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These materials are part of a collection of classroom-tested modules and courses developed by InTeGrate. The materials engage students in understanding the earth system as it intertwines with key societal issues. The collection is freely available and ready to be adapted by undergraduate educators across a range of courses including: general education or majors courses in Earth-focused disciplines such as geoscience or environmental science, social science, engineering, and other sciences, as well as courses for interdisciplinary programs.
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Student Reading: Hybrid and Electric Cars

Learning Goals: Students will be able to:

  1. Compare energy costs and environmental impacts associated with hybrid, electric, and fossil fuel-based vehicles.
  2. Determine energy efficiency improvements associated with regenerative braking.
  3. Use flywheel technology to convert kinetic energy into electrical energy (rowing machine hooked to a generator, or simple bike light generator).
  4. Evaluate mineral scarcity for rare earth elements used in batteries.

Learning Assessment: Students interpret graphs showing atmospheric CO2 and combustion engine/Industrial Revolution. Students analyze the use of flywheels to generate electricity.

Before the Automobile

The advent of the automobile in the late 19th century profoundly changed the way we live. Consider how people got around and transported goods across land prior to cars and trucks. Before the Industrial Revolution, people walked and used animal-drawn vehicles to travel and carry goods. The narrow streets and tightly clustered buildings of ancient cities reflect the modes of transportation of the era. In some places, canals were dug to facilitate barges that could carry much larger loads than animal-drawn wagons. Those barges were typically pulled by mules. Life moved at the pace of a walk or slow trot.

Rough and muddy roads impeded walking and wagons. In the early 19th century, the first railroads addressed this issue. Iron rails made for easier rolling of wagons with special flanged wheels. With the improvement of the steam engine by James Watt, an alternative source of power came to the rails. In 1814, George Stephenson built the first steam locomotive. It was used to haul coal from the mines in England. In 1825, the first public railway opened in England. Railways soon spread across Europe and the United States.

Railways increased the speed of life and enabled the Industrial Revolution to speed forward. Raw materials, manufactured goods, and people could now move between cities and towns in a fraction of the time required just a few years prior. Coal or wood fueled the early steam engines, leaving behind a cloud of dirty smoke. They were suitable for open country, but their pollution was a real nuisance in urban areas.

Experiments with electric locomotives began in the 1820s using batteries for power. That proved impractical. In 1879, Werner von Siemens in Germany developed the first electric railway. It carried passengers in Berlin. It pioneered the use of an insulated rail to conduct the electricity provided remotely from the train. Subsequently other electric trains used a similar system, or overhead wires, to obtain power.

Railways and electric street cars changed how people and goods circulated between locations. Modifications of railroads such as subways and monorail systems dominated urban life from between the mid-19th and 20th centuries in the United States, and still do in many European countries. As good as rail systems proved to be, there was still a need to use smaller vehicles to get between rail stops, businesses and homes. That fact and the wide open spaces of much of the United States gave great impetus to the development of the automobile.

Automobiles changed life in America

Perhaps the automobile more than any other invention of the 19th century did more to shape the way the United States developed in the 20th and 21st centuries. Of course, the automobile is a composite of numerous other inventions: electric lighting, storage batteries, internal combustion engines, hydraulics, etc. Yet the complete package transformed the way we live. The national landscape is crisscrossed by a network of roads that will deliver an automobile within a few steps of most destinations. Only agricultural lands, forests, wilderness areas, beaches, and areas put in preserve for parks are saved form the ever-present ribbons of asphalt and concrete. The design of our communities reflects the dominance of the automobile. Cars facilitated the growth of suburbia as places of residence remote from the work site. Shops and businesses that previously clustered in centers of towns and cities became widely dispersed along corridors of traffic, helping drive urban sprawl.

Cars and trucks made obsolete the vast network of interurban railways that linked towns, cities and countryside together between the 1880s and 1930s. The development of heavy trucks also diminished freight rail service.

