How Much Energy Will the World Need?

Any climate plan that doesn’t consider this question is bound to fail

Consider a simple thought experiment. Imagine that by the end of this century, everyone in the world will use energy at the same rate per person that a typical American does today: a steady stream of 9.5 kilowatts (kW), averaged over the year. That’s roughly the power consumed by 18 electric-stove burners running nonstop on high, all day, every day.

Does that assumption seem unreasonable? It shouldn’t. This is what economic progress looks like. According to energy
historian Vaclav Smil, Americans used just one-fifteenth as much useful energy per capita in 1860 as they do today. And during the twentieth century, he observes in his book Energy Transitions, annual energy use rose 17-fold globally while economic output soared by a factor of 16—even though nations had to invent and then build the enormous infrastructure needed to extract, process, and transport oil, gas, and electricity.

Now in this new century, technology, information, and wealth speed around the planet faster than ever before. Since 1990, 1.1 billion people have escaped from extreme poverty, with more than 140 million entering the burgeoning middle class every year. The ranks of the newly affluent are also swelling at an accelerating pace. History suggests that as these citizens of the world find more money in their pockets, they will spend much of it—directly or indirectly—on energy.

Add to these upward trends the steadily expanding number of people on Earth and the rapid increases in urbanization and car ownership, and it’s a safe bet that the great majority of people, no matter where they were born, will continue to work, vote, protest, and migrate in ways that tend to improve their standard of living over the long run. The future will doubtless see its share of economic downturns and periods of slow growth. But over the course of generations, the mission of humanity has been to enrich itself. There is no reason to expect it to fail now at that mission—or give up on it—after so much past success.

It’s natural for those concerned about the pace and risks of global climate change to hope that somehow these trends will change—that the poor can be persuaded to forego the energy-rich lifestyles that the wealthy have enjoyed, or that they will pay extra for clean energy even when dirty forms are cheaper and easier to get.

But such hopes are misplaced. Just as the farmers and laborers of America and Europe did in the nineteenth and twentieth centuries, the urbanizing middle classes of India, China, Brazil, Nigeria, and so many other countries are buying cars, refrigerators, water heaters, and air conditioners
almost as soon as they can afford the gas and electric bills. They are eating more meat and taking more long trips. No one has the power—let alone the right—to tell them not to. And any bold plan for saving the climate that fails to meet a massive increase in energy demand during this century is very likely to fail.

Since 1990, 1.1 billion people have escaped from extreme poverty, with more than 140 million entering the burgeoning middle class every year . . . History suggests that as these citizens of the world find more money in their pockets, they will spend much of it—directly or indirectly—on energy.

So how much energy will the world consume as the twenty-first century unfolds? Following our thought experiment, if average per capita energy demand rises to current US levels by the year 2100, we’re looking at some very big numbers.

Maybe the most important among them is this one: 18 trillion watts. In 2016, that was roughly the power needed to keep human civilization humming around the clock. This figure comes from BP’s annual report on primary energy use, a report which encompasses all commercially traded fuels and renewable sources.

The astounding size of that number is the main reason that meaningful change in the global energy system is
grueling. Any new, clean technology must have a power rating with lots of zeros behind it or must be adopted at an explosive rate (and preferably both), or it will simply be too little, too late to make much difference to climate change.

Big as 18 terawatts (or TW, shorthand for 1 trillion watts) may be, humanity’s energy intake will almost certainly be bigger tomorrow, and bigger still the day after that. The real action will happen in developing countries as incomes, population, and individual energy use all rise simultaneously.

Start with incomes. As recently as 1990, more than three out of every nine people in the world lived in extreme poverty, on less than US$1.90 per day. By 2013, fewer than one in nine did, and in that year alone 114 million more people (mostly children) escaped that precarious existence. The elimination of desperate destitution is in sight, and it will be one of the signal achievements of human civilization.

Lifting people from extreme poverty to stable subsistence actually costs relatively little energy. The trickle of electricity used by the poor is tiny compared to the gushing streams consumed by the rich. In fact, the International Energy Agency (IEA) has calculated that extending universal access to electricity, heating and cooking gases, and other modern forms of energy by 2030 would increase overall carbon dioxide emissions by less than 1 percent. That is a cheap price for all the suffering it would prevent and the enormous human potential it would unlock.

