Increased utility of existing energy storage

The electrical grid is facing a modernization due to installations of intermittent energy production from wind and solar energy. Energy storage fulfills an important role in this modernization, with potential to store overproduced electricity and use it at a later time. By balancing electricity production and consumption with energy storage, it can provide the grid with stability, increased flexibility and reduce the grid load. An energy storage also makes it possible to keep down the dimensioning at exposed points in the grid, as in connections with high power fast charging stations. In the electrical grid of Umea Energy, there is a battery storage of 118 kWh, connected to a fast charging station for electric buses. The high power required by the charging station risked affecting nearby customers, therefore a solution with a battery storage was installed to reduce the impact. With this type of solution, a proportion of power can be retrieved from the grid and the battery storage simultaneously to the fast charging station, which contributes to the power output being smoothed out. However, solutions with battery storage are currently very expensive. To be able to justify an investment of this type of solutions, it is of interest to investigate whether it is possible to increase the utility of a battery storage in order to make the solution more profitable. The purpose of this paper is thus to examine how Umea Energy can increase the utility of a battery storage connected to a charging station and when such a solution may become an economic alternative. In this paper, simulation models have been developed in the software MATLAB to investigate whether the battery storage can be used to: 1) reduce power peaks in the neighboring residential area, where the results show that it is possible to reduce a small amount of power in the residential area but that the reduction is limited by how frequent the electric buses charges. 2) Move the load in the grid by letting the battery storage discharge during peak load hours and then recharge it at a later time. The result shows that it may be achievable for a certain time but it could affect the lifetime of the battery storage due to higher depth of discharge (DoD) and 3) Reduce the power during charging of the battery storage. The result indicates that the power can be reduced down to a quarter until affecting the charging schedule of the battery. The economic calculations that were carried out compared the profitability of installing a battery storage of 118 kWh to grid investments of 1) two transformers of size 800 kVA each or 2) new grid station incl. two 800 kVA transformers. The result show that there is no economic benefit for Umea Energy to install a battery storage of the investigated type of lithium titanate (LTO) or lithium iron phosphate (LFP) with prices based on 2016 but that it may become profitable with estimated prices from 2030. The conclusion that has been drawn from the simulations is that with regard of expanding the utility of a battery storage, there is only a small gain in using the battery storage to reduce power peaks. However, a lower maximum power required from the grid, can advantageously be achieved with a battery storage. In addition, the grid power can be reduced by moving the load during charging of the battery storage between the high peak hours or by reducing the power during the charging of the battery storage. With current battery prices, a battery storage is not considered a profitable investment, and therefore should only be installed to meet specific needs that would otherwise require expensive grid investments. However, the price trend for battery storage looks promising and with prices from forecasts of year 2030 it may become a competitive alternative