth begins to accelerate, growing at 0.8% p.a. between 2020-2025 and 1.3% p.a. between 2025 and 2030.

The drivers behind electricity demand growth have been identified by a number of commentators - with increased electrification in transport together with a move towards greater electric space and water heating part of a package to steer the UK towards a low carbon economy ( CCC, 2009). While the timing and impact of such moves towards greater electricity use are uncertain, growing electricity demand is likely to emerge in the longer term.

Figure 2.2.1: Scottish Electricity demand growth

Figure 2.2.1: Scottish Electricity demand growth

Table 2.2.1: Scottish Electricity Demand Growth 3

2008

2010

2015

2020

2025

2030

TWh

35

34

35

36

37

40

2.2.1 Gross Consumption

The Scottish Government's targets for renewable electricity are expressed as percentages of gross electricity consumption. This is the total of consumption plus losses in the electricity transmission and distribution systems in Scotland. Transmission losses are arise due to the total amount of electricity generated - as this is the volume of energy that passes through the higher voltage transmission network. Distribution losses arise due the total amount of electricity consumed - as this is the volume of energy that passes through the lower voltage distribution network through which customers are supplied.

Statistics for electricity consumption and losses in Scotland are published by DECC. In 2008 transmission losses were 1.2% of total electricity generated, whereas distribution losses were 4% of electricity consumed.

These percentages have been used to estimate gross consumption in future years. Because of the inclusion of transmission losses, which are driven by generation levels, gross consumption estimates are slightly different for each scenario.

2.3 Scotland - Generation Scenario 1

2.3.1 Generation Capacity Assumptions

The first Scenario created is one that outlines a generation mix that could broadly achieve the Scottish Government's current renewable target for 2020. Table 3.1 shows the resulting generation capacity mix in Scotland over the period to 2030.

The total generation plant required to ensure that demand is met and security of supply is maintained is determined by a generation dispatch model. Once built, the plant is dispatched by the model on the basis of marginal cost. Using both market knowledge and the model we can determine the location and output of this capacity to ensure the system remains in balance and demand is met and security of supply maintained. This uses the assumptions of electricity demand growth, total generating capacity required etc.

Table 2.3.1: Scenario 1 Scottish Generation Capacity ( MW)

MW

2008

2015

2020

2030

CCGT

1,524

1,524

1,524

1,200

Pumped Storage

740

740

1,040

1,340

Biomass

123

150

300

500

CHP

275

313

368

478

Coal

3,456

2,304

2,304

1,200

Hydro

1,340

1,361

1,407

1,407

OCGT

55

55

55

55

Other 4

92

49

49

49

Offshore Wind

0

500

1,500

3,000

Onshore Wind

1,915

5,000

6,500

7,500

Nuclear

2,332

1,200

1,200

0

Tidal

0

0

200

400

Wave

0

0

300

600

Total

11,852

13,197

16,748

17,730

Renewables as % total capacity

29%

53%

61%

76%

Onshore Wind

Table 2.3.1 shows that in total, in Scenario 1, Scottish generating capacity increases significantly beyond current levels of around 12 GW to almost 17 GW by 2020, rising more slowly to 17.7 GW by 2030. Most of capacity increase results from increasing volumes of renewable generating capacity, particularly onshore and, to a lesser extent, offshore wind. There is currently around 2.4 GW of onshore wind operational in Scotland, with some 7.4 GW proposed by 2015 ( NGC 2009). Of these currently proposed sites we assume 5 GW may be developed by 2015, with up to 6.5 GW in total developed by 2020. Thereafter the build rate slows as most sites have been exploited and ROC support is assumed to be reduced for onshore wind. Some of the increase in capacity over the period modelled also results from repowering existing sites, particularly beyond 2025 as the initial ROC period ends.

Offshore Wind

Offshore wind also begins to be developed in Scottish coastal waters over the period to 2020. Based on our assessment of the factors underpinning offshore wind development, including prevailing development costs, comparative renewable generation costs, the operating environment and the subsidy mechanism, we consider that, in order to meet the current 2020 renewable target, installed offshore wind capacity may need to be around 1.5 GW, rising to potentially 3 GW by 2030. The location of this resource is based on the current Scottish Exclusivity Agreements with the Crown Estate. Scenarios 2 and 3 consider higher growth rates for offshore wind - in line with the recent bidding activity for offshore licences.

A number of factors combine that will influence the economically recoverable wind resource by 2020, these are outlined below.

