By Paul Wesslund
We depend on electricity 24/7, but have you ever wondered how it’s made, or where it comes from? To understand the basics of something so important to modern life, think about steam from a teakettle and those magnets stuck to your refrigerator door.
Magnetic metals in nature attract each other because parts of the atoms that make up the metals want to match up with others. Those restless atomic particles are called electrons— and that’s where we get the word “electricity.”
In the early 1800s, a scientist in England named Michael Faraday noticed that when he rotated a metal disk through the middle of a horseshoe-shaped magnet, he could get electrons to flow together in an electric current.
Engineers soon took over and made Faraday’s process really complicated—and really useful. Today, nearly all of our electricity comes from turbines that spin a magnet inside a coil of wires.
One way to turn those turbines is by heating liquid into steam that forces the turbine to spin, using the same principle that makes a teakettle sing.
When you boil water on your stove, that liquid expands more than 1,000 times as it vaporizes. If you’ve ever had your hand burned near boiling water, you’ve felt the power that steam produces.
The use of heat to spin a turbine generates two-thirds of the nation’s electricity from a pair of fossil fuels: coal and natural gas.
Another 20% comes from nuclear power, with hydroelectricity adding 7% and wind contributing 6.5%. Smaller amounts come from solar, biomass and geothermal.
Coal—which produces about a third of the nation’s electricity—is dug from the ground, either near the surface or from deep underground mines. It is then shipped to power plants, often by train, and stored in large piles on the ground until it is crushed into small pieces or powder and burned in a furnace.
The heat from that combustion is used to turn liquid into steam in a furnace/boiler that spins the steam turbine/generator, producing electricity.
Large transformers at the plant boost the voltage of the electricity—lowering the current and minimizing line loss potential—for shipment across the country through tall transmission lines. As it gets closer to where it will be used, a substation of transformers reduces the voltage to a level that can be safely delivered to a smaller transformer on the utility pole or pad-mounted transformer in your yard, decreasing the voltage further for use in your home.
The furnace burns the coal up to 3,000 degrees F, and the steam it produces gets hotter than 1,000 degrees.
Coal contains harmful elements that are captured and removed through sophisticated pollution controls. That environmental equipment can cost as much as the power plant.
Ancient plants and animals that died long ago turned into coal, oil and natural gas. That’s why all three are called fossil fuels.
Like coal, natural gas comes from the ground and produces about a third of the nation’s electricity. In a natural gas power plant, specially designed combustion turbines burn the gas to make them spin, generating the electricity. Natural gas turbines are a large, complicated version of what you see hanging on airplane wings.
Natural gas plants are simpler and cheaper to build than coal plants, require less staff, and can be shut down and powered up more quickly. Natural gas doesn’t contain as many pollutants as coal, so fewer environmental controls are needed. Burning natural gas also produces less greenhouse gas.
Although natural gas used to be more expensive than coal, fracking and other new drilling techniques changed that in the 1990s. As natural gas prices dropped, many utilities replaced coal generation with natural gas.
A nuclear power plant works basically the same as a coal plant, making steam to spin a turbine and generator. The difference is that instead of burning coal, heat from a nuclear reactor heats the liquid into steam.
The basic fuel for a nuclear power plant is uranium, which is mined from the ground. It then must be formulated into expensive and complex fuel components for utility use.
A little uranium can last a long time, making it a promising, incredibly cheap power source—and it produces none of the pollution or greenhouse gas that comes from burning coal or natural gas.
However, concentrated radioactivity in the nuclear reactor is potentially so dangerous, expensive safety measures need to be part of any nuclear plant. Highly technical control systems need to be in place to slow or shut down the level of heat produced, and the nuclear reactor needs to be inside a strong containment building to keep radioactivity out of the atmosphere in the event of a low-probability accident in the reactor core.
Another issue is how to dispose of the spent nuclear fuel, which can stay radioactive for millions of years before the radioactivity is brought down to naturally occurring radioactivity in the environment. Most of the spent fuel is stored in pools of water and dry storage casks at the site of the nuclear plant.
One way to turn an electricity-generating turbine is to store water behind a dam, then harness its power as it flows from the reservoir to the river below. Hydroelectric projects in the Columbia River Basin provide about 55% of the Northwest’s energy needs—much higher than the national average.
Unlike many other renewables, Northwest hydropower is dependable and predictable. Because it is a load-following resource, it can throttle up or down to match the daily peaks and valleys of our energy use—increasing in the morning when people start the day, and decreasing in the evening as people wind down.
Operators control the electrical output by choosing how much water to allow through water intakes in the dam. Opening and closing the intakes directly controls the amount of water flowing to the turbines, which determines the amount of electricity the dam generates.
Hydropower doesn’t create greenhouse gas or other chemical pollutants, which is an issue with burning fossil fuels.
Like other forms of generation, wind creates electricity by spinning a turbine that creates an electricity-producing magnetic field. The difference is the turbine is turned by enormous propeller-like blades designed to catch the wind from towers as high as 300 feet in the air.
Although still a small overall contributor to the nation’s electricity supply, wind power has increased significantly as costs decrease. It has increased about 35% during the past four years.
Because the wind does not blow all of the time, it is a tricky power source. Until large battery storage technology improves, for wind to provide reliable electricity, it needs the help of energy sources that can run 24 hours a day, 7 days a week—what is referred to as baseload sources—such as coal, natural gas, nuclear and hydropower.