A scientist at Pacific Northwest National Laboratory examines carbon capture system technology. Photo courtesy of Andrea Starr of the Pacific Northwest National Laboratory.
Photo courtesy of Andrea Starr of the Pacific Northwest National Laboratory.
Scientists at one of the country’s leading research laboratories have found a record-breakingly cheap way to capture carbon dioxide emitted from power plants and factories, including iron and steel plants.
Globally, industrial processes are responsible for 31 percent of total greenhouse gas emissions, with electricity generation accounting for 27 percent, according to Bill Gates in his book on climate, surpassing the 16 percent of total greenhouse gas emissions that come from the transportation sector.
The new technique, unveiled by the Pacific Northwest National Laboratory, costs $39 per metric ton and is the cheapest such carbon capture technique ever reported in a peer-reviewed scientific journal. By comparison, capturing carbon dioxide from a coal-fired power plant using current state-of-the-art technology costs $57 per ton, according to PNNL.
It would be even cheaper if we could switch to 100% clean energy and emit no carbon at all, but that’s not realistic in today’s global economy, says Casey Davidson, who leads the carbon management effort at PNNL.
Davidson said even if the electric grid is powered mostly by wind and solar, there still needs to be natural gas plants to keep the grid stable or to provide backup when the wind isn’t blowing or the sun isn’t shining.
Equally important, industrial processes such as iron, steel, cement, fertilizer, pulp and paper, and bioenergy can reduce carbon emissions with new technology. For example, scientists and entrepreneurs are working on greener ways to make cement and steel, but not at scale, Davidson told CNBC.
“We have the technology to be able to capture carbon dioxide from these industrial point sources. And waiting 20 years until we have the next generation of carbon-free steel technology 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 for removing the available CO2 from the air is known as direct carbon capture, an example of which is 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 is much more expensive than removing CO2 at the source, as PNNL does – direct air capture, which Climeworks does, costs “several hundred dollars” per ton, a spokesperson told CNBC.
“Imagine you’re trying to separate grapes from a big bowl of spaghetti, or you’re trying to separate grapes from a pool of spaghetti. You’ll still get grapes, but you have to do a lot more work in the pool than in the bowl,” Davidson explained.
“But in terms of climate change, the atmosphere doesn’t matter whether the grapes came out of a bowl of spaghetti or a pool of spaghetti — it has the same effect,” Davidson said. “From a public perspective, capturing it before it ever comes out when it’s $39 a ton versus capturing it when it’s already in the atmosphere at $200 or more a ton makes a lot more sense “.
The money to fund this carbon capture technology study totaled $1.2 million over about 3 years and was funded 50/50 between the Department of Energy and SoCalGas, the natural gas distribution utility, PNNL’s Robert Dougle told CNBC.
How is carbon captured at $39/ton?
PNNL’s technique uses solvent chemistry, explained David Heldebrant, PNNL’s principal scientist leading the research.
Dirty gas leaves a power plant or factory and moves into a very large chamber. At the same time, liquid is sprayed down from the top of the chamber. The gas rises and the liquid sinks, and the two substances mix. The treated gas exits the top of the chamber and the liquid containing the CO2 is siphoned away. This liquid is heated until the CO2 escapes as a gas. The CO2 is compressed for transport where most 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.
PNNL’s system is cheaper than other carbon capture systems because it operates with 2 percent water, as opposed to 70 percent water, which is 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 comes up to temperature much faster. So just think about it, because we’ve replaced the water essentially with something like oil.”
Even with this innovation, the carbon capture system requires a lot of energy. That energy comes from a power plant that has a carbon capture system attached to it, Yuan Jiang, a PNNL chemical engineer who works with Heldebrant, told CNBC.
The installed carbon capture machine will use up to 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 must burn more energy. Even so, the technique would eventually result in a net reduction in carbon emissions of 87 percent for every megawatt of net electricity produced, Heldebrant and Jiang told CNBC.
David J. Heldebrant, PNNL’s principal scientist, is seen here with a vial of methanol produced by a process built into a point-of-care carbon capture facility. Photo courtesy of Andrea Starr of the Pacific Northwest National Laboratory.
