Could the World Ever Run Entirely on Renewable Energy?

Could the World Ever Run Entirely on Renewable Energy?

This week’s question — could the world ever run entirely on renewable energy? — is shadowed by a much larger one: Namely, will politicians and powerful forces of delay like Big Oil ever allow the world to run entirely on renewable energy? For the most part, we have put that larger question aside for this instalment; the experts below are interested primarily in whether it’s feasible.

To not switch to renewables in the very near future would, we know, summon a host of awful consequences. Unchecked carbon emissions would make vast swaths of the planet uninhabitable by century’s end; survivors of the heat-apocalypse would spend their days fortifying little hutments, or surgically excising mould from rotten squirrel meat. This is not the future we want — which is why planning for a renewable transition, and ensuring we bring it off, is so important. Hard as it might be, it’s worth setting aside your doomy visions of the future to consider, for a moment, what we can actually achieve. For this week’s Giz Asks, we’ve assembled a panel of experts to discuss whether the world could ever run entirely on renewable energy — and what it would take to get there.

Mark Z. Jacobson

Professor of Civil and Environmental Engineering and Director of the Atmosphere/Energy Program, Stanford University, and the author of 100% Clean, Renewable Energy and Storage for Everything

My team and I have been studying whether the world can run entirely on clean renewable energy since about 2008, and we’ve concluded, in over a dozen studies, that it is absolutely possible. And when I say clean renewable energy, I mean just wind and water and solar power — onshore and offshore wind, solar panels on rooftops, concentrated solar power, geothermal power, etc. We don’t include biomass or bioenergy or any type of biofuel, because it’s not clean — you burn it, and it usually takes up large amounts of land. We also don’t include fossil fuels, or carbon capture, or direct air capture, or nuclear power, as we consider all of these things to have opportunity costs. We’ve done calculations in 143 countries representing 99.7% of all emissions worldwide, and we’ve found that it is possible to power all of these countries with just wind, water and solar, plus storage electricity, heat storage, cold storage and hydrogen storage. The idea, really, is to electrify everything, and to combine the electricity with wind, water and solar.

There are four major energy sectors: electricity, transportation, buildings, and industry. For transportation, we’d go with electrical vehicles, hydrogen fuel cell vehicles. For buildings, all heating and cooling would be done with electric heat pumps; water heating would be done with electric heat pumps; stoves would be induction cooktops. It turns out that when you do this, you reduce power demand worldwide by about 57%, because of the efficiency of electricity over combustion. When you electrify everything, you reduce demand, but you’re also eliminating all of the energy that goes into mining, transporting, and refining fossil fuels and uranium, which make up 12% of all energy worldwide. You end up eliminating up to 7 million air pollution deaths per year that are linked to fossil fuel and biofuel combustion; you eliminate the emissions associated with global warming; and you provide energy security and stability. Because you’re using 57% less energy, your costs go down at least 57%, but in fact go down much more, because wind and solar, the cheapest forms of electricity today, are half the cost of gas. Cost per energy unit, accordingly, goes down by over 60%. And that’s not to mention money saved on health costs and climate costs. Factoring that in, expenditure goes down about 90% compared with business as usual, which is mostly fossil fuels.

The bottom line is that we’re confident that, with current technologies, we can transition the world to solve these problems. It does take political will, but it’s feasible pretty much everywhere and is already starting to happen — 61 countries now have 100% renewable; energy laws; 13 states in the U.S. have laws or executive orders; 180 U.S. cities and 300 worldwide have laws. It’s a growing movement. A lot more needs to be done, but the public is behind it. We have popular support for costs coming down through renewables.

Emily Grubert

Assistant Professor of Environmental Engineering, Construction and Infrastructure Systems Engineering, and Sustainable Communities, Georgia Tech

I think the answer is yes, but we have to design the systems to make that possible. Right now, we don’t have a system that’s designed to be fully renewable energy, so we often see weaknesses in that system, because we haven’t had to assume that it’s purely renewable. But we can absolutely design systems that will allow us to run full renewable energy.

At some level, if you really think about human existence historically, we were running on renewable energy for a very long time. The question is: What do we want from our energy systems? Mostly, we have to think about how the supply and demand sides of an energy system fit together, and then we need to think carefully about some of the parameters we want our system to deliver. What should it look like in terms of reliability? What should it look like in terms of cost? What should it look like in terms of environmental characteristics? You probably can’t always get the lowest possible cost for the highest possible social/environmental standards, or the highest possible reliability standards, so there can be some tradeoffs — but that’s true of the fossil-based system as well.

I think we will eventually get there, and that we need to be very thoughtful about how we push ourselves in that direction. What we need is a shared social understanding of what our overall priorities are. Is that ‘we need to avoid climate change?’ Is it ‘we need to actually make sure that we’re providing safe energy systems to ourselves?’ But in terms of what happens on the ground, I think a lot of this comes down to regulators, national standards, international agreements, that sort of thing.

Sarah Johnston

Assistant Professor, Agriculture and Applied Economics, University of Wisconsin-Madison, whose research interests include industrial organisation and energy and environmental economics

Yes, but we will still need some technological advancement to get there. We already have the technology to cost-effectively produce massive amounts of electricity from renewable resources. Yet, we currently do not have much ability to store this electricity for times when it is not sunny or windy. Current battery storage systems are improving, but can only provide electricity for hours, not days. So I think technological advancement in terms of storage will be key. Another option is to figure out how to economically transform electricity from renewables into other forms of energy that can be stored. We can use electrolysis to convert it into hydrogen, but this is still expensive, so that’s another margin on which technological progress could help. Looking at the progress in the last 20 years, I am optimistic that we will get there.

I think another interesting question is, should 100% be the goal? A key principle of economics is increasing marginal costs. In transitioning away from fossil fuels and toward renewable energy, we will (hopefully) make the lowest cost changes first. Currently, this means transitioning electricity generation from fossil fuel sources to renewables. Next, it might mean replacing gas-powered vehicles with electric vehicles. As we are using fossil fuels less and less, the actions we must take to replace them with renewables will get more costly. For example, to replace natural gas heat with electric heat for homes in cold climates, we would have to pay to retrofit tens of millions of homes with electric heat pump systems that currently cost far more to purchase and install than a natural gas furnace. So while the impact on climate change of going from 99% renewable energy to 100% renewable energy may be similar to the impact of going from 50% to 51%, the incremental cost could be orders of magnitude greater. I think this logic makes it important not to get too fixated on 100% targets.

Steven Davis

Professor of Earth System Science, University of California, Irvine

Yes, it’s possible we’ll meet all our energy demands with renewable sources, but there are still some techno-economic challenges if the share of variable sources like wind and solar gets really high, like say >80%. That’s because those sources keep their own schedules that don’t always align with the timing of our demands, and we haven’t figured out a sufficiently cheap and scalable way of storing really large quantities of energy. Other renewable sources of energy like hydroelectricity, geothermal, or biomass may help, but often face their own, different challenges of sustainability. I therefore think making renewable fuels could be a key to affording an all-renewable energy system. For example, some of our recent work shows that even though current technologies for converting renewable electricity to fuel and back are expensive, they’d already make an otherwise-all-solar-and-wind electricity system cheaper.

Brian Kahn contributed reporting for this story.

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