How Much Electricity Will EVs Require?
John Ewbank posted on November 07, 2017 | 2800 views
Electric vehicles (EVs) are the future of transportation.

The UK, France and Netherlands will ban internal combustion engine vehicle (ICEV) sales by 2040; China is likely to follow. Will the US and Canada impose a ban, or will the economics of electric vehicles (EVs) alone compel people to switch?

The financial services firm UBS believe EVs will be cheaper to purchase than internal combustion engine vehicles (ICEVs) by 2023. With EVs already having lower running costs, will there be any reason to buy a petroleum-powered vehicle, post-2023?

If EVs become the dominant mode of transportation, then we’ll be depending on the electric grid for our fuel, but how much electricity will EVs require? That can be answered that by looking at total transportation fuel use in North America.

Fuel use represents all the road vehicle journeys across the continent. We can take the fuel use and factor in the inefficiencies of ICEVs, EVs and the electric grid, to estimate how much electricity will be required to charge EVs.

2016 Canadian and 2015 United States Fuel Consumption

Based on information from Statistics Canada and the Department of Transportation, we can see that 541,092,702,000 liters (l) of gasoline and 170,308,421,000 l of diesel are used in North America per year. Now we need to know how this equates to energy.

There are 34.7MJ/l in gasoline and 37.9MJ/l in diesel.

Multiplying the fuel used per year by the fuel’s energy density will give the total energy from the fuel. Dividing the total energy released by the number of seconds in a year will provide the energy released per second, or power, in watts. This figure can then be compared with North America’s electricity generating capacity.

The total energy released by fuel across the North America in a year is 6964.2 TWh, which amounts to an average energy release of 795 GW. To provide an idea of how much energy this is the US electricity grid produced 4077.6 TWh of electricity in 2015.

However, EVs are far more efficient than ICEVs, so 795 GW is not representative of the energy EVs will require. To calculate the power EVs will require, we need to investigate engine efficiencies.

 

Electric Vehicle Power Requirements

To predict the amount of electricity EVs will need to charge, we must look at tank/battery-to-wheel efficiencies of ICEVs and EVs. As the electricity grid will have to supply EVs with power, we must factor in these transmission losses.

The efficiency of diesel vehicles, factoring in idling, transmission and heat losses, is 24 percent and  20.9 percent for gasoline vehicles. The mean efficiency for a battery electric vehicle is 68 percent; this value is from 2011 and is somewhat dated. EVs will improve in efficiency as battery and motor technology is refined; therefore, a value of 75 percent was used in this analysis, this should represent efficiency improvements over the next few decades, though it does contain an element of conjecture. Electricity transmission losses are 5 percent.

With our efficiency values, we can see if all vehicles were electric and travelled the same distance as vehicles now, the average electricity requirement would be 234.1GW. This is over 25 percent of the capacity of the grid, but it’s not peak load, which is the maximum value the electricity grid would have to provide. To calculate peak load, we must look at simultaneous charging of EVs.

 

Peak Power Draw from EVs

In a Norwegian survey, 59 percent of EV owners reported that they charged daily, with up to 70 percent charging concurrently during winter. Of course, many North American vehicles would be sitting idle and hence not need to be charged daily. However, that still leaves the question of how many vehicles can be charging at once.

A tricky question to grapple with, it involves predicting charging patterns, which is difficult at the current rate of EV ownership. Instead, let us stick with facts: the number of EVs charging simualtaneously will dictate peak electricity demand.

Now we need to know, in North America, how many vehicles that might be.

In the US and Canada, there are 264 and 24 million registered road vehicles, respectively, for a total of 288 million. How quickly are these likely to be replaced with EVs?

That is the trillion dollar question.

Let us assume, uncontroversially, that EVs will become far more prevalent in the future. The graph below shows peak EV power draw in North America, relative to the total number of EVs and the proportion charging concurrently.

The North American electricity grid comprises of four main parts, these and their 2015 summer capacities, and anticipated reserve margins are shown in the table below. The reserves appear to give the grid significant breathing room; however, a 15 percent reserve capacity needs to be maintained to compensate for power station closures and outages. Therefore, the EV demand that would exceed the required reserve is around 100 GW. 

The generating capacities of the separate sections are totalled for simplicity’s sake; this does not accurately represent how the grid functions, since there is a minimal transfer of energy between the different grids.

The 234.1GW average demand of EVs would equate to over 25 percent of North America’s entire generating capacity. If the North American electricity grid does not increase in capacity, the average demand from EVs under a full adoption scenario will exceed demand. Of course, that could well be thirty years in the future, so it doesn’t mean all that much.

Let us consider peak load under lower levels of adoption, which will be reached sooner.

Twenty percent of 75 million, or ten percent of 150 million EVs, charging simultaneously on 7.7kW chargers would produce a load exceeding 115GW, leaving less than a 15 percent reserve capacity. Will that many EVs charge simultaneously?

Well, 59 percent of EV users in Norway charge daily, with up to 70 percent concurrently, so it’s not beyond the realm of possibility; it may even be likely. When might North America have 75 million EVs on the road? We will only be able to make accurate predictions as production ramps up in the coming years. However, if EV sales in North America grow yearly by 130 percent, this scenario will be reached before 2035.

At full EV adoption, 20 percent of EVs charging would demand over 430GW. Evidently, EV peak charging loads need to be investigated and mitigated. In the long term, there need to be EV charging protocols.

The UK government recently announced that future EV chargers will be controlled centrally, thereby limiting peak demand. However, turning off chargers does not change the amount of energy that must transferred to vehicles each day, and in North America this would be 5.8TWh. Peak load can be mitigated, but vehicles still need to be charged.

How quickly will EVs be adopted? Will grid-level battery storage advance quickly enough to address renewables intermittency? Can we use EVs batteries to store renewable energy - not if they are not plugged in?

There is much talk suggesting that EVs will not require any adjustment to electricity grid; however, transportation uses 29 percent of energy in the North America, and if this does not come from the fuel, then it must come from electricity. Technology will advance, and the world will change, but there is one thing we can be certain of EVs will require massive amounts of electricity.


John Ewbank specialised in Finite Element Analysis, before embarking on a round the world voyage. He now runs an online tea store, in Brighton, England, focusing on fine and unusual teas. Much of his downtime is spent researching EVs, power systems and renewable energies. In 2018 he intends to publish a book, considering the economical and environmental consequences of their adoption. For more information, visit his websites at mitea.co.uk and johnewbank.co.uk

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