Photo courtesy of Andrea Starr of the Pacific Northwest National Laboratory
Creating a material incentive
These carbon capture systems are large and expensive: installing one per power reactor would cost $750 million. Without strict government mandates or financial incentives, power plant operators and factory owners will have little reason to spend that money.
In an attempt to make the technology more economically attractive, PNNL researchers have designed a smaller modular reactor that will pump one to two percent of the solvent from the carbon capture system into another smaller modular reactor and use it to produce a product that companies can sell.
“If we can provide an economic incentive — if they can convert just 1 percent of the carbon dioxide they’re capturing at one of these big facilities,” Heldebrant told CNBC, then maybe plants can “sell enough things like methanol , or methane or other types of carbonate products to at least provide a financial incentive, so they’re actually going to want to build a capture unit in the first place,” Heldebrant told CNBC.
They start with methanol, which is currently $1.20 per gallon. This means that 20 gallons of methanol produced will be paid for per 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 latest EPA data.
“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 be the source of energy for trucks, buses, ships, fuel cells, boilers and stoves.
“If we can start replacing fossil-derived methanol with carbon-dioxide-derived methanol, that can at least be part of a chemical approach to producing carbon-negative fuels and chemicals, as opposed to carbon-positive, just by taking syngas from fossil fuels,” Heldebrant said.
Converting carbon dioxide into methanol doesn’t use a lot of energy, Jiang told CNBC. But it requires hydrogen, which requires energy to produce. Bu hydrogen can be made in processes powered by renewable energy sources, Jiang said.
An infographic of a bear walking through a tunnel in a mountain shows the efficiency of methanol production from carbon capture.
Image courtesy of Nathan Johnson of Pacific Northwest National Laboratory
What happens to the rest of the carbon dioxide?
While some small percentage of carbon dioxide can be displaced to produce a product such as methanol, the rest will need to be scavenged. According to Todd Schaef, a PNNL sequestration scientist, the volumes of carbon dioxide that will need to be sequestered are “staggering.”
As a rule, absorbing carbon dioxide is much cheaper than capturing it. More than half of U.S. land-based carbon sequestration is valued at less than $10 a ton, according to a special report on carbon use and storage by the International Energy Agency.
In his research, Schaef injected carbon dioxide 830 meters deep into the Earth’s interior, where the geology is a specific basaltic rock, and returned two years later to find that the carbon dioxide had reacted with the rock and turned into carbonate, permanently. storing it underground.
“That carbon dioxide has reacted with the rock and formed a solid, so the gas no longer exists,” Sheff told CNBC. “These minerals are stable over geologic time scales. Millions and millions of years.”
Todd Shaif (left) and Casey Davidson (right) see here a geology analysis of basalt, which is a type of rock that is particularly good at sequestering carbon. Photo courtesy of Andrea Starr of the Pacific Northwest National Laboratory.
Photo courtesy of Andrea Starr of the Pacific Northwest National Laboratory.
There is also the moral hazard argument that some climate change activists make against carbon capture technology: focusing on decarbonizing fossil fuel emissions, rather than reducing and eliminating them entirely, simply delays the necessary transition.
It’s “an obsessive topic,” Schaef admitted. “It comes up at almost every conference I go to,” he said.
But he says it is counterproductive to not absorb the carbon that has already been emitted and will continue to be emitted for as long as it takes for global infrastructure to transition from the way it operates now to more climate-friendly processes.
“Whether you want to admit it or not, there are going to be countries that use fossil fuels,” Schaef told CNBC. While the global use of coal-fired power plants is markedly lower than it was a few years ago, there are still more than 2,400 coal-fired power plants and additional coal-fired capacity is under construction at more than 189 plants, according to the 2022 Global Energy Monitor report.
In the United States, where renewable energy sources such as 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 don’t flow, when the sun doesn’t shine, we need some option that allows us to keep the lights on. And I know it’s hard for some to understand or realize that, but we have to have a gas-powered option. Well, we can sequester that carbon dioxide. We can capture and sequester it.”