- the effective operation as measured by a comparison of production with cost
- energy efficiency refers to the measure of the useful energy
- 2nd Law of Thermodynamics states that in any spontaneous change the quality of energy deteriorates gradually over time
- output is mechanical work or energy
- Cannot exceed 100% because of the Law of Conservation of Energy
- Positive feedback will result in exponential growth (its's BAD)
- the negative feedback the output of one type acts as input that moves the system in the opposite direction (GOOD)
- 84% of all commercial energy used in the U.S. is wasted
- 41% wasted due to 2nd law of thermodynamics
- Fuel-efficient vehicles powered by a fuel cell that runs on hydrogen gas are being developed
- Costa Rica gets 92% of its energy from renewable resources
- China aims to get 10% of its total energy from renewable resources by 2020
- California got about 12% of its electricity from wind and plans to increase this to 50% by 2030
- We can heat buildings by orienting them toward the sun or by pumping a liquid such as water through rooftop collectors
- water in dams can spin a turbine to create energy
- Wind power is the world’s most promising energy resource because it is abundant, inexhaustible, widely distributed, cheap, clean, and emits no greenhouse gases
- Plant materials and animal wastes can be burned to provide heat or electricity
- Motor vehicles can run on ethanol, biodiesel, and methanol
- crops like sugar cane and corn can be made into ethanol
- hydrogen might be the best replacement for oil
- Governments can use a combination of subsidies, tax breaks, rebates, taxes and public education to promote or discourage use of various energy alternatives