Market Conditions

The cost of offshore wind turbines has escalated in recent years - with the capital costs of offshore wind farms increasing 100% in real terms between 2005-2008 ( BWEA, 2009) with the installed capital cost of an offshore wind farm now over £3,000/kW. The rise in capital costs of offshore wind since 2005 can be attributed to a number of effects, in particular:

  • Rising commodity prices
  • Supply and demand tightening
  • Technical issues
  • Supply chain constraints - vessel availability
  • Exchange rates

Over the period 2005-2008 commodity prices rose substantially - peaking in summer 2008 with oil at $150/barrel and coal at over $220/tonne. The rise in commodity prices partly driven by changes in exchange rates has a knock on impact on the cost of manufacturing turbines and components. For offshore wind it is estimated that around half of the increase in turbine prices can be explained by globally rising commodity and materials costs (Carbon Trust, 2008).

Together with rising commodity prices the wind turbine industry began to rapidly accelerate after 2005. This expansion began to place strain on the supply/demand balance as demand outstripped supply. In addition, most of the offshore wind turbine technology applied to date has essentially been marinised versions of the largest onshore wind designs. This has had a key impact on the market - the engineering challenge required to operate in the marine environment is considerable and some of the early offshore turbines have experienced multiple failures, particularly in gearboxes.

Such failures increased the perceived risk associated with supplying machines offshore. As a result manufacturers had less incentive to develop offshore turbines given the very buoyant and less risky onshore market. Over the 2007/8 period the offshore industry was effectively reduced to a single supplier (Siemens Wind Power). Furthermore wind turbine manufacturers have sought to increase the profitability of their operations in a more mature onshore wind market, leading to greater margins and less aggressive pricing strategies and therefore higher costs. While new suppliers are entering and re-entering the market, and both GE and Siemens have announced plans to build capacity in the UK, the market cannot be described as oversubscribed.

Since 2007 the limited availability of installation vessels has led to a large increase in day rates. In addition the availability of electrical equipment, such as transformers and subsea cables, has been in short supply - with upward price pressure resulting. To address this market shortage new vessels have been commissioned as highlighted by the Offshore Valuation Group (2010).

The value of sterling has dropped dramatically against the Euro since mid 2008. The result has been that prices for UK projects approaching agreement on major construction contracts substantially increased.

Table 2.3.2 shows the impact of changes in capital costs on the overall lifetime levelised cost of offshore wind and compares offshore wind to the current cost of onshore wind. Clearly offshore wind is substantially more costly than onshore wind - with current costs over £125/ MWh5.

Table 2.3.2: Cost Components and Levelised Costs.

Onshore wind

Offshore wind

Capex* (£/kW)

1,200

2,000

2,600

3,000

Fixed operating costs (£/kW)

25.1

52.5

52.5

52.5

Discount rate

10%

10%

10%

10%

Load factor

30%

40%

40%

40%

Life (years)

20

20

20

20

Lifetime levelised cost (£/ MWh)

69

88.7

110.9

125.6

In addition to high costs problems with installation and construction at some offshore sites have also exacerbated the investment risk, and the perception of risk, associated with offshore wind development.

Given our assessment of the factors discussed above we do not consider that the costs of investment in offshore wind will change dramatically from current levels over the next 3-5 year period. Indeed costs appear to be continuing to rise. As a result, given forward electricity wholesale prices of around £40-50/ MWh combined with the currently high capital cost of offshore wind, increased ROC support is likely to continue to be required for increased offshore development to be undertaken by 2020. Given currently high capital costs and the challenges of developing offshore compared to onshore, we have limited offshore development in Scotland in Scenario 1 to around 1.5 GW by 2020. Scenarios 2 and 3 show the impact of higher growth rates for offshore wind.

Wave and Tidal

The Scottish Government's Forum for Renewable Energy Development in Scotland's ( FREDS) Marine Energy Group ( MEG) report of 2009 suggests that, in a central scenario, up to 1 GW of marine energy in Scottish waters may be feasible by 2020, with an upper scenario of 2 GW and a lower scenario of 500 MW (Marine Energy Group 2009). The 2009 MEG report represents a revision of its assessment in 2004 where it suggested that 1.3 GW could be provided by marine energy by 2020 (Marine Energy Group 2004).

The MEG highlighted that marine energy in Scotland has not developed as quickly as expected in its 2004 due, in part, to technical difficulties and financial constraints relating to technology development. Marine technology in Scotland, despite its ultimate technical resource, remains an infant technology.

