Note: Since I wrote this post, PG&E had to go to rolling blackouts on August 14, 2020. Please see the Addendum below.

I happened by a science website the other day, and read a statement that, until recently, most of our electricity came from coal and natural gas. I looked at that a moment and went “Eh.” Hydroelectric power has been around since the start of electrification and once made up a pretty big chunk of generation. Biomass and coal go back just as far, and I suspect natural gas does as well. Solar panels date to the 19^th Century, with the first installed on a roof the same year Grover Cleveland was first elected president. Wind has been around about as long, and geothermal dates from the early 20^th Century. Nuclear power dates from the middle 20^th Century. US utilities have long produced electricity from a variety of sources, and offhand think we may be closer to getting most of our power now from coal and natural gas than we were in the past. That’s a change from well over thirty years ago, when I think natural gas made up maybe 10% of US electric generation.

Of course, the point of that statement was a lead-in to how generation has changed, and for all I know might hold for where the web site is located. Still, it made me a bit uneasy. Most people only seem to know that they flip a switch and the lights come one, and something’s wrong if it doesn’t. But if people are going to make sound decisions about where their electricity comes from, they need to have some idea how utilities generate electricity and what goes into deciding how they do it.

First we have to understand the problem. Generating enough electricity to go around is pretty obvious; less so is that load isn’t constant. You can observe this in your own home just by noticing when you use the most electric appliances and lights. If you use electricity for heating and cooling, you use more when it’s cold and when it’s hot. All this means that the load, called the demand, fluctuates with the time of day, outside temperature, and even the day of the week. Times of the highest load is the peak demand, and the lowest demand is the base load, and utilities have to provide enough electricity to cover both. If they don’t, they end up with brownouts and rolling blackouts. You also have to plan for a gradual increase in load, because that happens with a growing population and expanding economy.

How utilities produce electricity depends on regional conditions and electrical needs. You can’t have hydropower if you don’t have water or a place to put a dam. Utilities tend to use what’s available and what’s cost effective to produce electricity.

Now, let’s look at some different ways of generating electricity, concentrating on the most common:

Type	How it Works	Pros	Cons
Biomass	Burns material like wood to turn generators	Constant output	Produces CO2
Coal	Burns coal to turn generators	Constant output	Produces CO2
Geothermal	Uses heat from the earth to turn generators.	Constant output, uses no fuel	Limited area, some methods may trigger earthquakes
Hydroelectric	Uses water to turn generators	Constant output, uses no fuel	Limited areas, reservoirs and dams disrupt ecosystems
Natural Gas	Burns natural gas to turn generators	Constant output	Produces CO2
Nuclear	Uses heat from atomic fission to turn generators	Constant output	Produces radioactive waste
Solar	Uses photovoltaic cells to product electricity	Uses no fuel	Variable output, doesn’t work at night.
Wind	Uses wind to turn generators	Uses no fuel	Limited area, variable output. Have caused bird kills.

There’s also issues of cost, but my information is dated, and I won’t go there. Just know that some cost more than others, and that can lead to higher electric bills.

While we’re here, let’s look at something surprising: there’s not much in the way of storing power. Maybe the best large scale applications uses two reservoirs. Utilities use excess electricity to pump water from the lower to higher one, and using it to turn generators as it flows from the higher to the lower. It has the same limitations as hydroelectric, and while they’re some units around, there isn’t all that many. There’s also small-scale energy storage using different methods. It’s significant that utilities find it more cost effective to build generators to run during peak demand than energy storage. That says much about the costs involved.

There are other pieces to this puzzle, such as transmission lines, but we have enough general information to start thinking about how to provide enough electricity to go around. The next thing we need to do is to ask what are our top priorities. Keeping the lights on is at the very top, or should be. What else? Cost? That’s influenced generation choices since the very beginning. Pollution? That’s a valid concern. Carbon dioxide? I’m not going to argue anthropogenic global warming one way or the other, only note it as a concern. The list can go on and on. But what we have to do is to pick one as our top priority, another as our next most important priority, and so on all the way down through our list.

