So, you’ve been thinking about “going green” by purchasing and driving an electric car — you think you’ll be helping to save the environment. I have news for you – you’ll still produce carbon emissions and other waste, and you’ll tax the already-overburdened power grid.
We’ll compare electric to conventional gas and diesel engines, and examine some truly environmentally-friendly alternatives.
1. How do electric cars work?
Electric cars basically run on a big battery. Electric motor(s) in the car convert electricity from the battery in to motion, turning the wheels.
If an electrically-conductive material (such as metal) moves within a magnetic field, the result is that electricity is generated within the conductor. Likewise, if an electric current passes through a conductive material, the result is a small magnetic field that surrounds the conductor (wire). By looping the conductor over and over again, the resulting coil is capable of generating a much stronger magnetic field.
Conventional motors operate using an electromagnetic coil, which creates a magnetic field that pushes against permanent magnets within the motor’s housing. This pushing force is harnessed as torque, used to turn the motor’s shaft.
Modern electric cars use a special kind of digital motor, called a stepper motor. A conventional motor spins whenever current is applied to it, spins faster as voltage increases, and spins freely when not under power. Unlike a conventional motor, a stepper motor only moves through part of one rotation at a time, requiring an external “pulse” signal that tells the motor to advance the shaft one position. Stepper motors have a more complex arrangement of magnets and coils, and do not spin freely when not under power.
The advantages of using stepper motors:
- Stepper motors are very precise, even at high speeds. With a conventional motor, it’s difficult to determine the exact rotational speed as well as the position of the motor shaft. With stepper motors, all of that can be tracked and calculated by keeping track of the “pulses” that have been sent to it.
For example, if you have a robot driven by a conventional motor, and tell it to “move forward 10 feet”, it will absolutely need some kind of external reference, and a separate tracking circuit to tell the motor to turn on or off. With a stepper, the controller circuit can calculate the exact number of pulses that have to be sent to the motor, in order to travel the required distance, and no other sensors or references are required.
- Generally, stepper motors are brushless, and thus last much longer and require less maintenance than a conventional motor. The brushes are small components that carry current from the power source to the motor’s magnetic coils, and because they are constantly touching a moving surface, they eventually wear out and must be replaced.
- Stepper motors have lightweight shafts, and can therefore accelerate much faster than conventional motors, using less current.
- Stepper motors are much more energy-friendly. Conventional motors draw a lot of current as they come up to speed. You may have seen the lights dim when your air conditioner kicks on, or when you run a power saw – this is known as surge current, drawn by the motor as it comes up to operating speed. Steppers only energize the coils for a fraction of a second, and therefore, the current draw is already limited. Since batteries are measured in Amp-hours, and electric current is measured in Amps, fewer Amps of current draw means longer battery life, which means longer run time between charges.
In an electric car, the gas pedal determines how many pulses per second are sent to the motor. If your foot is off the pedal, zero pulses are sent to the motor, resulting in zero motion. As you press the pedal down further, pulses are sent more frequently, and the car accelerates.
Most electric vehicles use “direct drive”, meaning that the motor or motors are directly connected to the wheels of the vehicle, without the need for a transmission. In a gas-powered vehicle, the transmission allows the engine to operate within its most efficient RPM (Revolutions per Minute) range, because gas engines don’t operate well at extremely low or high RPM ranges. The transmission allows the wheels to turn very fast or very slow without bogging down the engine, or burning it up. With electric stepper motors, the pulse frequency determines how much torque (spin power) the motor applies to the wheels, regardless of how fast or slow the wheels are turning.
Transmissions are generally inefficient, because the combustion engine hardly ever runs at its optimum RPM (rotational speed), but constantly speeds up and slows down to accommodate the gears in the transmission, which are linked to the wheels, which spin at the rate determined by the linear speed of the car. In addition, friction converts some of the mechanical energy of the motor in to heat energy, which is completely wasted. By directly driving the rear wheels with a stepper motor, electric cars don’t lose energy in the transmission process, and electric stepper motors aren’t subject to the very narrow efficiency band of a combustion engine.