Following MEG's earlier 2004 report, the Scottish Government commissioned an SEA to examine the potential environmental effects from the development of wave and tidal power. The SEA concluded that relative 'newness' of the wave and tidal industry compared to, for example, wind energy meant that limited information was available to fully assess the impact on the marine environment. The effect of wave and tidal devices/arrays on shipping and navigation was assessed as being of major potential significance. However, while the SEA has identified that wave and tidal devices could affect the use of the area for international navigation, further work has since been undertaken, including the first stage of the Marine Spatial Plan for the Pentland Firth and Orkney. The Scottish Government revealed the first stage of its master plan for use of Pentland Firth and Orkney waters on 29 March 2010, providing a marine spatial plan framework and draft regional locational guidance for wave and tidal energy development. In addition in 2010 the first leasing round for wave and tidal energy was undertaken, with 1.2 GW of sites identified by the Crown Estates for marine development around the Pentland Firth.

The SEA concluded that between 1,000 MW and 2,600 MW of marine renewable energy generating capacity could potentially be achieved within the SEA study area due mainly to environmental limitations. The first stage of the Marine Spatial Plan for the Pentland Firth and Orkney outlined some of the risks to achieving Scotland's marine potential, including lack of grid infrastructure and a lack of port and other land based infrastructure. The combination of these factors, together with technological issues, are likely to limit the contribution of marine by 2020.

In 2010 we expect there will be no continuously operating wave or tidal current generation in UK waters. Our assessment is based on the current status of the various prototype devices currently under development. The most advanced of these are just commencing operation but are not expected to operate continuously for an extended period in 2010.

By 2015, the first generating facilities built under Department for Energy and Climate Change's ( DECC's) Marine Renewables Deployment Fund ( MRDF) and the Scotland's Wave and Tidal Energy Research and Development Scheme ( WATERS) scheme could be operational.

The MEG report in 2009 outlined a central scenario aspiration of 1 GW. Scenario 1 considers a figure around the lower projection in the 2009 FREDSMEG report. Given the pilot stage of much of the current marine technology we consider that a realistic projection for the deployment of wave and tidal energy in Scotland compatible with meeting the 2020 renewables target for Scenario 1 may be 500 MW by 2020 rising to 1000 MW by 2030. Scenarios 2 and 3 show the impact of higher growth rates for wave and tidal energy generation.

Biomass

Scenario 1 assumes that some new biomass plant is commissioned - amounting to 300 MW by 2020, rising to 500 MW by 2030. Initially the location of biomass plant is assumed to be near forestry locations, but in the longer term imported biomass may also be used either at dedicated biomass plant, or co-firing with coal.

Hydro

Some new hydro plant is also commissioned in Scenario 1 - with the developments based on currently proposed schemes outlined in the National Grid Seven Year Statement.

Pumped Storage

At present Scotland has two pumped storage schemes at Cruachan and Foyers. SSE has proposed 2 new pumped storage schemes. The proposed schemes are on the north side of the Great Glen and, subject to final design and agreements, it is envisaged they would have an installed capacity of between 300 MW and 600 MW each and be able to produce a total of 1,000 GWh of electricity in a typical year. A smaller 60 MW scheme is proposed for the existing Loch Sloy natural flow hydro scheme. The following table shows the potential growth of pumped storage.

Table 2.3.3 Pumped Storage in Scotland

Capacity ( MW)

Annual Output ( GWh) 6

Existing Scottish Pumped Storage

700

1.2

Planned Scottish Pumped Storage

660 to 1,260

1.1

Projected Totals

1,340 to 1,960

2.3

The scenarios assume 1,340 MW of pumped storage capacity in 2030.

Thermal Plant

In terms of thermal generation, Peterhead CCGT is assumed to partially close between 2020 and 2025. Peterhead's operating characteristics are likely to change. As the level of wind generation increases the charges under the locational element of transmission pricing will increase. Hence conventional stations such as Peterhead, who cannot claim ROCs, will be under increasing financial operational pressure. Peterhead will increasingly operate flexibly depending upon the wind output - with a subsequently declining average annual load factor. As a result Peterhead will increasingly act as 'shadow' capacity.

In terms of coal-fired generation - Cockenzie power station is assumed to close by 2015 in both Scenarios. Beyond 2020 a new 1200 MW 'cleaner' coal plant, potentially with carbon capture and storage ( CCS) capability is constructed and the existing coal-fired power station at Longannet retires. As a result by 2030 1200 MW of coal plant is installed in Scotland.

It is assumed that, in line with existing Scottish Government policy, no new nuclear plant is constructed in Scotland. As a result when the existing AGRs at Torness and Hunterston are decommissioned, no nuclear capacity remains in Scotland.

Interconnectors

In this initial Scenario study we assume that the Beauly Denny reinforcement is constructed, we also assume the current plans for the East and West coast offshore transmission lines are constructed. These are described in more detail in Section 6.1.3.

