Practical examples of using a flywheel to demonstrate energy storage

Classroom-scale examples of using a flywheel to demonstrate energy storage

When people ask for examples of using a flywheel to demonstrate energy storage, they usually mean: What can I actually build and show in front of students? Let’s start with simple classroom rigs you can assemble with standard lab gear and a modest budget.

Bench-top flywheel with falling mass

One of the best examples of using a flywheel to demonstrate energy storage is the classic setup: a metal or wooden disk mounted on low-friction bearings, with a light string wrapped around its axle and a small hanging mass.

You raise the mass a known height, let it fall, and watch the flywheel spin up. The gravitational potential energy of the mass is converted into rotational kinetic energy of the wheel (plus some losses). This single setup lets you:

• Measure the angular speed with a photogate or optical sensor.
• Compare the initial potential energy \(mgh\) with the final rotational energy \(\tfrac{1}{2}I\omega^2\).
• Discuss where the “missing” energy goes: bearing friction, air drag, heating.

As an example of a quantitative lab, students can vary the mass, the drop height, or the moment of inertia (by adding removable weights at different radii) and build an energy budget. This is one of the most reliable examples of using a flywheel to demonstrate energy storage while also teaching experimental error and data analysis.

Hand-cranked generator and flywheel combo

Another classroom-friendly example of using a flywheel to demonstrate energy storage pairs a flywheel with a small DC generator or motor. Students turn a hand crank connected to the flywheel through gears. As they crank, the flywheel speeds up. Once it’s spinning, you disconnect the crank and connect the shaft to:

• A tiny light bulb or LED array
• A buzzer or small fan

The stored rotational energy keeps the generator running for a few seconds even after the crank is released. Students feel the difference in effort when:

• The flywheel is light versus heavy.
• The radius of the mass distribution is changed.

This is a tactile example of energy storage: students literally feel the resistance as they “charge” the flywheel, and they see the payoff when the lights stay on after they stop cranking.

Bicycle wheel as a flywheel

If your budget is minimal, a standard bicycle wheel on a low-friction axle is one of the best examples of using a flywheel to demonstrate energy storage with household hardware.

You can:

• Spin the wheel by hand and time how long it takes to slow down.
• Add masses to the rim and compare spin-down times and angular speeds.
• Mount the wheel horizontally and use a small belt to power a toy car or a simple generator.

One powerful example of energy storage here is to have students compare a lightly loaded wheel to one with extra mass at the rim. The heavier-rim wheel is harder to start but keeps going longer. This drives home the role of moment of inertia in how flywheels store and release energy.

Real-world examples of using a flywheel to demonstrate energy storage concepts

Classroom rigs are great, but students often ask, “Where is this used in real life?” Modern engineering offers several real examples of using a flywheel to demonstrate energy storage that you can point to, research, or even approximate with small-scale models.

Hybrid vehicles and kinetic energy recovery systems

Racing and high-performance vehicles use flywheel-based kinetic energy recovery systems (KERS) to capture energy during braking and reuse it during acceleration. While most consumer hybrids rely on batteries, flywheel KERS has been explored in Formula 1 and endurance racing.

In class, you can:

• Show a small cart with a flywheel coupled to its wheels via gears.
• Let the cart roll down a ramp, spinning up the flywheel.
• Then send it onto a flat surface and watch the flywheel give some of that energy back, extending the travel distance.

This small cart is a scaled-down example of using a flywheel to demonstrate energy storage in regenerative braking. It connects directly to conservation of energy, power, and efficiency—topics that appear in most physics curricula.

For deeper background on energy storage technologies in transportation, students can explore resources from the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy: https://www.energy.gov/eere

Grid-level flywheel energy storage

On the grid side, companies have built flywheel farms that store electrical energy as rotational energy. These systems use large, high-speed flywheels in vacuum enclosures to provide fast-response power for grid stabilization.

In a teaching lab, you obviously won’t build a utility-scale flywheel, but you can:

• Use a small motor to spin a lab flywheel to a set speed.
• Disconnect the motor and switch the flywheel to generator mode, powering a small load.
• Monitor voltage and current over time as the flywheel slows.

This is a clean example of using a flywheel to demonstrate energy storage at the systems level: mechanical energy buffering electrical supply and demand. It’s also an opportunity to discuss round-trip efficiency and compare flywheels with batteries and other storage systems. For broader context on grid storage, the U.S. Energy Information Administration provides accessible overviews: https://www.eia.gov

Flywheels in uninterruptible power supplies (UPS)

Some data centers and hospitals use flywheel-based UPS systems to bridge the gap between a power outage and the startup of backup generators. Instead of relying solely on batteries, a flywheel spinning continuously can provide a few seconds of high-power output.

In the classroom, you can model this with:

• A continuously spinning flywheel driven by a small motor.
• A switch that cuts power to the motor but routes the shaft to a generator.
• A load such as LEDs representing the “critical equipment.”

When you cut the main power, the flywheel keeps the lights on briefly, mimicking what happens in a real UPS. This is an applied example of using a flywheel to demonstrate energy storage in reliability engineering and emergency systems.

Institutions like the National Institute of Standards and Technology (NIST) publish guidance on power quality and reliability; their resources can help you frame this example in the context of real infrastructure: https://www.nist.gov

Hands-on lab examples of using a flywheel to demonstrate energy storage

Let’s zoom back into the lab and look at more detailed setups that support calculation-heavy courses and project-based learning.

Measuring efficiency and losses in a flywheel system

One sophisticated example of using a flywheel to demonstrate energy storage is to treat the system like a mini power plant and track where every joule goes.