1.1. Regenerative Braking
Electric cars can use the stepper motor or motors as a brake! In its natural state, when power is NOT applied to a stepper motor, its internal magnets create drag. In addition, the current direction can be reversed and the pulses will subsequently apply “negative torque” to the wheels, to slow the vehicle down.
Because magnets create electricity, and electricity creates magnetism, we can understand that a motor and a generator are virtually interchangeable. If you spin the shaft of a motor independent of its magnetic coil, it becomes a generator. If you apply current to the magnetic coils of a generator, it becomes a motor.
A side effect of this concept is that “reverse” torque causes pulses in some of the stepper coils, which can be captured and stored in a capacitor, or back in the battery as chemical energy. This is known as regenerative braking, and actually re-captures some of the car’s kinetic energy, converted through the angular motion of the coils and magnets of the motor, back to electrical energy, to help charge the battery.
A battery converts chemical energy to electrical energy, and a rechargeable battery does just the opposite. This means that a reversible chemical reaction either creates ions (positively-charged molecules), freeing electrons in the process, or absorbing electrons during a recharge cycle, by reversing the chemical reaction.
Unfortunately, you can have efficient batteries, or powerful batteries, but not both.
To-date, the most powerful batteries available (lead-acid) can create and maintain a huge surge of electrons (current) because the chemical reactions that produce free electrons happen very quickly, and in parallel. However, in powerful batteries, this reaction isn’t very efficient, meaning that the batteries have a relatively low run time, and wear out relatively quickly. This is why you have to change your (conventional) car battery every 2 to 3 years – it simply loses the ability to hold a charge.
Conversely, the most efficient batteries available (polymer lithium-ion) store energy extremely efficiently, and last a very long time, but the side effect is that they can only supply a little bit of current under sustained use.
Like a battery, a capacitor stores an electric charge, but it doesn’t use a chemical reaction. Instead, large conductor plates are capable of “parking” a huge quantity of electrons by creating a negative bias on one side, and a positive bias on the other. The two polarities attract each other within the capacitor, thus preventing the electrons from simply draining off.
Capacitors, compared to a battery, store very little electricity, but are capable of delivering nearly all of their capacity almost instantaneously, which makes them able to handle surge, or a sudden demand for current.
In electric cars, special capacitors are often used as a buffer between the battery and motor. The batteries slowly charge the capacitors using a small current flow, and the capacitors can quickly supply the motors with as much instantaneous current as they need.
1.3. Advantages and Disadvantages of Electric Cars
Electric cars are incredibly efficient because they use capacitors to manage energy from highly-efficient batteries, to drive highly-efficient stepper motors, which drive the wheels directly, rather than requiring an inefficient transmission.
Advanced features such as capacitor banks and regenerative braking allow electric cars to efficiently store and even recapture some of the electrical energy used to drive the motors.
Electric cars require electricity. Although there are a few electric recharge stations, electric cars lack the ubiquitous infrastructure of gasoline-powered cars, where there is a gas station on every corner. In addition, although there are some standards out there, there are no homogeneous, industry-wide connector, cabling, and voltage standards.
Basically, you charge your car at night, and when you run out of juice the next day, your electric car turns in to an expensive sofa until you can figure out how to recharge it. This requires advanced planning, to make sure you can accomplish all of your daily tasks, and make it home safe and sound, without completely draining the batteries, in order to repeat the process.
Because electric cars don’t emit carbon, one might be tempted to call them environmentally-friendly, but the problem with electric cars is that the electricity has to come from somewhere, and it has to be transmitted over already-taxed power grids, in to the car’s batteries. We will explore the negative impacts in greater detail.
2. How is electricity created and transmitted?
2.1. Where does electricity come from?
We’ve discussed that a motor can be used as a generator, and the electric company has power stations with huge generators. Electricity is created by converting some other energy source in to rotational mechanical motion, which the generators then use to produce electricity.
2.2. What is “some other energy source”?
Generators are driven by kinetic energy from moving water, wind, steam, or some other source, which spins a propeller (known as a turbine), which then turns the generator.
