TOPICS > Science > The Leading Edge

Could carbon capturing make ‘clean coal’ a reality?

June 14, 2017 at 6:25 PM EDT
Coal is still very much at the center of the debate on the future of energy. For some, the holy grail is a new type of technology that captures some coal carbon emissions. Science correspondent Miles O’Brien joins Judy Woodruff to take a closer look at the results coming out of one of the largest fossil fuel power plants in the country and the obstacles stopping them from collecting more.

JUDY WOODRUFF: The future of coal is very much at the center of debate right now when it comes to the politics and business of energy.

Whatever you may think about those questions, the U.S. still uses a lot of coal. About 30 percent of our energy, of our electricity is generated by it.

For some, the Holy Grail is new technology that captures some of coal’s worst problems with greenhouse gases.

Miles O’Brien reports on the largest facility trying to do so.

It’s part of our weekly series on the Leading Edge of science and technology.

MILES O’BRIEN: At the W.A. Parish power plant southwest of Houston, they are piling up coal, getting ready for another long, hot, aggressively air-conditioned summer.

One of the largest fossil fuel power plants in the country, Parish can generate about one-fifth of the city’s electricity using coal- and gas-fired turbines. And it is leading the nation down a promising, yet problematic path.

Here, they are trying to make clean coal more than a political slogan.

Mauricio Gutierrez is CEO of NRG, owner of the plant.

MAURICIO GUTIERREZ, President and CEO, NRG: We built the world’s largest carbon capture system on an existing coal-fired power plant. It is the first commercial scale facility of this kind in the United States.

MILES O’BRIEN: They are capturing and storing carbon dioxide, the greenhouse gas that is the main driver of global warming. This is prompting some unexpected support from members of the Trump administration.

Listen to Energy Secretary Rick Perry at the ceremonial opening in April.

RICK PERRY, U.S. Secretary of Energy: I think the solutions to many of the challenges that we have in the world today are displayed behind me.

MILES O’BRIEN: The same Rick Perry who wrote a book calling climate scientists members of a secular carbon cult who manipulate data and climate science a contrived, phony mess, but not here.

RICK PERRY: It shows we don’t have to pit the environment on one side weighing and the economy on the other side. We can and we will be good stewards of both.

MILES O’BRIEN: The steward of this project for NRG is David Greeson, the vice president of development.

DAVID GREESON, Vice President of Development, NRG: We’re interested in doing more carbon capture as a part of our overall sustainable energy future plan, and so we’re going to see how this one works.

MILES O’BRIEN: They call the billion-dollar carbon capture and storage system Petra Nova. NRG built it in partnership with the Japanese oil company JX Nippon using a $190 million grant from the Department of Energy doled out during the Obama administration.

DAVID GREESON: So we’re capturing about 200 tons of CO2 per hour. On an annual basis, that’s about 1.6 million tons per year. That’s the equivalent of 350,000 cars being taken off the road.

MILES O’BRIEN: While it may be the world’s largest carbon capture facility, it is still only removing about 10 percent of the CO2 created by the four coal-fired generators here. The only obstacle to capturing more is money.

DAVID GREESON: We’re just now reaching the point where this technology is mature enough to be considered for rollout to the broad coal-fired fleet in the United States and around the world.

MILES O’BRIEN: Here’s how it works. Flue gas, with carbon dioxide in it, flows through a duct to the carbon capture facility. One vessel contains amine, an ammonia-based chemical in liquid form. It naturally binds with carbon dioxide.

With the carbon now in solution, the liquid goes to another vessel, where it is heated up. As that happens, the process is reversed and the CO2 pops out as a gas. It is captured, and, after it is compressed, ready for underground storage.

MICHAEL WEBBER, University of Texas at Austin: I think Petra Nova is a shining example of what technology offers, and so, as an engineer, I’m very enthusiastic about it. I think it’s very exciting.

MILES O’BRIEN: Michael Webber is deputy director of the Energy Institute at the University of Texas at Austin. He says the energy sector is watching this project very closely.

MICHAEL WEBBER: We’re getting a lot of scrutiny because people want to know if carbon capture and sequestration will work. And there are examples around the nation, around the world where it hasn’t really quite come together the way people want. It’s really expensive and hard to do, so you wouldn’t do it unless you had to, or it’s in your economic favor to do so.

MILES O’BRIEN: And a coincidence of geography has made that possible here. The CO2 from the Petra Nova facility is sent 80 miles to the southwest, to the West Ranch oil field. Here, the gas is as good as gold, black gold, Texas tea.

JILL FISK, Senior Vice President, Hilcorp: That was the hope, if you marry up a partnership between a CO2 emitter where they can capture the CO2 and reduce their CO2 emissions, but then that CO2 can be used to increase oil production. That’s really a win-win.

MILES O’BRIEN: Jill Fisk is a senior vice president for Hilcorp, the current operator of this oil field, which first opened in the 1930s. At its peak in the ’70s, it produced 50,000 barrels of oil a day. Today, it’s down to less than 300 barrels a day. Normally, it would be time to cap the wells here.

