Balancing of wind and solar power production in Northern Europe with Norwegian hydropower
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- Institutt for elkraftteknikk 
The European Union (EU) aims to reduce the green-house-gas emissions from the power system to nearly zero in 2050. The future power system in Europe will include high share of variable wind and solar resources. Norway has nearly half of the hydropower storage capacity in Europe, about 84 TWh. The flexible Norwegian ydropower is a possibility for balancing variable production in neighbouring countries, like Germany, the Netherlands and United Kingdom. A previous study, "SINTEF Energi. TR A7195. Increased balancing power capacity in Norwegian hydroelectric power stations", showed how the Norwegian hydropower generation capacity can be increased from presently approximately 30 GW to 41 and further to 49 GW. The study assumed no increase in reservoir capacity. The overall research question investigated in this thesis is if Norway can have a role in balancing large-scale renewable power production in Europe in the future. The overall question is broken down to four sub-questions: 1. a) What will the variability of high shares of wind and solar power production in a future European power system be? b) What will the need for balancing and storage of that production be? 2. Can increases in the Norwegian hydropower generation capacity combined with increases in interconnectors between Norway and other countries contribute to balance variable production in Europe in the future? 3. How will increases in the Norwegian hydropower generation capacity combined with increases in interconnectors between Norway and other countries influence the Norwegian power system in the future? 4. How will two different methodological approaches for optimisation of dispatch in a power system with pumped storage and high shares of variable wind and solar resources influence the results of the analyses? Investigation of question 1 for West-Central Europe (United Kingdom, Ireland, France, Belgium, the Netherlands, Luxembourg, Germany, West-Denmark, Switzerland, Austria, Slovenia and the Czech Republic) uses hourly weather data from the COSMOEU model for 2011-2015. Furthermore, it uses assumption about wind and PV power capacities from four different scenarios from the EU 7th Framework project eHighway2050. It assumes no limitations in transmission capacities and analyses in a first step the hour-by-hour wind and PV power production. The analyses show a volatile production varying between about 2 % to 65 % of installed capacity for the whole West-Central Europe. The variability is analysed for the countries separately, and for the whole region assuming no limitations on interconnectors. Grids only to limited degree smooth out the hourly variability in wind and PV power production for this region. In a next step, the net load (the load minus the wind and the PV power production) is calculated. Consecutive periods with low production are in this thesis defined as periods where the net load is above its 80 percentile. For three out of four scenarios the longest periods with low production are around 125 hours. The scenario with the highest share of PV power capacity relative to the total wind and PV power capacity has the lowest mean production and the highest variability in terms of minimum values, 10 percentiles, ramps and long consecutive periods with low production. The assessment of the need for balancing and storage uses an eHighway2050 scenario where the wind and PV plants supply 67% of the annual demand in West-Central Europe. It splits each year into twelve equal periods and assumes that base load production that is equal to the mean net load supplies the net load in each period. The need for storage, calculated as the aggregated annual sum of the hourly deviation from the base load production, is between about +21 TWh (filling) to - 23 TWh (depleting). The hourly need for balancing capacity, calculated as the deviation between the mean net load and the hourly net load, varies between about +300 GW and - 200 GW. Answers to the three last research questions are based on assumptions about installed power production and transmission capacities, annual demand and fuel prices from the eHighway2050 scenario 100 % renewables (wind, radiation, hydro and bio). 75 years with hourly weather data are constructed based on historical data for inflow to the Norwegian and Swedish hydropower systems and Reanalysis data for wind and solar radiation. Capacities in the Norwegian hydropower system are increased from presently about 30 GW to 41 GW and further to 49 GW based on findings in “TR A7195”. Simulations of the whole European power system use two different stochastic optimisation models: 1) EMPS, a model used for decades in the Nordic region and 2) SOVN, a prototype developed to take into account unpredictable fluctuations in unregulated generation. Research question 2 is answered by studying the effects that an increase in Norwegian hydropower generation capacity has on smoothing power prices in neighbouring countries. In the simulations, an increase in the hydropower generation capacities significantly reduce peak and average prices in Germany, United Kingdom and the Netherlands. The results are case sensitive due to periods with rationing of demand and rationing prices of 10000 Euro/MWh (according to eHighway2050). However, including a possibility for demand reduction/flexibility of 5 % for time steps where the power prices are above 350 Euro/MWh, removes all needs of rationing of demand and results in less volatile prices. Analyses with both 5 % flexibility in demand and 11 GW increases in Norwegian hydropower capacities show that the prices are further reduced with 14 % in average for e.g. United Kingdom compared to the case with present hydropower capacity in Norway and the mentioned demand flexibility. Producers with increases in production capacity, without pumping capacity, lose money due to the reduced prices. The studies show that the increased hydropower capacity is only partly utilised. SOVN manages to reduce the peak prices and smooth out prices to a much larger degree than EMPS. The great price reduction is due to better capability of SOVN to uncover short-term variability in a complex hydropower system. Two prerequisites for a power system in Europe based on high share of wind and solar resources are public acceptable prices and secure supply. By showing the effect on power prices and reduction of rationing, this thesis has shown that Norwegian hydropower can contribute to balance variability in wind and solar power production in neighbouring countries in the future. In such a way, Norway can contribute to make EU's ambitions about a power system with low emissions of green-house-gases possible.