by Bill Gates
Tip: Remember that emissions come from five different activities, and we need solutions in all of them.
3. How Much Power Are We Talking About?
This question mostly comes up in articles about electricity. You might read that some new power plant will produce 500 megawatts. Is that a lot? And what’s a megawatt, anyway?
A megawatt is a million watts, and a watt is a joule per second. For our purposes, it doesn’t matter what a joule is, other than a bit of energy. Just remember that a watt is a bit of energy per second. Think of it like this: If you were measuring the flow of water out of your kitchen faucet, you might count how many cups came out per second. Measuring power is similar, only you’re measuring the flow of energy instead of water. Watts are equivalent to “cups per second.”
A watt is pretty small. A small incandescent bulb might use 40 of them. A hair dryer uses 1,500. A power plant might generate hundreds of millions of watts. The largest power station in the world, the Three Gorges Dam in China, can produce 22 billion watts. (Remember that the definition of a watt already includes “per second,” so there’s no such thing as watts per second, or watts per hour. It’s just watts.)
Because these numbers get big fast, it’s convenient to use some shorthand. A kilowatt is 1,000 watts, a megawatt is a million, and a gigawatt (pronounced with a hard g!) is a billion. You often see this shorthand in the news, so I’ll use it too.
The following chart shows some rough comparisons that help me keep it all straight.
How much power does it take?
The world
5,000 gigawatts
The United States
1,000 gigawatts
Mid-size city
1 gigawatt
Small town
1 megawatt
Average American house
1 kilowatt
Of course, there’s quite a bit of variation within these categories, throughout the day and throughout the year. Some homes use much more electricity than others. New York City runs on upwards of 12 gigawatts, depending on the season; Tokyo, with a larger population than New York, needs something like 23 gigawatts on average but can demand more than 50 gigawatts at peak use during the summer.
So let’s say you want to power a mid-size city that requires a gigawatt. Could you simply build any one-gigawatt power station and guarantee that city all the electricity it’ll need? Not necessarily. The answer depends on what your power source is, because some are more intermittent than others. A nuclear plant runs 24 hours a day and is shut down only for maintenance and refueling. But the wind doesn’t always blow and the sun doesn’t always shine, so the effective capacity of plants powered by wind and solar panels might be 30 percent or less. On average, they’ll produce 30 percent of the gigawatt you need. That means you’ll need to supplement them with other sources to get one gigawatt reliably.
Tip: Whenever you hear “kilowatt,” think “house.” “Gigawatt,” think “city.” A hundred or more gigawatts, think “big country.”
4. How Much Space Do You Need?
Some power sources take up more room than others. This matters for the obvious reason that there is only so much land and water to go around. Space is far from the only consideration, of course, but it’s an important one that we should be talking about more often than we do.
Power density is the relevant number here. It tells you how much power you can get from different sources for a given amount of land (or water, if you’re putting wind turbines in the ocean). It’s measured in watts per square meter. Below are a few examples:
How much power can we generate per square meter?
Energy source
Watts per square meter
Fossil fuels
500–10,000
Nuclear
500–1,000
Solar*
5–20
Hydropower (dams)
5–50
Wind
1–2
Wood and other biomass
Less than 1
* The power density of solar could theoretically reach 100 watts per square meter, though no one has accomplished this yet.
Notice that the power density of solar is considerably higher than that of wind. If you want to use wind instead of solar, you’ll need far more land, all other things being equal. This doesn’t mean that wind is bad and solar is good. It just means they have different requirements that should be part of the conversation.
Tip: If someone tells you that some source (wind, solar, nuclear, whatever) can supply all the energy the world needs, find out how much space will be required to produce that much energy.
5. How Much Is This Going to Cost?
The reason the world emits so much greenhouse gas is that—as long as you ignore the long-term damage they do—our current energy technologies are by and large the cheapest ones available. So moving our immense energy economy from “dirty,” carbon-emitting technologies to ones with zero emissions will cost something.
How much? In some cases, we can price the difference directly. If we have a dirty source and a clean source of essentially the same thing, then we can just compare the price.
Most of these zero-carbon solutions are more expensive than their fossil-fuel counterparts. In part, that’s because the prices of fossil fuels don’t reflect the environmental damage they inflict, so they seem cheaper than the alternative. (I’ll return to this challenge of pricing carbon in chapter 10.) These additional costs are what I call Green Premiums.*2
During every conversation I have about climate change, Green Premiums are in the back of my mind. I’ll come back to this concept repeatedly in the next several chapters, so I want to take a moment to explain what it means.
There isn’t one single Green Premium. There are many: some for electricity, others for various fuels, others for cement, and so on. The size of the Green Premium depends on what you’re replacing and what you’re replacing it with. The cost of, say, zero-carbon jet fuel isn’t the same as the cost of solar-generated electricity. I’ll give you an example of how Green Premiums work in practice.
