Battery supported charging infrastructure for electric vehicles : And its impact on the overall electricity infrastructure

University essay from KTH/Skolan för industriell teknik och management (ITM)

Abstract: The Paris Agreement was formed in 2015 to reduce the environmental impact and limit the increase in temperature to 2°C compared to pre-industrial levels. It is believed that an electrification of the transport sector will reduce its negative environmental impact. To reach the goals set by the Paris Agreement we are in need of quick development towards an electrified fleet of vehicles. Despite this urgency electric vehicles (EVs) have failed to reach the majority of the market, instead it has stuck in the chasm between the early adopters and the early majority of the markets. This is due to three main challenges; EVs are relatively expensive compared to conventional petrol- and diesel-powered vehicles, EVs have an inadequate driving range, and the access to a functional charging infrastructure is limited. This thesis focuses on the third challenge regarding charging infrastructure. The charging infrastructure is dependent on the existing electricity distribution infrastructure, i.e. the grid. It is rather time-consuming and costly to strengthen the grid, which is deemed necessary for enabling a roll-out of a charging infrastructure that meets the needs of current and near-future EV operators. This research provides an alternative way of approaching the issues. Instead of strengthening the grid by digging up old cables it looks into the opportunities of incorporating stationary battery storages as a buffer between the EV charging stations and the grid connection point. This battery solution can reduce the power outtake and smoothen out the load from EV charging, thus limiting the impact of EV charging from a grid perspective. The research assesses what type of pathways this solution could follow to successfully drive the adoption of EVs. Furthermore, the study tries to understand how these solutions could be designed to deliver the necessary values regarding EV charging and reducing the overall power outtake from grid connection points. The thesis is carried out by analyzing collected quantitative and qualitative data through the lens of three main theories. These are transition theory, theory on eco-innovations, and theory on the diffusion of innovations. The thesis finds that the two pathways for a battery supported charging infrastructure that will be most efficient in speeding up the adoption rate of EVs is within a workplace and public charging setting in city and urban environments. For both pathways it is expected that a centralized concept, with one battery solution connected to several charging points, will be most feasible in the short-term, which is important as the need for developments are very urgent. The workplace charging will provide 3,6 kW AC-charging while the public charging provides 150 kW DC-charging. The solution is expected to be cost-efficient for specific locations, especially for public charging in city environments with strained grid infrastructures. The study provides an initial assessment for the city of Stockholm which indicates that the power outtake can be reduced by 63,5–112,2 MW in 2030. This means that the current grid infrastructure could support a larger number of EVs, thus reducing the greenhouse-gas emissions from the transport sector and bringing us closer to reaching the goals set by the Paris Agreement.

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