2015-09, Menn, Claudio, Geissler, Achim

Battery energy storage (BES) systems for residential buildings can contribute to power grid stability. The demand for decentralized storage capacity in Switzerland is expected to rise due to political decisions that facilitate renewable energies with power fluctuations such as photovoltaics (PV). Using lithium based BES to meet this demand could have a significant environmental impact as a result of energy intensive production-processes. Furthermore, currently available conventional BES (C-BES) systems are not eco-nomically viable. Within this context, a second use of electric vehicle batteries for 2nd-life-BES (2nd-BES) can be an environmentally sound alternative that facilitates grid integration of residential PV-systems. A model describing the economic viability of 2nd-BES based on the Net Present Value (NPV) method is presented. On the basis of one example building each, results are given for single-family-houses (SFH) and multi-family-houses (MFH), focusing particularly on the market situation found in Switzerland. Results show a cost advantage for 2nd-BES in MFH compared to C-BES systems if a Cycle Life (CL) of 800 and more is available. In SFH, a 2nd-BES shows only a slightly better economic performance than a C-BES system if a CL of 4800 and more can be guaranteed. Notwithstanding the relatively low Levelized Cost of Electricity (LCOE), the NPV for both 2nd-BES and C-BES in both SFH and MFH is negative. Reasons for this are high initial system costs and an electricity tariff scheme with low incentives for con-sumers to store electricity. In this paper, only the current tariff structure in Switzerland is considered. However, alternative tariff schemes, e.g. real time pricing for residential consumers, have become reality in some countries. The impact of such tariff schemes on the economic performance of 2nd-BES is left to future research.

2015-08, Kim, David Pascal, Geissler, Achim, Hengevoss, Dirk, Menn, Claudio

Aufgrund der Energieperspektiven 2050 des schweizerischen Bundesamtes für Energie (BFE) wird das zukünftige Potenzial von gebrauchten Lithium-Ionen-Batterien aus Elektrofahrzeugen als stationäre Stromspeicher in Gebäuden untersucht. In drei Szenarien wird der Umweltnutzen für das Jahr 2035 und 2050 ermittelt. Hierzu wird berechnet wie viel Kapazität an herkömmlichen Speichern durch eine gewisse Kapazität an wiederverwendbaren gebrauchten Batterien substituiert werden kann. Das Substitutionspotenzial wird mit ausgewählten Wirkindikatoren wie dem Treibhauspotenzial (GWP) und dem kumulierten Energieaufwand (CED) analysiert. Im Jahr 2050 können dadurch 760 bis 1170 MWh an herkömmlichen Speichern durch 2nd-Life-Speicher substituiert werden. Dabei kann das Treibhauspotenzial pro Jahr um 11'000 bis 16'000 t CO2 Äq gesenkt und der kumulierte Energieaufwand um 207'000 bis 305'000 GJ verringert werden. Die Resultate zeigen, dass der Einsatz von 2nd-Life-Batterien in stationären Anwendungen einen signifikanten Beitrag zur Reduktion der Umweltbelastung von Batterien beitragen kann.