Megan Hall: Welcome to Possibly, where we take on huge problems like the future of our planet and break them down into small questions with unexpected answers. I’m Megan Hall. 

We’ve used the Earth’s heat as an industrial energy source for over a century, but geothermal power only plays a minor role in our energy grid. Why? And is that about to change? 

Here to tell us more are Charlie Adams and Albert Wu from our Possibly Team.

Charlie Adams: Hi, Megan!

Albert Wu: Hey Megan! 

Megan Hall: When I hear “geothermal” I think Old Faithful and Icelandic hot springs, is that right?

Charlie Adams: Right. Geothermal energy comes from reservoirs of hot water below the Earth’s surface. 

There’s lots of it and not just in Yellowstone and Iceland.

Joseph Moore: if we took even 2% of the energy stored within the shallow crust, that would be more than 2000 times the energy we use annually.”

Albert Wu: That’s Joseph Moore, a research professor at the University of Utah’s Energy and Geosciences Institute.

Charlie Adams: He says, one of the best parts about geothermal is it can produce renewable 24-7 power without burning fossil fuels.

Megan Hall: Wait, how do you get electricity from heat underground?

Albert Wu: There are a few ways. But a typical geothermal power plant drills a mile or two underground to access reservoirs of hot water and pulls them to the surface.

Charlie Adams: As the super hot water rises and experiences lower pressure, it turns to steam, which can spin a turbine to make electricity– just like other power plants!

Megan Hall: Interesting! So how much power do we get from geothermal?

Albert Wu: Right now the U.S. has 64 plants that make up 0.4% of our total electricity generation.

Megan Hall: Why so little?

Charlie Adams: Exploration, drilling, and equipment costs are high compared to other renewables. 

Albert Wu: Also, outside of the Southwest, it’s hard to find the right mix of heat close to the surface, water reservoirs, and the right type of rocks for drilling.

Charlie Adams: But advances in technology may be changing this.

Megan Hall: How?

Albert Wu: Enhanced Geothermal Systems or EGS technology is attracting lots of attention right now.

Charlie Adams: EGS creates human-made underground fracture networks and reservoirs in places where geothermal isn’t usually possible. According to Joseph

Joseph Moore: Enhanced geothermal systems can be developed anywhere in the world.

Megan Hall: How does the process work?

Albert Wu: Some of these breakthroughs have come from using fracking technology. 

Megan Hall: Wait, fracking? That sounds like a problem.

Charlie Adams: While the concept is the same, EGS avoids many of the pitfalls of fracking because oil and gas aren’t involved so they don’t contaminate surface water or soil. 

Albert Wu: To learn more about the differences we spoke with Jeff Tester, a professor of Sustainable Energy Systems at Cornell University.

Charlie Adams: He says a key difference is that when you’re fracking for fossil fuels, water from the underground system has to be removed and then treated at a separate location. 

Albert Wu: That contaminated water can be disastrous if it spills, and reinjecting underground water has caused earthquakes. 

Jeff Tester: but that is not the way in which geothermal operates because there, water is your friend not your enemy, you’re trying to circulate water through the system.

Megan Hall: So, because geothermal circulates water, and doesn’t have to dispose of lots of contaminated water, it’s less likely to have nasty environmental side effects?

Albert Wu: In theory yes, but Tester says it’s still important to monitor it. This is a relatively new process, so there could be unanticipated consequences.

Megan Hall: Got it. So how does the future look for enhanced geothermal systems? 

Charlie: Things are looking up. The Department of Energy has invested tens of millions of dollars in EGS.

Albert Wu: They say EGS could unlock enough energy to power 67 million homes by 2050! 

Charlie Adams: Despite all this, geothermal faces similar hurdles as other renewable energies. There’s a long road ahead. 

Albert Wu: It’s unlikely geothermal will become a major source of energy in the US any time soon, but it is set to play an important role in our efforts to transition away from fossil fuels.

Megan Hall: Great! Thanks, Charlie and Albert! 

That’s it for today. For more information, or to ask a question about the way your choices affect our planet, go to the public’s radio dot org slash possibly. Or subscribe to us wherever you get your podcasts. 

Possibly is a co-production of The Public’s Radio and Brown University’s Institute for Environment and Society and Climate Solutions Initiative.

