They are being utilized in thousands of different applications. They complement a primary energy source which cannot repeatedly provide quick burst of power. For example, an internal combustion engine, fuel cells, or battery. The future looks bright, but how far are we from ultracapacitors becoming the standard?
It is best that we start this section with an analogy. Batteries need time to charge and discharge energy. Think of it as the time it takes for a dam to fill with rain during the rain, and then slowly drain. On the other hand, ultracapacitors, can store charge and discharge rapidly. It is like routinely opening the floodgates in a dam as it rapidly refills with rain.
With that in mind, here are the five main differences between the two.
Number one, definition of the two items. Batteries store their potential energy in the form of chemical reactions before converting it into electrical energy. Capacitors, on the other hand, store potential energy in an electric field. Their voltage is variable and proportional to the amount of electrical charge stored on the plates.
The second difference is in the way of application. Batteries can store a larger amount of electrical charge. An ultracapacitor, however, cannot store large amounts of energy. They can handle high voltage applications and they are ideal for frequent uses.
The charge and discharge rate is the next difference. The rate of capacitors is much faster than the one of batteries. That is because the capacitor stores the energy directly onto the plates.
Both these devices can store electrical energy. But they do it in a different way. Batteries store energy in the form of chemical energy. Capacitors store electrical energy in a magnetic field.
Last, but not least, is the polarity of capacitors and batteries. Polarity of the electronic circuit must be reverse while charging a battery. It must be the same as it is supposed to be while using in the case of a capacitor. Batteries maintain a constant voltage flow across the terminals.
Here are a couple of situations where ultracapacitors have found their usage. They are quite beneficial and utilized in these situations.
- They can be used to harvest power from regenerative braking systems and release power to help hybrid buses accelerate
- They can be used in blade pitch systems to increase reliability and stability to the energy grid
- Semi-trucks in cold weather can drain energy from capacitors when batteries are drained from repetitive starting or in-cab electric load
- We can use ultracapacitors to capture energy and provide burst power to assist in lifting operations
- Provide cranking power and voltage stabilization in start/stop systems and peak power for key automotive applications
- Provide energy to data centers between power failures and initiation of backup power systems
- Capture energy from regenerative braking systems and release power to assist in train acceleration
- Open aircraft doors in the event of power failure
- Provide energy storage for firming the output of renewable installations and increasing grid stability
Elon Musk is one of the great minds of our generation. When he first came to California, he wanted to pursue a PhD at Stanford studying ultracapacitors. He ended up becoming an internet entrepreneur instead. But his love for the technology stayed.
In February 2019, Tesla bought Maxwell, a company known for making ultracapacitors. They have found usage in the auto industry. Maxwell has customers like General Motors, Lamborghini, and Volvo. They use ultracapacitors to absorb energy when braking and then releasing when the car accelerates.
While fast charge and discharge make capacitors better than batteries, they have their disadvantages. The biggest one is the limitation. The total amount of energy capacitors store is just a fraction of what batteries store. To run electric cars on ultracapacitors, for example, you need many devices. That would make the car too heavy to run efficiently.
But the technology is just in its beginning. After a couple of years, we might see ultracapacitors replacing batteries. This is the time to invest knowledge and time in them.