Bellringer What is one form of biomass? How do we use it for energy? Test TOMORROW, SO START STUDYING!

Alternative Energy

Review: Issues with conventional energy sources: Nonrenewable Limited supply Harm the environment

Solar Energy Solar Energy – producing power by harnessing the Sun’s radiant light and heat Can be passive or active

Solar Energy Passive solar energy – Directly absorbs and stores heat from the sun Distributes solar heat in the winter and rejects solar heat in the summer without any technology Can provide up to 70% energy needed to heat a house

Solar Energy Active solar energy – the sun’s heat is collected (via solar panel) and stored in a solar collector A pump will carry the heat to places where it is needed in a building

Solar Energy Solar panels on a roof can heat water up to 149oF, which is warm enough to take showers and wash dishes and clothing

Solar Energy NC’s solar farm industry (thousands of solar panels in one location) is booming due to many factors such as an abundance of flat land that receives amply sunlight and significant tax credits to the farmers Solar farm at SAS Institute in Cary. They use sheep to keep the grass around the panels under control.

Solar Energy Advantages: Light is free, unlimited, indefinitely renewable Solar panels require little maintenance Silent Causes no pollution

Solar Energy Disadvantages: Not able to efficiently collect/store energy at night (and reduced power on cloudy days) Today’s most efficient cells only convert about 20% of Sun’s rays into electricity Initial cost of the panels is very expensive

Hydroelectric Energy Hydroelectric energy – producing power through the use of falling or flowing water The rapidly-moving water turns turbines, which produces mechanical energy that converts into electric energy

Hydroelectric Energy Waterfalls (like Niagara Falls) or dams that allow water through at a controlled rate

Hydroelectric Energy Kinetic (moving) energy from ocean waves can also be used to generate electricity

Hydroelectric Energy Advantages: Abundant and reliable The US has many locations that are suitable for hydroelectric power Able to control water flow to produce electricity on demand Causes no pollution Reservoirs created by hydropower can be used for fishing, swimming, and boating

Hydroelectric Energy Disadvantages: Fish populations impacted if fish cannot migrate past dams to mate This can be aided by fish ladders that trap and haul fish over the dam Downstream passage aided by screens that divert around the turbines Can impact water quality and flow (decreases dissolved oxygen levels, which impacts aquatic ecosystems)

Geothermal Energy Geothermal Energy – producing power through the Earth’s natural steam and hot water The steam turns a turbine, which produces mechanical energy that converts into electrical energy (just like hydroelectric power)

Geothermal Energy Geysers shoot up heated water and steam, like Old Faithful in Yellowstone National Park What is fueling the heat at Yellowstone?

Geothermal Energy Advantages: Abundant, renewable, and reliable (“old faithful…”) Untapped resource; predicted that geothermal reservoirs could produce up to 30 times more energy than the US currently uses! Only requires small amounts of land Causes minimal pollution

Geothermal Energy Disadvantages: Expensive to initially build the geothermal power plants and heating/cooling systems in homes Very location-specific (only realistic for areas close to the power sources) The steam often contains minerals that can clog pipes or pollute surface water

Wind Energy Wind Energy – producing power by capturing the wind The wind turns a turbine, which produces mechanical energy that converts into electrical energy (noticing a trend here?) The US is the world’s leading producer of wind energy, though countries like the Netherlands have been using windmills for thousands of years

Wind Energy Advantages: Abundant and renewable Causes no pollution Doesn’t require a lot of land space – so the land below can also be used for grazing or farming Remote areas not connect to the electricity power grid can use wind turbines to produce their own electricity

Disadvantages: Do not work when wind isn’t blowing, so people have to rely on backup systems when the wind dies down Only useful in areas with steady winds Noisy (60-70dB, equivalent to road noise when traveling 70mph) In 2012, an estimated 573,000 birds died flying through wind farms

Study Guide Take out all of your notes for Unit 3 You may listen to music while you work I will come around periodically and check on your progress