Power vs Energy. What is energy? What is power? How do they work together? And why does it matter to you? These are all important questions in helping you understand what fuels the light, heat, and electronics in your home.
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What is energy?
Energy is defined as a measurement of how much fuel is contained within something or used by something over a specific period of time. This is what your utility company uses to determine how much energy you consume each month, and they measure it in kilowatt hours (kWh), which is how many kilowatts per hour you use. So you know that consumption charge you see on your bill that says something like 652 kWh? It means your residence has used 652 kWh worth of energy in a month.
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What is power?
Power is the rate at which energy is generated or used. It is the measure of how fast something is generating or using energy. A kilowatt (kW) is a good example of a measurement of power. You measure power by how fast something is generating or using energy. For example, the higher number of kW a building pulling, the faster that building is using energy.
How do they work together?
We’ve already found out that power is the rate at which something uses energy, so for something to have power it also has to somehow have energy to work. For your TV to have power, it has to be plugged into the wall where the electricity can connect to it. The electricity is the energy that gives your TV the power to project the new episode of The Big Bang Theory that you’ve been waiting to see. The energy you used is the amount of power over the duration of the time you watched TV.
The units that power and energy are measured in, kW and kWh respectively, are also related. This fact may be relatively obvious since they look pretty similar, but there is actually a little bit more involved. The two measurements are connected through math. (“OH NO! MATH!” But I promise this math is easy to understand.) To get energy, you multiply power by time. For kWh, it is kWh(energy)= kW(power)*time (usually hours). To get power, you divide instead of multiply. You divide the energy by time. For kW, it is kW(power)= kWh(energy)/ time. This is how the measurements are calculated.
Why does it matter to you?
We already know that power and energy are what powers (you see what I did there???) our day-to-day lives. It’s what charges our smartphones for us to stay connected during the day; it’s what turns our lights on when night time comes so we don’t trip over shoes on the floor or stub our toes on the furniture. (Although, stubbing my toe on furniture happens to me during the day time, so I don’t think that is the electricity’s problem.) In modern times, most of us couldn’t function properly without somewhere to charge our phones, a microwave to heat our food or something to heat the water for our showers. Understanding power and energy and how they work together is a good first step in understanding and appreciating the comforts most of us enjoy daily.