Eco-Living Magazine

What is the Difference Between a Kilowatt and Kilowatt-hour Anyway?

Posted on the 08 December 2011 by 2ndgreenrevolution @2ndgreenrev

What is the Difference Between a Kilowatt and Kilowatt-hour Anyway?I wish I knew. The energy economy can be confusing, especially for consumers. I, for example, still have no frame of reference for watts and kilowatts. If I’m told a plant produces X kilowatts of electricity or a solar panel produces Y amount of energy that doesn’t really mean much to me. I have no frame of reference. I know I am not alone in this. Say “60 watt bulb” and an image pops up in my mind. I know what 60 watts “looks like” and what it can power, but trying to envision the electricity needed to light the bulb is tough. Say gallon and an milk jug pops up as an image in my mind. Say 880 watts and nothing pops up (even if doing the math yields 14 and a half 60 watt bulbs). This is all part of the disconnect between us and understanding our energy use.

What about electric bills and kilowatts (kW) versus kilowatt-hours (kWH)? Here is a site that may help give us a frame of reference. Energy consumption is measured in kilowatt-hours and is the amount of watts multiplied by the total number of hours used. So a 100 watt bulb burning in your lamp for 10 hours consumes 1,000 watt-hours  of energy (100×10=1,000). 1,000 watt-hours is the same as 1 kilowatt-hour. The graphic below helps bring it all together. That same bulb is also demanding 100 watts of electricity from the grid the entire time it is on. The power plant therefore has to have 100 watts, or 0.1kW ready for whenever that light gets turned on.

So I guess that explains it, but it’s still not intuitive. It’s still like hearing temperatures in Celsius or distances in kilometers for Americans. It just doesn’t quite compute (getting better, now that I’m in Japan, however). Perhaps it is just repetition that breeds familiarity and if we get used to learning about and hearing about energy, it will sink in. 


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