For the sake of discussion, let’s pick eliminating CO₂ from power generation as the priority right below keeping the lights on. That’s a popular topic these days. Immediately, that removes all methods from our list that involves burning something to turn a generator. That leaves geothermal, hydroelectric, nuclear, solar, and wind. All of them have bad that goes along with their good. Geothermal has a limted area, and some methods may trigger earthquakes; hydroelectric has a limited area, and reservoirs and dams disrupt ecosystems; Nuclear produces radioactive waste; solar has variable output and doesn’t work at night; wind has a limited area, variable output, and has caused bird kills. If you want to see what’s viable in geothermal, solar, and wind, here’s this site at the National Renewable Energy Laboratory: https://www.nrel.gov/gis/geothermal.html. Links to solar and wind are found on the sidebar on the NREL site.

These are the choices. Which one do you pick?

Solar, you say? All right: How do you handle the variable output? Output depends on cloud cover. What about at night? Wind works at night, but also has variable output and a more limited area. What do you do when there’s not enough wind? What about when there’s too much? In both cases, you either have to build sufficient storage so that you have constant output (like the huge water tank found on wind powered water pumps), or you have to have some other form of generation to take up the slack.

Hydroelectric give you constant output, if you have the terrain to build it. It also floods wherever you build the reservoir. That can disrupt ecosystems, including fish spawning.

Geothermal has a limited area. Newer technologies expand that range somewhat, but may trigger earthquakes.

That leaves nuclear. Nuclear provides constant output and produces no CO₂, but produces radioactive waste. Some people are also afraid of it.

Whatever method you chose, you’re going to run into problems. That’s life. The best you can do it to pick which downside you can live with best and go on. Think of that as another list, one ranking the drawbacks you can live with most and going down to those you can live with least.

Let’s say you want absolutely no production of CO₂. That means you’re going to have to live with the drawbacks of the others. Don’t like the idea of building storage or alternate generation for when solar and wind can’t produce enough electricity? That leaves you with geothermal, hydroelectric, and nuclear. Don’t like radioactive waste? You can try to build geothermal and hydroelectric with enough capacity to cover times when solar and wind doesn’t produce enough, but if you don’t have the terrain and geology for it, you’re going to have to rely on CO₂ producing generation as a back-up. If you consider nuclear waste as worse can dumping CO₂ into the atmosphere, that’s a workable solution. But if you consider CO₂ ultimately more damaging than nuclear waste, then nuclear power becomes an option.

That’s the problem with dealing with things in real life. It can be messy and involve compromise, and you have to work with what you have, not how you wish things were.

Pick a power source yet? I know what I would pick, based on my priorities, and no, I won’t say. The point is for you to think about this, for you to decide the option you think is best. If you do, you will have done more than a good many people all around the world. Newsflash: Grand ideas don’t change how things work, not one little bit. And if you don’t address the messy questions, then someone’s going to be sitting in the dark.

Just keep in mind that there’s no such thing as a free lunch. There are downsides to almost everything, including how we produce electricity. It all comes down to what we’re willing to live with.

Addendum

Now it’s the middle of August, 2020, and PG&E had to go to rolling blackouts because there wasn’t enough electricity to go around in California’s heat wave. This is what happens when you don’t have enough generation to cover demand. This statement from PG&E says other utilities were to take similar measures.

This is a story about it from The Sacramento Bee. Note the statement that although the demand was easing off, the sun was going down and that eliminated solar power. Am I making a slam against solar power? No, only pointing out that you have to have generation to replace it when it’s not available.

This is why you it’s important to learn about how things work and why. What little news that filters here from California hasn’t left me impressed. But over twenty years ago I went into work and had to help draw up plans for a rolling blackout because there might not be enough power to go around, and that was when the only renewable power in the region was hydroelectric. Lack of generation capacity is simply that: lack of enough generation to supply everyone with electricity, and that can happen anywhere.

Fortunately, we didn’t have to go to rolling blackouts that long, hot, afternoon, but it was a near thing, and made a lasting impression. Whatever your priorities, if you don’t make sound choices concerning power generation, the lights go out.