The car changed society in countless ways. Modern suburban housing developments often lack sidewalks because designers scoffed at the idea that anyone would want to go anywhere on foot. Some architects design houses with the two-car garage dominating the front approach. Residents drive their cars to the garage door, press the remote control to admit the car, exit the car, and enter the house via a door from the garage. This makes it possible for people to isolate themselves from nature almost exclusively.

Cars gave new freedoms to teenagers. With a bit of money for gasoline, they could borrow the family car and escape from parental control. Untold numbers of children were conceived in the back seats of sedans. Drive-in movie theaters, fast food, and supermarkets exist only because of cars. Coming of age in the United States is marked by the earning of a driver's license. No baptism or bar mitzvah ceremony is as consequential as passing the driver's test.

Most Americans view access to an automobile as an essential part of life. As of 2013 there were 256 million cars for the nearly 325 million people in the United States. In 2013 the number of cars worldwide surpassed 1 billion, and some project that number to reach 2.5 billion by 2050. The United States accounted for about 18% of the world's energy consumption in 2014, and 28% of that went to transportation. Almost all of the transportation sector energy comes from petroleum. It is not hard to see that petroleum-burning cars cause massive amounts of pollution, including climate-changing emissions.

The first cars: steam, electric, and gasoline-powered

The earliest experimental automobiles used small steam engines and appeared circa 1900. Cars powered by steam required a period of heating prior to use, as steam pressure had to build up sufficiently to run the vehicle. Liquid fuels such as kerosene and gasoline provided the energy, but frequent stops were needed to refill the water tank. Steam cars remained on the scene until the early 1920s.

Experimental cars using electric motors and batteries appeared in the early 20th century. Electric cars saw commercial success between 1898 and 1920. Electric cars were ideal for urban settings, with their small commuting distances. The urban environment also meant close proximity to recharging stations, important since one might expect to travel about 35 miles before needing that service. The 20 mph of electric cars at that time seems slow by today's standards, but was fine for city streets, and still three or four times faster than horse-drawn vehicles or walking. In 1900 40% of cars in the United States were powered by steam, 38% by electricity, and 22% by gasoline. Sales of electric cars in the United States peaked in 1912, which saw over 33,000 registered electric cars on the road.

Electric cars were clean, quiet, and easy to start. Women found them easier to operate than gasoline cars, as they did not need the hand-cranking to start as discussed below.

Automobiles were eyed as a cure to one urban problem few of us think about today—horses and mules ran on biofuel, and littered the roads with countless piles of smelly and slippery dung.

The internal combustion engine was developed during the late 19th century and lagged behind electric motor development by several decades. So it is not surprising that the first commercially successful cars were driven by the more mature technologies of steam and electricity. However, the extended range and quick refueling of a car running on gasoline spelled the end of electric and steam cars. Gasoline-powered cars pushed electric cars off the road by 1930. This was enabled by two important events. First, discovery of oil in Texas made gasoline cheap. Second, Charles F. Kettering invented the electric starter for gasoline engines in 1912. Prior to Kettering's electric starter, one had to hand-crank a gasoline engine to start it. This took muscle and sometimes caused injury to the person operating the crank.

Specialized electric vehicles remained in use after the maturation of the gasoline engine. Electric-driven fork lifts could work indoors, where auto exhaust would be unsafe. Electric golf carts maintained the peace and quiet of fairways and greens.

The 1970s saw renewed interest in electric cars as a way to reduce pollution and use alternative sources of energy. In 1990, California passed a law requiring that 10% of the cars operated in that state produce zero emissions by 2003. This prompted General Motors to develop the all-electric EV 1, which it introduced on a lease basis in 1996. In 2003, GM had a change in heart and removed the vehicles from the market and crushed them. That was after GM and others successfully sued California to get rid of the 10% no-emission standard. George W. Bush, oilman and President of the United States, joined in that suit.

Astronauts used an electric car called the Lunar Rover to explore the surface of the moon during several of the Apollo missions in the early 1970s. The vehicle resembled a "dune buggy" of that era. The dune buggy was a modified Volkswagen used for driving on sand dunes. That NASA sent a car to the moon says much about the central role of the automobile in the life of Americans during the 20th century. If electric cars could work on the moon, why not Earth?

