The area Electrification Suite & Test Lab (ESTL) is dedicated to electric mobility that reduces local emissions and improves the quality of city living. For a seamless integration into the power system, demand side management strategies are under investigation. In order to make the electricity supply “greener”, alternative sources of energy and their storage options are considered, both from within and outside of Singapore. On-the-road charging and improvement of reliability using stationary energy storage systems are developed in close cooperation with area Rapid Road Transport as the charging infrastructure is mutually dependant on the Semi Rapid Transport layer. Design alternatives for the charging infrastructure in the presence of modular and scalable vehicles are also under investigation.
a) Charging infrastructure and strategies
We develop smart charging strategies and a charging infrastructure for electric public transport vehicles. This builds on our work in Phase I when we developed smart charging strategies for private electric vehicles. The term smart charging refers to the power system as well as to the in-vehicle battery. That means, the battery is preferably charged when market electricity prices (and consequently the load) are lower and the charging process itself is gentle on the battery with minimal reduction of the battery’s lifetime. In contrast to private vehicles, public transport vehicles such as taxis or buses have low standstill times and therefore require to be charged at high power in a short time. This makes smart charging much more challenging. Our research in this area focuses on smart charging strategies and an optimal charging infrastructure for public electric transport vehicles.
b) Demand side management for efficient operation of the electric transport system
Even if smart charging is applied, charging of electric vehicles leads to higher overall power demand. Especially the additional power demand for fast charging can be a challenge for the distribution grid. The purpose of our research is to minimise the grid impact of the electrification of public transport. Therefore, we first identify demand hot spots by analysing buildings and traffic. The results are used to identify strategies for optimal scheduling of electric loads, i.e. consumers of electricity. These measures are called demand side management and demand response and they can be applied to all kinds of consumers of electricity such as buildings, electric transport etc. We implement software tools and develop hardware demonstrators to demonstrate our results in real-life applications.
c) Integration of renewables for a sustainable transport system
Electrifying the transport system lowers local emissions of heat, noise and pollutants. Due to the high efficiency of electric motors, energy demand and consequently overall emissions decrease as well. However, in order to make electric vehicles more sustainable and to significantly reduce emissions, particularly of greenhouse gases such as CO2, increased share of renewable sources for electricity generation is essential. In Singapore, the kind of renewable source of energy with the highest potential is solar photovoltaics (PV). However, rapid changes of weather conditions are common in Singapore. Hence, the solar irradiance could drop to zero all over Singapore within minutes. Consequently, electricity generation from PV would quickly drop to zero as well. We work on the integration of PV and possible measures to cope with rapid changes of electricity production from PV. In this context, we also consider stationary storage systems to provide relief to the grid.