New technique from U.S. national lab to remove CO2 at record-low cost

A scientist at Pacific Northwest National Laboratory looking at the carbon capture system technology. Photo courtesy Andrea Starr at Pacific Northwest National Lab.

Photo courtesy Andrea Starr at Pacific Northwest National Lab.

Scientists at one of the country’s premier research labs have discovered a record-cheap way to capture carbon dioxide as it’s emitted from power plants and factories, including the likes of iron and steel manufacturing facilities.

Globally, industrial processes are responsible for 31 percent of total greenhouse gas emissions and electricity generation accounts for 27 percent, according to Bill Gates in his climate book, dwarfing the 16 percent of total greenhouse gas emissions that comes from the transportation sector.

The new technique discovered by the Pacific Northwest National Laboratory costs $39 per metric ton and is the cheapest technique for this kind of carbon capture ever reported in a peer-reviewed scientific journal. For comparison, it costs $57 per metric ton to capture carbon dioxide from a coal-fired power plant using current state-of-the-art technology, PNNL says.

It would be even cheaper if we could transition to 100{a78e43caf781a4748142ac77894e52b42fd2247cba0219deedaee5032d61bfc9} clean energy and didn’t have to remove carbon dioxide at all, but that’s not realistic in today’s global economy, according to Casie Davidson, who manages carbon management work at PNNL.

Even if the electric grid were powered primarily by wind and solar, there would still need to be natural gas plants to maintain grid stability, or to provide backup when the wind isn’t blowing or the sun isn’t shining, Davidson said.

Just as importantly, industrial processes such as making iron, steel, cement, fertilizer, pulp and paper, and bioenergy could all reduce their carbon dioxide emissions this new technique. Scientists and entrepreneurs are working on greener ways of making cement and steel, for example, but those are not at scale, Davidson told CNBC.

“We have the technology to be able to capture carbon dioxide from those industrial point sources. And sitting around waiting for 20 years until we have the next-generation steel technology that doesn’t generate carbon dioxide emissions doesn’t make a lot of sense,” Davidson told CNBC.

PNNL’s technique removes carbon dioxide at the source, rather than sucking it out of the air. The technique of vacuuming up existing CO2 out of the air is known as direct carbon capture, and is exemplified by the Swiss company Climeworks. Direct air capture may be necessary to combat climate change, since there is already so much carbon dioxide in the atmosphere, but it’s much more expensive than removing CO2 at the source, as PNNL is doing — the direct air capture that Climeworks is doing costs “several hundred dollars” per ton, a spokesperson told CNBC.

The rise of the carbon removal industry

“Imagine you’re trying to separate a grape out of a big bowl of spaghetti or you’re trying to separate the grape out of a swimming pool of spaghetti. You still get a grape, but you have got to do a lot more work in the swimming pool than in the bowl,” Davidson explained.

“But from a from a climate change perspective, the atmosphere doesn’t care whether that grape came out of the bowl of spaghetti or the swimming pool of spaghetti — it has the same impact,” Davidson said. “From a societal perspective, capturing it before it ever gets out there, when it’s $39 a ton to capture, versus capturing it when it’s already in the atmosphere for $200-plus a ton, makes a lot more sense.”

The money to fund this research into carbon capture technology came to $1.2 million over about 3 years, and was funded in a 50/50 split between the Department of Energy and SoCalGas, a natural gas distribution utility, Robert Dagle of PNNL told CNBC.

How is carbon captured for $39 a ton?

PNNL’s technique uses solvent chemistry, explained David J. Heldebrant, a chief scientist at PNNL who is leading this research.

The dirty gas comes out of the power plant or factory and is moved into a very large chamber. At the same time, a liquid is sprayed down from the top of the chamber. The gas rises and the liquid falls and the two substances mix. Treated gas leaves out of the top of the chamber and liquid containing the CO2 is siphoned away. That liquid is heated until the CO2 is released as a gas. The CO2 is compressed for transportation, where the majority of it will be stored. The remaining liquid, with the CO2 gas removed, is cooled and sent back to the first stage of the process.

This system is very large. It pumps 4 million liters of liquid per hour.

The PNNL system is cheaper than other carbon capture systems because its it operates with 2 percent water, as opposed to as much as 70 percent water, which is the upper boundary for previous and similar carbon capture technologies. It takes a long time and a lot of energy to boil water, so by removing the water from the system, the carbon capture process becomes much cheaper.

“It’s like heating oil on your pan versus boiling water,” Heldebrant said. “The oil gets to temperature much more quickly. So just think of it as we’ve replaced the water with essentially something like an oil.”

Even with this innovation, a carbon capture system takes a lot of energy. That energy comes from the power plant where the carbon capture system is attached, Yuan Jiang, a chemical engineer at PNNL who works with Heldebrant, told CNBC.

An installed carbon capture machine will use as much as 30 percent of the energy that a power plant generates to remove 90 percent of the carbon dioxide. This is called the “parasitic load” of the carbon capture technology. To get back to full energy capacity, the power plant would have to burn more energy. Even so, the technique would ultimately translate to a net carbon dioxide reduction of 87 percent on a per-megawatt net power generation basis, Heldebrant and Jiang told CNBC.

