Energy Excursions

The Electric Future

Everywhere you look it seems people are driving electric cars or discussing the latest electric car model. Today most electric vehicles (EV) look like normal cars. You can buy models that are SUVs, sedans, hatchbacks, and luxury vehicles. Why has the United States, and much of the world, placed a great deal of effort into promoting the use of EVs? Simply put – gasoline used in ‘traditional’ cars is a fossil fuel and an easy target for replacement if we transition to EVs.

The United States consumes over 19.4 million barrels of oil each day, with the largest uses of oil for gasoline (42%), diesel (22%), and jet fuel (9%). Given almost half of our oil consumption is used for gasoline, it is no surprise the Federal government is incentivising a move towards EVss. However, to satisfy such a transition, we will need a lot more electricity. 

Gasoline Versus Electricity for Cars 

The average mile per gallon of gas in the US is approximately 25 miles per gallon (mpg). With a 25 gallon fuel tank, the average car can travel 625 miles on a tank of gasoline. If a gallon of gasoline contains roughly 120,286 BTU’s or about 35.25 kWh of energy, converting to energy use, the average car consumes about 1.41 kWh of energy per mile. Using a gasoline cost of $2.10 per gallon before highway taxes, the fuel cost is roughly $0.084/mile. Let’s compare this to electric vehicles. 

A Tesla long range car will travel about 400 miles on a full charge of 100 kWh – a rate of 0.25 kWh/mile. If you use the retail electrical cost of about $0.11/kWhr, the fuel cost is approximately $0.028/mile. Considering fuel costs, the Tesla fuel costs are about one third of the more traditional vehicle fueled by gasoline.

Additionally, if we want to calculate the equivalent miles per gallon (think fuel efficiency standard) a gas-powered car would need to match an EV, we can use the equation: 

\[\require{cancel}\text{Equivalent MPG}=\frac{\$ 2.10}{\text{gallon} } \times \frac{400\ \text{miles} }{100\ \cancel{\text{kWh}} } \times \frac{1\ \cancel{\text{kWh}} }{\$ 0.11} =76.4\frac{\text{miles} }{\text{gallon} } \]

Current and proposed fuel standards are a long way away from 76.4 mpg. In comparison, no gasoline car matches the fuel economy of a long range Tesla; however, this comparison is for fuel only. To produce a complete analysis, we would need to include car prices, maintenance costs, etc. 

Another consideration is both where electric vehicles can charge and how long it takes for a charge. While there are over 168,000 gasoline stations in the United States, according to a report by USA Today, there are about 42,000 public charging stations in the U.S.1Ott, M. (2021, July 13). Electric vehicle charging company Electrify America to double number of EV Chargers. USA Today. Retrieved October 4, 2021, from https://www.usatoday.com/story/money/cars/2021/07/13/electrify-america-chargers-ev-charging-electric-vehicles-cars/7950468002/. At a gas station, a person can fill up a tank in less than ten minutes, but batteries in electric vehicles take anywhere from four to eleven hours to recharge from empty. Of the 42,000 charging stations previously mentioned, only about 5,000 are considered direct-current fast chargers, according to the Department of Energy.2Ott, M. (2021, July 13). Electric vehicle charging company Electrify America to double number of EV Chargers. USA Today. Retrieved October 4, 2021, from https://www.usatoday.com/story/money/cars/2021/07/13/electrify-america-chargers-ev-charging-electric-vehicles-cars/7950468002/. These numbers illustrate that the ability to recharge batteries rapidly must be improved before electric vehicles can travel long distances, and the number of charging stations need to increase as well. 

How Much Electricity is Needed? 

Another crucial factor in analyzing the feasibility of a transition from gas-fueled cars to EVs is the increase in electricity generation required. As previously mentioned in the lesson, the United States consumes approximately 342 million gallons of gasoline per day, and the heat content in one gallon of gasoline equals 120,286 BTU’s. 

While we measure gasoline to run a car by the gallon, a simple unit of measurement for electricity is 1 kWhr (1 BTU = 0.000293 kWhr). To put this unit into perspective, 1 kWh of electricity is enough to charge your phone everyday for up to 2 hours for a single month or brew 12 cups of coffee.3How to visualize 1 kwh of energy. How To Visualize 1 kWh of Energy. (n.d.). Retrieved October 4, 2021, from https://welcome.arcadia.com/energy-101/energy-bills/how-to-visualize-one-kwh. Using the equation below, let’s first determine how much energy in kWhr per day the United States consumes in gasoline. 

\[\require{cancel}\text{Energy} =\frac{3.42\times 10^{8}\ \cancel{\text{gallons}} }{\text{day} } \times \frac{120{,} 286\ \cancel{\text{Btu}} }{\cancel{\text{gallon}} } \times \frac{2.93\times 10^{-4}\ \text{kWh} }{\cancel{\text{Btu}} } =1.2\times 10^{10}\frac{\text{kWh} }{\text{day} } \]

Therefore, converting the energy in gallons of gasoline consumed to kWh per day, we can determine that the United States consumes 12,000,000,000 kWhr (or 12 GWh, 12 billion Watt hours) of energy in the form of gasoline daily! That seems like a lot of energy. 

How can we generate that energy in the form of electricity? Let’s consider the GW’s of power needed for our national daily consumption of gasoline to be supplied by electricity (12 GWh). But first let’s consider 1 GW of power. A study completed by the Department of Energy published striking examples to help comprehend sources of power on the scale of 1 GW, including:4Office of Energy Efficiency and Renewable Energy. (n.d.). How much power is 1 gigawatt? Energy.gov. Retrieved October 4, 2021, from https://www.energy.gov/eere/articles/how-much-power-1-gigawatt. 

  • 3.125 Million Photovoltaic (PV) Panels 
  • 364 Utility-Scale Wind Turbines 
  • 110 Million LED light bulbs 
  • 1.3 Million horses (think of horsepower) 

Now that we have a better understanding of the resources needed for 1 GW of power, let’s calculate the GW of power needed for our national daily consumption of gasoline to be supplied by electricity (12 GWh). We need to use an equation to get from units of energy (GWh) to units of power (GW). And we need to remember that we are talking about daily energy consumption. 

\[\require{cancel}\text{Power} =1.2\times 10^{10}\frac{\cancel{\text{kW}}-\cancel{\text{hours}} }{\cancel{\text{day}} } \times \frac{1\ \cancel{\text{day}} }{24\ \cancel{\text{hours}} } \times \frac{1\ \cancel{\text{MW}} }{1{,} 000\ \cancel{\text{kW}} } \times \frac{1\ \text{GW} }{1{,} 000\ \cancel{\text{MW}} } =500\ \text{GW} \]

Our answer tells us that to replace all of this gasoline with electricity, we would require 500 GW of power generation daily. Currently, the United States has about 1,220 GW of generation capacity. So, this would be an increase of more than 40%. How would we satisfy such a large demand? We would have to begin adding multiple large power plants across the country – a huge infrastructure project – and one that would require both time and money. What primary energy source would we use for those power plants? Nuclear? Natural gas? Wind? Solar? Coal?

Image Credits: Sheila Fitzgerald / Shutterstock.com; Nakun/Shutterstock.com; Photo Courtesy of the Office of Energy Efficiency and Renewable Energy

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