The average retail price for a gallon of jet fuel in the United States over the past few years is $2.22. Advanced biofuels for jets, to the extent they’re available, cost on average $5.35 per gallon. The Green Premium for zero-carbon fuel, then, is the difference between these two prices, which is $3.13. That’s a premium of more than 140 percent. (I’ll explain all of this in more detail in chapter 7.)
In rare cases, a Green Premium can be negative; that is, going green can be cheaper than sticking with fossil fuels. For instance, depending on where you live, you may be able to save money by replacing your natural gas furnace and your air conditioner with an electric heat pump. In Oakland, doing this will save you 14 percent on your heating and cooling costs, while in Houston, the savings amount to 17 percent.
You might think that a technology with a negative Green Premium would already have been adopted around the world. By and large that is the case, but there is usually a lag between the introduction of a new technology and its being deployed—particularly for something like home furnaces, which we don’t replace very often.
Once you’ve figured Green Premiums for all the big zero-carbon options, you can start having serious conversations about trade-offs. How much are we willing to pay to go green? Will we buy advanced biofuels that are twice as expensive as jet fuel? Will we buy green cement that costs twice as much as the conventional stuff?
By the way, when I ask, “What are we willing to pay?” I mean “we” in the global sense. It’s not just a matter of what Americans and Europeans can afford. You can imagine Green Premiums high enough that the United States is willing and able to pay them but India, China, Nigeria, and Mexico are not. We need the premiums to be so low that everyone will be able to decarbonize.
Admittedly, Green Premiums are a moving target. A lot of assumptions go into estimating them; for this book, I’ve made the assumptions that seem reasonable to me, but different
well-informed people would make different assumptions and arrive at different numbers. What’s more important than the specific prices is knowing whether a given green technology is close to being as cheap as its fossil-fuel counterpart and, for the ones that aren’t close, thinking about how innovation might bring their prices down.
I hope the Green Premiums in this book will be the start of a longer conversation about the costs of getting to zero. I hope other people will do their own calculations of the premiums, and I’d be especially happy to learn that some of them aren’t as high as I think. The ones I’ve calculated in this book are an imperfect tool for comparing costs, but they’re better than no tool at all.
In particular, Green Premiums are a fantastic lens for making decisions. They help us put our time, attention, and money to their best use. Looking at all the different premiums, we can decide which zero-carbon solutions we should deploy now and where we should pursue breakthroughs because the clean alternatives aren’t cheap enough. They help us answer questions like these:
Which zero-carbon options should we be deploying now?
Answer: the ones with a low Green Premium, or no premium at all. If we’re not deploying these solutions already, it’s a sign that cost isn’t the barrier. Something else—like outdated public policies or lack of awareness—is stopping us from getting them out there in a big way.
Where do we need to focus our research and development spending, our early investors, and our best inventors?
Answer: wherever we decide Green Premiums are too high. That’s where the extra cost of going green will keep us from decarbonizing and where there’s an opening for new technologies, companies, and products that make it affordable. Countries that excel at research and development can create new products, make them more affordable, and export them to the places that can’t pay the current premiums. Then no one will have to argue about whether every nation is doing its fair share to avoid a climate disaster; instead, countries and companies will be racing to create and market the affordable innovations that help the world get to zero.
There’s one last benefit to the Green Premium concept: It can act as a measurement system that shows us the progress we’re making toward stopping climate change.
In that sense, Green Premiums remind me of a problem that Melinda and I encountered when we first started working in global health. Experts could tell us how many children died around the world every year, but they couldn’t tell us much about what caused those deaths. We knew that a certain number of kids died of diarrhea, but we didn’t know what caused the diarrhea in the first place. How could we know which innovations might save lives if we didn’t know why children were dying?
So working with partners around the world, we funded various studies to find out what was killing children. Eventually, we were able to track deaths with much more detail, and this data pointed the way to big breakthroughs. For example, we saw that pneumonia was behind a large number of children’s deaths each year. Although a pneumo vaccine already existed, it was so expensive that poor countries weren’t buying it. (They had little incentive to, because they had no idea how many children were dying from the disease.) Once they saw the data, though—and once donors agreed to pay most of the cost—they began adding the vaccine to their health programs, and eventually we were able to fund a much cheaper vaccine that’s now in use in countries around the world.
The Green Premiums can do something similar for greenhouse gas emissions. The premiums give us a different insight from the raw number of emissions, which shows us how far we are from zero but tells us nothing about how hard it will be to get there. What would it cost to use the zero-carbon tools we have now? Which innovations will make the biggest impact on emissions? The Green Premiums answer these questions, measuring the cost of getting to zero, sector by sector, and highlighting where we need to innovate—just as the data showed us that we needed to make a big push for the pneumo vaccine.