A typical setup might include:

• A flywheel on precision bearings
• A DC motor/generator with known efficiency curves
• A current and voltage sensor connected to a data logger

Students can:

• Input a measured amount of electrical energy to spin up the flywheel.
• Let the system run a load (like a resistor bank or lamp) until the flywheel slows to a set speed.
• Compare input electrical energy, stored mechanical energy, and recovered electrical energy.

The difference between these values becomes a real-world example of frictional and electrical losses. This experiment naturally leads to discussions about why high-end flywheel systems use vacuum chambers, magnetic bearings, and composite rotors.

Comparing shapes and materials: which flywheel stores more energy?

Another rich example of using a flywheel to demonstrate energy storage is a comparative study of flywheel designs. Give students disks of:

• Different radii but similar mass
• Different thicknesses
• Different materials (steel, aluminum, 3D-printed plastic)

Using the same motor and input energy, students spin each to the same angular speed (or for the same time) and then:

• Time how long each flywheel can power a small load.
• Estimate stored energy from \(\tfrac{1}{2}I\omega^2\).

They quickly discover that distributing mass farther from the axis increases the moment of inertia and thus the energy stored at a given speed. This lab is a vivid example of how geometry, not just mass, matters in energy storage design.

Flywheel and thermal effects: where does the lost energy go?

For advanced courses, you can extend these examples of using a flywheel to demonstrate energy storage into thermodynamics. When the flywheel slows down, the lost mechanical energy becomes heat.

Students can:

• Use an infrared thermometer to measure bearing temperature before and after a long spin.
• Wrap a light friction band around the flywheel and measure its temperature change.

While the temperature rise is small, it’s a concrete example of the conservation of energy: the energy you “lose” from the spinning wheel reappears as thermal energy in the bearings, air, and friction surfaces.

For a solid conceptual background on energy conservation and thermal effects, introductory physics resources from MIT OpenCourseWare are excellent: https://ocw.mit.edu

Project ideas and extended examples of using a flywheel to demonstrate energy storage

If you’re planning a semester project or science fair build, flywheels are fertile ground. Here are real examples that students can adapt and investigate.

Human-powered flywheel charger

Students design a stationary bike or hand-crank system where a flywheel smooths out the power from a human rider. The project becomes an extended example of using a flywheel to demonstrate energy storage in off-grid or emergency scenarios.

Typical investigations include:

• How flywheel size affects rider comfort and power fluctuations.
• How long a charged flywheel can keep a phone-sized load powered.
• Trade-offs between heavier, slower flywheels and lighter, faster ones.

This naturally connects to public health and disaster readiness discussions—how to maintain communication or refrigeration when the grid fails. For broader context on emergency preparedness, students can look at FEMA’s guidance: https://www.ready.gov

Model flywheel bus or tram

Urban transit once used flywheel-equipped buses and trams that charged at stations and coasted between them. Students can build a tabletop version: a wheeled cart with a flywheel that is “charged” at a station using a motor, then released to run along a track.

By measuring how far the cart travels between charges, they get a scaled example of using a flywheel to demonstrate energy storage in transportation. Variables to explore include track friction, cart mass, and flywheel design.

Data-driven comparison: flywheels vs batteries

For older students, a research project comparing flywheel energy storage to chemical batteries is timely. This doesn’t require building large hardware; it relies on data analysis.

Students can:

• Collect published data on energy density, power density, cycle life, and safety for modern flywheel systems and lithium-ion batteries.
• Analyze where each technology shines: grid smoothing, short-term backup, long-term storage.

The outcome is a nuanced example of how different energy storage technologies fit into the broader clean energy landscape, which is very much a 2024–2025 conversation.

FAQ: common questions about examples of using a flywheel to demonstrate energy storage

Q: What are some simple classroom examples of using a flywheel to demonstrate energy storage?
A: A falling-mass flywheel rig, a hand-cranked generator with a flywheel, and a bicycle wheel on low-friction bearings are all straightforward. Each gives a visible example of potential energy converting to rotational kinetic energy and then back to electrical or mechanical work.

Q: What is a real-world example of flywheel energy storage that students can relate to?
A: Flywheel-based uninterruptible power supplies in data centers and hospitals are highly relevant. They provide a real example of using a flywheel to bridge short outages, keeping equipment running while backup generators start.

Q: Are there examples of flywheels being used in modern transportation?
A: Yes. Experimental hybrid vehicles and some rail systems have used flywheel-based kinetic energy recovery systems to capture braking energy and reuse it during acceleration. A small cart with a flywheel and ramp is a classroom-scale example of using a flywheel to demonstrate energy storage in this context.

Q: How do I choose the best examples for different grade levels?
A: For middle school, stick with qualitative demos like hand-spun bicycle wheels and simple falling-mass setups. High school can handle timing, energy calculations, and efficiency comparisons. College-level courses can tackle full energy audits, material choices, and modeling of grid or vehicle systems as more advanced examples of using a flywheel to demonstrate energy storage.

Q: Are flywheel experiments safe for students?
A: Yes, if you keep rotational speeds moderate, use sturdy mounts, and shield rotating parts where possible. Avoid very high-speed, small-diameter flywheels in a school setting. With reasonable precautions, the best examples of classroom flywheel setups are safe, durable, and highly repeatable.

By combining hands-on rigs, real engineering case studies, and data-driven projects, you can move beyond abstract theory and give students multiple, memorable examples of using a flywheel to demonstrate energy storage that tie directly into how modern energy systems work.