Reusing electric vehicle batteries in storage units for smart grid concept

Many studies have been conducted in our country and in the world to overcome gradually increasing energy demand. Cleaner energy production and lower emission has taken into account. Renewable energy resources (RER) like wind, sun which has no limit and no negative impact on environment has been good alternative in energy production. Moreover, electric vehicle (EV), which is higher efficient and less emission, is also good solution considering big contribution of emission caused by transportation. However, RER integration takes long time because its intermittent nature makes connection difficult. Additionally, EVs are not getting popularity as expected because of high battery price. Reusing discarded EV batteries is offered to solve two problems at the same time. Accordingly, reusing batteries of EVs have provided cheap energy storage units in order to stabilize RER production. Battery producers, users and USABC have agreed on the residual capacity of vehicle batteries is around %80 when discarded from the EVs because of insufficient capacity for range. In near future, there will be many second life EV batteries according to present EV sales. Second use of EV batteries has been important issue for more than years. Many studies are continued to test the second life of EV batteries for battery degradation, performance, impacts on energy costs. In this project, performance and degradation of aproximately %10 degraded EV test battery and its impacts on energy costs are monitored during the project when feeding a house loads which is integrated with RER. Second life electric vehicle batteries (2LEVb), which are discarded from vehicle after their capacity decreases to %80, are no longer to serve mobility. However they can still have much more energy capacity and 2LEVb can be an alternative energy storage solution. In this study, 2LEVb are used to support residential energy demands. Thus 2LEVb are used specific time in a day for optimizing energy consumption considering power curve and cost of energy. Such as 2LEVb is charged during off-peak tariff, and discharged in peak time. The obtained result of this study shows that %35 daily energy consumption of residential house is supported by 2LEVb, which decrease %28 of the energy bill. Besides, degradation of 2LEVb for seven years is %1. Proposed study realized with MatLab&Simulink environment.