What If All Automobiles—Never Mind Motorcycles—Were Electric?

Fun with arithmetic…

Zero’s Rapid Charge System
Are we witnessing the sunset of the internal-combustion engine? Not likely. Zero’s Rapid Charge System works on a network of Level 2 stations and can accommodate as many as three independent charging modules. With all three installed, the SR/F can be “fueled” from 0 to 95 percent in about an hour.Zero

Quite obviously, and because of the capital and infrastructure costs involved, conversion of US vehicular traffic to electric power will take many years. But it’s fun to imagine what would result if a sort of TED Talking Tinker Bell were to wave a magic wand that did the job instantly.

Available figures tell us there are roughly 260 million cars and light trucks now operating in the US, each being driven what the DOT’s Federal Highway Administration says is an average of 13,476 miles per year.

I recently found another site that presented the claimed electricity consumption of present-day electric cars in the now-standard format of kilowatt-hours (kWh) per 100 kilometers (62 miles) of driving. This is clearly an average, since both rolling resistance and aero drag increase with road speed. The number presented as the average of many electric vehicle models was 18.5 kWh/100 km.

Let’s now convert the figures from the second paragraph into the total number of miles driven in the US, per year, convert that into kilometers, and use the result to work out the kWh of electricity that would be consumed by the 260,000,000 vehicles in a year.

At 13,476 miles per year per vehicle, we get as the total number of miles driven 3.5 trillion. Converted to kilometers, this is 5.65 trillion kilometers. To get from this to total electric power consumed in kWh, we must divide by 100 and multiply by 18.5, giving us 1.05 trillion kWh.

More arithmetic tells us that a standard-sized 600-megawatt electricity-generating station would produce 8,760 hours in a year times 600 mW equals 5.256 billion kWh per year, but because such plants are normally off-line for maintenance one month each year, we multiply times 11/12 to get 4.82 billion kWh per year, per each 600 mW plant.

To get the number of additional such plants that total conversion to electric vehicles in the US would require, we find we will need to build 218 new 600 mW electricity plants to power a 100 percent electric-vehicle fleet.

Oh, but wait. Not all of the power generated actually reaches the terminals that charge our vehicles. The power industry tells us that line and transformer losses between generating station and end user are about 11 percent, an efficiency of 0.89. To correct for this, we divide our first estimate of 218 new plants by 0.89 to get 245 new plants. That would represent a 31 percent increase in US power generation over the 4.17 trillion kWh generated in the US during 2018. This is in line with estimates made by others of the increases needed in other nations if their vehicle fleets were immediately converted to electric.

If those 245 extra electric plants were powered in the bad old way, by coal, we would need to burn roughly 8,000 tons per day, per electric plant, or on a yearly basis 365 x 8,000 x 245 = about 715 million extra tons of coal per year.

But in fact coal use in the US has been declining steadily since natural gas—now produced by the twin technologies of horizontal drilling and hydrofracturing—has lately become more plentiful and less expensive; no one can say how long this will remain so. In 2018, coal supplied 30.4 percent of US electricity and natural gas supplied 34 percent.

2020 Zero SR/F charge
On the Cycle World scales, a 2020 Zero SR/F with the optional rapid charger weighed 502 pounds, 56 more than a fully fueled Honda CB650R and 69 up on a similarly ready-to-ride Ducati Scrambler Cafe Racer. MSRP—$19,495 for the standard model—and readily accessible charging locations remain challenges.Zero

The argument has been made that because existing generating stations operate at less than 100 percent of their nameplate capacity, no additional stations need be built to power a notional 100 percent electric-vehicle fleet. Instead, existing stations can just be “throttled up” to supply the extra power.

Is this true? Power generation has to respond to demand that varies by the season and by the hour. That part of the load that does not vary is called “base load” and is generated by systems that are able to operate at constant power, 24 hours a day, month after month. Base load is handled by traditional coal-fired steam turbine plants, nuclear plants, and highly efficient combined-cycle gas-turbine plants firing on natural gas.

Other forms of power, such as hydroelectric, wind, and solar, are unable to supply base load because the natural forces that power them constantly vary.

To supply the substantial extra power consumed by summer air conditioning, so-called “peaking units” powered by cheaper-to-buy low-efficiency simple-cycle gas turbines firing on natural gas are added.

Other forms of power, such as hydroelectric, wind, and solar, are unable to supply base load because the natural forces that power them constantly vary. During 2018, hydroelectric power averaged a 42.8 percent capacity factor, meaning that the nation’s power dams produced only 42.8 percent of their installed nameplate generating capacity on a yearly average; rivers typically flow strongly in spring but dwindle in August. According to the Federal Energy Information Agency (EIA), the figures for wind and solar for that same year were 37.4 percent and 23.6 percent. Wind varies, the sun doesn’t shine at night, and less solar power is produced in heavy overcast. For example, solar PV’s capacity factor in cloudy New England is 13 to 16 percent, meaning that if you install a 1,000-watt solar panel in that region, on a yearly basis it will generate an average of 130 to 160 watts.

Natural-gas-fired power operated at 57.6 percent of nameplate capacity. Part of that is efficient combined-cycle turbines carrying base load at high-capacity factor, and part was peaking or load-following units of lower first cost and lower efficiency, operating part-time.

As more wind and solar farms are constructed, nearly equal amounts of fast-responding simple-cycle gas turbine power must also be built as backup to take over the load they cannot supply when wind drops, night falls, or heavy cloud cover forms. To respond instantly, such power is kept on hot spinning standby.

As the price of natural gas has fallen since 2005, it has become cheaper for power companies to rely more on combined-cycle gas-fired plants and less on coal, causing capacity factors of the former to rise and of the latter to fall. Neither type can be started or stopped quickly, so power companies try to run them as close to nameplate capacity as possible. It would be dollars-and-cents foolish for the power industry to have the equivalent of some 300 spare 600 mW plants worth of capacity standing idle, just in case Tinker Bell waves her wand.

Therefore the answer is no, the extra power that would be required by a 100 percent electric-vehicle fleet could not be supplied just by “throttling up.” More power will be required, delivered by whatever mix of sources the power companies find most profitable.