The most common source of energy used to create electricity is heat energy generated from fossil fuels. Fuel is burned (transforming chemical energy in to heat energy), which is then used to convert water to steam in giant boilers, where the water absorbs the heat energy and expands from a liquid in to a gas, creating tremendous air pressure in the process. Boilers build up steam pressure until there is enough to drive a turbine, which then drives the generator.
Likewise, nuclear energy produces heat, which is used to directly create steam from water (which also cools the reactor and keeps it from overheating), and the resulting steam drives a turbine, which then drives the generator. Nuclear has about the same fuel efficiency as fossil fuel-powered generators, at just over 30%.
Solar panels use a chemical process to release electrons that are displaced by photons of light, and driven by an electric bias in to a conductor grid, where the electrons are collected and can be used to charge a capacitor or drive a small electric circuit. Solar panels are “free” energy, but the rare chemicals and the manufacturing process are expensive. In addition, solar panels produce very little current, and wear out over time, so they contribute very little overall energy to the power grid.
Solar generators use the sun’s light, concentrated as heat energy, to drive a steam engine (either a turbine, or a Sterling “closed system” engine), which then drives a generator. Solar generators are incredibly cost-efficient (because sunlight is free), but require a large surface area for the reflector-concentrators, which are fragile, and have to be cleaned often to maintain efficiency. Solar generators are also very dependent upon the sun’s elevation and resulting angle of light input to the reflectors, meaning that a fixed reflector can efficiently generate electricity for only a couple of hours per day, unless coupled with a complex (expensive, fragile) “sun tracking” mechanism.
Although solar and wind farms are becoming more popular, they currently only contribute a small portion of the power grid’s energy. Because neither burns fossil fuels, both provide “free” energy, but require a significant investment and ongoing maintenance for very little relative output power, compared to fossil and nuclear sources.
2.3. What is Electrical Transmission?
Once electric energy is created at the power station, it has to be sent to YOU, to use… this is known as transmission. The electricity goes in to a step-up transformer, where the voltage increases, but the current drops, making the electrical energy easier to transmit over long distances.
When the electricity reaches your neighborhood, another set of transformers “steps down” the voltage level, increasing the current. The electricity then supplies multiple distribution transformers located all over your neighborhood (these are the ones that explode during lightning storms, or when someone clips a pole with their car), which then step the voltage down to the 120 Volts (increasing the current in the process) that you use in your house.
The typical household circuit breaker is 120 Volts at 15 Amps, where the transmission lines are 100,000 volts or more.
Electrical energy is lost in proportion to the distance it’s transmitted. In addition, electrical transformers that are used to change voltage levels are never 100% efficient, resulting in some electrical energy being converted to heat and magnetic energy in the process.
Electrical transmission and distribution, although necessary, actually result in the loss of some electrical energy.
All of the interconnections between power stations, transmission lines, and distribution networks are known collectively as the power grid.
2.4. What does all of this mean?
When converting energy from one form to another, such as converting fuel (chemical) to heat energy, or kinetic / mechanical energy to electricity, the process is never 100% efficient. Some energy is always lost, either as part of the transfer process, or due to friction or other inefficient work byproducts of the system itself.
If any system of energy conversion was 100% efficient, it could basically power itself forever!
Unfortunately, the second law of thermodynamics precludes 100% energy conversion efficiency, as well as perpetual motion.
This means that, at each step of the process, some energy is lost. By the time electricity comes out of your wall outlet, it’s about 60% efficient. What’s worse is that most electrical energy is created using good old fossil fuels, such as coal, oil, or diesel, which is at best about 35% efficient. So the end result, coming out of your wall outlet, is 60% of 35%, or about 21% efficient.
On top of the efficiency problem, the power grid has a fixed capacity, and most power grids are already taxed by the last decade’s construction boom, which resulted in a large number of huge houses that use electricity for heating and cooling, along with our ever-increasing demand for always-on, always-connected technology and power-hungry appliances.
Today, electric cars are in the minority – they are a toy or convenience for the few people who own them, so a few electric cars dispersed widely across a large power grid creates almost no impact at all. However, if everyone owned an electric car, tens of millions of car owners on each power grid would have to recharge their car every night, taxing the power grid beyond its limits. This would result in the need for billions of dollars worth of infrastructure upgrades, just to add capacity to the power grid.
