Scientists develop cheapest carbon capture system to date

The team at the Department of Energy’s Pacific Northwest National Laboratory (PNLL) has developed what is claimed to be the "least costly carbon capture system to date".

Using a PNNL-developed capture solvent, the system snatches CO2 molecules before they’re emitted, then converts them into useful, sellable substances.

As described in the journal Advanced Energy Materials, the system has been designed to fit into coal-, gas-, or biomass-fired power plants, as well as cement kilns and steel plants.

While commercial systems soak up carbon from flue gas at roughly $46 (£37) per tonne of CO2, a new study described in the Journal of Cleaner Production set the cost of running the methanol system using PNNL-developed capture solvents at just below $39 (£31) per tonne of CO2.

“We looked at three CO2-binding solvents in this new study,” said chemical engineer Yuan Jiang, who led the assessment. “We found that they capture over 90 per cent of the carbon that passes through them, and they do so for roughly 75 per cent of the cost of traditional capture technology.”

The development has been considered a fundamental step in the journey towards making carbon capture more affordable and widespread. 

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.

“That's essentially what we're trying to do here,” said Heldebrant. “Instead of extracting oil from the ground to make these chemicals, we're trying to do it from CO2 captured from the atmosphere or from coal plants, so it can be reconstituted into useful things.

"You're keeping carbon alive, so to speak, so it's not just ‘pull it out of the ground, use it once, and throw it away.’ We're trying to recycle the CO2, much like we try to recycle other things like glass, aluminium and plastics.”

Carbon capture and storage has been recognised as a critical technology to help energy-intensive sectors, such as cement and power generation, meet their net zero goals. However, the high cost of commercial capture technology is a longstanding barrier to its widespread use.

Converting CO2 into useful substances like methanol offers a path for industrial entities to capture and repurpose their carbon. Methanol, in particular, holds many uses as a fuel, solvent, and an important ingredient in plastics, paint, construction materials and car parts.

PNNL’s research is focused on using renewably sourced hydrogen in the conversion. This allows the team to 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.

In addition to methanol, the team can convert CO2 into formate (another commodity chemical), methane and other substances.

“The team’s integrated approach opens up a world of new CO2 conversion chemistry," said Casie Davidson, manager for PNNL’s Carbon Management and Fossil Energy market sector. "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.”

Although creating methanol from CO2 is not new, carbon capture and conversion has traditionally occurred as two distinct steps, separated by each process’s unique, often non-complementary chemistry.

“We’re finally making sure that one technology can do both steps and do them well,” said Heldebrant, adding that traditional conversion technology typically requires highly purified CO2.

The new system is the first to create methanol from 'dirty' CO2.

In the UK alone, the carbon capture and storage (CCS) sector could be worth £100bn to the economy by 2050, according to an Offshore Energies UK (OEUK) report. The UK government’s official Net Zero Strategy estimates that around 50 million tonnes a year will need to be captured by 2035.

Last June, the country opened its first licensing round of large-scale carbon capture projects in 13 areas within the North Sea, specifically in locations off the coast of Aberdeen, Teesside, Liverpool and Lincolnshire.