Most carbon capture and utilisation (CCU) technologies, which recover carbon dioxide from the atmosphere and use it for other emission-lowering processes, emit more carbon than they capture, according to a study.

A majority of these systems do not reduce emissions sufficiently to comply with the Paris Agreement and may fail to help the world reach net-zero emissions by 2050, the study by environmental scientists from Radboud University said. The study was published in the academic journal, One Earth, on February 5.

Also read: View | The seven top technology trends to watch out for in 2022

Kiane de Kleijne, lead author and climate researcher at Radboud University, told Down To Earth that most of carbon capture systems are energy-intensive and release carbon dioxide into the atmosphere.

CCU technologies either capture carbon dioxide directly from the air or absorb it at polluting sources. The technologies then use the captured carbon dioxide in processes such as making fuel, plastics and concrete. Contrary to straightforward carbon capture technology, CCU does not store the carbon dioxide for long periods but converts it into fuels or uses it to drive other industrial processes such as oil extraction or growing plants.

Also read: Using tech to suck carbon dioxide from atmosphere, explained

The researchers suggested countries should narrow down the CCU technologies and channelise investments into those that hold more promise. These could be solutions that do not release emissions during the CCU process.

For their research, Kiane de Kleijne and her colleagues at Radboud University in the Netherlands evaluated 74 CCU processes on two criteria -- emissions during the process and technology maturity level to support the conversion. Of the 74 technologies that were evaluated, the research found only eight could potentially halve emissions by 2030, while four could help the world reach the net-zero emissions target by 2050.

Also read: Carbon offsetting: What does it mean, its significance, how can you offset your carbon footprint

Use of CCU to replace a conventional fuel with a synthetic fuel like methanol can be a promising mitigation strategy if the CO2 is captured using clean energy, Varun Agarwal, senior project associate at the think-tank World Resources Institute, told Down to Earth.

The Centre has also announced setting up two CCU centres in Mumbai and Bengaluru.

Also read: These startups are turning CO2 into vodka, shoes and car interiors

(Edited by : Shoma Bhattacharjee)