3. How do Gasoline Engines Work?
Gasoline combustion engines work by taking the chemical energy stored in gasoline, and converting it to mechanical energy through a string of tiny explosions that rapidly convert vaporized gasoline and air in to carbon dioxide / carbon monoxide gas. The process of rapidly-oxidizing liquid fuel in to its gaseous byproducts creates a sudden spike in air pressure, which is converted to mechanical work by using the pressure change to drive linear pistons inside the engine. This linear motion is then converted to rotational motion through a linkage from each piston to the crank shaft of the engine.
In a 4-cycle engine, each piston fires once every two crank shaft rotations. During the first rotation, air and fuel are injected in to the cylinder, which is then compressed. At the beginning of the second rotation, the fuel and air are highly-compressed, and a spark plug detonates the mixture, resulting in downward force. At the end of the second rotation, the exhaust gasses are forced out of the cylinder, and the process repeats. So a four cylinder, 4-cycle engine running at 6000 RPM (Revolutions per Minute) has 12,000 of these tiny explosions occurring inside the engine every minute! This works out to be 200 per second!
Diesel engines basically work in the same manner as a gasoline engine, but rely on compression alone (along with a small, heated “glow” plug) to detonate the fuel/air mixture. Diesel engines are known for being extremely reliable, and very powerful for their size.
If all of this sounds a little complicated, that’s because it is. As a result of all of this back-and-forth energy conversion, as well as friction, the most efficient (clean diesel) combustion engines are only about 40% efficient.
On top of that, combustion engines require optimum fuel/air mixtures, incredibly-precise timing, they operate within a very narrow power band, and the type of fuel drastically affects efficiency and performance.
Gasoline engines are only about 20% efficient, yet account for over 99% of all vehicles on the road, as well as over 99% of all hydrocarbon fuel consumed by combustion engines.
At first glance, this puts electric cars roughly even, but the electric car’s lead increases when we account for the inefficient gas engine’s need for a transmission and extremely narrow power band, but the electric car also loses a couple of percentage points due to inefficiencies in the batteries and charging circuit, and mechanical friction. At the end of the day, electric cars are only ahead of gas-combustion cars by perhaps a couple of percentage points.
4. Electric Cars are NOT Friendly at All
Electric cars simply shift carbon emissions from the car to the power plant.
- Electric cars are about as efficient as gasoline internal combustion cars.
- Most electrical power grids use a significant percentage of some combination of nuclear and fossil fuels to power the generators that generate electricity.
- Conclusion: Electric cars simply shift carbon emissions in to the power plant, and do not significantly reduce overall emissions per vehicle.
Internal combustion engines do not have a nuclear waste byproduct.
- In areas that use nuclear-generated electric power, charging an electric car means using at least some nuclear-generated electricity.
- Nuclear-generated electricity, unlike fossil-fueled generators, produce nuclear waste that is clearly harmful to the environment because living organisms can’t be directly exposed to the radiation. Nuclear waste remains radioactive for thousands of years, and must be specially handled and disposed.
- Conclusion: Electric cars that are recharged from a nuclear-powered grid contribute, at least in part, to nuclear waste, which is directly harmful to the environment.
Internal combustion engines do not create industrial waste.
- Industrial waste consists of materials and chemicals that have already been used once, and can’t be recycled.
- Electric cars must have their batteries replaced regularly, and some components and chemicals within the battery can’t be recycled, resulting in industrial waste.
- Conclusion: Maintaining an electric car results in significantly more industrial waste than a gas-powered car.
Electric car adoption will drive up the cost of electricity for all consumers.
- Electric cars lack any significant, commercial refueling infrastructure, compared to gasoline combustion cars that can refuel at the ubiquitous corner gas station.
- Owners who recharge their electric cars at night risk taxing the power grid, as adoption rates increase. The government and power companies will need to make significant investments in order to expand the power grid to account for the increase in demand, and these costs will be directly passed on to the consumer.
- Conclusion: Everyone, including people who don’t even own an electric car, will be forced to pay for the infrastructure to support them, through higher utility and tax rates.
