A worker inspects solar panels northwest of Lanzhou, Gansu Province.
A worker inspects solar panels northwest of Lanzhou, Gansu Province. Carlos Barria/Reuters

A speedy transition to wind, water, and solar could avert catastrophic climate change. For the 139 countries that backed the Paris agreement, it’s within reach.

Updated on August 24 at 3 p.m.

How quickly could the majority of planet wean itself off of coal, oil, and gas? For $124.7 trillion, perhaps within just a few decades.

That’s according to the latest research by the Stanford University professor of civil and environmental engineering Mark Z. Jacobson. In a study published in the new peer-reviewed scientific journal Joule, Jacobson and a slew of co-authors detail “roadmaps” for 139 countries to move toward 100 percent renewable, clean energy sources by 2050—that is, all wind, water and solar power, for all energy purposes.

From Albania to Zimbabwe, the authors show how electrifying heavy-emitting sectors through renewables could help avert catastrophic global warming, prevent millions of deaths, and increase access to energy worldwide.

This paper builds on earlier work by Jacobson demonstrating how the U.S. alone could make such a transition, and at a quite “reasonable” cost, given the gruesome downsides of fossil-fuel-induced global warming. That work has been widely used by renewable energy advocates, and this new paper is likely to be influential as well.

In it, the authors begin by estimating the average annual power demand of all 139 countries by 2050—both in a business-as-usual and a fully electrified “wind water solar” scenario. For each country, the researchers analyze available environmental resources (such as rooftops for photovoltaic panels, coastlines for tidal power, and open land for turbines) to determine the mix of solar, wind, hydropower, and geothermal technologies to meet that demand. (Notably, Jacobson excludes nuclear energy from his recommendations, due to its environmental impacts and safety risks.)

Projected power supply and demand in “business-as-usual” and complete “WWS” scenarios. (Jacobson et al/Joule)

Drawing on earlier analyses, the researchers estimate how much energy storage capacity each nation would need to meet fluctuating supply and demand. To move to 100 percent renewable by 2050 (and 80 percent by 2030, the study’s other benchmark), no energy mix is quite the same: Sudan might rely heavily on rooftop solar panels, while Switzerland would depend on hydroelectric. The U.S. would lean on wind power. If these plans were fully deployed, 58 percent of the world’s energy would come from solar, 37 percent from wind, and the rest from hydroelectric, geothermal, tidal, and wave energy. Worldwide, all households, businesses, and governments would switch to electric appliances and heating systems—plus cars, trains, boats, planes, and heavy-duty vehicles.

That level of transformation sounds daunting, and incredibly costly: Jacobson and co-authors peg the upfront cost of installing nearly 50 terawatts’ worth of wind, water, and solar technologies around the world at an astounding $125 trillion.

But that’s cheap, considering the alternatives, they write. A massive transition among the 139 nations that ratified the Paris agreement may be the only way of meeting the ambitious goal of limiting global warming to 1.5 degrees C. By 2050, decarbonized grids could also prevent nearly 5 million deaths to air pollution every year, estimate Jacobson et al., and save an annual $28 trillion from a changing climate’s catastrophic impacts to coastlines, fisheries, and agriculture, and deaths caused by heat, famine, drought, wildfires, and severe weather.

While the study predicts that certain technologies—such as batteries and underground heat storage—will become substantially more efficient in coming decades, almost all of the energy generators, storage systems, and electric replacements upon which Jacobson et al base the roadmaps are already commercially available and widely used. There are few notable exceptions—electric aircrafts, for example, are likely a solid 30 years from taking flight. But already, more than 95 international companies and over 30 cities have committed to 100 percent clean, renewable energy sources.

Jacobson’s claims are bold, even audacious. They certainly have their detractors. A peer-reviewed paper published in PNAS in June called into question parts of his methodologies, such as the degree to which storage technology is likely to soon improve, and whether a “clean energy” mix that excludes nuclear could be fully reliable. These disputes largely boiled down to differing assumptions about what is economically “feasible”—which is a political question more than anything.

No one disagrees that moving 100 renewable energy is technologically possible. In the U.S., solar and wind generation has far outpaced predictions made even five years ago. Counter to the findings of a new, highly anticipated federal study commissioned by Energy Secretary Rick Perry, renewables are becoming more and more reliable. Monday’s “Great American Eclipse” provided an all-natural test to that question overshadowing the sector, with nary a flicker in the largest solar-producing states. Jacobson’s roadmaps are not a prediction of what will happen. They are possible routes towards a fossil fuel-free future, if the political and social will were great enough to follow them.

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