by Bill Gates
As is so often the case in global warming, you have to consider a number of factors…
How much carbon dioxide can a tree absorb in its lifetime? It varies, but a good rule of thumb is 4 tons over the course of 40 years.
How long will the tree survive? If it burns down, all the carbon dioxide it was storing will be released into the atmosphere.
What would’ve happened if you hadn’t planted that tree? If a tree would’ve grown there naturally, you haven’t added any extra carbon absorption.
In what part of the world will you plant the tree? On balance, trees in snowy areas cause more warming than cooling, because they’re darker than the snow and ice beneath them and dark things absorb more heat than light things do. On the other hand, trees in tropical forests cause more cooling than warming, because they release a lot of moisture, which becomes clouds, which reflect sunlight. Trees in the midlatitudes—between the tropics and the polar circles—are more or less a wash.
Was anything else growing in that spot? If, for example, you eliminate a soybean farm and replace it with a forest, you’ve reduced the total amount of soybeans available, which will drive up their price, making it more likely that someone will cut down trees somewhere else to grow soybeans. This will offset at least some of the good you do by planting your trees.
Taking all these factors into account, the math suggests you’d need somewhere around 50 acres’ worth of trees, planted in tropical areas, to absorb the emissions produced by an average American in her lifetime. Multiply that by the population of the United States, and you get more than 16 billion acres, or 25 million square miles, roughly half the landmass of the world. Those trees would have to be maintained forever. And that’s just for the United States—we haven’t accounted for any other country’s emissions.
Don’t get me wrong: Trees have all kinds of benefits, both aesthetic and environmental, and we should be planting more of them. For the most part, you can get trees to grow only in places where they’ve already grown, so planting them could help undo the damage caused by deforestation. But there’s no practical way to plant enough of them to deal with the problems caused by burning fossil fuels. The most effective tree-related strategy for climate change is to stop cutting down so many of the trees we already have.
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The upshot of all this is that we’ll soon need to produce 70 percent more food while simultaneously cutting down on emissions and moving toward eliminating them altogether. It’ll take a lot of new ideas, including new ways to fertilize plants, raise livestock, and waste less food, and people in rich countries will need to change some habits—we’ll have to eat less meat, for instance. Even if burgers run in the family.
Skip Notes
* Fritz Haber had a complicated history. In addition to his lifesaving work on ammonia, he pioneered the use of chlorine and other poisonous gases as chemical weapons in World War I.
CHAPTER 7
HOW WE GET AROUND
16 percent of 51 billion tons a year
Let’s start with a quick quiz—just two questions.
Which of these contains the most energy?
A. A gallon of gasoline
B. A stick of dynamite
C. A hand grenade
Which of these is the cheapest in the United States?
A. A gallon of milk
B. A gallon of orange juice
C. A gallon of gasoline
The correct answers are A and C: gasoline. Gas contains an amazing amount of energy—you’d need to bundle 130 sticks of dynamite together to get as much energy as a single gallon of gas contains. Of course, dynamite releases all its energy at once, while gasoline burns more slowly—which is just one reason we fill up our cars with gas and not sticks of explosives.
In the United States, gasoline is also remarkably cheap, even though it may not always seem that way when it’s time to stop at the gas station. In addition to milk and OJ, here are some things that it’s less expensive than, gallon for gallon: Dasani bottled water, yogurt, honey, laundry detergent, maple syrup, hand sanitizer, latte from Starbucks, Red Bull energy drink, olive oil, and the famously low-cost Charles Shaw wine you can buy at Trader Joe’s grocery stores. That’s right—gallon for gallon, gasoline is cheaper than Two Buck Chuck.
As you read the rest of this chapter, keep these two facts about gasoline in mind: It packs a punch, and it’s cheap.*1 They’re a good reminder that when it comes to how much energy we get for each dollar we spend, gasoline is the gold standard. Aside from similar products like diesel and jet fuel, nothing else in our daily lives comes close to delivering as much energy per gallon at such a low cost.
The twin concepts of energy delivered per unit of fuel and per dollar spent are going to matter a lot as we look for ways to decarbonize our transportation system. As you’re no doubt aware, the burning of fuels in our cars, ships, and planes emits carbon dioxide that’s contributing to global warming. To get to zero, we’ll need to replace those fuels with something that’s just as energy dense and just as cheap.
You may be surprised that I’m bringing it up so late in this book and that transportation contributes only 16 percent of global emissions, ranking fourth behind how we make things, plug in, and grow things. I was surprised too when I learned it, and I suspect that most people are in the same boat. If you stopped some random strangers on the sidewalk and asked them what activities contribute the most to climate change, they’d probably say burning coal for electricity, driving cars, and flying planes.
The confusion is understandable: Although transportation isn’t the biggest cause of emissions worldwide, it is number one in the United States, and it has been for a few years now, just ahead of making electricity. We Americans drive and fly a lot.
In any case, if we’re going to get to net-zero emissions, we’ll have to get rid of all the greenhouse gases caused by transportation, in the United States and around the world.
