Scientists launch less expensive carbon capture system

Scientists carve a path to profit from carbon capture by creating a system that efficiently captures CO2 and converts it into one of the world’s most widely used chemicals: methanol.

The need for technology that can capture, remove and repurpose carbon dioxide grows stronger with every CO2 molecule that reaches Earth’s atmosphere. To meet that need, scientists at the Department of Energy’s Pacific Northwest National Laboratory have cleared a new milestone in their efforts to make carbon capture more affordable and widespread. They have created a new system that efficiently captures CO2 — the least costly to date — and converts it into one of the world’s most widely used chemicals: methanol.

Snaring CO2 before it floats into the atmosphere is a key component in slowing global warming. Creating incentives for the largest emitters to adopt carbon capture technology, however, is an important precursor. The high cost of commercial capture technology is a longstanding barrier to its widespread use.

PNNL scientists believe methanol can provide that incentive. It holds many uses as a fuel, solvent, and an important ingredient in plastics, paint, construction materials and car parts. Converting CO2 into useful substances like methanol offers a path for industrial entities to capture and repurpose their carbon.

PNNL chemist David Heldebrant, who leads the research team behind the new technology, compares the system to recycling. Just as one can choose between single-use and recyclable materials, so too can one recycle carbon.

As described in the journal Advanced Energy Materials, the new system is designed to fit into coal-, gas-, or biomass-fired power plants, as well as cement kilns and steel plants. Using a PNNL-developed capture solvent, the system snatches CO2 molecules before they’re emitted, then converts them into useful, sellable substances.

A long line of dominoes must fall before carbon can be completely removed or entirely prevented from entering Earth’s atmosphere. This effort — getting capture and conversion technology out into the world — represents some of the first few crucial tiles.

Deploying this technology will reduce emissions, said Heldebrant. But it could also help stir the development of other carbon capture technology and establish a market for CO2-containing materials. With such a market in place, carbon seized by anticipated direct air capture technologies could be better reconstituted into longer-lived materials.

In April 2022, the Intergovernmental Panel on Climate Change issued its Working Group III report focused on mitigating climate change. Among the emissions-limiting measures outlined, carbon capture and storage was named as a necessary element in achieving net zero emissions, especially in sectors that are difficult to decarbonize, like steel and chemical production.

PNNL’s research is focused on doing just that — in alignment with DOE’s Carbon Negative Shot. By using renewably sourced hydrogen in the conversion, the team can produce methanol with a lower carbon footprint than conventional methods that use natural gas as a feedstock. Methanol produced via CO2 conversion could qualify for policy and market incentives intended to drive adoption of carbon reduction technologies.

Methanol is among the most highly produced chemicals in existence by volume. Known as a “platform material,” its uses are wide ranging. In addition to methanol, the team can convert CO2 into formate (another commodity chemical), methane and other substances.

A significant amount of work remains to optimize and scale this process, and it may be several years before it is ready for commercial deployment. But, said Casie Davidson, manager for PNNL’s Carbon Management and Fossil Energy market sector, displacing conventional chemical commodities is only the beginning. “The team’s integrated approach opens up a world of new CO2 conversion chemistry. There’s a sense that we’re standing on the threshold of an entirely new field of scalable, cost-effective carbon tech. It’s a very exciting time.”

Commercial systems soak up carbon from flue gas at roughly $46 per metric ton of CO2, according to a DOE analysis. The PNNL team’s goal is to continually chip away at costs by making the capture process more efficient and economically competitive.

The team brought the cost of capture down to $47.10 per metric ton of CO2 in 2021. A new study described in the Journal of Cleaner Production explores the cost of running the methanol system using different PNNL-developed capture solvents, and that figure has now dropped to just below $39 per metric ton of CO2.

Different systems can be used depending on the nature of the plant or kiln. But, no matter the setup, solvents are central. In these systems, solvents wash over CO2-rich flue gas before it’s emitted, leaving behind CO2 molecules now bound within that liquid.

Creating methanol from CO2 is not new. But the ability to both capture carbon and then convert it into methanol in one continuously flowing system is. Capture and conversion has traditionally occurred as two distinct steps, separated by each process’s unique, often non-complementary chemistry.

The process of capturing CO2 and converting it to methanol is not CO2-negative. The carbon in methanol is released when burned or sequestered when methanol is converted to substances with longer lifespans. But this technology does “set the stage,” Heldebrant said, for the important work of keeping carbon bound inside material and out of the atmosphere.

Other target materials include polyurethanes, which are found in adhesives, coatings, and foam insulation, and polyesters, which are widely used in fabrics for textiles. Once researchers finalize the chemistry behind converting CO2 into materials that keep it out of the atmosphere for climate-relevant timescales, a wide web of capture systems could be poised to run such reactions.

This technology is available for licensing. Please contact Sara Hunt, PNNL commercialization manager, to learn more.

This work was supported by the Department of Energy’s Technology Commercialization Fund, the Office of Fossil Energy and Carbon Management, and Southern California Gas. Part of the work was performed at EMSL, the Environmental Molecular Sciences Laboratory, a DOE Office of Science user facility at PNNL.

Tags: Carbon Capture, Methanol, Scientists