David J. Heldebrant, a chief scientist at PNNL, seen here holding a vial of methanol, made with a process integrated into a point source carbon capture facility. Photo courtesy Andrea Starr at Pacific Northwest National Lab.

Photo courtesy Andrea Starr at Pacific Northwest National Lab

Creating a financial incentive

These carbon capture systems are large and expensive: To tack one onto a power reactor would cost $750 million. Without strict government mandates or financial incentives, power plant or factory owner operators will have little reason to spend that money.

In an effort to make this technology more economically attractive, PNNL researchers have developed a smaller modular reactor that would pump one to two percent of the solvent from the carbon capture system into another smaller modular reactor and use it to make a product that companies can sell.

“If we can give an economic incentive — if they can convert just 1 percent of the carbon dioxide that they’re capturing in one of these big facilities,” Heldebrant told CNBC, then perhaps the factories can “sell enough of things like methanol, or methane or other types of carbonate products to at least provide a financial incentive, so they would actually want to build the capture unit in the first place,” Heldebrant told CNBC.

They’re starting with methanol, which currently costs $1.20 per gallon. That means 20 gallons of methanol produced would pay for a metric ton of carbon dioxide to be captured. For some sense of scale, the United States emitted 4.7 billion metric tons of carbon dioxide in 2020, according to the most recent data available from the EPA.

“We chose methanol because it’s probably the third- or fourth-largest chemical made by man,” Heldebrant told CNBC. Methanol is used in hundreds of common products including plastics, paints, car parts and construction materials, according to the Methanol Institute. It can also be a source of energy for trucks, buses, ships, fuel cells, boilers and cook stoves.

“If we can start replacing fossil-produced methanol with carbon-dioxide-derived methanol, that can at least start being a part of a carbon-negative chemical approach to manufacture fuels and chemicals, as opposed to carbon-positive by just taking synthesis gas from fossil fuels,” Heldebrant said.

Converting carbon dioxide to methanol does not consume a lot of energy, Jiang told CNBC. But it does require hydrogen, which itself takes energy to produce. Bu hydrogen can be made in processes that are powered by renewable energy, Jiang said.

The infographic of the bear going through the tunnel in the mountain serves to represent efficiencies realized in making methanol from carbon capture.

Graphic courtesy Nathan Johnson at Pacific Northwest National Lab

What happens with the rest of the carbon dioxide?

While some small percentage of the carbon dioxide could be siphoned off to make a product, like methanol, the rest will have to be sequestered. According to Todd Schaef, a PNNL scientist who works on sequestration, the volumes of carbon dioxide that will need to be sequestered are “staggering.”

Generally, sequestering carbon dioxide is a lot cheaper than capturing it in the first place. More than half of carbon dioxide sequestration in the U.S. on land is estimated to be less than $10 per ton, according to a special report on carbon capture utilization and storage from the International Energy Agency.

In his research, Schaef has injected carbon dioxide 830 meters into the subsurface of the Earth, where the geology is a specific basalt rock, and come back two years later to find that the carbon dioxide reacted with the rock and converted to a carbonate, permanently storing it underground.

“That carbon dioxide reacted with the rock and it made a solid so that gas no longer exists,” Schaef told CNBC. “These minerals are stable on geologic timescales. Millions and millions of years.”

Todd Schaef (left) and Casie Davidson (right) seen here analyizing the geology for basalt, which is a type of rock that is especially favorable for carbon sequestration. Photo courtesy Andrea Starr at Pacific Northwest National Lab.

Photo courtesy Andrea Starr at Pacific Northwest National Lab.

There’s also a moral hazard argument that some climate change activists make against carbon capture technology: Focusing on removing carbon dioxide from fossil-fuel emissions, instead of reducing and eliminating them entirely, simply delays the necessary transition.

This is a “touchy topic,” Schaef acknowledged. “It comes up at almost every conference I go to,” he said.

But he says it is counterproductive not to sequester the carbon dioxide that’s already been emitted and will continue to be emitted for as long as it takes to transition global infrastructures from how they currently operate to more climate-conscious processes.

“Whether you want to admit it or not, there are going to be countries that use fossil fuels,” Schaef told CNBC. While global use of coal fired power plants is markedly lower than it was a handful of years ago, there are still more than 2,400 coal plants, and additional coal-fired capacity is under construction at more than 189 plants, according to a 2022 report from the Global Energy Monitor.

In the United States, where renewable energy sources, like wind, hydro and solar are critical components of the energy grid, natural gas is still used, Schaef told CNBC.

“When the wind doesn’t blow, when the rivers aren’t running, when the sun’s not shining, we need some type of option that lets us keep the lights on. And I know it’s hard for some to understand that or realize that, but we have to have that gas-powered option. Well, we can sequester that carbon dioxide. We can capture and sequester it.”

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