Making methane from carbon dioxide: Carbon capture grows more affordable

In their ongoing effort to marque c seizure much affordable, researchers astatine the Department of Energy's Pacific Northwest National Laboratory person developed a method to person captured c dioxide (CO₂) into methane, the superior constituent of earthy gas.

By streamlining a longstanding process successful which CO₂ is converted to methane, the researchers' caller method reduces the materials needed to tally the reaction, the vigor needed to substance it, and ultimately, the selling terms of the gas.

A cardinal chemic subordinate known arsenic EEMPA makes the process possible. EEMPA is simply a PNNL-developed solvent that snatches CO₂ from powerfulness works flue gas, binding the greenhouse state truthful it tin beryllium converted into utile chemicals.

Earlier this year, PNNL researchers revealed that utilizing EEMPA successful powerfulness plants could slash the terms of c seizure to 19 percent little than modular manufacture costs—the lowest documented terms of c capture. Now, successful a survey published Friday, August 21 successful the diary ChemSusChem, the squad reveals a caller incentive—in cheaper earthy gas—to further thrust down costs.

When compared to the accepted method of methane conversion, the caller process requires an archetypal concern that costs 32 percent less. Operation and attraction costs are 35 percent cheaper, bringing the selling terms of synthetic earthy state down by 12 percent.

Methane's relation successful c capture

Different methods for converting CO₂ into methane person agelong been known. However, astir processes trust connected precocious temperatures and are often excessively costly for wide commercialized use.

In summation to geologic production, methane tin beryllium produced from renewable oregon recycled CO₂ sources, and tin beryllium utilized arsenic substance itself oregon arsenic an H₂ vigor carrier. Though it is simply a greenhouse state and requires cautious proviso concatenation management, methane has galore applications, ranging from household usage to concern processes, said pb writer and PNNL chemist Jotheeswari Kothandaraman.

"Right present a ample fraction of the earthy state utilized successful the U.S. has to beryllium pumped retired of the ground," said Kothandaraman, "and request is expected to summation implicit time, adjacent nether clime alteration mitigation pathways. The methane produced by this process—made utilizing discarded CO₂ and renewably sourced hydrogen—could connection an alternate for utilities and consumers looking for natural gas with a renewable constituent and a little c footprint."

Calculating costs and capturing carbon

To research the usage of EEMPA successful converting CO₂ to methane, Kothandaraman and her chap authors studied the reaction's molecular underpinnings, past assessed the outgo of moving the process astatine standard successful a 550-megawatt powerfulness plant.

Conventionally, works operators tin seizure CO₂ by utilizing peculiar solvents that douse flue state earlier it's emitted from works chimneys. But these accepted solvents person comparatively precocious h2o content, making methane conversion difficult.

PNNL researchers are processing technologies to seizure CO₂ from concern emissions and from the atmosphere. Here, manager of the Carbon Management and Fossil Energy Market Sector, Casie Davidson, explains CO₂ mitigation technologies and however they mightiness deploy astatine scale. Credit: Casie Davidson / Pacific Northwest National Laboratory

Using EEMPA alternatively reduces the vigor needed to substance specified a reaction. The savings stem partially from EEMPA's quality to marque CO₂ dissolve much easily, which means little unit is needed to tally the conversion.

The authors' appraisal identified further outgo savings, successful that CO₂ captured by EEMPA tin beryllium converted to methane connected site. Traditionally, CO₂ is stripped from water-rich solvents and sent disconnected tract to beryllium converted oregon stored underground. Under the caller method, captured CO₂ tin beryllium mixed with renewable hydrogen and a catalyst successful a elemental chamber, past heated to fractional the unit utilized successful accepted methods to marque methane.

The absorption is efficient, the authors said, converting implicit 90 percent of captured CO₂ to methane, though the eventual greenhouse state footprint depends connected what the methane is utilized to do. And EEMPA captures implicit 95 percent of CO₂ emitted successful flue gas. The caller process gives disconnected excess heat, too, providing steam for powerfulness generation.

Making much from CO₂

The chemical process highlighted successful the insubstantial represents 1 way among many, said Kothandaraman, wherever captured CO₂ tin beryllium utilized arsenic a feedstock to nutrient different invaluable chemicals.

"I'll beryllium gladsome erstwhile I tin marque this process enactment for methanol arsenic efficiently arsenic it does for methane now," she said. "That's my semipermanent goal." Methanol has galore much applications than methane, said Kothandaraman, who has sought to uncover the catalytic reactions that could nutrient methanol from CO₂ for astir a decade. Creating plastics from captured CO₂ is different way the squad plans to explore.

"It's important that we not lone seizure CO₂, but find invaluable ways to usage it," said Ron Kent, Advanced Technologies Development Manager astatine SoCalGas, "and this survey offers a cost-effective pathway toward making thing invaluable retired of discarded CO₂."

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More information: David Heldebrant et al, Integrated Capture and Conversion of CO2 to Methane utilizing a Water‐lean, Post‐Combustion CO2 Capture Solvent, ChemSusChem (2021). DOI: 10.1002/cssc.202101590