Gasoline-powered cars dominate much of the 20th century

Liquid fuel consumption is driven to a large extent by the use of liquid gasoline in motorized vehicles for transportation, which were introduced around the turn of the 20th century. The central feature of motorized vehicles powered by liquid fuel is the internal combustion engine. Through burning of fossil fuels, chemical energy stored in the fuel is oxidized (burned) and converted to mechanical energy to power the vehicle, and CO2 is emitted as a by-product of combustion (along with water and other chemicals).

In the United States alone, we collectively drive about 3 trillion miles annually. If we take an optimistic look at gas mileage and say that on average vehicles get 30 mpg, then Americans are consuming 100 billion gallons of liquid gasoline annually and emitting CO2 as a by-product to the atmosphere.

Refined gasoline comes from crude oil—about 45% of the volume of a barrel of oil (42 gallons) becomes gasoline. That crude oil, of course, is removed from the ground in locations around the world, some of which are economically and politically "active." Our reliance on fossil fuels has many global ramifications socially and environmentally.

OK, what to do? The simplest solution to overzealous fuel consumption is to stop driving. Since this does not sit well with most Americans, the next thing to do is increase fuel efficiency of the internal combustion engine. This has been done over the years, with modest success: fuel economy generally has improved as automakers have designed more efficient engines placed into smaller cars. Alas, the average number of miles per gallon of the US auto fleet has not improved steadily, since American drivers prefer larger vehicles that get worse gasoline mileage than so-called "economy cars." The US auto fleet includes its share of fuel-efficient cars and gas-guzzlers.

The era of the Hybrid

The early 21st century saw the serious return of electricity to power cars. The first advance was the hybrid gasoline-electric car. Honda brought this system to the market with its original subcompact Insight. The electric motor would assist the small gasoline engine when more torque was needed, such as when accelerating. The motor also operated as a generator, being turned by the gasoline engine to make electricity that was stored in a large battery. A big advance was that the electric motor/generator also served as the primary brake for reducing speed. The unused momentum of the car was turned into electricity by the generator as the car coasted. For the first time, energy from braking was being stored for future use. Prior to this, brakes simply converted kinetic energy of the car to heat. This early model Insight got an estimated 73 mpg on the highway and 63 mpg combined city/highway! However, its small size kept its sales to only 17,020 units worldwide during its seven-year run (1999–2006). Keep in mind that gasoline was very cheap during this period. It was not until 2008–2014 that prices at the pump exceeded $3 and briefly jumped to over $4 per gallon.

Toyota launched its own hybrid, the Prius, in 1997. It was only sold in Japan originally and introduced to the US market in 2001. The Toyota Prius has a conventional gasoline engine, an electrical generator and motor, and a large nickel-hydride rechargeable battery pack. The battery pack charges while the car is running (just like a conventional car with an alternator), but additional electrical energy is generated by using brake energy to store kinetic energy otherwise lost as heat. Standard or disc brakes rely on friction to slow the vehicle; in a hybrid, the generator is engaged to slow the vehicle, and electricity recharges the battery. Electrical energy from the battery, in turn, is used to run the electric motor that supplements the gasoline-powered engine running the vehicle. Without the gasoline engine, the Prius is only able to go a couple miles on only electrical energy stored in the battery. When used in concert, however, the coordinated use of gasoline and electricity (with regeneration during operation) lets the Prius increase fuel efficiency. The mileage estimates for that first model got city/highway 42 mpg. The Prius 2 (2004–2009) achieved 45 mpg, and the Prius 3 (2010–present) gets 51 mpg. Toyota now has a smaller version that gets 53 mpg (Prius C) and a larger one that gets 44 mpg (Prius V). To date, the Prius is the most successful hybrid vehicle, with cumulative sales of nearly 3.7 million units by April of 2016, 1.7 million of those in the US market.

