1 What is energy? Energy is the ability to do work or change the system. What are the various sources of energy? Fossil fuels Oil (Petroleum) Propane Natural gas Coal Alternative fuels Nuclear Wind Solar Hydroelectric (dams) Geothermal Ethanol (Biofuels)
2 What is the difference between renewable and non-renewable energy sources? Renewable energy source can the regenerated in a relatively short period of time. Nonrenewable energy source cannot be regenerated or replenished in a practical amount of time Which energy sources are renewable and nonrenewable? Nonrenewable energy sources Oil (Petroleum) - fossils Propane - fossils Natural gas - fossils Coal - fossils Nuclear Uranium is nonrenewable Renewable energy sources Wind Solar Hydroelectric - dams Geothermal steam from the ground Biomass vegetable oils, animal fats, greases, biological waste products
3 How are fossil fuels used? We use fossil fuels to Power transportation vehicles (diesel and gasoline are made from oil) Generate electricity Where did fossil fuels come from? Fossil fuels formed during the time of the dinosaurs. Fossil fuels: Dead and decaying plants collected in the bottom of swamps. Pressure from the rocks and increased temperature make the fossils into crude oil, coal, and natural gas. Energy stored is chemical energy.
4 Why do fossil fuels have stored energy? The energy of sun was stored by plants that absorbed sunlight. Plants converted the sun s energy into chemical energy. What are the problems with using fossil fuels? Fossil fuels concentrated this chemical energy from dead plants, which ultimately came from the sun. Fossil fuels: Produce air pollution (smog) Produce carbon dioxide and other Greenhouse gases, linked to the cause of Global Warming Are a nonrenewable energy source we will eventually run out
5 Why does burning fossil fuels contribute to Global Warming? global-warming.html What is Global Warming? From Live Science. What is the problem with Global Warming? Global warming is the gradual increase of the overall temperature of the Earth s atmosphere, surface, and oceans. Burning fossil fuels release carbon dioxide and other Greenhouse gases that trap the heat of the Sun within the atmosphere. Rising sea levels because the ocean is warming and expanding will flood coastal cities Extreme weather patterns hurricanes Extreme temperatures (both highs and lows) Dying ecosystems in the oceans, which depend on cooler ocean temperatures
6 Why are gases that trap Sun s heat (infrared light) called Greenhouse Gases? A greenhouse is made mostly from glass. Glass lets visible light from the Sun pass though, but blocks heat radiation (infrared). After visible light gets in, it warms the inside and is converted to infrared light. This infrared light is stuck inside the glass. Greenhouses gases (carbon dioxide and methane) act just like the glass in a greenhouse. What is the problem with Global Warming? Rising sea levels because the ocean is warming and expanding will flood coastal cities Extreme weather patterns hurricanes Extreme temperatures (both highs and lows) Dying ecosystems in the oceans, which depend on cooler ocean temperatures
7 How do we generate electricity using fossil fuels? Most of our current electricity is generated by burning fossil fuels to heat water. The steam spins a steam turbine, which drives a generator to create electricity. How does the Sun generate light energy? Extremely high temperature in the Sun causes atoms to fuse together. This process is called nuclear fusion. When atomic nuclei (protons) fuse, a lot of light energy is emitted. Light is energy!
8 Generating Electricity More sun More power How do we generate electricity using solar panels ( photovoltaic cells )? photo = light volt = voltage photovoltaic = generating voltage from light Sunlight hits the solar panel and knocks off electrons from atoms in the panel. These electrons provide DC (direct current). The DC current is converted to AC (alternating current) to be carried by power lines. Why? Nicolas Tesla discovered the transmitting electrical power via AC current was more efficient, and less energy was lost to heat.
9 Generating Electricity Faster wind More power How do we generate electricity using wind turbines? Wind energy comes from the Sun: because the atmosphere is not warmed evenly by sunlight, differences in temperature create flow or air or wind. The curved shape of the wind turbine blade uses Bernoulli s principle to turn when hit by the wind (similar to airplane wings). Wind energy is converted to spinning the turbine. The spinning turbine generates electricity. Shape of blade uses Bernoulli s principle
10 Generating Electricity How do we generate electricity using hydroelectric dams? hydro = water hydroelectric = electricity from water Dam near a lake collects water and increases the water height, which increases pressure at the bottom. Pressurized water flows down to spin a turbine, which spins a generator. Generator generates electricity. More water height More power Ultimately, hydropower depends on the Sun evaporated water condenses and rains into the lake.
11 Generating Electricity How do we generate electricity using geothermal vents? geo = earth thermal = heat geothermal = heat from the earth Find a location where there are large amounts of underground steam (water heated by heat energy inside the earth). There are very few such sites. Drill a well to capture the steam. Steam spins the turbine, which spins the electrical generator to produce electricity. Cooled water is cycled back into the ground. More steam More power
12 Generating Electricity How do we generate electricity using nuclear power? More heat More power Uranium is a radioactive material. Radioactive means that the atoms are unstable and want to split - fission. As the atoms split, a lot of heat energy is released. In a pressurize water nuclear reactor: Heat from fission heats water and turns it to steam Steam spins the turbine Turbine spins the generator, which generates electricity. All components that touch the uranium and water are sealed. The vapor leaving the Cooling Tower is non-radioactive water steam!
13 Which energy sources originally get their energy from the sun? Fossil fuels plants got solar energy Solar panels use solar energy Wind turbines use wind, which is generated by solar energy heating the atmosphere unevenly, causing air flow Hydroelectric dams sun evaporates water Which energy sources DO NOT get their energy from the sun? Geothermal relies on the heat inside the Earth from the time the Earth formed Nuclear relies on the fission (splitting ) of unstable atoms
14 Which power technologies generate electricity by heating water into steam? Fossil fuels Geothermal vents Nuclear reactors (water-based) What are the biggest problem with the various alternative power sources? Wind and Solar: The wind is not always blowing, and the sun is not always shining. This means you need fossil fuels to supplement wind and solar. Geothermal: Few locations are available with natural geothermal vents. Wells can run out of water. Hydroelectric: Impact the ecosystems around the dam. Affected by droughts. Can cause floods. Nuclear: No fail-proof way to handle radioactive waste.