But, instead, they’re drilling new ones, getting ready to pump a lot more oil by injecting carbon dioxide deep underground. Liquid CO2 has been used to liberate the most stubborn oil for about 40 years.

JILL FISK: Essentially, what’s happening is the oil is stuck to rock, if you can imagine that. The CO2 is injected, it dissolves into that oil that’s stuck to the rock, loosens up the oil, lightens it up, which — so it can then flow toward a producer and produce additional oil.

At West Ranch, we’re expecting to recover an additional 60 million barrels of oil that would otherwise be left in the ground and be unrecoverable without a project of this type.

MILES O’BRIEN: Right now, with oil prices so low, Petra Nova is breaking even, but, over the next decade, they expect to make a tidy profit capturing and burying carbon dioxide.

But doesn’t this just transfer greenhouse gas emissions from a power plant smokestack to automobile tailpipes?

JILL FISK: So, I think that demand for oil is either going to be met by foreign oil that the United States has to purchase or by our own production that we’re able to supply. So this project is breathing new life into a field in the U.S. to help supply that demand for oil.

MILES O’BRIEN: But how can we be certain buried CO2 will stay underground? Scientists from the University of Texas are running tests at 22 monitoring wells at West Ranch, getting baseline data so they will know later if the injected CO2 triggers some unintended consequences, like earthquakes or the release of deep dwelling salt water, minerals, or chemicals.

At this test site in Austin, they are finding new ways to monitor the buried CO2.

SUE HOVORKA, University of Texas at Austin: You ready to start?

MILES O’BRIEN: They pump the gas into groundwater to simulate leaks. They use a sensor that measures light. It is coated with a polymer that thins when it reacts with CO2. If there’s any trouble, the sensor detects more light, and an alarm is transmitted automatically.

Geologist Sue Hovorka leads this effort.

SUE HOVORKA: We need to get good enough to provide value to the atmosphere, and we need to avoid unacceptable consequences.

MILES O’BRIEN: Hovorka analyzes deep rock core samples stored in a cavernous warehouse at the Bureau of Economic Geology in Austin. She says there are ample places to bury carbon dioxide produced by all types of fossil fuel power plants, not just coal burners. That would be a monumental step toward addressing climate change.

SUE HOVORKA: If consumers want to use coal and want to reduce the carbon from that, the system to do that is ready to go. They have to pay for it. It’s not outrageous. It’s totally possible, but it’s not free.

MILES O’BRIEN: Up until now, clean coal has been nothing more than a marketing myth. It could become a reality at no small cost, but at a small fraction of the toll if the industry does nothing to stop global warming.

In Richmond, Texas, I’m Miles O’Brien for the PBS NewsHour.

JUDY WOODRUFF: And as Miles just said, costs are just one of the questions about whether this model could be replicated more widely.

And Miles joins me now from Boston.

So, Miles, tell us more about why — and so this is the first plant of its kind. What are the challenges in trying to replicate this somewhere else and getting the same results?

MILES O’BRIEN: Well, Judy, the secret sauce of this one, according to the innovators behind it, is, they reduced the cost of creating the carbon capture.

When I say cost, the cost in power. Normally, what the assumption is, that it reduces the output of any given power plant by as much as 30 percent in order to run the carbon capture system.

What they did in this case was they decided not to use the actual turbines which light the lights that I’m using right now, but rather a separate co-generation plant air, a smaller power plant on site that can be run much more efficiently.

And they say that they — it’s costing them about 15 percent of the power-generating capacity of that plant. So that’s a big hurdle that they have gotten over. Now, 15 percent is still a big number, and unless you have some commodity or the CO2 has some value, the business model doesn’t add up just yet.

JUDY WOODRUFF: And you were telling us, Miles, there are also some physical challenges as well.

MILES O’BRIEN: Well, being 80 miles near an old oil field that could use that CO2 to capture and recover a lot of stubborn oil from the ground makes it all work.

The question is, could a fossil fuel plant of any kind that’s a long way away from an oil field, could it avail itself of this kind of transaction? And CO2 can be pumped in pipelines for an indefinite amount of distance, as long as you recompress every now and then, sort of have a booster system in.

But, again, that’s going to be a significant cost. It is not an insurmountable thing technologically, and it could be done. We already have significant CO2 pipelines in the oil sector. You could extend it out, if you were determined to do this.

JUDY WOODRUFF: And, just quickly, you were also saying other practical limits.

MILES O’BRIEN: Well, yes.

It’s — the limits on this are — there are some concerns, for example, about putting CO2 in seismically active places, for example. You wouldn’t want to put buried CO2 underneath San Francisco, for example.

But, having said all that, when you consider all the places that it can be stored, the experts tell me, we have enough storage capacity underneath the continental United States to last about 900 years of CO2 production.

So, it’s just a question of societal priorities and whether we want to pay a little more for power to get the carbon dioxide out.

JUDY WOODRUFF: Miles O’Brien, thanks very much.

MILES O’BRIEN: You’re welcome, Judy.