IRA FLATOW: This is Science Friday. I’m Ira Flatow. Every week we hear about more solar or wind resources coming online. So, is an entirely renewable future a possibility? Just using renewables, nothing else.

A new study finds that countries around the world could shift their economies entirely over to renewable energy sources, such as solar, wind, hydroelectric– could do the switchover by the year 2050. The researchers map out the blend of energy sources that each of 139 countries would need to completely switch their energy to electric power. The report was published this week in the journal Jewel.

Mark Z Jacobson is a professor of civil and environmental engineering at Stanford. He’s also director of the Atmosphere Energy Program there and one of the authors of the report. And he joins me today from the Stanford campus. Welcome back to the program.

MARK JACOBSON: Thanks for having me on, Ira.

IRA FLATOW: Seems like a huge challenge you would have here to get most of the world entirely on renewable energy, what, in the next 30 some years?

MARK JACOBSON: Yeah, it is a challenge, but it’s very important to do. In fact, we want 80% of it by 2030 and 100% by 2050. And the idea here is to electrify all energy sectors. That’s transportation, heating, cooling, industry, agriculture, forestry, and fishing, and provide that electricity with 100% wind, water, and solar power for all these purposes.

IRA FLATOW: And you found in surveying all these countries that that is possible?

MARK JACOBSON: Well, we think it’s possible, at least in terms of the resources available, in terms of the energy supplying the energy needed, and in terms of the costs and also the benefits. There are so many benefits that far outweigh the costs.

There are some countries that are going to be more challenging, others– particularly high density, really small countries like Singapore, Hong Kong, and Gibraltar. But most countries, it’s actually a little bit easier than I thought it would be.

IRA FLATOW: Really? Give me an idea what you mean.

MARK JACOBSON: Well, especially bigger countries there’s plenty of resource. There’s plenty of solar resource, plenty of wind resource, and, well first of all, when you electrify, you reduce your power demand significantly. And if you provide that with clean renewable energy, you go down 13% of energy because you no longer need to mine, transport, or refine fossil fuels. And 13% of all energy worldwide is used for just that.

And then we get another 23% power reduction, demand reduction, due to the fact that electricity is more efficient than combustion. For example, an electric car only– sorry, 80% to 86% of the electricity going into the car goes to move the car and the rest is waste heat. Whereas a gasoline car, only 17% to 20% of the energy in the gasoline goes to move the car and the rest is waste. So when you electrify your cars, you actually reduce your power demand by about 70% to 80%.

But when you average over all sectors, it’s about 23%. So you’ve got 23% down there, 13% from eliminating mining, transporting, refining fossil fuels. That’s 36% reduction of demand, and then we think we can squeeze 7% more down due to end use energy efficiency improvements. Of course, by 2050 there’s going to be higher population and more energy demand from that growth, and some countries will want more energy use so we have to account for that as well. But overall from the 2050 without changing to 2050 with a clean renewable energy, we reduce our power demand 43% almost.

IRA FLATOW: But you’d also have to do away with jet engines, wouldn’t you?

MARK JACOBSON: Yeah, so that’s the most difficult part. So about 97% of the technologies are here. In transportation, we’d use electric cars, some hydrogen fuel cell. But for long distance aircraft, well, short distance aircraft we think we can electrify. There are already companies that are building electric aircraft that will go up to 1,500 kilometers length, but for a– distance. And then for higher, longer distance aircraft, we’ll probably need a combination of hydrogen fuel cell and electric.

Now there are some prototypes. There’s a four engine, four seat hydrogen fuel cell plane that already goes 1,500 kilometers, and the space shuttles and most rockets have propelled to space on hydrogen. So it’s an existing technology. It just hasn’t been scaled up to long distance aircraft yet.

IRA FLATOW: But you’d also have to change the infrastructure, right? The grid and all those things to get this to work.

MARK JACOBSON: Yeah, exactly. Well, we’d need to expand the grid. Not necessarily change it, but make more long distance transmission, high voltage direct current transmission, and more storage too. But a lot of the things people can do on their own in their own home in terms of a transition– like, you can get rid of your gas heaters and even gas stoves, because there are now induction cook-top stoves that are extremely efficient. There are heat pump air heaters and water heaters, and air conditioners and refrigerators that run on heat pumps which use like one fourth the energy as old resistance, electric resistance heaters. And so they’re very efficient and they’re just run on electricity, and so most people in their own homes don’t even need gas anymore because of the efficiency of the electricity.

And there are electric cars now on the road, and then people can put solar panels on their roofs. There are batteries you can now put in your house to actually– so you don’t even need grid electricity most of the time. But you do need large scale transition. For an industry, that’s going to be difficult, but there are– for the high temperature industrial processes usually use some fossil fuels, but there are electric machines that have been a while around for a while that can replace them.

And so you can do it in heating. You can do it in transportation. Pretty much everything we have, appliances or devices, that can be used right now to transition everything to electricity, and then there’s– we found in 139 countries we examined for which there are data available, there’s plenty of resource of wind, water, and solar.

IRA FLATOW: Are they on board, the rest of the country?

