What are the benefits of smart and bidirectional charging for users today and in the future?

Smart charging (the ability to control charging processes through time shifting and power control) and bidirectional charging (additional discharging of electric vehicles) are essential for the decarbonization of the electricity sector. From an energy system perspective, these charging and discharging strategies can help to integrate electric vehicles (EVs) in an efficient and beneficial way.

To accelerate the ramp-up of EVs, corresponding use cases of smart charging and bidirectional charging should not only be beneficial for the energy system, but also offer financial value for private users of EVs. Different use cases, such as trading on the spot markets or optimizing self-consumption of PV electricity, have the potential to render use cases profitable for users, even taking into account the associated additional costs. What’s more, smart charging strategies offer the opportunity to save additional greenhouse gas emissions by reducing the emissions contained in the electricity that is charged into the EV.

Journal paper evaluating the profitability and emission savings of exemplary use cases

In a new FfE publication, the use cases spot market trading, PV self-consumption optimization and the combination of both cases (multi-use) for smart unidirectional charging and bidirectional charging in German households are simulated and analyzed using the FfE model eFlame. The approach includes sequential spot market trading on the day-ahead market, the intraday auction and the continuous intraday market. For the multi-use case, both individual use cases are applied simultaneously. In addition to the base cases, various sensitivities (levy exemption, battery ageing, commuters, etc.) are examined. The most important features of the journal paper are:

  • realistic scenarios for today (2021, 2022) and the future year 2030,
  • incorporating additional costs of the technologies to assess their economic viability, and
  • the assessment of operational greenhouse gas emissions, expressed in kgCO2-equivalents.

The results presented in the paper show that smart charging is profitable in most cases today and in all cases in 2030 and enables annual electricity cost savings of over € 500 per EV compared to simple direct charging (uncontrolled charging). Bidirectional charging, which today is only profitable for the multi-use case of PV self-consumption optimization plus spot market trading, will be consistently profitable in 2030 with electricity cost savings of between € 300 and € 2,700 per EV per year. The figure below shows an example of the results of the profitability analysis for the base year 2021 for the multi-use case.

Figure: Exemplary results on profitability and emission reduction of bidirectional charging compared to direct charging for the 2021 scenario per vehicle (EV) and year based on 200 individual simulation runs of the eFlame model [figure from paper, https://www.sciencedirect.com/science/article/pii/S0306261924010626#s0215]

The most important influencing factors include specific annual price characteristics, user behavior, charging restrictions and regulations for supplied electricity. In terms of emissions for the 2021 and 2022 analysis, some charging strategies reduce operational greenhouse gas emissions, while others increase emissions. The application of smart and bidirectional charging is therefore not always beneficial in terms of emissions at present. In 2030, however, emissions decrease in all cases, which is positively influenced by a lower greenhouse gas intensity of the German electricity mix and less restrictive limitations on charging and discharging processes.

All results and conclusions are presented and discussed in detail in the open access paper “Prospects of electric vehicle V2G multi-use: Profitability and GHG emissions for use case combinations of smart and bidirectional charging today and 2030” of the Applied Energy Journal. The paper can be found here.