The post How can we get more energy from heat in the ground? appeared first on TPR: The Public's Radio.

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Megan Hall: Welcome to Possibly, where we take on huge problems like the future of our planet and break them down into small questions with unexpected answers. I’m Megan Hall.

Today we’re taking on a listener question. 

“Hi, my name is Megan Heinz. I have a question for Possibly. My child has a car pick up line. And I’m wondering if it’s better for me to turn the car on and off again as the line moves forward. Because I really don’t want to idle while I’m waiting.”

We had Albert Wu and Charlie Adams from our Possibly team look into this question.

Albert Wu: Hi, Megan! 

Charlie Adams: Hey, Megan!

Megan Hall: So listener-Megan wants to know if repeatedly starting her car releases more emissions than just idling while she’s waiting in the pickup line at her son’s school. What did you find out?

Albert Wu: It turns out, the answer to this question really depends on the type of car you drive.. Megan mentioned that she had…

Megan Heinze: “a 2007 Volvo XC 90”

Albert Wu: … which is an older gas car. 

Charlie Adams: In those types of cars, idling burns a constant, steady stream of gasoline to keep the engine running at the slowest rate possible without stalling. But starting the car also uses fuel. 

Megan Hall: Which uses more fuel?

Albert Wu: It depends on how long you idle your car. A study by the Argonne National Lab found that the break-even point was about 10 seconds. 

Charlie Adams: Basically, if you’re planning to idle your car for longer than 10 seconds, it’s better to shut off the engine and start when you need to move.

Megan Hall: Great, that sounds like a pretty simple answer! Just follow the 10 second rule!

Charlie Adams: Pretty much. It gets a little more complicated in freezing weather, because starting a cold engine requires more energy and creates more pollutants. 

Albert Wu: But people usually keep their cars on in the winter to stay warm, anyway.

 Megan Hall: What about all the wear and tear on your car from starting and stopping?

Albert Wu: You shouldn’t need to worry about that. It takes 5 to 10 minutes for all the oil to run back down to the pan, so restarting for the kind of wait times you’ll have in a school pickup line isn’t really an issue. 

Megan Hall: So, what’s your advice for Megan?

Albert Wu: On most days, she’s better off turning her car off and restarting it when she needs to move up in the pick-up line, but on very cold days, she may be better off idling.

Megan Hall: Huh, so how big of a carbon dioxide emissions difference does turning her car off and on make? Would it make a big difference if she idled every day instead?

Charlie Adams: Turning her car off instead of idling would reduce her overall car emissions by around 1% per year. 

Megan Hall: So, not a big deal?

Albert Wu: Well, for your personal emissions, that might sound small. But the same study found that if everyone in the US followed this rule, it would be the equivalent of taking five million cars off the road.

Charlie Adams: It’s a pretty easy thing to do, so I’d say, it’s worth the effort. 

Megan Hall: But what about newer cars and hybrid cars? Does the ten second rule apply to them too?

Albert Wu: Most newer cars have something called an auto start-stop mechanism. 

Megan Hall: What does that mean?

Albert Wu: They’re systems that automatically stop your engine when you press down on the brake pedal hard enough. 

Charlie Adams: For those cars, you don’t have to worry about consciously turning the engine off and then on again. It’s stopped whenever you are! 

Megan Hall: Do you also need to think about temperatures and wait times?

Albert Wu: That’s not necessary for newer models. Vehicles with the start-stop system have pumps that keep the engine hot while they’re stopped, and if the engine drops in temperature too much then it’ll automatically restart.

Megan Hall: Ok, so what’s the take-away here? 

Charlie Adams: For older cars you should stop idling if you’re going to be still for longer than ten seconds, if it’s not super cold outside.

Albert Wu: And for many newer cars, there’s often no need to think about it at all- many manufacturers have done the work for you!  

Megan Hall: Great, thanks Albert and Charlie! 

That’s it for today. For more information, or to ask a question about the way your choices affect our planet, go to the public’s radio dot org slash possibly. Or subscribe to us wherever you get your podcasts.

You can also follow us on Twitter and Facebook at ask possibly.

Possibly is a co-production of Brown University’s Institute for Environment and Society, Brown’s Climate Solutions Initiative, and the Public’s Radio.

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