SMART CHARGING 101: Increasing electric vehicles would destroy power grids & infrastructure: Is it true?

The massive intake of electric vehicle transport brings many benefits, including reduced CO2 emissions ; but also triggers worries about the existing power-grid infrastructure and how the grid will cope-up with increasing power demand, especially during the peak hours!. 

Don’t we all keep hearing statements such as: “Electric vehicles are not practical” and “increasing EVs would destroy the existing power grids & infrastructure?.” Are these statements true?. This article may answer them with facts from various trials and studies (Source: IRENA - International Renewable Energy Agency) conducted globally.

EVs impact on electricity capacity and demand

If EVs were charged simultaneously in an uncontrolled way they could increase the peak demand on the grid, contributing to overloading and the need for upgrades at the distribution level. The extra load may even result in the need for upgrades in the generation capacity (or at least in an altered production cost profile).

Below are the three main impacts of EVs on the electricity system and how these impacts can be mitigated:

1. There will be increase in supply demand; but very limited & manageable:

➤ In a 100% electric mobility scenario for Europe, the energy needs of EVs might represent no more than 10% to 15% of total electricity production. However, EV grid integration might lead to local power issues with increasing EV volumes (source: Eurelectric, 2015).

➤ If all 2.7 million cars in Norway were EVs, they would only use 5-6% of the country’s annual hydropower output (BoA/ML, 2018a).

➤ In a 25% electric mobility scenario for Germany, 10 million EVs by 2035 would translate to an overall consumption increase of only 2.5-3% (Schucht, 2017).

➤ If all light-duty vehicles in the US were electric, they would have represented about 24% of the total electricity demand in the country. Below analysis by Energy Institute, Austin shows the impact of Golden State’s grid capacity at 100% electric vehicles scenario in California.

2. The impact on peak demand can be much greater; but can be mitigated by smart distribution :

Modelling of EVs in New England showed that a 25% share of EVs in the system charged in an uncontrolled fashion would increase peak demand by 19%, requiring significant investment in grid and generation capacities. 

However, by spreading the load over the evening hours, the increase in peak demand could be cut to between 0% and 6%. and charging only at off-peak hours could avoid any increase at all in peak demand. 

In a 10 million EV scenario for the UK by 2035, evening peak demand increases by 3 GW if charging is uncontrolled, but increases by only 0.5 GW if charging is smart. Below experiment conducted by Mckinsey in 150 homes shows that the reshaping of the load curve can reduce peak grid demand close to 50%. (from +30% peak demand to +16%).

Below graph may give an world-wide estimate for 2040: 

3. The impact on local distribution grids might also be significant ; but smart charging already mitigates it:

➤ Xcel Energy, Colorado in the US demonstrated that 4% of distribution transformers could be overloaded at EV market penetration of 5% if charging is aligned with peak load times (Xcel Energy, 2015).

➤ "My Electric Avenue Project" in the UK identified a need for 32% of distribution circuit upgrades with a 40-70% share of electrified cars (EA Technology, 2016).

➤ In Germany, “dumb” charging of EVs under a 10 million EVs by 2035 scenario would lead to a 50% increase in low-voltage grid and transformer costs, while optimised peak shaving using smart charging would avoid these investments (Schucht, 2017).

EV Impact on grid infrastructure

EV charging will have an impact on distribution grid infrastructure too; thus will require investment for grid expansions. The scope of grid investments (in terms of cables and transformers) that will need to be made in a given location will depend at least on the following parameters:

➤ Congestion: such as in the local distribution network prior to any EV deployment.

➤  Simultaneity factor: as applied based on the size of each distribution grid. The simultaneity factor/coefficient measures the probability that a particular piece of equipment will need to be switched on at the same time as another piece of equipment. Every distribution system operator considers a different simultaneity factor.

➤ Load characteristics: for example, the impact of uncontrolled EV charging will be higher in locations with high shares of electric heating (thus leading to higher grid reinforcement). But if smart charging is used in such locations, it may be included with lower grid reinforcements than in locations where no electric heating is used, as the local grids are dimensioned for higher peaks.

➤ Generation assets connected at low voltage level: for example, integration of high shares of solar PV connected at low voltage level could be facilitated with smart charging, whereas in locations with no or very low shares of solar PV, EVs could increase the strain on local grids.

➤ Grid code limits and other regulations: for example, national grid codes define physical constraints in terms of both voltage and frequency variations that distribution system operators have to respect, and investment in grid reinforcement if these country-specific limits are exceeded due to EV charging.

To summarize with a straight forward answer for the title: Yes, the extent of possible impacts on peak demand & grid infrastructure is inevitable, but can be mitigated with smart charging!