In some cases, such as the jet fuel example I mentioned earlier, the direct approach to estimating Green Premiums is simple. But when we apply it more generally, we have a problem: We don’t currently have a direct green equivalent in every case. There’s no such thing as zero-carbon cement (at least not yet). How do we get a sense of the cost of a green solution in those cases?
We can do it by conducting a thought experiment. “How much would it cost to just suck the carbon out of the atmosphere directly?” That idea has a name; it’s called direct air capture. (In short, with DAC you blow air over a device that absorbs carbon dioxide, and then you store the gas for safekeeping.) DAC is an expensive and largely unproven technology, but if it can work at a large scale, it would allow us to capture carbon dioxide no matter when or where it was produced. The one DAC facility now in operation, which is based in Switzerland, is absorbing gas that might have been spewed out by a coal-fired plant in Texas 10 years ago.
To figure out how much this approach would cost, we need just two data points: the amount of global emissions, and the cost of absorbing emissions using DAC.
We already know the emissions number; it’s 51 billion tons each year. As for the cost of removing a ton of carbon from the air, that figure hasn’t been firmly established, but it’s at least $200 per ton. With some innovation, I think we can realistically expect it to get down to $100 per ton, so that’s the number I’ll use.
That gives us the following equation:
51 billion tons per year x $100 per ton = $5.1 trillion per year
In other words, using the DAC approach to solve the climate problem would cost at least $5.1 trillion per year, every year, as long as we produce emissions. That’s around 6 percent of the world’s economy. (It’s an enormous sum, though this theoretical DAC technology would actually be far cheaper than the cost of trying to reduce emissions by shutting down sectors of the economy, as we’ve done during the COVID-19 pandemic. In the United States, according to data from the Rhodium Group, the per-ton cost to our economy came to between $2,600 and $3,300. In the European Union, it was more than $4,000 per ton. In other words, it cost between 25 and 40 times the $100 per ton we hope to achieve someday.)
As I mentioned, the DAC-based approach is really just a thought experiment. In reality, the technology behind DAC isn’t ready for global deployment, and even if it were, DAC would be an extremely inefficient method for solving the world’s carbon problem. It’s not clear that we could store hundreds of billions of tons of carbon safely. There’s no practical way to collect $5.1 trillion a year or make sure everyone pays their fair share (and even defining everyone’s fair share would be a major political fight). We’d need to build more than 50,000 DAC plants around the world just to manage the emissions we’re producing right now. In addition, DAC doesn’t work on methane or other greenhouse gases, just carbon dioxide. And it’s probably the most expensive solution; in many cases, it will be cheaper not to emit greenhouse gases in the first place.
Even if DAC can eventually be made to work on a global scale—and remember that I’m an optimist when it comes to technology—it almost certainly can’t be developed and deployed quickly enough to prevent dire harm to the environment. Unfortunately, we can’t just wait for a future technology like DAC to save us. We have to start saving ourselves today.
Tip: Keep the Green Premiums in mind and ask whether they’re low enough for middle-income countries to pay.
* * *
—
Here’s a summary of all five tips:
Convert tons of emissions to a percentage of 51 billion.
Remember that we need to find solutions for all five activities that emissions come from: making things, plugging in, growing things, getting around, and keeping cool and warm.
Kilowatt = house. Gigawatt = mid-size city. Hundreds of gigawatts = big, rich country.
Consider how much space you’re going to need.
Keep the Green Premiums in mind and ask whether they’re low enough for middle-income countries to pay.
&nbs
p; Skip Notes
*1 These percentages represent global greenhouse gas emissions. When you’re categorizing emissions from various sources, one of the questions you have to decide is how to count products that cause emissions both when you make them and when you use them. For example, we produce greenhouse gases when we refine oil into gasoline and again when we burn the gasoline. In this book, I’ve included all the emissions from making things in “How we make things” and all the emissions from using them in their respective categories. So oil refining goes under “How we make things,” and burning gasoline is included in “How we get around.” The same goes for things like cars, planes, and ships. The steel that they’re made of is counted under “How we make things,” and the emissions from the fuels they burn go under “How we get around.”
*2 I consulted with many people about the Green Premium, including experts at the Rhodium Group, Evolved Energy Research, and climate researcher Dr. Ken Caldeira. For information on how the Green Premiums in this book were calculated, visit breakthroughenergy.org.
CHAPTER 4
HOW WE PLUG IN
27 percent of 51 billion tons per year
We’re in love with electricity, but most of us don’t know it. Electricity is consistently there for us, making sure our streetlights, air conditioners, computers, and TVs always work. It powers all sorts of industrial processes most of us would rather not think about. But, as sometimes happens in life, we don’t realize how much it means to us until it’s gone. In the United States, power outages are so rare that people remember that one time a decade ago when the lights went out and they got stuck in an elevator.