Electrical energy provides power not only for homes, but also for industries and transportation. Without it, almost everything stops. Several sources of energy can generate electrical energy, and their roles in the energy marketplace are changing. Some sources can provide energy without involving electricity, like the wind moving a sailboat or water turning a mill's water wheel.
The worldwide supply of fossil fuels is finite, meaning there's only so much to be found and extracted. Coal is currently the leading fossil fuel for power generation in the United States, according to the U.S. Energy Information Administration. Natural gas and petroleum follow it. Each fuel has its own advantages and disadvantages. Historically, coal has been the cheapest and most abundant fuel, but increasing pollution limitations and the dropping price of natural gas are shifting the market toward gas. Market Realist reports gas as moving to take over more of coal's role in power generation as power plants shift from coal to gas.
Heat generated by the nuclear breakdown -- fission -- of uranium or plutonium atoms also generates electricity, through steam-driven turbines, similar to fossil fuels. Nuclear power generation doesn't create the greenhouse-gas pollution products of fossil fuels, but it presents hazards of small and large radiation leaks, and long-term storage of spent fuel. Another form of nuclear energy is fusion, the same process that fires our sun and the stars. There's no spent fuel to dispose of, but fusion isn't practical for power generation yet because, in current laboratories, it still takes more energy to cause a fusion reaction than the reaction will produce.
Hydropower uses the energy of water flowing downhill to spin turbines, instead of the steam generated by fossil and nuclear power generation. No fuel is used or spent, so it's renewable energy as long as water flows. The U.S. Geological Survey lists advantages of hydropower, including reliable support of electric grids, freedom from fuel market price swings and pollution-free energy. Hydropower brings disadvantages like loss of habitat, including human settlements, to make way for reservoirs flooding the land. IEA Hydropower also describes habitat problems downstream from dams, which alter the flow of rivers.
Wind and sunlight are renewable sources of energy, because like hydropower, they use no combustion. Wind can power turbines to generate electricity, but only when there is enough wind, and not too much. The U.S. Office of Energy Efficiency and Renewable Energy explains that wind can provide power at a low cost compared to other renewable sources, but its cost must compete against the changing prices of fossil fuels. It is also made more expensive per kilowatt hour by its lack of generation when the wind isn't just right. Solar energy comes from the sun's massive nuclear fusion reaction. Materials used in solar panels absorb the energy in the sun's visible light, causing them to emit electrons, creating a current. NASA explains how photovoltaic solar panels can be combined to make small or large arrays. Solar's advantages are limited to daylight hours and the availability of clear skies. Batteries are needed to store energy for times when solar or wind energy is not being generated.
- U. S. Energy Information Administration: What is U.S. Electricity Generation by Energy Source?
- Market Realist: Natural Gas Nosedives on Massive Inventory Data
- University of Michigan Health Physics Society: Risks of Nuclear Power
- World Nuclear Power: Nuclear Fusion
- U.S. Geological Survey: Advantages of Hydroelectric Power Production and Usage
- IEA Hydropower: What Are the Advantages and Disadvantages of Hydroelectric Power Systems?
- U.S. Office of Energy Efficiency and Renewable Energy: Advantages and Challenges of Wind Energy
- NASA Science News: How do Photovoltaics Work?