Monday, 2 October 2017

Alternative to Batteries - Ultracapacitors

Have you thought of having something that can store energy just like batteries, but are not batteries? You guess right! Ultracapacitors. This is also called supercapacitors. So in this article, we would used the two terms interchangeably. In this article we would consider the following:
  • What are Ultracapacitors
  • How does Ultracapacitors work
  • Design of Ultracapacitors
  • Ultracapacitor versus conventional capacitor
  • Comparison between Batteries and Ultracapacitors
  • Application of Ultracapacitors
Let's start with the first one.

What are Ultracapacitors?
 Sometime called Supercapacitors are devices that store electric energy just like batteries. But unlike batteries, ultracapacitors can store power for an extended period of time. Unlike batteries too, ultracapacitors does not have a lifetime, they can continue to work as long as they are always recharged. The structure of an ultracapacitor is given in Figure 1, showing the basic components

Figure 1: Basic Components of an Ultracapacitor

How Does Ultracapacitors Work?
Remember that capacitors are electronic devices that store charges.So when you switch off your television set, the indicator light does not go off immediately, it stays for a few seconds after power is turned off. This is power stored in capacitors.
Supercapacitors work based on the same principle. I discuss design of ultracapacitors in the next section.

Design of Ultracapacitors
In line with the principle of my blog, I would keep this discussion simple and to the point.
The same basic components of a capacitors also forms the basic components of an ultracapacitor namely:
Two Electrodes with a material(dielectric) separating the two. The material in between is what makes the difference. For normal capacitors, the separating material. In untracapacitors, this materials is made up of double layer of different ion-permeable materials. When voltage is applied on both electrodes, they become polarized and ions move from on end to another, thus generating electricity. The effect generated is called double-layer effect.

Ultracapacitors vs Conventional Capacitors
 While conventional capacitors could store powers for few seconds, supercapacitors are designed to retain power for several minutes or even hours. With respect to the design, the separating material in ultracapacitors is double layer as opposed to single layer in conventional capacitors. That is why ultracapacitors are sometimes called double-layer capacitors.

Comparison Between Batteries and Ultracapcitors
The question that logically arise is: "Could ultracapacitors replace batteries in future?". Let's answer that question by making a brief and simple comparison between batteries and ultracapacitors.
1. Batteries store charges for a longer time than ultracapacitors.
2. Ultracapacitors deliver a lower amount of voltage compared to batteries.
3. Ultracapacitors maintain much longer lifetime than batteries.
4. Ultracapacitors are said to have low energy density. This means that unlike batteries, they cannot be used as a continuous energy source.

Applications of Ultracapacitors 
Ultracapacitors are applied in various areas today including the following:
1.Home Electronic:: For many home and small electronics such as laptops, pcs, PDAs, portable media players, ultracapacitors is used to produce a UPS(uninterruptible power supply) effect allowing the device to continue functioning even when power goes out.

2. Wireless Electronic Tools:  This could be screwdrivers, blowers, drilling machines etc. which may be used in areas where the cables from the mains could not easily be connected. Ultracapacitors can provide the needed power.

3. Electric Vehicles: This is the most notable area of application. Although, batteries may be used in electric vehicles, ultracapacitors are used to provide alternative or supplementary power for the vehicle's auxiliary devices.

4. Transportation: In trams, metro trains, metro buses etc, ultracapacitors can be used to supply auxiliary power.

5. Field of Medicine: They can be applied in defibrillators in the treatment of certain heart diseases.

6. Street Lighting: Ultracapacitors could be used in street lighting to retain power in the event of a temporary power outage.

How Electric Vehicles Work (For Novice)

There a whole lot of things we use everyday without knowing how they work.This should not be the case. You need to have a basic idea of how devices around you operate. Not only would this equip you with the knowledge to solve minor problems, it would also enlighten you on what actually a technician does when you need to fix a broken gadget.

Today we would discuss electric vehicles and in line with the principles of my blog, I would keep it very simple.

Topics to be covered include:
1. How Electric Vehicles Work
2.Main Components of an Electric Vehicle
3. Energy Sources of Electrical Vehicles
4. Challenges of Electric Vehicles

How Electric Vehicles Work
Electric Vehicles are vehicles  that a driven by electrical energy. That is the main driving force of the vehicle comes from electrical energy. In electric vehicles, there are not internal combustion engine. However, in appearance, electric vehicles may have same look with engine vehicles, just that in electric vehicles, combustion of fuel in an engine to produce mechanical movements does not take place.
There is also Hybrid-Electric-Vehicles (HEV).
These ones have both an internal combustion engine and an electrical circuit. The internal combustion engine is there to provide power needed to charge the batteries from time to time. Then the vehicles drive is powered by electrical energy stored in the batteries.

Main Components of Electric Drive
1. Main Electric Drive: This is the main component of the Electric Vehicle. It manages the movement of the vehicle. The contains the main electric motor as well as the power electronic circuit and control devices

2. Main Electric Circuit: This is made up of the electrical circuit of each of the components needed for the movement/traction of the vehicle. This include the circuit that monitors the acceleration and speed, the electrical circuit for the braking etc.

3. Auxiliary Devices: These are devices  that are not involved in the vehicles traction. This devices includes devices for the air conditioning,  safety devices like the airbags, sit belts, internal lights etc.

4. Auxiliary Electrical Circuit: Each of the auxiliary devices are connected to electrical circuit that performs the control of the device. These electrical circuit for the control of the auxiliary devices make up the Auxiliary Circuit.

Energy Sources of Electric Vehicles
Some think all electric vehicles are powered by batteries, but that is not true. Let's look at a number of power sources of electric vehicles.

  • Batteries: This is the most basic one. Electric vehicle could have a battery or series of rechargeable batteries that store energy used for driving the vehicle. This batteries could be made of Lithium-ion, Nickel-Cadmium or other chemicals.
  • Public Power Supply: This is used to power trams, metro trains or metro buses. This vehicles move on fixed paths and connect to the public power through special connectors either overhead or on the vehicles track.
  • Fuel Cell: I have discussed this in another post here. A fuel cell is a special type of cell that stores hydrogen and produces electrical energy through a reaction between hydrogen and oxygen
  • Solar-Energy Based Vehicles: Cars base on solar energy are normally build to have the body made of solar panels. However the solar energy is used to charge batteries  that directly produce the vehicles drive.

Benefits of Electric Vehicles
I have outline three important benefits of electric vehicles below:

Environment Friendly: Electric vehicles does not have the problem of pollution created by cars running on internal combustion engine. Carbon monoxide or other harmful gases are are not released into the environment.

Low Noise: This could be considered as part of being environment friendly but I have separated it to show that the effect of noise could be as harmful to the environment as well.

Lower Maintenance Cost: With vehicles running only on electric power, then the cost of maintenance becomes very low. This is due to the in part to the relative complexity of the internal combustion engine compared to electric vehicles. Since the technology is relatively easy to understand, the replacement of damaged parts may even be done by an experienced user without an expert knowledge of vehicle engineering.

Challenges of Electric Vehicles
The biggest challenge facing electric vehicles production is in the are of durable energy source. Although this challenge have been overcome in case of lightweight vehicles like personal cars, metro trains, bikes and short-distance cars, it largely remains that they can't efficiently be applied is driving heavy duty vehicles and trucks across long distances.
The need for recharge after some minutes or hours limits the effectiveness of electric vehicles.
In high-powered military vehicles that require much power, used of electrical drive would not be able to provide the needed power.

I would like to stop here for now and I would like to thank you for reading. Do leave a comment to let me know how you feel.