# Module 1: The Fundamentals ## Lecture 1: How does an EV work? __Motor and Energy Storage__ https://www.dropbox.com/s/taa6y8k961vp5a5/eCARS2x_2018_T1-1_Motor_and_energy_storage-slides.pdf?dl=0 My name is Auke Hoekstra and I’m an expert on electric mobility at the Eindhoven University of Technology. In this video I will be going over the main differences between electric vehicles and conventional vehicles, because once you get that, everything else sort of falls into place. I do a lot of outreach to mainstream media and I found that most people don't understand the basics when it comes to comparing conventional cars with electric cars. In essence there are two fundamental characteristics that all cars have that you have to understand. If you do, as I said, everything else falls into place. 1. The first fundamental characteristic is the energy storage. 2. The second fundamental characteristic is the motor. Let's start with the motor. The motor converts potential energy into kinetic energy. You might think that there are many types of motors out there, and if you look at all the articles about different types of gasoline engines you might think that’s true, but in essence there are only two types of motors. This has been true since the beginning of human history. So pay attention because this is information that you can use forever. The first motor is the heat engine, and the second one is the electric engine. In a heat engine, burning releases the potential chemical energy in a fuel. This heat produces expansion and this in turn drives some mostly rotary motion. This is true for steam engines, sterling engines, diesel engines and gasoline engines. The picture shows how a four stroke engine works.  This is basically the modern gasoline engine and it was invented 150 years ago. On the first stroke, gasoline is injected into a chamber by opening a valve that is then closed again. On the second stroke, the cylinder moves upwards and the gasoline is compressed. On the third stroke the energy in the fuel is harvested by igniting it. The resulting explosion drives the cylinder down and that produces a rotating motion. This is comparable to a bicycle basically, where pushing down the pedal moves the bicycle forwards. On the fourth and final stroke, the energy burned is emitted. It’s all very ingenious but a heat engine has numerous problems. The entire engine requires hundreds of precisely crafted moving parts. That makes the engine heavy and expensive. And since all the heat and explosions cause a lot of wear and tear, you need a lot of maintenance and even then it wears down pretty quickly. The heat engine also wastes a lot of energy. In theory we could improve the efficiency to about 50%, but that would mean a couple of things. Firstly, the engine would become more expensive. Secondly, it would have to run at an almost constant number of explosions per minute, which is very hard to do in the real world. Finally the motor should be run at almost maximum power. In practice, even though we've been improving the internal combustion engine for more than 150 years now, a regular car wastes more than 75% of the energy it consumes as heat. And a sports car like the Bugatti Veyron wastes more than 95% of energy if you drive it in regular city traffic. For health and climate change the biggest problem is the exhaust fumes. These fumes are unhealthy but the biggest problem is that burning 1 liter of gasoline produces 2.3 kilogram of carbondioxide gas. Now let’s look at the electric engine. It all works completely different. We will dive into all the types of electric engines later, but fundamentally they all work by using magnetic fields. You might still remember from school that magnets have poles. We say they have a north pole and a south pole, just like earth. If you put two magnets together you will see that opposites attract. If we take a coil of wire and make electricity flow through it, it creates its own magnetic field. It has become a magnet. If we place this magnetic coil between two magnets, one side of the coil will be pushed up and the other side will be pushed down. This makes the coil turn until it is vertical. At that moment we quickly change the polarity. That way you can create rotary motion and what you are seeing here is a simplified direct current motor in action. The advantages of the electric motor are numerous. It only has one moving part, we call that the rotor. Therefore, it can be relatively light, compact and inexpensive. And since magnetic fields are very gentle, an electric motor can last essentially forever without any maintenance. Energy efficiency, that’s very important, can be close to a 100% and you can even win back energy when braking. So theoretically, it takes you over 100% if you compare it to the gasoline engine that is only 25% efficient. Because of this, the average electric car is four times more efficient than the average conventional car. And if you compare sports cars the electric car is up to twenty times more efficient. So oversizing an electric engine doesn't materially reduce efficiency and the engines are cheap and light. That's one reason why, in practice, electric vehicles can accelerate much faster. For health and climate the biggest advantage is clear: it can run on renewable energy and the motor itself has zero emissions. This sheets sums it all up and it's clear the electric motor is superior in every way.  So why did we end up with the gasoline engine? The answer to that question is energy storage. When you look at motors, the electric engine has the upper hand. But if you look at energy storage, the heat engine has the upper hand: Fuel is a really marvelous way to store energy. Batteries compare very poorly to that. A lead acid battery from 1900 stored only around 0.01 kWh per kg: that's more than 1000 times less than gasoline! No wonder the gasoline engine won! A lead acid battery at the end of the last millennium was better at 0.035 kWh per kg but that's still about 350 times worse. A nickel metal hydrate available at the turn of the new millennium stores 0.08 kWh. This is still 150 times less. But then people woke up, primarily because they needed lighter batteries for cell phones and laptops. And now a lithium battery as produced by the Tesla Gigafactory has about 0.25 kWh/kg, still 50 times worse. In the near future (say within ten years) we can expect batteries that store double that, still 30 times worse. Theoretically, lithium air batteries can even hold more energy than gasoline. But that is very very theoretical. So if we take the efficiency of the motor into account, we could have a theoretical situation where actually the batteries are lighter. However that is only a very long-term perspective. Now it’s really important that you understand how this works in practice because in practice the difference becomes much smaller. So imagine we make a car; a conventional car and an electric car and we want to be able to drive a distance of 500 kilometers, right? So average car, 500 kilometers. In 1900 we would have needed to take 10.000 kg with us: a very very big elephant in your ordinary car. No wonder the gasoline engine won right! At the end of the last century you still had to take a rhinoceros on top of your car, about twice or three times as heavy as your own car. The nickel metal hydrate battery turned it into an 800 kilogram Bison. But with the advent of the lithium battery, you remember the one we did because we needed light batteries for our smart phones, the 10.000 kg elephant has now turned into a 400 kg silverback gorilla. Still a big guy to take with you, but better right? Within ten years it will be a 200 kg or a pig. Now you might say: a 200 kg pig is still pretty heavy. But if you take the weight of the drivetrain into account, the electric drivetrain is so much lighter that the entire electric vehicle will actually be lighter overall in 2025! So the idea that batteries make electric cars heavy will soon be something of the past. Really! The reason that I put so much emphasis on weight is not just because it allows you to build lighter and nimbler vehicles. Just as important is the fact that something that is lighter needs less raw materials and in the end that means it’s probably going to be cheaper. By making the battery plus drivetrain lighter for an electric vehicle, we can also make it cheaper. And then all the efficiency advantages come into play. And you also save 25 000 liters of fuel over the lifetime of the car. So to wrap it up: There are essentially only two motors for cars: heat engines to propel the car forward by burning fuel. Electric engines that use much more gentle and efficient magnetic fields. Electric engines are superior in almost every way: They’re lighter, smaller, cheaper, require no maintenance, are four times more efficient, cause no exhaust, and can run on renewable electricity. The problem was that batteries used to be incredibly heavy. Heavier than an elephant! But due to incredible developments in battery technology in the first years of this millennium, the weight of battery plus drivetrain will soon be less for an electric vehicle. Taking the fuel savings and efficiency into account that means the electric vehicle will be much, much cheaper to own. So if you look at the fundamentals, the adoption of the electric vehicle is not a question of if. It's only a question of how fast. Extra video: https://youtu.be/ewcWN-rHQ6Q Resource: How IC engine works:  ---------- How EV motor works:  ----------