A team of researchers from the Massachusetts Institute of Technology (MIT) has designed a revolutionary air filter that allows common buildings to capture carbon dioxide (CO₂) directly from their ventilation systems, with a net efficiency of 92% and without requiring additional energy.
This innovation could mark a turning point in the fight against climate change, by integrating carbon capture into existing urban infrastructure.
Distributed capture: an alternative to DAC plants
Unlike traditional direct air capture (DAC) plants —large, costly, and energy-intensive—, this solution is based on a decentralized logic: thousands of small points capturing CO₂ from HVAC systems (heating, ventilation, and air conditioning) already installed in homes, offices, and factories.
The filter is composed of carbon nanofibers (CNF) coated with polyethylenimine (PEI), a polymer that allows for passive CO₂ adsorption without altering the airflow.
Efficient regeneration with solar or electric energy
One of the biggest challenges of capture technologies is the release of captured CO₂. This filter stands out for its ability to regenerate with renewable sources, through two methods:
- Solar thermal regeneration: reaches 80°C with direct solar heat, thanks to its high absorptivity (94.4%) and low heat capacity
- Electrothermal regeneration (Joule heating): through a 1–2 second electric pulse, leveraging the conductivity of the nanofibers (38.7 ohms/sq), ideal for clean energies like solar, wind, or hydroelectric
Costs and scalability: a viable urban solution
Estimated cost per ton of captured CO₂:
- With solar energy: 362 USD
- With electricity: 821 USD
- With tax incentives (like the Inflation Reduction Act in the U.S.): between 199 and 638 USD
Potential impact:
- Up to 25 million tons annually of CO₂ captured in the U.S.
- Up to 596 million tons globally, equivalent to the annual emissions of countries like Australia or South Korea
Key applications and benefits:
- Decarbonization of buildings without structural reforms
- Transformation of homes and offices into climate assets
- Reduction of dependence on large industrial infrastructures
- Promotion of citizen adoption without altering lifestyles
- Ideal complement for energy efficiency and electrification policies
Challenges and next steps
The main obstacle is not technical, but logistical: how to manufacture, distribute, and maintain these filters on a large scale. However, this challenge is more manageable than building new DAC plants.
Startups like Heirloom and CarbonBuilt are already exploring their implementation in residential buildings, and cities like Copenhagen and San Francisco are evaluating their incorporation into sustainable building regulations.
Towards carbon-capturing cities
This technology will not solve the climate crisis on its own, but it can be integrated into a ecosystem of decentralized solutions that include renewable energies, energy efficiency, and electrification.
Turning every building into an active carbon capture unit is no longer a utopia: it is a concrete technical possibility.
