Evaluation of available electricity storage technologies and the possible economic gain for Växjö Energi

Abstract: As the renewable energy sources are finding more place in the energy generation technologies,the Swedish energy market is also undergoing transformations. Renewable energy sources inthe energy generation system brings more volatility and price fluctuations which can mean challenges and opportunities. Svenska Kraftnät, as the authority responsible for safety and stability of Swedish transmission system, addresses the challenges with higher shares of renewable energy sources to some extent with more frequency stabilizing solutions but the electricity prices are controlled by free market which is led by NordPool. Växjö Energi is a state-owned company with energy generation facility of combined heat and power, operating in SE4 area of electricity market. As SE4 is the region affected the most with the price fluctuations, Växjö Energi is interested in analyzing the possibility of increasing their profit by utilizing the available energy storage technologies in the market in long term energy storage applications. The available energy storage solutions and the ones under development have each, their own pros and cons that this project attempts to go through from economical, technical, and sustainability perspective. Technologies such as compressed air energy storage and pumped hydro are more mature and there are more data available about them with less uncertainty. However, technologies such as gravity power module are new and there is not much information so the uncertainty of data is higher. A model has been developed in this project from earlier work of other researchers, to measure the highest possible profit for each energy storage technology in a specific price time series through electricity storage. The result suggests the compressed air energy storage, gravity power module, and pumped thermal electricity storage are the interesting technologies for further study. We show through this work that their costs and possible revenues are comparable. The future work on this subject is to include the suggested technologies with more details and adaptation to Växjö Energi conditions for more detailed and reliable results.