Where Does Electric Power Get Its Power?

The electric grid is not something to take for granted. But where does our electricity come from?

I turned on my lights today, just flipped a switch and they worked. My furnace is running, which is good, because it’s cold outside. My phone and computer got recharged last night, not sure what I’d do without them. If I ever worry about electricity, it’s only if there’s a big storm, and then I assume I might go an hour or so without power. It’s hard to imagine what might happen if electricity was unavailable at all. But the electric grid is actually quite fragile.

I just listened to a fascinating podcast with Meredith Angwin, Grant Williams, and Michael Kao. Angwin discussed how the grid works, and understanding that has given me lots of food for thought.

So flip a switch and everything just works, right? It’s much more complicated than that. Electricity is generated from a number of power sources, then it is transmitted from where it’s generated to where it will be used. Getting electricity from its source, to the utility, to the consumer requires a network of transmission lines that traverse hundreds of miles of land that belongs to other people (they might not want those lines on their land). Demand for electricity isn’t stable, it fluctuates depending on the weather, the time of day, and many other factors. Somebody has to predict electric demand, then call up the resources that are needed. And swiftly act when demand surges beyond expectations. The whole production is quite a dance.

Electricity Power Sources

It’s interesting just to look at the major sources of electric power and some of the unique characteristics of each of them. Here are the top energy sources, with percentages of usage provided by the U.S. Energy Information Association. All of them have advantages and disadvantages that impact the grid.

Natural Gas (43%)

Natural gas plants are the biggest source of electricity in the U.S. Gas plants can provide what is called “base power”, a steady, reliable source of power that isn’t dependent on external factors like whether the sun is shining or the wind is blowing. They also are “dispatchable”, meaning it is relatively easy to turn them on and off to respond to changes in demand.

Gas plants can also provide “intermediate” capacity, meaning they have the ability to ramp up at pre-scheduled times of the day, like early evening hours when demand is always high. But they excel at providing “peaker” capacity, which means they have the ability to ramp up quickly on demand for unexpected surges in electric demand. Gas is the most expensive of the fuels, so it is not ideal for base or intermediate load, but it is ideal for peaker capacity, and gas is really the only fuel that currently can provide peaker capacity.

In addition to being an expensive fossil fuel, gas has another weakness as a power source. Gas plants are supplied via pipelines. They store little or no gas on site. That makes them vulnerable to anything that interrupts the flow of natural gas. If there is a big demand for natural gas, like during a cold snap, gas lines to homes are prioritized over gas lines to power plants. That means gas plants may be unable to run at capacity at those times. And they will be affected in real time if there are any shortages of natural gas.

Nuclear (19%)

Nuclear plants provide about 19% of all electricity in the United States. Nuclear plants are a natural source of base power. Nuclear plants store their fuel on site, so they aren’t dependent on just-in-time delivery of fuel, making them less vulnerable to supply chain disruptions. They are very self-sufficient. On the other hand, it is not easy to turn nuclear plants on and off. They work most efficiently if they are turned on and left on, or turned off and left off. Of course, the biggest downside of nuclear power is the radioactivity of the fuel, and the problems of safely disposing of nuclear waste. There are lots of rules and safeguards in place to address the safety issues, but they are still a concern to most people.

Many nuclear plants exist in the U.S., but most were built a long time ago, and some of them have been de-commissioned. It would take years to get new ones built today, or even to re-commission decommissioned plants. There are promising new developments in small nuclear reactors that use less radioactive fuel, and in the ability to re-use nuclear fuel to reduce waste, but again, it will probably take years to get those innovations into widespread use.

Coal (16%)

Coal fired plants are being phased out in many places, but still provide about 16% of the electricity in the U.S. Coal used to be very dirty, although modern coal plants are much cleaner than they used to be. Coal is not the future for the electric grid, but it does comprise a significant part of the grid we have today. Coal plants provide base power that can be available regardless of weather. Coal plants also typically store fuel on site, providing some protection against supply chain disruptions. Coal is more “dispatchable” than nuclear, coal plants can be turned on and off to respond to demand. Coal plants are less flexible than gas plants. They are appropriate for providing “intermediate” capacity, but less useful for “peaker” capacity.

Wind and Solar (14%)

Wind and solar currently provide about 14% of the power in the U.S. They are green and renewable sources of energy. But they are not dispatchable. If the sun is not shining or the wind is not blowing, there is no power. They can be turned off on demand but cannot be turned on on demand. There is one other big problem with wind and solar. Compared to other power sources they are very distributed. There are not a few big plants with a few sets of transmission lines, there are hundreds of locations. Even if they are organized into farms, the volume of connections is much larger than traditional power plants. So they require a bigger investment of time and money in transmission lines. And it is more challenging to manage that many sources when matching power to demand.

There is a potential to offset the dispatchability problem by using batteries to store electricity from wind and solar. Electricity stored in a battery would become dispatchable, and batteries could potentially provide base load, intermediate, or peaker capacity. But that requires grid scale battery arrays that don’t currently exist. Battery production on this scale would require huge amounts of critical metals that are in short supply, including copper and rare earths. Those metals have to be mined and then processed. Both mining and processing of those metals is dirty. At the moment, almost all such metal processing is done in China, which is not a reliable partner for America’s grid. Once the metals are processed, they have to be manufactured into batteries, another dirty business that is mostly done in China right now. Even if we ramp up manufacturing batteries in the U.S. there are problems. Angwin notes that she would not want to live by a battery factory, that she knows of one that has caught on fire repeatedly. There are lots of hurdles before batteries will be a significant part of the energy solution in the United States.

Since we don’t yet have batteries at grid scale, wind and solar power has to be offset with predictable, dispatchable, sources of power, like natural gas, to handle surges and periods when there is no sun or wind. Wind and solar cannot yet supplant all other sources of power.

Hydropower (6%)

Hydropower provides about 6% of the electricity in the U.S. Hydropower is a nearly perfect source of power for the grid. It’s green, clean, renewable, and dispatchable. It can provide base load or intermediate load. But there are only a few locations that are suitable for building giant hydroelectric dams, and most of them were built years ago. Building a new dam today would probably be quite an endeavor, A new dam would flood hundreds of acres of land. The approval process would be torturous and take years, not to mention the time it would take to build and bring online.

Geothermal (.4%)

Geothermal power is created by using the heat in the middle of the earth to turn water to steam, then turn that steam into electricity. The earth is a giant natural, but safe, nuclear reactor. This is a solution that could have everything going for it. It’s fossil-free, green, clean, and a geothermally-powered steam turbine would be dispatchable and suitable for base, intermediate, or peaker capacity. Currently geothermal is a tiny fraction of the total because it’s only been possible in a few places where the hot magma at the center of the earth is very close to the surface. But there are some very interesting new developments that might make it possible to produce geothermal power anywhere by digging as deep as necessary in any location. For more information on geothermal power, I highly recommend a MacroVoices podcast with Robert Friedland. This is another solution that won’t help in the immediate future, but will be fascinating to watch.

Where Next?

As you can see, every one of these power sources presents big challenges that will take years to resolve. I have to confess that the one that excites me the most is geothermal. I certainly hope that plays out!

Regardless, I have a new respect for the electric grid. And, maybe, I won’t just take it for granted that I can turn the lights on any time I want to.