When the Sun goes down : Solar Energy Storage in the Neighborhood

Abstract

Anthropogenic global warming poses a great challenge for our society and the earth's ecosystem, and this requires decisive action. Therefore, the focus of this PhD thesis is on two options that can potentially reduce greenhouse gas (GHG) emissions: the deployment of photovoltaic (PV) electricity generation and its integration through the use of batteries, and the operation of an increasing amount of electric vehicles (EVs) resulting from a switch from vehicles with an internal combustion engine to EVs.

The first research of this thesis determines the GHG emission reduction potential of so-called Energy Communities in which PV systems, batteries, EVs and heat pumps are deployed in eight European countries. Taking the full life cycle of these technologies into account, it is shown that these technologies can reduce the emissions of an energy community by 55-73%. However, it is also found that stationary batteries increase the emissions of the energy community.

This last finding signifies the importance taking GHG emissions into account when operating a battery. For this purpose, marginal emission profiles are developed to be used as input for emission optimization. In a next research, a multi-objective optimization of costs and emission is performed. It is shown that emissions associated with electricity consumption of a community can decrease with 57% when a community battery is used to minimize the community’s emissions at limited additional cost. A balanced charging schedule is also presented, in which costs and emissions can be decreased simultaneously, i.e. by 9.5% and 27.2%, respectively. This analysis is expanded to study smart charging and vehicle-to-grid (V2G) when deploying EVs. It is shown that in case of smart charging, emissions can be decreased by 24% compared to uncontrolled charging and by 67% when applying V2G. Further, EVs’ cost and emissions can be decreased simultaneously; a balanced schedule results in a cost reduction of 17.9% accompanied with an emission reduction of 15.9% in case of smart charging, and a cost reduction of 13.9% accompanied with an emission reduction of 50.8% in case of V2G.

In the last part of the thesis, we address the limited availability of PV-generated electricity in peak load hours. We show on the distribution system level that batteries, optimal-sized for PV self-consumption, can decrease the community’s peak load by 51%. On the power system level, we provide insights on the contribution to the resource adequacy of PV when coupled with batteries and EVs using the Capacity Value Ratio (CVR), which is the expected output of technology divided by its capacity. The CVR of PV systems can be increased from 1% to 47% when they are coupled to batteries. The CVR of smart charging was found to be 78% and the CVR of V2G 9%.

In conclusion, findings show the large economic, technical and environmental contribution that battery-based energy storage can have in the energy system. Policy measures to provide appropriate incentives, guided by an overall vision on the energy transition, are recommended to steer the operations of flexible distributed resources towards a sustainable future.