Nyhet | 2016-09-30 | 12:54

Grid scale battery energy storage systems – opportunities for DSO’s in Sweden

Master of Science thesis by Paulina Erikson Brangstrup and Magnus Johnson at The Royal Institute of Technology (KTH).

Supervisors at Vattenfall: Johan Grelsson and Tom Nordin.

Abstract

A central pre-condition for a stable electrical grid is that supply needs to equal demand at every point in time. The challenge of this objective lies in the electricity system’s just-in-time characteristic where electricity cannot be stored, meaning that electricity generation need to be instantly regulated according to fluctuating demand. Large scale-deployment of intermittent renewable generation has complicated this objective even further, since grid operators have to worry about fluctuating supply as well, which creates challenges in maintaining system stability. This constitutes one of today’s many challenges associated with operations of an electricity system.

In the transition towards a more efficient and resilient electricity system, electrical energy storage is seen as an important component. Battery energy storage (BES) has recently received attention for grid scale applications due to rapid technological advancements and cost decline.

The purpose of this study is to identify opportunities for Distribution System Operators (DSOs) in Sweden to implement battery energy storage (BES). The research was conducted as an experimental case study at Vattenfall Distribution, one of Sweden’s largest DSOs. The findings presented in this reports are based on data collected through multiple research methods such as interviews with internal as well as external stakeholders, database searches and archive searches. By studying the overall benefits of BES, the legal status of BES, the DSO role and the current regulatory environment in which the DSO is operating, we found a total of five benefits available for DSOs in Sweden.

Our findings show that DSOs in Sweden can benefit from BES by reducing charges to overlying grids, deferring or avoiding grid investments and to increase quality of supply of electricity towards consumers in terms of increasing reliability, voltage support and increasing power quality. From evaluating these benefits using the current regulation and incentive structures our findings show that the most promising benefit of implementing BES as for today lies within the long-term financial benefit of adding incremental capacity to the grid, thereby enabling deferral or avoidance of capital expenditures in grid infrastructure.

Even though using BES to defer or avoid investment shows to be an attractive application in this study, the current regulatory environment in Sweden is not adjusted in a way that enables the full value from this technology to be assessed. Despite these regulatory barriers, this study furthermore identifies new trends in Sweden’s electricity consumption. These trends could increase the demand for BES in the electricity system within a near future, which could induce regulatory changes in which incentives for BES implementation would be more appealing.