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CHAPTER 18.1: RENEWABLE ENERGY TODAY
Renewable energy – energy form sources that are constantly being formed- Reduces environmental problems caused by nonrenewable energy, but renewable energy sources affect the environment too- Nearly all forms come directly or indirectly from the sun (except geothermal) There are 6 kinds of renewable energy:1. Passive solar energya. uses the sun’s energy to heat something directlyb. By location and building design (window placement, insulation, orientation)c. advantages – no fuels neededd. disadvantages – efficiency depends on location 2. active solar energya. energy from the sun is gathered by collectors and the energy is used to heat water which is used to heat a building with a heat exchangerb. photovoltaic cells (solar cells) - convert the sun’s energy to electricity with a semiconductor i. advantages – non-polluting and have no moving parts ii. inefficient (don’t make much electricity) and expensive 3. wind power – converting wind into electric energya. energy from the sun heats earth surface unevenly and causes air masses to flow. wind is createdb. advantages – cheap and abundant (wind farms are easy to set up)c. disadvantages – getting it from its source to where it is needed is hard 4. biomass – power from living thingsa. wood, poop, methane (from when bacteria decompose organic waste), and alcohol (from fermentation of fruit or agricultural waste)b. advantages – less pollutionc. disadvantages – can become a problem if used in a nonrenewable way (cutting down trees faster than they can be replaced)d. examples: cars that use gasohol or ethanol 5. hydroelectricity – energy from moving watera. energy form the sun gets the water cycle moving. flowing water (controlled by dams) turns a turbine. the turbine is connected to an electric generator. it generates electricityb. advantages – cheap to operate, non-pollutingc. disadvantages – can have adverse effects on the environment and surrounding population (dam projects can displace people, disrupt ecosystems, destroy habitats and decrease farm productivity)d. alternative – microhydropower – uses streams, no dams 6. geothermal energy – power from heat in the earth’s crusta. heated water or steam is pumped up from inside earth and powers a turbine which is used to generate electricityb. geothermal heat pumps for homes – circulate fluid in a pipe underground and back to the surface to heat or cool a housec. advantages – geothermal power plants are less pollutingd. disadvantages – hydrothermal water deposits can be depleted, facilities are expensive to build.CHAPTER 18.2: ALTERNATIVE ENERGY AND CONSERVATION
Alternative energy – energy sources still in development3 alternative technologies:1. Tidal power – uses tides to power a turbine that generates electricityo expensive to build, few suitable locations 2. Ocean thermal energy conservation (OTEC) – uses low pressure and warm water to boil water and generate powero to make electricity OTEC drives a turbine with steam that has been heated by warm surface water à steam is turned back to liquid by cooling with cold water from the deepo inefficient 3. Hydrogen – can be burned directly or stored in a fuel cell and combined with oxygen to produce electricityo hydrogen is the most abundant element around us, it is non-pollutingo takes a lot of energy to produce (maybe use wind or solar energy to make it) 2 main ways to reduce energy use1. increasing energy efficiency – getting more work out of the energy we usea. efficient transportation – fuel cells instead of internal combustion engines, mass transit, hybrid cars (currently the most energy-efficient vehicles)b. cogeneration – making 2 useful forms of energy from the same fuel source. i. Ex: waste heat from an industrial furnace can power a steam turbine 2. energy conservation – reducing the amount of energy we usea. use energy-efficient devices and waste less energy i. walk or bike for short trips, carpool, mass transit ii. insulate properly, seal leaks iii. recycle iv. turn stuff off or put it to sleep v. turn the thermostat down vi. use less resources
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