Charging Infrastructure

EV charging infrastructure is vital to the success of EV uptake in the UK due to the significantly shorter trip durations when compared to conventional vehicles due to a smaller driving range [51]. Charging infrastructure consists of three main types; slow chargers (up to 3kW), fast charging (7-22kW) and rapid charging (typically 40 to 90kW). A summary of the charge point types and their specifications is given in Table 1.

Table 1 – Example charging station ratings (taken from [52])

Charge Point Power Rating Power Supply Requirement Approx. Charge Time

3kW AC 13/16A 220-240V 6-8Hr

7kW AC 32A 220-240V 3-4Hr

21kW AC 32A 415V 1-2Hr

50kW DC 80A 415V 20-30mins

The location of charging stations across the UK is widespread, with Figure 8 demonstrating the multiple locations [53]. Whilst already fairly extensive, increasing the number of charging stations across the UK is important to ensuring timely uptake of the technology [51].

| 32 Figure 8 – Charge point locations in the UK [53]

The ULEV uptake pathway predicted by EE is heavily supported by OLEV, with the Plug-in Car Grant providing £400 million of funding to reduce the purchase price of ULEVs for customers. The scheme allows 35% of the price of a car to be paid for by the grant, up to a value of £5,000 and 20% off the price of a van, up to a maximum of £8,000 [54]. OLEV attribute the increasing success of ULEVs to this grant, along with the charging point schemes that have also been offered, including Plugged-in Places (PiP) and the electric vehicle homecharge scheme [55][56]. By March 2013, PiP had facilitated the installation of over 4,000 charging points, 65% with public access [55]. The homecharge scheme has run in two parts, with up to 75% of the installation cost for a charging post being funded through the scheme [57].

There has been much research into the development of models to predict the best location of charging stations based upon driver behaviour. Wang et al. [58] developed a non-linear multi-objective planning tool to predict the most suitable location of charging stations based on characteristics such as planning requirements, the power network capabilities, consumer practice and EV sustainable development. The final output was the creation of an algorithm able to predict the most suitable location of charging points in a changing energy and EV landscape [58]. Jia et al.

[59] performed a similar analysis for a small area in Beijing, using population rates within the city and forecasting EV uptake in combination with calculating average daily mileage and energy consumption. Charging demand was divided into slow, medium and rapid, with the planning developed around each charge type providing different results due to infrastructure and ease of access [59]. Overall results indicated rapid charging was best placed at road sides, with slower charging more suitable for inner city car parks [59]. This largely correlates with the UK charging infrastructure, with rapid charging largely occurring at motorway service stations and on busy A

Electric Vehicles and the Wider Energy System| Rebecca Gough

| 33 roads. However, Amsterdam Schiphol Airport have implemented EV taxis, indicating the need for city centre based rapid charging may become more prevalent in the future as EV and PHEV uptake increases.

Current charging infrastructure in the UK is largely located to provide the vehicle user with easy access for re-charging, with charging occurring as soon as the vehicle is plugged in [42]. However, with increasing vehicle numbers, a lack of managed charging could present issues with overloading of the electricity network. EV charging and usage models exist that explore aggregated charging of multiple EVs. One such example is the model created by Druitt and Früh [60] that follows electricity market pricing. The research used a stochastic trip generation profile and simulated 1000 EVs with random sampling of journey distributions [60]. The model looked to explore how managed charging can contribute to demand management and network grid balancing [60]. The research concluded that users would benefit from flexible electricity buying/ selling tariff structures and user demand driven charging [60]. However, the research does make several assumptions as to vehicle destination and therefore overall availability for local network balancing. Additionally, network demand data was based upon NG profiles as opposed to high grain details of specific network requirements, potentially making the results less accurate than would be possible with low voltage network data [60].

Mal et al. [61] also identified smart charging (managed, intelligently controlled charging) as an effective method of avoiding network overloading during peak demand. They calculated a 7% cost saving with charge scheduling and a 56% decrease in peak load for drivers with a variable drive schedule compared to an unmanaged system [61]. Hadley and Tsvetkova [62] identified studies in which PHEVs were preferred to pure EVs, indicating the necessity in understanding the grid support opportunities for PHEVs and PEVs. Whilst PHEV charging represents a smaller charging demand on the network than the larger batteries of pure EVs, aggregated demand can still cause performance reductions and network overloading if uncontrolled [63]. Deilami et al. [63] modelled uncoordinated charging of PEVs vs. real-time smart load management charging to demonstrate the reduced network impact through controlled charging. The model looked at random arrival and departure patterns of available 10kWh PEV batteries to demonstrate effective worst case scenario managed charging success [63].

Using Digby, Nova Scotia in Canada as a case study, Pearra and Swan [64] demonstrated the benefits of smart charging through evaluation of three EV charging strategies; convenience, time of day (based on electricity tariffs) and smart charging. Through smart charging they made an additional

| 34 3MW of capacity available to export during peak demand times and increased the charging of EVs through renewable generation by 73% [64].

A summary of the perceived benefits of EVs in the UK is given in Table 2.

Table 2 – Summary of the perceived benefits of EVs to the UK Perceived Benefit or

Policy Value Type Quantified Benefit

ULEV Car/ Van Grant Economic Cars – 35% off cost of new vehicle up to £5,000 Vans – 20% off up to a value of £8,000 [54].

Plugged-in Places Grant Economic and infrastructure More than 4,000 charge points installed UK wide with around 65% with public access [55].

EV homecharge scheme Economic £15 million grant funding for domestic charging points [56].

Air quality Environmental and health

NOx and particulates reduction – 11 to 17%

reduction from 40% EV adoption rate [47].

CO2 savings – 0.6 TCO2 per vehicle per annum through PV smart charge/ discharge [65].

Grid security Infrastructure and energy Estimated as much as 11.3GWh of storage capacity available through V2G provision [40].