Waste heat facts for kids

Waste heat is extra heat that machines and other processes create, but it's not used for anything helpful. Think of it like a leftover that nobody wants!

When machines work, they use energy. But not all of that energy turns into what the machine is supposed to do. Some of it always changes into heat. This happens because of things like friction, which is when parts rub together. Even liquids can create friction.

Machines that change energy from fuels (like coal or gas) into movement or electricity make a lot of waste heat. This is because no machine can be 100% perfect at changing energy. Some energy always escapes as heat.

It can be tricky to use this waste heat. It's hard to move the heat to where it's needed, and it's also hard to save it for later. But sometimes, people use special systems called cogeneration to capture and reuse this heat. This can help save energy and money!

What Is Waste Heat?

Waste heat is simply heat that is produced but not used. It's a by-product of many things we do every day. For example, when you use a computer, it gets warm. That warmth is waste heat. When a car engine runs, it gets very hot, and much of that heat is also waste heat.

How Is Waste Heat Created?

Waste heat is made whenever energy changes from one form to another. This is a basic rule of physics. For instance, when you rub your hands together, they get warm. That warmth comes from the energy of your movement changing into heat because of friction.

In big machines, like those in power plants, a lot of energy is used to make electricity. But not all of that energy becomes electricity. A big part of it turns into heat that just goes into the air or water. This happens because machines are not perfectly efficient. They can't turn all the input energy into useful work.

Why Is Waste Heat a Problem?

Waste heat can be a problem for a few reasons:

• Wasted Energy: It means that some of the energy we put into a system is not used effectively. This can be expensive and not good for the environment.
• Heating Up the Planet: When a lot of waste heat is released into the air, it can add to the overall warmth of our planet. This is called anthropogenic heat, meaning heat created by humans.
• Machine Performance: Sometimes, too much heat can make machines work less well or even break down. That's why many machines have cooling systems to get rid of this extra heat.

Can We Use Waste Heat?

Yes, sometimes we can! Using waste heat is called cogeneration or combined heat and power (CHP). This means we capture the heat that would normally be wasted and use it for something else.

For example, a power plant might make electricity, and the waste heat from that process could be used to warm homes or buildings nearby. This is a smart way to get more out of the energy we use.

However, using waste heat can be difficult. It's often hard to move the heat from where it's made to where it's needed. Also, storing heat for later use is not always easy. Scientists and engineers are always looking for new ways to make better use of this unused energy.

Images for kids

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  Air conditioning units take heat from inside a building and release it outside as waste. They also make more heat from the electricity they use.

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  A Coal-fired power station changes chemical energy into electricity. But a lot of the energy (52%-64%) becomes waste heat.

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  Cooling towers letting off steam at Ratcliffe-on-Soar Power Station in the United Kingdom. These towers help get rid of waste heat.

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  Heat created by human activities.

See also

In Spanish: Calor residual para niños