BIOL 111 Study Guide - Final Guide: Energy Conversion Devices, Straw, Passive Solar Building Design
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IMPROVING ENERGY EFFICIENCY
1. Energy efficiency measures useful energy produced by energy conversion devices compared to others.
2. In N. America, 84% of energy is lost (41% due to thermodynamics & 43% is wasted unnecessarily).
3. One can save money and energy by:
Having a lower life-cycle cost — the initial cost plus lifetime operating costs.
Keeping the number of steps in an energy conversion process as low as possible.
Having the highest possible energy efficiency for each step in an energy conversion process.
4. Ways to improve energy efficiency:
Cogeneration (combined heat and power systems are produced from the same fuel source).
Replacing energy-wasting electric motors, which consume 25% of electricity in N. America.
Replacing incandescent lighting to fluorescent lighting and light-emitting diode (LED) lighting.
Using better cars (eg, Toyota Prius), which use hybrid-electric internal combustion engines.
Using super-efficient electric cars, which use fuel cells to produce electricity and water vapor.
Building energy-efficient houses (eg, strawbale houses) that use 90% less heating and cooling.
Having eco-roofs covered with gardens to provide good insulation and absorb more rainwater.
Using energy-efficient windows, appliances and lighting, and insulating and plugging leaks.
5. Using solar energy to provide heat and electricity:
Solar energy is converted directly into electrical energy by photovoltaic (PV) or solar cells.
A passive solar heating system absorbs heat from the sun directly within a structure.
An active solar heating system absorbs heat by pumping water in solar collectors on the roof.
6. Using the water cycle to produce electricity:
Large-scale hydropower: water in reservoir created by dam flows into pipes to spin turbines.
Small-scale hydropower: a dam with no reservoir in a stream allows water to spin turbines.
Pumped-storage hydropower: water is stored at high elevations & released to spin turbines.
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