Greentech Media

If you're learning about greentech, especially renewable energy, you can't help running into statements like these:

• A 26-watt CFL produces light equivalent to a 100-watt incandescent bulb.
• The energy value of a gallon of ethanol varies from 75,700 BTU to 84,000 BTU.
• The Toyota Prius Hybrid Synergy Drive includes a 67-horsepower electric motor.

But what are watts, BTUs and horsepower? What do they measure and how do they relate to renewable energy? How many watts, for example, does a wind turbine generate and how many homes will that power? How many BTUs does it take to heat an average house and how much natural gas does that require?

Before you can answer such questions, you have to master some basic concepts and vocabulary:

• What are energy and power and how do they relate to each other?
• What are the standard units of energy and power used by scientists?
• What are the traditional units used in industry, and how do they relate to the standard units?
• How do the various units apply to applications like lighting, heating and transportation?

This report is a quick review of energy, power and the units used to measure them. But don't worry; it's not high school physics all over again. It's more like a Berlitz course on energy-speak - just enough to let you read the menu and maybe eavesdrop on the natives.

Here's a list of the contents:

• Page 2 - SI: The International System of Units
• Page 3 - Energy 101: Joules, Watts & Newtons
• Page 4 - Mechanical Energy: Foot-Pounds & Horsepower
• Page 5 - Electrical Energy: Volts, Amps & Kilowatts
• Page 6 - Thermal Energy: BTUs, Calories & Tons
• Page 7 - Comparing Units & Conversion Factors

- Bob Bellman is a freelance technology writer and marketing consultant.