How hard will that be? Pretty hard. But not impossible.
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For the first 99.9 percent of human history, we managed to move around without relying on fossil fuels at all. We walked, rode animals, and put ships under sail. Then, in the early 1800s, we figured out how to run locomotives and steamboats on coal, and we never looked back. Within the century, trains were crossing entire continents and ships were moving people and products across the oceans. The gas-powered automobile came along in the late 19th century, followed in the early 20th century by the commercial air travel that would become so essential to today’s global economy.
Although it’s been barely 200 years since we first burned fossil fuels for transportation, we’ve already come to depend on them in a fundamental way. We will never give them up without a replacement that is nearly as cheap and that’s just as capable of fueling long-distance travel.
Here’s another challenge: We won’t just need to eliminate the 8.2 billion tons of carbon we produce from transportation today; we’ll need to get rid of even more than that. The Organization for Economic Cooperation and Development predicts that demand for transportation will keep growing through at least 2050—even after accounting for the fact that COVID-19 has limited travel and trade. It’s aviation, trucking, and shipping—not passenger cars—that account for all the emissions growth in this sector. Maritime shipping now handles nine-tenths of the goods traded around the world by volume, producing nearly 3 percent of global emissions.
A lot of the transport emissions come from rich countries, but most of those countries hit their peak in the past decade and have actually declined somewhat since then. These days, nearly all the growth in transport-related carbon is coming from developing countries as their populations grow, get richer, and buy more cars. As usual, China is the best example—its transportation emissions have doubled over the past decade and gone up by a factor of 10 since 1990.
COVID-19 is slowing—but not stopping—the growth of transportation emissions. A
lthough emissions will shrink in many places, they will grow so much in low- and middle-income countries that the overall effect will be an increase in greenhouse gases.(IEA World Energy Outlook 2020; Rhodium Group)
At the risk of sounding like a broken record, I’ll make the same point about transportation that I’ve made about electricity, manufacturing, and agriculture: We should be glad that more people and goods are moving around. The ability to travel between rural areas and cities is a form of personal freedom, not to mention a matter of survival for farmers in poor countries who need to get their crops to market. International flights connect the world in ways that were unimaginable a century ago; being able to meet people from other countries helps us understand our common goals. And before modern transportation, our food choices were limited most of the year. Personally, I like grapes and enjoy eating them year-round. But I can do that only because of container ships that bring fruit from South America and that currently run on fossil fuels.
So how can we get all the benefits of travel and transportation without making the climate unlivable? Do we have all the technology we need, or do we need some innovations?
To answer those questions, we’ll need to figure the Green Premiums for transportation. We’ll begin by digging deeper into where these emissions are coming from.
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This pie chart shows you the percentage of emissions that comes from cars, trucks, planes, ships, and so on. Our goal is to get every one of them to net zero.
Notice that passenger vehicles (cars, SUVs, motorcycles, and such) are responsible for almost half the emissions. Medium- and heavy-duty vehicles—everything from garbage trucks to 18-wheelers—account for another 30 percent. Airplanes add in a tenth of all emissions, as do container ships and other marine vessels, with trains accounting for the last bit.*2
Cars aren’t the only culprit. Passenger vehicles are responsible for nearly half of all transportation-related emissions. (International Council on Clean Transportation)
Let’s take these one at a time, starting with the biggest slice of the pie—passenger cars—and look at our current options for getting rid of emissions.
Passenger cars. There are about a billion cars on the road around the world. In 2018 alone, we added roughly 24 million passenger cars, after accounting for the ones that got retired. Because burning gasoline inevitably releases greenhouse gases, we need an alternative—either fuels made from carbon that’s already in the air rather than the carbon that’s in fossil fuels, or some other form of energy altogether.
Let’s take the second option first. Fortunately, we do indeed have another form of energy that—although far from perfect—has already been proven to work. In fact, cars that use it are probably being sold at an auto dealer near you right now.
Today you can buy an all-electric car from more than half the alphabet: Audi, BMW, Chevrolet, Citroën, Fiat, Ford, Honda, Hyundai, Jaguar, Kia, Mercedes-Benz, Nissan, Peugeot, Porsche, Renault, Smart, Tesla, Volkswagen, and others too numerous to mention, including manufacturers in China and India. I own an electric vehicle, and I love it.
Although EVs used to be far more expensive than their gas-burning counterparts, and they’re still the pricier option today, the difference has come down dramatically in recent years. That’s largely due to a huge drop in the cost of batteries—an 87 percent decrease since 2010—as well as various tax credits and government commitments to get more zero-emissions cars on the road. But EVs still come with a modest Green Premium.
For example, consider two cars, both produced by Chevrolet: the gas-powered Malibu and the all-electric Bolt EV.
