Do Now (silently!!)Explain one disadvantage and one advantage of nuclear power

Solar EnergyPassive solar collection uses

buildings designed to maximize direct absorption of sunlight in winter as they keep the interior cool in summerInvolves installing low, south facing windows to maximize sunlight capture in the winter

Overhangs shade windowsHeat absorbing construction materials

Solar cookers are portable ovens that use reflectors to focus sunlight onto food and cook it

Active solar energy uses technological devices to focus, move, or store solar energy

Photovolatics video

Photovoltaic cellsPhotovoltaic cells (PV) collect

sunlight and convert it to electrical energy directly

Light strikes one of a pair of metal plates, causing the release of electrons, which are attracted to the opposing plateThe flow of electrons creates an electrical current, which can be converted into alternating current (AC) and used for power

Benefits of Solar PowerPractically inexhaustible energy source

PV cells use no fuel, are quiet and safe, contain no moving parts, require little maintenance, and do not require a turbine or generator to work

Benefits of Solar PowerThey allow for local control over

power without needing a power plant

Does not pollute the air with greenhouse gases and other air pollutantsManufacturing PV cells requires fossil fuel use

Benefits of Solar PowerIn developing countries, solar

cookers enable families to cook food without gathering fuelwoodLessens deforestation and can relieve social problems

In developed countries, families with solar panels are connected to the electrical grid and can sell their excess energy back

Negatives of solar energyNot all regions are sunny enough to provide adequate power, given current technology

The up-front cost of investing in the equipment is higher than other renewable energy sources, and much higher than fossil fuels

Wind Power

Modern Wind Turbines•Wind turns the blades

of a rotor, which rotate the machinery inside a compartment called a nacelle (with a generator), which sits aside a tall tower

•Usually, a group of turbines is set up in an area called a wind farm

Wind Power today•Wind provides a small portion of the world’s power needs, but it is growing very quickly▫5 nations provide 82% of the world’s wind energy output (US, Germany, Spain, Denmark, India)

▫In Denmark, wind farms provide 20% of the nation’s power

Benefits of wind power

•Produces no emissions once the equipment is installed

•Is very energy efficient (produce 23 times more energy than they consume)▫Nuclear is 16:1, coal is 11:1, and natural

gas is 5:1•Wind turbines can bring economic benefits to rural areas when they sell the electricity

Negatives of wind power

•We have no control over when wind with occur, so wind cannot be the sole source of electricity

•Some areas do not have enough wind to support a wind farm▫Many places with the required amount of wind are not large population centers

•Wind farms are not aesthetically pleasing

•May pose a threat to birds and bats

Urban wind tower video??