Sunday, April 20, 2014Register
What's Watt?

The watt (W), named after Scottish engineer James Watt, is our most fundamental unit of power; it is how we measure the rate at which energy is produced or consumed. Electric power, expressed in watts, is power generated from an electric generating system which could range in size from a small solar photovoltaic system to a large nuclear, hydroelectric, or coal-fired utility plant. One kW (kilowatt) is equal to 1,000 watts, while 1 MW (megawatt) is equal to 1,000,000 watts. A residential solar system may produce about 3.5kW of electric power; whereas, a large coal-fired power plant may generate 1 GW (gigawatt) which is equivalent to 1,000 MW of electric power.

If you look at your electricity bill you will see that the amount of electric power used for a given amount of time is expressed in kWh (kilowatt hours). The cost of your electric bill reflects the amount of electric energy your household used for that month. According to the Energy Information Administration (EIA) [1], the average Texas home uses 1,136 kWh of electricity per month at an average rate of 12.24 cents per kWh.

We use electricity everyday for lighting, cooking, washing , drying , computers, televisions, radios, small appliances, electric toothbrushes, etc., that we often become unaware of the amount of electricity we consume and waste until …………we see the electricity bill! To provide an example of electricity usage, a 75 watt light bulb that is left on for 2 hours every day will consume about 4.5 kWh worth of electricity in a month (75W x 60hours/month). If electricity sells for 12.24 cents/kWh, the cost of keeping that 75W light bulb on for 2 hours every day is 55 cents per month (4.5 kWh x 12.24 cents/kWh).

Not all watts are created equal!

Some utility companies will determine the cost of each kWh by the demand of electricity needed for a particular time of day. For example, the cost of a kWh in August at 2 P.M., when air-conditioners are running full blast and people are working, would cost more than the kWh used at 2 A.M. when the night is cooler and most people are sleeping. When the sun shines, solar panels work – offsetting electricity that would be purchased through the grid. According to the Department of Energy, each kWh is equivalent to releasing approximately 1.37 lbs of CO2 (carbon-dioxide) emissions in Texas. By switching to a renewable energy source, such as solar or wind power, we are able to bypass the emissions generated by today’s power plants.

As a homeowner and consumer we may be concerned about the cost of each kilowatt hour, but as a community we should also be concerned with the amount of GHG emissions we produce. As Texans we are fortunate to have the ability to utilize the sun as a natural renewable and sustainable energy resource.




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