But few people are content to stop there—they naturally set their sights on a middle-class lifestyle. Already about 3.2 billion people have achieved that and enjoy annual household incomes between about $15,000 and $150,000, according to a recent analysis by Homi Kharas of the Brookings Institution. The rate of entry into middle class-dom is accelerating, particularly in Asia, and will likely lift total membership to 5 billion by 2030, Kharas forecasts.
Economic security for all, beyond basic poverty alleviation, will come at a steep price in energy. Per capita energy consumption today averages just 2.5 kW worldwide. Lifting all of humanity to the current US standard of living by 2100—an average of 9.5 kW per person, probably a conservative projection—thus means generating more than 51 TW of energy on top of everything we already produce today.

In our thought experiment, the year 2100 will thus see demand reach a mind-boggling 70 TW. Take every coal-fired generator, nuclear power plant, wind turbine, and solar farm and then multiply it by four. The scale of the challenge should be starting to sink in.

But we’re not done yet. We haven’t accounted for two major factors: population growth and urbanization. Let’s look first at the global headcount.

The number of people alive swept past 7 billion in 2011, on its way to probably 11 billion by the end of this century, according to the latest forecasts made by the United Nations Commission on Population and Development. That latter number is uncomfortably squishy because of uncertainty about how quickly fertility rates will continue to fall. Since the 1970s, population has not grown exponentially, as many feared it would, but instead has followed an essentially linear track. Women in China, Indonesia, and other fast-growing Asian economies rapidly reduced the number of children they bore through 2000—and those in India and many parts of Africa continue to do so. The current fertility rate in the US, at 1.9 children per woman, is now below the replacement rate; in India, it is around 2.4 and falling.

As a result, an inflection point is coming in the long arc of humanity’s growth. The timing of that change in direction matters a lot: global population could hang at 10 billion or explode to nearly 13 billion by this century’s end. Factor population growth into our thought experiment, and global energy use undergoes another big bang, to an astonishing 95–123 TW annually. The span of that range, due to the uncertainty in population growth, is far bigger than the entire global energy system is today.

Crossing the 7-billion milestone in world population got a lot of attention, but humanity actually crossed an arguably more important threshold two years earlier. In 2009, for the first time in human history, a majority of the human population was living in cities. This trend toward increasing urbanization looks unstoppable for the foreseeable future, and it has big implications for energy use.

In poorer parts of the world, moving to the city means easier access to electricity, gas for heating and cooking, roads, retail centers, and energy-intensive products (such as computers) and services (such as restaurants). City dwellers tend to have higher incomes, so they consume more energy on average than their rural counterparts. Although some efficiencies do kick in when people live and work in higher-density buildings, higher incomes swamp that effect. So the mass migration of the rural poor into cities—to the tune of 1.6 billion urban residents added over the past 25 years—is boosting individual energy use.

Although some efficiencies do kick in when people live and work in higher-density buildings, higher incomes swamp that effect.

Urbanization is also spurring the disaggregation of households. An extended family of 11 once would commonly share a single house in the country. Now families are much smaller, and kids tend to move out and live solo in an apartment. Despite a dramatic collapse in the fertility rate in China, the billion or so children born in the peak years are now inhabiting many more dwellings, each with its own kitchen, laundry, lighting, heating, and cooling systems. This pattern is occurring in almost every emerging economy. And it contributes to yet another huge factor in energy demand: the explosion of car ownership.

In 2009, China surpassed the US as the world’s largest market for new cars. Last year, over 24 million cars were sold there—about 3.5 times as many as in the US. The growth curve looks almost parabolic, and it’s anyone’s guess where it plateaus. The US has four cars for every five people; in the EU, it’s just under three cars. India and China could together host almost 2 billion cars by mid-century if they follow the same path.

Let’s hope those vehicles are electric, so that their emissions come from factories and power plants rather than tailpipes. The road to that goal, however, looks long. Last year, just 750,000 EVs were sold worldwide, and only 2 million or so are now in service, according to the IEA.

As with renewable energy sources, it’s difficult for the new entrants to keep up with surging demand. Analysts estimate that 1.2 billion cars are now on the road worldwide, and the International Monetary Fund projects that the number will reach 3 billion by 2050. So even though most countries have all but stopped using oil to make electricity—so that they can use it instead for gasoline, diesel, jet fuel, and plastics—experts still think it is likely that we will burn as much oil over just the next 30 years as we did in all of the previous years since 1869.