There are now sixty-one different models of cars with hybrid gasoline/electric systems offered for sale in the United States in 2016. However, some of these hybrid systems are on vehicles that use them to make their dismal mileage rating only slightly better.

The plug-in hybrids

In 2010, several makers of hybrid cars introduced a new variation—the plug-in hybrid. Prior to that, there was a thriving cottage industry that converted the standard Prius to a plug-in version. Instead of relying on electricity stored from regenerative braking (giving you just a couple miles of gasoline-free driving), you could plug in your vehicle, store lots of electrical energy, and get 20 miles of gasoline-free driving or more. Charging a hybrid-electric plug-in vehicle yields around 100 mpg relative efficiency (this takes into account the fuel at the power plant needed to generate the electricity). Examples: Ford Hybrid C-max Energi and the Kia Optima PHEV. The Chevrolet Volt has been one of the most successful plug-in hybrids. It is rated up to 53 miles on a charge. After that, the gasoline engine kicks in, and it operates as a regular hybrid. Toyota and Ford also offer plug-in versions of their hybrids. Versions with larger batteries get better range on a charge, but they also tend to be more expensive to purchase.

EV — the return of the all-electric car

In 2008, a new company introduced the first major production run of an EV in 8 decades. Tesla Motors premiered its EV Roadster at $108,000, selling over two thousand by 2010. It could go 245 miles per charge and 0–60 mpg in 6 seconds! The company now makes less expensive and tamer versions of the car. Tesla vehicles have massive electrical energy storage up to 100 kWh, sufficient to power a car for hundreds of miles on a single charge. One gallon of gasoline is equivalent to about 33 kWh of electricity; thus, the Tesla is getting over 100 miles per equivalent gallon of gasoline. This is gasoline-free driving (no tailpipe!), with the caveat that energy is being generated to operate the car at the power plant (that uses coal, natural gasoline, nuclear, hydro, or some other alternate energy strategy).

YouTube Video of Tesla accelerating from 0–60 mph in 3 seconds

For the less well-heeled, 2010 saw the introduction of EVs at more affordable prices. The Nissan Leaf, for example, has a range up to 107 miles on a charge and in 2017 had a base price of $33 K. The Chevy Bolt has a range up to 238 miles on a charge and in 2017 had a base price of $37.5 K.

The success of the EV depends upon a network of charging stations. To encourage use of EVs, some states provide free charging stations along highways. There are smartphone applications to help drivers locate charging stations. Look at this map to locate charging stations near you.

Electric Vehicle (EV) FAQs:

Where do Electric Vehicles charge?

1. Primarily at home overnight, using surplus electricity.

2. At one of many public charging stations in the area, and at work.

3. At a fast charger along selected highways.

How long does it take to fully charge?

Level 1: 120V AC, charge overnight.

Level 2: 240V AC, charge in 3–5 hours.

Fast Charge: 480V DC, charge in 25–45 minutes.

Actual time depends on vehicle, charge rate, battery size, state of charge, and other factors.

How much does charging add to a home's electric bill?

About $40 to drive 1000 miles/month.

What are the tax incentives for purchasing a new EV?

Federal: Up to $7500 Tax Credit.


  • DC: Exemption from excise tax imposed on original certificate of title.
  • Reduced vehicle registration fee of $36.
  • Maryland: Up to $2000 Excise Tax Credit.
  • EV Supply Equipment (EVSE) Tax Credit – 20% of cost up to $400.
  • Virginia: Reduced personal property tax in Arlington and Loudon counties.
  • Discounted electricity rates for off-peak residential EV charging.

Electric Vehicle energy storage: the importance of Rare Earth Elements

Those who do not have $75K (or even $40K for their newer, less expensive models) to purchase a zippy new Tesla (raise your hands!) might wonder about the environmental impact of vehicles built with electrical generation and storage in mind. Yes, more technology and advanced components in the car translate into greater energy use to construct and assemble the parts, but the energy efficiency of electric and hybrid electric vehicles—over the lifetimes of the vehicles—more than covers the upfront energy costs of creating the vehicles. More important environmentally, however, are the battery packs for hybrids and electric cars. Both nickel-hydride batteries and lithium-ion batteries rely on the mining of nickel, copper and so-called rare earth elements (REEs). The REEs are used both in electric motor construction and in electricity storage in the battery.

