New technique to extract CO2 at record low cost from US national lab


Pacific Northwest National Laboratory scientist looks at carbon capture system technology. Photo courtesy of Andrea Starr at Pacific Northwest National Laboratory.

Photo courtesy of Andrea Starr at Pacific Northwest National Laboratory.

Scientists at one of the country’s main research laboratories have discovered a record-breaking cheap way to capture carbon dioxide emitted from power plants and factories, including iron and steel plants.

As Bill Gates notes in his climate book, globally, industrial processes account for 31 percent of total greenhouse gas emissions, while electricity generation accounts for 27 percent, dwarfing the 16 percent of total greenhouse gas emissions 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 such carbon capture ever reported in a peer-reviewed scientific journal. By comparison, it costs $57 per ton to capture carbon dioxide from a coal-fired power plant using modern technology, PNNL says.

According to Casie Davidson, who leads carbon management at PNNL, it would be cheaper if we could switch to 100% clean energy and not have to emit carbon dioxide at all, but that’s not realistic in today’s global economy.

Even if the power grid is powered primarily by wind and solar, natural gas plants will still be needed to maintain grid stability or provide backup when the wind doesn’t blow or the sun doesn’t shine, he said.

Most importantly, industrial processes such as iron, steel, cement, fertilizer, pulp and paper production, and bioenergy can reduce the carbon dioxide emissions of this new technology. Scientists and entrepreneurs are working on greener ways to make cement and steel, for example, but not at scale, Davidson told CNBC.

“We have the technology to capture carbon dioxide from these industrial points. It doesn’t make a lot of sense to wait 20 years until we have next-generation steel technology that doesn’t generate carbon dioxide emissions,” Davidson told CNBC.

PNNL’s technique removes carbon dioxide from the source instead of absorbing it from the air. An existing technique for vacuuming CO2 from 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 because there is already a lot of carbon dioxide in the atmosphere, but it costs much more than removing CO2 at the source, as PNNL does — the cost of direct air capture, which Climeworks does.” A few hundred dollars a ton,” a spokesperson told CNBC.

“Imagine trying to separate grapes from a large bowl of spaghetti, or trying to separate grapes from a pool of spaghetti. You still get grapes, but you have to do more work in the swimming pool than in the bowl,” Davidson explained.

“But from a climate change perspective, the atmosphere doesn’t care if that grape comes out of a bowl of spaghetti or a pool of spaghetti — it has the same effect,” Davidson said. “From a total perspective, it makes more sense to capture it with $200-plus a ton already in the atmosphere when it’s $39 a ton to capture before it gets out there.”

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

How is carbon captured at $39 a ton?

PNNL’s technique uses solvent chemistry, explained David J. Heldebrant, a PNNL senior scientist who led the study.

Dirty gas leaves a power plant or factory and is transferred to 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. The purified gas exits the top of the chamber and the liquid containing the CO2 is filtered out. This liquid is heated until the CO2 gas is released. CO2 is compressed for transport and most of it is stored here. The remaining liquid is degassed, cooled, and returned to the first stage of the process.

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

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

“It’s like heating oil in a pan versus boiling water,” Heldebrant said. “Oil heats up faster. So think of it as essentially replacing water with something like oil.”

Even with this innovation, the carbon capture system requires a lot of energy. Yuan Jiang, a chemical engineer at PNNL who works with Heldebrant, told CNBC that the energy comes from a power plant connected to a carbon capture system.

The installed carbon capture machine will use 30 percent of the energy generated by the power plant to remove 90 percent of the carbon dioxide. This is called the “parasitic load” of carbon capture technology. To return to full energy capacity, the power plant will have to burn more energy. Even so, the technique would ultimately translate into an 87 percent net carbon dioxide reduction based on net electricity production per megawatt, Heldebrant and Jiang told CNBC.

David J. Heldebrant, PNNL’s chief scientist, held a vial of methanol made with a process integrated into a point-source carbon capture device. Photo courtesy of Andrea Starr at Pacific Northwest National Laboratory.

Photo courtesy of Andrea Starr at Pacific Northwest National Laboratory

Creating financial incentives

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

To make the technology more economically attractive, PNNL researchers 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 could sell. .

Heldebrant told CNBC, “If we can provide an economic incentive — if we can convert just 1 percent of the carbon dioxide that they capture in one of these large facilities, then the factories will produce enough methanol, or methane, or other types of carbonate products to at least financially incentivize, they actually they’d like to build a capture unit first,” Heldebrant told CNBC.

They start with methanol, which is currently $1.20 a gallon. This means that 20 gallons of methanol produced will pay for one metric ton of carbon dioxide to be captured. In terms of scale, the US 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 human-made chemical,” Heldebrant told CNBC. According to the Methanol Institute, methanol is used in hundreds of common products, including plastics, paints, auto parts and building materials. It can also power trucks, buses, ships, fuel cells, boilers and cook stoves.

“If we can start replacing fossil-derived methanol with carbon dioxide-derived methanol, that could at least be part of a carbon-negative chemical approach to producing fuels and chemicals, as opposed to carbon-positive by just taking syngas from fossil fuels,” he said. Heldebrant.

Jiang told CNBC that turning carbon dioxide into methanol doesn’t use much energy. But this requires hydrogen, which itself requires energy to produce. This hydrogen can be produced in renewable energy-powered processes, Jiang said.

An infographic of a moon passing through a mountain tunnel serves to represent the efficiency gained in making methanol from carbon capture.

Graphic courtesy of Nathan Johnson at Pacific Northwest National Laboratory

What happens to the rest of the carbon dioxide?

Although some small percentage of carbon dioxide can be filtered to make a product such as methanol, the rest must be sequestered. The amount of carbon dioxide that needs to be sequestered is “staggering,” according to Todd Schaef, a PNNL scientist working on sequestration.

In general, capturing carbon dioxide is cheaper than capturing it in the first place. According to the International Energy Agency’s special report on carbon capture use and storage, more than half of US land-based carbon sequestration is estimated to cost less than $10 per ton.

In his research, Schaef pumped carbon dioxide 830 meters under the Earth, a special type of basalt rock, and found that after two years, the carbon dioxide reacted with the rock and became permanently carbonated. keep underground.

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

Here, Todd Schaef (left) and Casie Davidson (right) analyze the geology of basalt, a type of rock that is particularly suited to carbon sequestration. Photo courtesy of Andrea Starr at Pacific Northwest National Laboratory.

Photo courtesy of Andrea Starr at Pacific Northwest National Laboratory.

There’s also the moral hazard argument some climate change activists make against carbon sequestration technology: Focusing on removing carbon dioxide from fossil fuel emissions simply delays the necessary transition, rather than reducing or eliminating them entirely.

Schaef admitted that it was a “touchy subject.” “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 has already been released and will continue to be emitted for as long as it takes for global infrastructures to transition from where 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. Although the global use of coal-fired power plants is significantly lower than a few years ago, there are still more than 2,400 coal-fired plants and more than 189 plants are building additional coal-fired power. Global Energy Monitor.

Natural gas is still used in the U.S., where renewables like wind, hydro and solar are critical components of the power grid, Schaef told CNBC.

“We need some kind of option that allows us to keep the lights on when the wind doesn’t blow, the rivers don’t flow, the sun doesn’t shine. I know that’s hard for some to understand or understand. , but we have to have that gas-powered option. Well, we can sequester that carbon dioxide.” we can. We can capture it and sequester it.”

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