Chevy versus Chevy. The gas-powered Malibu and the all-electric Bolt EV. (Chevrolet)
Their features are roughly comparable when it comes to engine power, the amount of space for passengers, and so on. The Bolt costs $14,000 more (before any tax incentives that might make it cheaper), but you can’t figure the Green Premium using only the purchase price of the car. What matters isn’t just the cost of buying the car but the overall cost of buying and owning the car. You have to account for the fact that EVs need less maintenance, for example, and run on electricity instead of gas. On the other hand, because EVs are more expensive, you’ll pay more for auto insurance.
When you account for all these differences and look at the total cost of ownership, the Bolt will cost 10 cents more per mile driven than the Malibu.
What does 10 cents a mile mean? If you drive 12,000 miles a year, that’s an annual premium of $1,200—hardly negligible, but low enough to make EVs a reasonable consideration for many car buyers.
And that’s a national average in the United States. The Green Premium will be different in other countries—the main factor being the difference between the cost of electricity and the cost of gasoline. (Cheaper electricity or more expensive gasoline will make the Green Premium smaller.) In some parts of Europe, gas prices are so high that the Green Premium for EVs has already reached zero. Even in the United States, as battery prices continue to drop, I predict that the premium for most cars will be zero by 2030.
That’s great news, and we should get lots of EVs on the road as they become even more affordable. (I’ll say more about how we can do this at the end of this chapter.) But even in 2030, there will be some drawbacks to EVs versus a gas-powered car.
One is that gasoline prices vary a lot, and EVs are the cheaper option only when gas prices are above a certain level. At one point in May 2020, the average price of gas in the United States had dropped to $1.77 per gallon; when gas is that cheap, EVs can’t compete—the batteries are simply too expensive. With the price of today’s batteries, EV owners save money only if gas costs more than around $3 per gallon.
Another drawback is that it takes an hour or more to fully charge an EV, yet you can gas up your car in less than five minutes. In addition, using them to avoid carbon emissions works only if we’re generating electricity from zero-carbon sources. This is another reason why the breakthroughs I mentioned in chapter 4 are so important. If we get our power from coal and then charge up our electric cars with coal-fired electricity, we’ll just be swapping one fossil fuel for another.
Plus, it’ll take time to get all our gas-burning cars off the road. On average, after a car rolls off the assembly line, it runs for more than 13 years before reaching its final resting place in the junkyard. This long life cycle means that if we wanted to have every passenger car in America running on electricity by 2050, EVs would need to be nearly 100 percent of auto sales within the next 15 years. Today they’re less than 2 percent.
As I mentioned, another way to get to zero is to switch to alternative liquid fuels that use carbon that was already in the atmosphere. When you burn these fuels, you’re not adding extra carbon to the air—you’re just returning the same carbon to where it was when the fuel was made.
When you see the phrase “alternative fuels,” you might think about ethanol, a biofuel that’s usually made from corn, sugarcane, or beet sugar. If you’re in the United States, you’re probably running your car on some of this biofuel already—most gasoline sold in America contains 10 percent ethanol, virtually all of it made from corn. There are cars in Brazil that run on 100 percent ethanol made from sugarcane. Few other countries use any at all.
Here’s the problem: Corn-based ethanol isn’t zero carbon, and depending on how it’s made, it may not even be low carbon. Growing the crops requires fertilizer. The refining process, when the plants get turned into fuel, produces emissions too. And growing crops for fuel takes up land that might otherwise be used for growing food—possibly forcing farmers to cut down forests so they have someplace to grow food crops.
Alternative fuels are not a lost cause, though. There are advanced, second-generation biofuels that don’t have the problems of conventional biofuels. They can be made from plants that aren’t grown for food—unless you’re a big fan of switchgrass salad—or from farming residue (such as cornstalks), by-products left over f
rom making paper, and even food and yard waste. Because they’re not food crops, they need little or no fertilizer, and they don’t have to be grown on farmland that could otherwise be dedicated to food for people or animals.
Some advanced biofuels will be what experts call “drop-in” fuels—meaning you can use them in (or “drop them into”) a conventional engine without modifying it. One more benefit: We can transport them using the tankers, pipelines, and other infrastructure we’ve already spent billions to build and maintain.
I’m optimistic about biofuels, but it’s a tough field. I had a personal experience that shows just how hard it is to make a breakthrough. A few years ago, I learned about a U.S. company that had a proprietary process for converting biomass, such as trees, into fuels. I went to visit its plant and was impressed by what I saw, and after doing due diligence, I invested $50 million in the company. But its technology just didn’t work well enough—various technical challenges meant the plant couldn’t produce at nearly the volume it needed to be economical—and the plant I visited eventually shut down. It was a $50 million dead end, but I’m not sorry I did it. We need to be exploring lots of ideas, even knowing that many of them will fail.
Unfortunately, research on advanced biofuels is still underfunded, and they’re not ready to be deployed at the scale we need for decarbonizing our transportation system. As a result, using them to replace gasoline would be quite expensive. Experts disagree on the exact cost of these and other clean fuels, and there’s a range of estimates out there, so I’ll use average costs from several different studies.
Green Premium to replace gasoline with advanced biofuels
