# Maximizing Flywheel Energy and Power for Passenger Bus Design

• Mitchlan
In summary, the design of a passenger bus proposes using a flywheel to store energy and electric motors to accelerate it to a maximum rotation rate of 3.0 x 103 revolutions per minute. The maximum kinetic energy that can be stored in the flywheel is 68.832 kJ. For a bus requiring 20kW of power and traveling at an average speed of 36 km/h, the maximum possible distance between stations on a level surface can be calculated by determining the time the stored energy can power the bus and using the given speed to find the distance.
Mitchlan

## Homework Statement

In the design of a passenger bus, it is proposed to derive the motive power from the energy stored in a flywheel. The flywheel, which has a moment of inertia of 4.0 x 102 kgm2, is accelerated to its maximum rate of rotation of 3.0 x 103 revolutions per minute by electric motors at stations along the bus route.
a) Calculate the maximum kinetic energy that can be stored in the flywheel.
b) If, at an average speed of 36 kilometres per hour, the power required by the bus is 20 kW, what will be the maximum possible distance between stations on the level?

## The Attempt at a Solution

Part A:

K (Rot)Energy = 1/2 I omega^2
= 1/2 * 4 * 10^2 * 314.159^2
= 68.832 kJ

Part B:

Please help: do I need to find torque and angular displacement, use this to find work then distance?

Any nudge in the general direction greatly appreciated. Thanks in advance.

The bus requires 20kW or 20 kJ/s, so for how long will 68.832 kJ carry it?

That will give you a time, and you are given a speed of 36 km/h so you can get distance.

rock.freak667 said:
The bus requires 20kW or 20 kJ/s, so for how long will 68.832 kJ carry it?

That will give you a time, and you are given a speed of 36 km/h so you can get distance.

Great! Thanks for that!

## What is flywheel energy and how does it work?

Flywheel energy is a form of energy storage that uses a spinning disc or wheel to store rotational energy. This energy can then be converted into power when needed. The flywheel works by using a motor to spin the wheel and store energy, and then a generator to convert the energy back into power.

## What are the benefits of using flywheel energy?

Flywheel energy has several benefits, including high power density, fast response time, and long life span. It also does not produce any emissions and can be used as a backup power source in case of power outages.

## How does flywheel energy compare to other forms of energy storage?

Flywheel energy storage is more efficient and has a longer lifespan compared to batteries. It also has a faster response time than pumped hydro storage. However, it is not suitable for long-term energy storage like some other methods.

## What are some practical applications of flywheel energy?

Flywheel energy storage is commonly used in uninterruptible power supplies (UPS) and backup power systems for data centers, hospitals, and other critical facilities. It can also be used in hybrid vehicles and renewable energy systems for smoothing out power fluctuations.

## Are there any limitations or drawbacks to using flywheel energy?

One limitation of flywheel energy storage is that it is not suitable for long-term storage, as the energy can slowly dissipate over time due to friction. It also requires a constant energy input to maintain the spinning motion. Additionally, flywheels can be expensive and bulky compared to other forms of energy storage.

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