2.3.2 Generation Output

Table 2.3.4 shows the generation output by plant type over the period to 2030.

As a result the fundamental electricity output mix in Scotland changes significantly, with the role of 'controllable' generation diminishing to be increasingly replaced by variable intermittent generation.

Table 2.3.4: Scenario 1 Scottish Generation Output 7

TWh

2008

2015

2020

2030

CCGT

6.7

8.4

6.9

3.2

Pumped Storage

1.0

1.1

1.6

2.1

Biomass

0.9

1.1

2.2

3.7

CHP

1.9

2.0

2.9

3.8

Coal

14.8

6.3

5.3

3.1

Hydro

2.9

2.7

3.0

2.9

OCGT

0.0

0.0

0.0

0.0

Other

0.6

0.4

0.4

0.4

Offshore Wind

0.0

1.8

5.4

10.6

Onshore Wind

5.0

13.4

17.1

19.8

Nuclear

14.3

8.5

7.8

0.0

Tidal

0.0

0.0

0.5

0.9

Wave

0.0

0.0

0.7

1.4

Total

48.2

45.8

53.6

51.9

Total Renewable Generation

9.1

19.2

29.1

39.5

Gross Consumption

37.1

36.9

38.1

42.2

Renewables as % of Scottish gross consumption

25%

52%

76%

94%

The table highlights three key points:

  • Total Scottish electricity output rises by around 17% by 2020, primarily due to the increase in renewable capacity comes on line.
  • The 2020 target of satisfying 50% of Scotland's electricity demand from renewables is achieved as renewable capacity increases and;
  • Wind generation alone accounts for some 42% of Scottish generation output in 2020, with the majority onshore wind operating at an annual average load factor of around 30%.

2.3.3 Scottish Generation Summary Scenario 1

The current Scottish renewable generation targets will have some potentially key impacts on Scottish generating capacity over the period to 2020:

  • Total Scottish generating capacity rises markedly, increasing from around 12 GW today to 17 GW by 2020 and close to 18 GW by 2030.
  • The rise in capacity is driven by renewables, in particular wind, which begins to dominate Scottish generating capacity. By 2020 renewables account for over 60 per cent of Scottish capacity, rising to 80 per cent by 2030.
  • In the absence of any demand side management and/or storage schemes, in order to maintain system security, larger amounts of 'back up' capacity will be together with grid reinforcement, as shown in the Scenario developed, further detail in Section 6.

2.4 Scenario 2

In Scenario 2 we assume that Scottish renewable capacity expands further, in line with recent indications from the offshore wind sector and the bidding for offshore licences. This Scenario also further 'stress tests' the system by assuming a larger increase in renewable generation capacity, while maintaining the same level of thermal generation as outlined in Scenario 1.

Table 2.4.1: Scenario 2 Scottish Generation Capacity ( MW)

MW

2008

2015

2020

2030

CCGT

1,524

1,524

1,524

1,200

Pumped Storage

740

740

1,040

1,340

Biomass

123

150

400

600

CHP

275

313

368

478

Coal

3,456

2,304

2,304

1,200

Hydro

1,340

1,361

1,407

1,407

OCGT

55

55

55

55

Other

92

49

49

49

Offshore Wind

0

500

6,400

11,200

Onshore Wind

1,915

5,000

6,000

6,500

Nuclear

2,332

1,200

1,200

0

Tidal

0

0

300

500

Wave

0

0

400

800

Total

11,852

13,197

21,448

25,330

Renewables as % total capacity

29%

53%

70%

83%

In Scenario 2, by 2020 total installed capacity in Scotland increases from around 12 GW to 21.5 GW. The increase in capacity over the period to 2020 is driven by renewables - with over 12 GW of wind, 700 MW of marine and 400 MW of biomass capacity installed by 2020. By 2030 offshore wind increases to 11.2 GW, onshore to 6.5 GW, biomass to 600 MW and marine to 1.3 GW.

Table 2.4.1 shows the resulting output from the capacity mix outlined above, when assessing Scotland within a GB context. The results show that total Scottish generation output increases to over 70 TWh in 2020 and 78 TWh by 2030 compared to current output of around 48 TWh.

Scottish generation output becomes dominated by renewables. By 2020 65% of Scottish generation output is renewable, rising to 86% by 2030, with the majority of renewable output from intermittent sources of generation. The output of thermal generation declines and the load factor of the thermal plant reduces as thermal generation is displaced by additional, low marginal cost renewable generation.

In terms of the target of meeting 50 per cent of Scotland's electricity demand from renewables, this is achieved in 2015. By 2020 Scotland is producing electricity considerably in excess of demand. We analyse the impact of this generation output in Section 6.

