Energy Efficiency World
Fossil Fuels: Coal, oil, and natural gas are burned to heat water into steam, which is pressurized and used to turn a turbine. They are called fossil fuels because they were formed millions of years ago, when plants and tiny sea creatures were buried by sand and rock. Their bodies decomposed and, as a result of the earth’s heat and pressure, they turned into fossil fuels. The processes that formed them are no longer occurring, so fossil fuels are non-renewable.
Nuclear Power: Nuclear power plants also create heat that is used to convert water into steam, which is used to turn a turbine. The uranium that runs nuclear power plants must be mined from the ground. Like fossil fuels, uranium supplies are finite and non-renewable.
Hydropower: Hydropower plants rely on falling water to turn turbines. The most common form of hydropower uses dams on rivers to create large reservoirs. Water in rivers is continually replenished, so hydropower is renewable. In fact, hydropower is currently one of the largest sources of renewable power.
Solar Energy: Solar energy captures radiant energy from the sun and converts it into electricity. The sun’s energy will never run out, so solar energy is renewable.
Biomass: Like fossil fuels and nuclear energy, biomass is used to heat water into steam, which is pressurized and used to turn a turbine. Wood is the largest source of biomass energy, followed by corn, sugarcane wastes, straw, and other farming by-products. Although it is possible to use biomass faster than we produce it, more can be grown, so biomass is renewable.
Wind Power: Wind power relies on moving air to turn turbines, which are connected to windmills. The wind will be around as long as the earth is, so wind power is renewable.
Geothermal Energy: Steam or hot water from geothermal energy facilities can be used to turn turbines. This word comes from “geo” for earth and “thermal” for heat. The hot molten rock inside the earth isn’t going away anytime soon, making geothermal energy renewable. Although it is renewable, geothermal energy has some limitations: people must be careful not to draw steam or hot water out of the earth faster than it can be replenished.
Page 6: Go with the Flow
Objective: To teach the characteristics of an electrical circuit.
Background/Discussion: Electrical circuits require a complete loop through which an electrical current can pass; Electrical circuits provide a means of transferring energy when heat, light, sound, and chemical changes are produced.
The light bulb, base, battery, and wire can be found at electronics retailers. Before doing the activity, introduce the concept of a closed path. Explain that a closed path is like a continuous loop with no breaks or obstacles in it. Ask students to name some shapes that are closed paths and some that are open. (Some examples of closed paths are a circle, square, rectangle, and triangle. Examples of open paths are a spiral, a line, and a U-shape.) For electricity to flow, it needs to travel on wires that are a closed path with no breaks or obstacles. This is called a circuit. The electricity in your school or home flows in a circuit. It goes from the power outlet to the appliance along one wire inside the appliance cord and back from the appliance to the outlet on the other wire inside the cord. Electricity on power lines also flows in a circuit. Simply put, it flows out from the power plant or substation on one power line and back on another. Ask students to list the various things that electricity in circuits can do. (Run motors, product light, create sound, make heat, etc.)