Impact of cell design and maintenance strategy on life cycle costs of vanadium redox flow batteries

摘要

The all-vanadium redox flow battery (VFB) is a suitable stationary energy storage system for a broad variety of applications. Many techno-economic models are described in literature in order to provide orientation in investment decisions on alternative technologies for the storage of energy from renewable sources. In a consistent approach, a sustainable investment should be based on life cycle costs (LCC) that include the expected service life, operational and maintenance costs in addition to the investment. In the present study a LCC model with a focus on production and use phase of different VFB systems is presented. A residential VFB system (1 kW, 4 kW h) and two industrial systems (1 MW, 4 MW h) are considered. The latter can be build either by numbering up of small cell stacks or by scale up of the electrode area. The impact of this design choice and different possible maintenance strategies on net present value (NPV) and levelized cost of storage (LCOS) for a system life of 20 years are assessed in detail. A main finding is the shift in the cost structure towards cell components and peripherals instead of the vanadium electrolyte which is clearly dominating when focusing on investment costs. The study reveals that LCOS are highly sensitive to E/P ratio and assumed discount rate of the investment. However, with a discount rate of 8% a profitability of VFB systems at LCOS below of 0.30 (sic) (kWh)(-1) is highly probable.