Table 2.4.2: Scenario 2 Scottish Generation Output ( TWh)

TWh

2008

2015

2020

2030

CCGT

6.7

8.1

6.3

2.3

Pumped Storage

1.0

1.3

1.7

2.0

Biomass

0.9

1.1

3.0

4.4

CHP

1.9

2.0

2.9

3.7

Coal

14.8

6.9

5.3

2.8

Hydro

2.9

3.1

3.0

2.7

OCGT

0.0

0.0

0.0

0.0

Other

0.6

0.4

0.4

0.4

Offshore Wind

0.0

1.8

22.6

39.9

Onshore Wind

5.0

13.4

15.7

17.1

Nuclear

14.3

8.5

7.8

0.0

Tidal

0.0

0.0

0.7

1.2

Wave

0.0

0.0

0.9

1.8

Total

48.2

46.6

70.3

78.3

Total Renewable Generation

9.1

19.6

46.1

67.3

Gross Consumption

37.0

37.0

38.3

42.5

Renewables as % of Scottish gross consumption

25%

53%

120%

158%

2.5 Scenario 3

Scenario 3 represents a more ambitious view of the potential role of renewable generation in Scotland. This is Scenario represents a transformation of the electricity sector and would have much more significant challenge in terms of investment, grid infrastructure etc.

Scenario 3 is strongly informed by the bidding for the recent offshore wind, wave and tidal sites. While not all of these sites will come to fruition, there is also potential for further licence rounds in the period to 2020.

Table 2.5.1: Scenario 3 Scottish Generation Capacity ( MW)

MW

2008

2015

2020

2030

CCGT

1,524

1,524

1,524

1,200

Pumped Storage

740

740

1,040

1,340

Biomass

123

150

400

600

CHP

275

313

368

478

Coal

3,456

2,304

2,304

1,200

Hydro

1,340

1,361

1,407

1,407

OCGT

55

55

55

55

Other

92

49

49

49

Offshore Wind

0

3,000

11,200

15,000

Onshore Wind

1,915

4,000

5,000

6,000

Nuclear

2,332

1,200

1,200

0

Tidal

0

0

400

800

Wave

0

0

600

1,200

Total

11,852

14,697

25,548

29,330

Renewables as % total capacity

29%

58%

74%

85%

By 2020 total installed capacity in Scotland increases from around 12 GW to 25.5 GW. The increase in capacity over the period to 2020 is driven by renewables - with over 16 GW of wind, 1 GW of marine and 400 MW of biomass capacity installed by 2020. By 2030 offshore wind increases to 15 GW, onshore to 6 GW, biomass to 600 MW and marine to 2 GW.

Table 5.2 shows the resulting output from the capacity mix outlined above, when assessing Scotland within a GB context. The results show that total Scottish generation output increases to 84 TWh in 2020 and 91 TWh by 2030 compared to current output of around 48 TWh.

Scottish generation output becomes dominated by renewables. By 2020 73% of Scottish generation output is renewable, rising to 88% by 2030, with the majority of renewable output from intermittent sources of generation. The load factor, and thus output, of thermal plant reduces further in Scenario 3 as the economic dispatch model 'runs' thermal plant below low marginal cost renewables.

In terms of the target of meeting 50 per cent of Scotland's electricity demand from renewables, this is achieved in 2015. By 2020 Scotland is producing electricity considerably in excess of demand. This Scenario shows the outcomes that could occur if all existing plans for generation were realised plus a number of additional developments that could follow on from the recent licensing activity.

Table 2.5.2: Scenario 3Scottish Generation Output ( TWh)

TWh

2008

2015

2020

2030

CCGT

6.7

8.0

6.1

1.9

Pumped Storage

1.0

1.2

1.7

2.2

Biomass

0.9

1.1

3.0

4.4

CHP

1.9

1.9

2.9

3.6

Coal

14.8

6.7

4.3

2.6

Hydro

2.9

3.0

2.9

2.8

OCGT

0.0

0.0

0.0

0.0

Other

0.6

0.4

0.4

0.4

Offshore Wind

0.0

10.6

39.6

52.7

Onshore Wind

5.0

10.6

13.1

15.8

Nuclear

14.3

8.5

7.7

0.0

Tidal

0.0

0.0

0.9

1.8

Wave

0.0

0.0

1.4

2.8

Total

48.2

52.1

83.9

91.0

Total Renewable Generation

9.1

25.5

61.1

80.5

Gross Consumption

37.0

37.0

38.4

42.7

Renewables as % of Scottish gross consumption

25%

69%

159%

189%