ARI SHAPIRO, HOST:
When Donald Trump did talk about coal during the campaign, he often referred to it as clean coal.
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DONALD TRUMP: We're going to go clean coal. And that technology is working. I hear it works, so.
SHAPIRO: To learn more about what he means when he says clean coal, we've got NPR's science correspondent Chris Joyce here in the studio. Hi, Chris.
CHRIS JOYCE, BYLINE: Hello, Ari.
SHAPIRO: What is clean coal, exactly?
JOYCE: That depends on how you define clean, actually. There are a couple of processes. What people are looking for is a way to get the carbon dioxide out of it. That is the main greenhouse gas that warms the planet. You can pressurize coal and add chemicals, heat it without oxygen so it doesn't technically burn. And you get a gas that you can use to make electricity. And you get the carbon dioxide stripped away and you can keep it.
There's another way to do it after it's burnt, that - capture the CO2 before gives up the stack. Those are the two main ways. You know, this in a sense is kind of like the holy grail for people.
SHAPIRO: Holy grail suggests that it's still out of reach. We just heard Donald Trump say the technology is working. Which is true?
JOYCE: Well, it's working in demonstration. But it's not necessarily working in a commercial sense. There have been a couple of projects, the FutureGen project in the Bush administration. It failed. It involved industry but it was very expensive. There's one now in Mississippi called Kemper. It, again, is way over budget. There's some small demonstration projects. There's some projects in Europe. People are interested. But they just can't seem to get it to work commercially.
SHAPIRO: What's the problem been? Why isn't it working?
JOYCE: Well, it's expensive. I mean, you have to use a lot more coal in order to make the energy to strip the CO2 out. So in effect, you know, you're using more coal to make cleaner coal. So that doesn't work very well.
But the other thing is, what do you do with the carbon dioxide? I mean, this is called carbon capture and sequestration. You capture it and we have to put it somewhere. You've got to put it underground, really. Where do you do that? You have to find a place that's geologically safe, where the CO2 won't come up. If it comes up, then the whole effort's useless. Once you find a geologically-safe place, it may not be where your coal plant is. So you got to transport it. How many pipelines do we have to build? All of this is money, money, money, money in an industry that's trying to compete in a difficult world.
SHAPIRO: Is there commercial interest in pursuing this, quote, unquote, "clean coal"?
JOYCE: Well, what I hear from utility people is they go to banks and they go to financiers and they're told, look, why bother? This is very expensive. Natural gas, as we just heard in the previous story, is just cheap right now. So there's not a lot of interest in trying to make coal competitive when it's going to cost that much more.
SHAPIRO: So do you think clean coal will get off the ground during a Trump administration?
JOYCE: Well, we've been at it for a long time. George Bush tried it under his administration, didn't get off the ground. Obama tried it as well under his administration, didn't get off the ground. So that's the record so far.
SHAPIRO: NPR's Chris Joyce, thank you.
JOYCE: You're welcome. Transcript provided by NPR, Copyright NPR.