FROM Integrate 2012 Team (

Extraction of any economic reserve materials depend on four factors: a) abundance of the material in the crust; b) tendency of the material to form economic reserves; c) ease of mining, or ability to mine at a profit; and, d) ease of processing to extract the metal from the ore.

Abundance of REEs in the crust: Despite being called Rare Earth Elements, these elements are actually more abundant in Earth's crust than gold and silver, as shown in the graph here from USGS fact sheet 087-02. Therefore, China's current monopoly on REEs is not due to the scarcity of REEs elsewhere in the world.

Economic Reserves of REEs: The current USGS estimate for worldwide REE reserves indicates that more than enough REE reserve exists globally to meet current and expected future demand. According to the USGS, about 12% of global REE reserves exist in the United States in 2013. Clearly, more than enough REE deposits exist outside China to adequately meet global demand.

Ease of mining, or ability to mine REEs at a profit: This depends on the "ore grade," or the concentration of the valuable material in the ore. A higher-grade ore generates higher profit. The average REE ore grade for Mountain Pass deposit in California is 9.2%. Considering the fact that copper, a relatively cheaper ore, can be profitably mined at a grade of 0.5%, there is no question that REEs can be mined at a considerable profit without having to depend on China as the sole supplier.

However, common REE ores like monazite contain radioactive elements like thorium. Safely disposing of thorium-rich mine waste is ahuge challenge for REE mining in the United States.

Ease of processing: This is the biggest hurdle in the path of REE production. The fifteen rare earth elements that naturally occur together in the ore have very similar chemical properties. Separating them out from each other is therefore technologically challenging, cost intensive, time-consuming, and energy intensive. Different REE ores, such as monazite and bastnäsite, require different processing methods. The lack of a single standardized processing method adds to the cost of processing and remains a technical challenge. Safely extracting and removing radioactive byproducts also adds to the overall challenge. As of right now, most commercially viable REE processing plants are located in China. Until other countries are able to economically separate the different REEs from the ore, China will remain the sole supplier of REEs in the global market.

In recent years China has reduced the REE export quota, claiming that it should meet the demands of Chinese industries before supplying global demand. As of 2010, China consumes almost 70% of its own REE production. China also claims to have tightened its mining regulations to minimize the environmental impacts of REE mining, resulting in lower REE production. The reduction of REE supply in the face of increased demand has driven up REE prices worldwide:

Class Discussion

Some common uses, supply, and demand for five of the rare earth elements are shown in the above table (data from Bade, 2010: Rare Earth Review). Think about the ways in which supply-demand imbalances might impact the future of clean energy initiatives, and brainstorm some feasible ways to address these issues. Another potential problem associated with electrical storage in dense, high-energy batteries is the risk of overheating—a point made clear by the recalled Samsung Galaxy 7 batteries with design flaws that caused them to overheat and catch on fire. Was this simply a case of the company hastily putting a product on the market without sufficient testing, or are the risks of battery failure increased by increasing energy storage? Are Teslas and other EVs any more or less safe than cars driving around with tanks full of flammable gasoline?

Resource Books:

David MacKay: Sustainable Energy Without the Hot Air, Technical Chapter on Cars

Denton, T. 2016. Electric and Hybrid Vehicles. Routledge Press. 200 pp.

These materials are part of a collection of classroom-tested modules and courses developed by InTeGrate. The materials engage students in understanding the earth system as it intertwines with key societal issues. The collection is freely available and ready to be adapted by undergraduate educators across a range of courses including: general education or majors courses in Earth-focused disciplines such as geoscience or environmental science, social science, engineering, and other sciences, as well as courses for interdisciplinary programs.
Explore the Collection »