Nanotechnology can help clean the air in several ways. Nano can help capture carbon dioxide created during industrial processes, keeping it out of the air supply.

Much of the production of carbon dioxide comes from power plants burning fossil fuels such as coal, oil, or natural gas. According to the U.S. Environmental Protection Agency, “The process of generating electricity is the single largest source of CO2 emissions in the United States, representing 41 percent of all CO2 emissions.”

Coal burning plants are still the main type of electricity generator in the United States, producing as much as 36 percent of our power.

It is possible to capture carbon dioxide at a fossil fuel–powered power plant and store it, or even turn it into another form of fuel such as methane. The first step in this process is to capture the carbon dioxide produced by power plants. Researchers are developing the following methods:

  • Use of nanoporous membranes to remove carbon dioxide from power plant smokestacks: In a new type of membrane, carbon nanotubes form the nanopores. Carbon dioxide (CO2) molecules flow through the nanotubes to a storage tank, and the rest of the exhaust stream, largely nitrogen, continues out the smokestack.

    Carbon nanotubes, unlike other nanopores, have a very smooth inside surface. Therefore, after molecules enter the openings of these nanotubes, they encounter less resistance and move through more efficiently.

    Molecules flowing through a carbon nanotube to filter out contaminants. [Credit: Photo from Lawrenc
    Credit: Photo from Lawrence Livermore National Laboratory
    Molecules flowing through a carbon nanotube to filter out contaminants.
  • Development of nanomaterials to trap carbon dioxide: Researchers at UCLA are building structures called metal-organic frameworks (MOFs). These structures take their name from the fact that metal molecules and organic molecules are connected in a framework. These so-called crystal sponges contain pores that offer an easy way to store gases that are otherwise hard to store or transport.

    Researchers have designed MOFs with pores that are just the right size to let carbon dioxide molecules in. Cavities inside the MOFs provide space to store the carbon dioxide.

After capturing carbon dioxide, you need to get rid of it (a process called sequestration). It can be pumped underground and stored in layers of permeable rock or pumped into oil fields to boost the recovery of oil by increasing pressure in the field and reducing viscosity of the oil so it flows more easily. Either way, with the carbon dioxide tucked into the ground, it can’t contaminate the air.

The sequestration process with a power plant pumping the captured CO<sub>2</sub> underground. [Cred
Credit: Adapted from an image courtesy of the United States Department of Energy
The sequestration process with a power plant pumping the captured CO2 underground.