5. Better Options
There are many good alternatives to electric cars, that actually can save you money and / or provide an environmental benefit.
5.1. Smaller Internal Combustion Engine
Buy a fuel-efficient car with a small gas or diesel engine.
Although this won’t increase the thermal efficiency of your engine, meaning, the amount of work your engine performs for a specified amount of fuel it burns, a smaller engine will generally use less fuel, resulting in more miles to the gallon, fewer gallons to purchase, and fewer carbon emissions per mile driven.
What’s nice about this option is that it’s the least expensive. Not only will you save money, but you will reduce your carbon emissions at the same time. Win / win.
5.2. Diesel and Clean Diesel
Modern diesel engines are controlled by software that constantly monitors fuel efficiency and power output in order to keep the engine running at its optimum settings, including fuel / air mixture, and on some vehicles, even the valve timing is controlled by the computer.
As a result, diesel engines are one and a half times as efficient as gasoline engines, at about 30% compared to about 20%.
The improved engine efficiency of diesel over gas results in more miles per gallon, as well as less carbon emitted per mile driven. Diesel fuel and engines are generally more expensive than their gasoline counterparts, so you won’t save any money going this route. The good news is that diesel engines have a significantly longer lifespan than gas engines, and require less overall maintenance.
Many car manufacturers now offer a “clean diesel” option, which is a diesel engine that has been optimized to run hotter, and burn the fuel more efficiently than regular diesel. “Clean diesel” engines can reach up to 40% efficiency (twice as efficient as gasoline), adding miles per gallon and reducing emissions per mile.
Hybrid vehicles are the best of both worlds.
They are built like electric cars, where the wheels are directly-driven from electric stepper motors, but they also have a small gasoline or diesel engine, which is used to turn a generator, which charges the batteries and capacitors. Naturally, since hybrids are “constantly” recharging, they don’t need as many batteries, and the fossil fuel engine therefore displaces more than its weight in batteries.
The advantages of this design:
- Hybrids get as much as 50 miles per gallon, compared to 22 for the average conventional vehicle, or 35 for a conventional “economy” car. Greater fuel efficiency means lower fuel costs, as well as lower carbon emissions per mile.
- Hybrids can be refueled at the local corner gas station, and don’t require an expensive, proprietary infrastructure to refuel.
- The vehicle is lighter, because it has fewer batteries, which increases fuel efficiency, and further reduces emissions.
- Electric cars have expensive, heavy batteries that have to be regularly replaced, which contributes to industrial waste. Hybrids have many fewer batteries, resulting in much less industrial waste.
- The fossil fuel engine in a hybrid only runs when needed. For example, the engine stops whenever the vehicle is stopped, or when the entire system is not under load (for example, when driving down hill).
- Hybrids benefit from all of the advanced technologies, concepts, and efficiencies of an electric car, such as direct-drive stepper motors, capacitors, and even regenerative braking.
Even though the engine in a hybrid car has the same thermal efficiency as that of a regular gas / diesel vehicle, it can run continuously within its optimum power band, but doesn’t need to run constantly, and doesn’t require a transmission, because it’s not linked to the wheels, and therefore the fuel efficiency is much higher.
5.3.1 Gas-electric hybrid
Most manufacturers sell gas-electric hybrids, with a price points that are usually about 1.5 times that of equivalent, conventional gasoline-powered vehicles.
Diesel has many advantages over gasoline, including more power, greater fuel efficiency, and fewer carbon emissions.
Most large-scale moving and hauling equipment use a diesel-electric scheme, because it’s so powerful and efficient.
Diesel generators provide electricity to the giant direct-drive motors in the hub of each wheel.
Unfortunately, there are very few diesel-electric consumer vehicles on the market, because the price point is significantly higher for the car itself, and many consumers have a negative perception of diesel.
As clean diesel becomes more pervasive, diesel-electric hybrid will become more practical within the consumer space.