Even as the number of humans gradually levels off and perhaps begins to slowly dwindle late in the century, more people will be living alone or in small households, more will live in cities, and many more will be driving and flying. So overall energy use per person seems likely to rise quickly—certainly much faster than efficiency improvements can be found to rein it in.

This puts the onus to save the climate squarely on decoupling economic growth from emission growth. That means undertaking a massive and very rapid transformation of the energy-production system to scalable emissions-free sources such as solar, wind, and nuclear. It also means smartly designing twenty-first-century cities to minimize vehicle transport and energy used for heating and cooling.

If your reaction to all this is “It can’t be done,” you’ve missed the point. The lesson of the past 200 years is that something like this very likely will be done, absent a nuclear war, a runaway plague, a massive meteor impact, or some other catastrophic societal collapse. As is already happening in China, people will organize, institutions will bend, and investors will deploy capital to generate the energy needed to power economic growth. The reason for this may be hard to remember for those of us who already spend our days juggling multiple computers and think nothing of boarding a jet. But it is simple: energy is an indispensable ingredient to a life of basic human dignity.

Without sufficient energy, poor farmers cannot get the fertilizer they need for their crops. A complete lack of access to electricity still prevents a billion people from getting good medical care, running refrigerators, and turning on reading lights and radios. Most of the 2 billion poorest people still burn wood, charcoal, dung, or leftovers from farming to cook their food. Those open fires cause respiratory problems that kill 4 million every year, mainly women and children. Affordable electricity could put an end to that—and solve so many other problems as well.

So the question looming over this century is not whether energy use will expand dramatically, but how—how will all of this new energy be produced? And what can those of us in rich economies do to prevent the coming energy expansion from wrecking the climate?

It’s tempting for high-tech societies to focus foremost on transforming their own energy systems to be as clean and efficient as possible. Certainly, it’s important to set a good example.

Transformation of the North American and European energy systems is not irrelevant, but it becomes increasingly less relevant as energy use in currently low-income regions catches up to that of the high-income nations

But it’s also important to realize that, to a first approximation, all the new energy to be created as this century unfolds will have to be generated in the poorer parts of Asia, Africa, and South America—because that’s where the people are who will use it. Transformation of the North American and European energy systems is not irrelevant, but it becomes increasingly less relevant
as energy use in currently low-income regions catches up to that of the high-income nations.

Over the long term, the best thing the rich and emerging economies can do is to push better energy technology forward as far and as fast as possible so that it can be deployed globally in the decades to come. Unfortunately, our track record to date
is not great.

Fifteen years ago, a group of far-thinking physicists, energy experts, and engineers published a seminal article in Science laying out various ambitious paths for developing emissions-free technologies to generate the 25 TW of clean power they estimated would be needed by 2050 or so. They surveyed a range of challenging but technically plausible approaches, including fusion reactors, space-based solar plants, and schemes to capture and permanently store carbon dioxide emissions from power stations.

Now we are a third of the way down that road to 2050. Energy use is up 50 percent, but unfortunately only 0.9 TW of the 5 TW added since 2002 came from renewable energy sources, and half of that was hydropower. Fusion and space solar are still stuck in the experimental stages, and research into carbon sequestration is starved for funding. Due to declines in nuclear energy production, the fraction of global energy provided by fossil fuels is about the same today (86 percent) as it was in 2002.

Clearly, we must do better to produce, demonstrate, and perfect cheap new technologies for creating, storing, and transmitting emissions-free energy. We also need to push hard to improve energy efficiency everywhere possible so that energy use grows more slowly than income—and so that emissions don’t increase at all but actually start to fall. As Robert Jackson describes on page 44, the two longest levers we have for applying the brakes to emissions and keeping warming in check are how cleanly we make energy and how efficiently we use it to support our standard of living.

That is why we need breakthroughs in energy to help people in modernizing societies enjoy the basics that those in the richer parts of the world have long taken for granted. We keep saying we need to do more with less. No. We need to do more with more: make a lot more energy—a lot more cleanly—and use it a lot more efficiently for the benefit of a lot more people.

W. Wayt Gibbs is a freelance science writer and editor based in Seattle. He is a contributing editor with Scientific American and editorial director at Intellectual Ventures. His work has appeared in Science, Nature, Discover, IEEE Spectrum, and The Economist.