page title icon Electricity grid challenges with increasing EV use

Overview

This blog article provides a brief introduction to grid challenges facing incumbent suppliers. Future articles will explore these subjects separately in detail.

In most countries (certainly in the UK) the electricity grid is based around large-scale technologies and isn’t sufficiently distributed with the smaller scale solutions that will be needed to support the growth of electric vehicles. A press release from the The Green Alliance report (2017) has stated:

 “Without change, just six electric cars charging in close proximity at peak time could overload the grid and disrupt the local power supply, and today, one in five of the UK’s local grids are unable to accept distributed energy like rooftop solar”.

Local grids may not have the capacity to support increased EV demand and peaks in fast charging, potentially in the worst case resulting in network damage and/or ‘brownouts’. In Norway this has already been evident at an EV penetration of 7%.

Market disruption is coming

V2G (Vehicle-to-Grid) pilots are now underway to shift demand away from peak times. However wider scale deployment of smart metering will be needed in order to support this. Dale Vince the founder of Ecotricity has said that “Our relationship with the grid will be quite different, from being utterly dependent on the grid for power, people may become a bit more independent, giving or taking.”

The reducing cost of solar PV and residential battery storage means that small-scale energy technologies will be economic as soon as 2020. The Green Alliance estimates that repurposed second-life EV batteries in local stationary applications could be only £39 per kilowatt hour, which will make off-grid entirely viable for many businesses and consumers.

Increasing charge rates of EVs

The majority of electric cars can charge at 50 kW using a DC fast charger, but in the pipeline are cars that can accept much higher rates of charge. Porsche has a prototype that will charge at up to an ultra-fast 400 kW – which would provide 100km of range in a mere 3 minutes. With the majority of EV owners charging at home this use-case isn’t necessarily the highest consumer priority, with range being the No 1 obstacle to electric car adoption.

The recently announced (Q1 2019) production Audi e-tron has reportedly been able to accept 136 kW in real-world testing, but currently very few chargers are capable of delivering these rates.

The impact of these vehicles will be higher peak demand with consequent risk of brownout and higher demand charges (where these apply).

Local battery storage at charging stations

McKinsey are proposing local battery storage attached to charging stations which smooth out the peaks.  These can charge from the grid at times when there is less demand (at a lower price), store this power locally and then supply it into the car when needed.

In their model “When a car arrives, the battery can deliver electricity at 150 kilowatts without drawing power from the grid. If two vehicles arrive, one can get power from the battery and the other from the grid. In either case, the economics improve because the cost of both the electricity itself and the demand charges are greatly reduced”.

This has obvious benefits to the wider grid in smoothing out the demand/supply, as well as a reduction in demand charges where these apply.

Sources:

McKinsey.com

Green Alliance: People power: How consumer choice is changing the UK energy system (2017)

National Grid: Future Energy Scenarios (2016)

 

 

 

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