5.4. Fuel Cells
Fuel cells work by ionizing hydrogen, and then using the resulting surplus of electrons to drive a circuit. Later, when the hydrogen ions are combined with oxygen to form water, an electrical bias draws the electrons through the circuit, from the anode (where the hydrogen ions are formed) to the cathode (where they are used during the chemical reaction).
Unlike a battery, which can only store a fixed amount of energy, fuel cells continue to produce electricity as long as there is a supply of fuel – in this case, hydrogen.
Fuel cells have zero carbon emissions, which at first glance, appears to be a benefit. However, fuel cells emit water vapor as the byproduct of the chemical reaction. Water vapor is the number one greenhouse gas, because it is capable of reflecting light and trapping a tremendous amount of heat energy. Therefore, water vapor emissions must be collected and condensed back in to water before being reused or discarded. Fortunately, this is a passive process, unlike trying to trap the carbon dioxide and carbon monoxide gasses that are emitted from fossil fuel engines.
In addition, fuel cells can act as a rechargeable battery, since the chemical reaction can be reversed by applying electricity, which breaks water down in to hydrogen and oxygen in a process called electrolysis. This means that a solar cell or other non-fossil fuel source can be used to trickle charge the fuel cell when not in use.
Even though fuel cells have been around since the 60’s, and powered the manned moon missions, fuel cell vehicles are considered impractical for a few very good reasons.
- Fuel cell vehicles run on hydrogen, which means that every fuel cell car is basically running around with a small bomb strapped to it. In the event of an accident, if the hydrogen tank were to be punctured, it would explode. For example, after the hydrogen dirigible Hindenburg was destroyed in an accident resulting in multiple injuries and loss of life, hydrogen dirigibles were deprecated. Hydrogen burns very hot, and very quickly – it can be very dangerous and destructive.
For hydrogen fuel cell vehicles to be considered practical, there must be a mechanism in place to quickly vent the hydrogen gas in the event of an accident.
- There is no hydrogen refueling infrastructure. Fortunately, with a little rain water and solar-generated electricity, self-replenishing hydrogen fuel stations could be widely deployed, very inexpensively. This also means that you could refuel your car at night, at home, using your garden hose and a conventional power source. Because electrolysis is so efficient, it takes much less electricity than recharging an equivalent, conventional battery.
- Because water vapor is so much more environmentally-damaging than carbon emissions, the water vapor emitted from fuel cells must be condensed back in to water, and either stored for reuse or safely discarded. In theory, a fuel cell vehicle could simply run on water, if it had a separate hydrogen storage tank, and a constant supply of electricity to run the electrolysis process. Waste water vapor from the fuel cell’s chemical reaction could simply be returned to the water reservoir.
Fuel cells can be up to 60% efficient, or nearly three times as efficient as a gasoline-powered internal combustion engine, but there are some serious issues that need to be addressed before fuel cells are ready for the mainstream consumer market.
Despite a lack of consumer-ready fuel cell vehicles, fuel cells are widely available today, and could be adapted to help offset electrical usage in various ways, in order to make an electric vehicle more practical to own, and more environmentally-friendly.
People talk about “going electric” as a means to become more environmentally friendly. In reality, electric vehicles simply move carbon emissions from your car in to the power plant, and are no more energy-efficient than gasoline combustion vehicles. Electric vehicles also create industrial waste, and might even contribute to nuclear waste, if your power grid is partially fed from nuclear sources. In addition, electric vehicles create an all new set of problems, relating to infrastructure and distribution for increased electric demand, to recharge them.
There are more cost-effective and/or more environmentally-friendly options out there today, such as simply buying an economy gas-powered car, going diesel, or going hybrid.
Other truly environmentally-friendly technologies, such as diesel-electric hybrid and fuel cell vehicles aren’t quite consumer-ready, but are on the horizon.
When making a decision to “go green”, it’s important to evaluate each option comprehensively. As a case in point, electric cars seem friendly because they don’t have a gas engine, and don’t directly produce carbon emissions. However, a comprehensive analysis bears out that the negative, hidden impacts of pollution and waste clearly offset the highly local positive impact of not having a tail pipe, and in some cases, the negative impact is greater because widespread adoption of electric cars would cause new problems such as overtaxing the power grids, and rising utility costs.