MARK JACOBSON: Well, I haven’t checked them all out, but I think a lot of people are on board. yeah, from polling– I mean, there was a poll in Australia that said there was around 65% of the people wanted 100%, clean, renewable energy. In the United States, there have been polls in seven states that are pretty representative that said that about 65% were strongly in favor of 100% clean, renewable energy. And another 18% were somewhat in favor, so that’s about around 83% total, somewhat or strongly supported in the United States.

IRA FLATOW: Let me go to the phones. Let’s go to Brewster Town, Tennessee with Terry. Hi, Terry.

TERRY: Hello, Ira. Thank you. Yes, I’ve been reading that the solar arrays the size of the state of Rhode Island would power the United States with electricity, and it would take about a similar array of wind turbines. So that would take care of part of the time that this solar array was not working. And in Germany, they’ve been using excess wind turbine electricity to manufacture hydrogen that they put into the natural gas line. And people don’t realize how long it takes to bring a coal-fired power plant or a nuclear-fired power plant back online.

IRA FLATOW: Terry, do you have a question, because I’m running out of time.

TERRY: Why should it take 2050?

IRA FLATOW: OK, good question.

MARK JACOBSON: Yeah, good question. So actually our proposal is 80% by 2030. And just to get the last few percent, particularly for the long distance aircraft which we don’t expect to come online till maybe 2035 or 2040, but we really want– it has to start right away and with 80% conversion by 2030. And we’re talking, first of all, all energy sectors. It’s not just electricity. So the number you gave might be just for the electric power sector, and electricity is only 20% of all energy. So we really need to satisfy five times the electric power, and so that’s going to be a challenging– but we can do it– we hope we can do 80% by 2030.

IRA FLATOW: What kind of mix would we have here in the states? How do you foresee that?

MARK JACOBSON: Well, in the states we would have– it’s going to be mostly solar and wind, and either onshore– in terms of winds, it’s about two thirds onshore and maybe one third offshore. And solar it can be– it will be divided into rooftop solar, PV or photovoltaics, photovoltaics and power plants or more centralized plants– also what’s called a concentrated solar power, which is coupled with storage. And that’s more like in really sunny, desert regions. And so it’s close to 50-50, but depending on how much wind gets in the Midwest. But then there’s maybe 4% hydroelectric power all existing [INAUDIBLE].

IRA FLATOW: Why not just pick one section– I mean, I live in Utah or whatever, but I know there are open spaces, and create giant centralized grids, solar arrays like going on in California, Utah, other places, and create a central system.

MARK JACOBSON: Yeah, I mean that’s one idea. It’s always a trade off between transmission and storage. So yeah, you have great resources in the Great Plains, southwest US for solar, but you do have to transmit it to the coasts or in other places in the south where there’s not so good of resources for wind, in particular. So there is this cost trade off between– where sometimes storage might be less expensive to do it locally, especially for heat and cold storage where you can do things– you can use ice or underground rocks or boiled water in tanks. So that’s not that expensive actually, and so that’s actually better off to do that locally.

But you have this huge resource in the Great Plains for wind. It’s referred to as the Saudi Arabia of wind, and sometimes it might even be cheaper to transmit it to the east coast rather than use offshore wind off the east coast. But on the other hand, because the offshore wind costs are coming down pretty rapidly, it will be cheaper or probably is cheaper right now, especially in terms of getting transmission sighted. Because that’s another thing. Zoning for transmission is not the easiest thing in the world. Having local energy is a lot more efficient in terms of transmission.

IRA FLATOW: One last question. Are there any new technologies that need to be invented, and do you anticipate them coming on schedule?

MARK JACOBSON: Well, we always hope there are going to be new ones, but we don’t rely on them. I mean, I think the ones that will really help a lot are floating offshore wind turbines. That’ll be extremely important.

The concentrated solar power with storage, the storage costs have come down quite a bit and so now are becoming competitive, even with solar PV and battery costs, of course, are coming down and that’s beneficial. Electric car costs are coming down, so all those things are really good signs because you’d need a lot of cars. You need a lot of batteries. You’ll need a lot of power and storage other types of storage.

So the storage costs, floating offshore wind– that will really be a game changer. Because once you can go further offshore where people aren’t even concerned about looking at the turbines, even though they’re not that big even when they’re out there, that will make it even easier.

IRA FLATOW: So we just got to get the transmission figured out. We got to get transmission lines. You say direct current, big direct current transmission lines?

MARK JACOBSON: Yeah. High voltage direct current, which is not so much technological challenge. It’s more of a zoning issue, trying to get states and localities to permit it in those areas. Each state has different rules as well.

IRA FLATOW: So I guess Thomas Edison wins in the end on this sort. It’s a recurrent war of the currents.

MARK JACOBSON: Yeah, electricity– the benefit of all this is you eliminate four to seven million air pollution deaths prematurely each year that are caused by combustion, primarily from fossil fuels and biofuels. And we eliminate global warming. Even if you don’t believe in it, it’s there and we would eliminate it.

But we do save cost of energy. We stabilize energy prices. We have less terrorism risk because we have more decentralized power. Solar and wind are more decentralized.

IRA FLATOW: Sounds like a win-win-win for everybody here. Thank you Mark. Mark Jacobson, professor of civil and environmental engineering at Stanford University.

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