På väg mot en elförsörjning baserad på enbart förnybar el i Sverige En studie om behov av reglerkraft och överföringskapacitet Version 4.0 Lennart Söder Towards a power supply based on renewable energy only in Sweden A study of the need of regulating power and transmission capacity

Background 4th version in a series of studies Differences from version 3 Sweden divided into 4 areas Transmission capacities between these areas have been studied Costs of gas turbines are higher

Research questions How can the balance between consumption and production be maintained in a system with a large share of renewable energy? What is the change in need of regulating power and transmission capacity in case of a larger share of renewable power production? Is it possible to integrate 60 TWh of wind and solar power (corresponds to 43% of the total electricity consumption and 40% of total production)?

Input data Data for wind power production from 1992, base case 4000 MW Scaled to match the production of a better, modern wind power plant Data for solar power production from 1999 Data for maximum and minimum hydro power production from 2008 Electricity consumption from 2011 (139,2 TWh/year) All data averages for 1-3 hours

Assumptions Sweden isolated from neighbouring countries 50% increase of CHP in each area compared to levels in 2011 Possible to decrease CHP production with 75% compared to planned level Nuclear power phased out Reserves: gas turbines No forecast errors accounted for Wind + solar production maximum 83% of total consumption Losses proportionally distributed in the four areas

Methods 1/2 Guarantee method instead of LOLP-based method Minimum amount of power produced guaranteed 90% of the time Balanced calculated for the entire country Balanced calculated for each area Adjustments Simplified calculations to enable use of Excel and to make the results easy to understand

Methods 2/2 In case of surplus, decrease of CHP first, then wind and solar power In case of deficit, use of non-spinning reserves Distribution of losses and power production Transmission between areas Adjustment to match transmission capacity

Transmission capacity

Scenarios Case A1 48 TWh wind power ( MW, 2013: 4470 MW) + 12 TWh solar power ( MW, 2011: 15,8 MW) Same distribution as in original report (50% of wind power capacity in SE4) Unlimited transmission capacity Case A2 Same as A1, but transmission capacity limited: SE2  SE MW, SE4  SE MW Case B1 48 TWh wind power + 12 TWh solar power Wind power distribution according to recent development (40% in SE3) Case B2 Same as B1, but transmission capacity limited as in A2

Hourly energy balance in Sweden (Case A1)

Results 1/3 Case A1 results Case A2 results Case B1 resultsCase B2 results

Results 2/3 Case A1: SE1, SE2 and SE4 export areas Hourly variations more common but not bigger Variations in four hours more common and bigger Case A2: More reserve power production needed than in Case A1 Case B1: SE1 and SE2 export areas Larger transmission volumes from SE1  SE2 and SE2  SE3 than in Case A1 Less reserve power production needed Case B2: More reserve power production needed than in Case B1

Results 3/3 In all cases the transmission capacity need to be increased, cost around 2 öre/kWh Increased operational costs but less need of transmission capacity in Case 2 When transmission is large from SE1  SE2, there is also a lot of hydro power production Electricity consumption varies more than a large amount of wind power from hour to hour  no dramatic change in regulating power needed Location of wind power plants significant for transmission capacity

Further studies could include: Calculations for windy or dry years etc., here only an average year Analysis of future electricity market Analysis of effect of forecast errors Study of a larger area, e.g. all Nordic countries Closer study of the transmission capacity between areas (voltage) Study of economical methods to get renewable energy also from reserves, e.g. gas turbine driven by bio gas Study of how an insignificant amount of nuclear power affects the NTC (can only be done by Svenska Kraftnät)

Summary No actual wind data All data only from one year Reliability not calculated with a LOLP-based method Voltage variations in grid and affect on transmission not studied Import and export possibilities haven’t been taken into account

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