Warm Up (3/11/2014) • A home uses ten 100-watt lightbulbs for five hours per day. Approximately how many kilowatt-hours of electricity energy are consumed in one year by using the lightbulbs? • 365 • 1,825 • 5,000 • 10,500 • 365,000
John Muir (1838-1914) • Avid hiker who spent most of his life wandering in – and fighting to preserve – the wilderness of the Western US. • His efforts of preservation led to the creation of Yosemite Nat’l Park, Sequoia Nat’l Park, and millions of other conservation areas. • In 1892, Muir and other founded the Sierra Club “to make the mountains glad”.
V: Energy Resources and Consumption (10-15%) • E. Hydroelectric Power • (Dams; flood control; salmon; silting; other impacts) • F. Energy Conservation • (Energy efficiency; CAFE standards; hybrid electric vehicles; mass transit) • G. Renewable Energy • (Solar energy; solar electricity; hydrogen fuel cells; biomass; wind energy; small-scale hydroelectric; ocean waves and tidal energy; geothermal; environmental advantages/disadvantages)
Announcements • Energy/Content FRQ on Thursday (25 mins) • Multiple choice exam on Friday(50 mins) • We will begin our last and final unit on Thursday. • Practice AP exam to come (before spring break). • Office hours: today until 5:45pm and I’ll be here at least 1 hr on Wed and Thursday.
What is Renewable Energy??? • Potentially Renewable Energy Sources • Ex: biomass and Wood • Renewable as long as humans don’t use it faster than it can be replenished. • Nondepletable Energy Sources • EX: Solar, wind, water
How Can We Use Less Energy? • Energy Conservation • Ex: Lower thermostat during winter months • Energy Efficiency • Getting the same result from using a smaller amount of energy. • Use more efficient appliances • Sustainable Design • Your house doesn’t move, and you know the height/angle of the sun during the seasons…so why not build SMART
Biofuels • Any source of energy that is derived from biomass or any substance that was once living. • Examples: Grease, ethanol (corn, sugar, or cellulosic) algae • Pros: • Burn cleaner (less pollutants) • Plants remove CO2 from atmosphere through Photosynthesis • Cons: • Requires energy to grow and extract product • Land use
BrainPop Break • Biofuels
Hydroelectricity • Electricity generated by the kinetic energy of moving water. • RUN-OF-THE-RIVER • Low dams are used. • Water is not stored in a reservoir • Low upstream flooding • Impoundment Systems (next slide) • Tidal Energy • Movement of water is driven by the gravitational pull of the Moon. • Use of turbines
How Does This Damn Dam Work? Kinetic Energy of moving water pushes turbine (mechanical E), which is converted into electrical Energy by the generator
Problems with Hydropower • Silting • A fast-moving river carries sediments that settle out when the river feeds into a reservoir created by a hydroelectric dam. • The accumulation of these sediments= siltation • Disruption of salmon migratory patterns • Release of CO2 into the atmosphere during the production of cement • Low nutrients downstream (after dam) • Flooding upstream (before dam)
BrainPop Break • Hydropower
Solar Power Design Active Passive Heat up the house without the need for pumps or other mechanical devices. • Capture the energy of sunlight with the use of an intermediate technology such as a pump of photovoltaic cell. • Examples • Solar water heating • Photovoltaic systems
Solar Water Heating • A nonfreezing liquid is circulated by an electric pump through a closed heating loop. • The liquid moves from a water storage tank to a solar collector on the roof, where its heated, and back to the tank, where its heat is transferred to water
Photovoltaic Cell System • PV cells convert sunlight into direct current (DC) electricity. • An inverter converts DC into alternating current (AC), which powers the house. • Excess electricity is exported to the grid.
Solar Thermal Power Plant Mirrors and reflectors concentrate the Sun’s energy onto a “power tower”, which uses the sunlight to heat water and make steam for electricity generation.
Geothermal Energy • Examples: • Hot groundwater can be piped directly into household radiators for heating a home. • Heat exchangers are drilled into the ground and collect heat by circulating cool liquid underground, where it’s heated, and returning it to the surface. • Iceland, a small nation with VAST geothermal resources, heats 87% of its homes this way.
Wind Energy • Just like hydroelectric energy is harnessed from water, a wind turbine converts the kinetic energy of wind into electrical energy.
How do Wind Turbines Generate Electricity? Hmm, this is starting to get REAL repetitive…
How Would I Study For The Exam? • 1) Read Ch. 8 of Princeton Review • Take the end of the chapter quiz and FRQ • 2) Re-read ch. 15/16 Instructor manuals • 3) Review answers to RG • 4) Study Vocab from crossword puzzles • 5) Practice radioactive math
How Can We Make the Transition to a More Sustainable Energy Future? • 1) There will be a gradual shift from large, centralized macro-power systems to smaller, decentralized micro-power systems. • 2) The best alternatives combine improved energy efficiency and the use of natural gas and sustainably produced biofuels. • 3) The abundance and price of fossil fuels will cause their continued use. We need to find ways to reduce their environmental impacts.