Pollution power? A new device turns carbon dioxide into fuel

     

Is it possible to turn carbon dioxide into fuel?

    We present another story in our series that focuses on technologies and actions that can slow down climate change, reduce its negative impacts, or help communities adapt to a rapidly changing world. Human activities that release carbon dioxide (CO2), a common greenhouse gas, are contributing to the warming of Earth's atmosphere. The concept of extracting CO2 from the air and storing it has been around for a while, but it's been challenging to implement, especially at an affordable cost. A new system aims to address the problem of CO2 pollution in a different way by chemically converting this climate-warming gas into a fuel.

    On Nov. 15, the Massachusetts Institute of Technology (MIT) in Cambridge introduced their latest invention in Cell Reports Physical Science.  The MIT system is made up of two components. The first component produces the fuel by transforming airborne CO2 into a molecule called Formate salt. Similar to CO2, Formate contains a carbon atom and two oxygens. It also includes a hydrogen atom, and a Formate salt contains other elements as well. The research team used a variation of Formate salt that contains either sodium or potassium.

                         

       Formate salt                                                 Carbon dioxide        

                   

                                         

        Formate salt contains sodium                           Formate salt contains potassium

    The system's second part involves the utilization of a Formate salt for fueling a fuel cell, which then generates electricity. Typically, most fuel cells operate on hydrogen, which is a flammable gas that requires pipelines and pressurized tanks for transportation. However, Formate salts can also be used to power fuel cells. According to materials scientist Ju Li, who led the development of the new system, Formate salts contain the same amount of energy as hydrogen. Furthermore, Formate offers a few advantages over hydrogen, as it is safer and does not need to be stored at high pressure. The MIT researchers created a fuel cell to experiment with their CO2-derived Formate. Initially, they mixed the salt with water and then introduced the mixture into the fuel cell. Inside the cell, the Formate underwent a chemical reaction, releasing electrons. These electrons flowed from the fuel cell's negative side to its positive side, generating a circuit that resulted in electricity. In their experiment, the flowing electrons or electricity ran for 200 hours.

The role of CO2 in this experiment. 

    The researchers from MIT utilized chemical reactions to convert CO2 gas into a crucial component required to produce their fuel. Initially, they introduced it to an intense alkaline solution, specifically sodium hydroxide (NaOH), also referred to as lye. This led to a chemical change that gave rise to sodium bicarbonate (NaHCO3), a substance commonly known as baking soda.

    Afterward, an electric charge was applied. This caused a new chemical reaction to occur, which removed an oxygen atom from each molecule of baking soda. As a result, sodium Formate (NaCHO2) was produced. The process was highly efficient, with over 96 percent of the CO2's carbon being converted into this salt. The energy that was needed to remove the oxygen was stored in the chemical bonds of Formate. This energy can be stored for a long time without losing its potential power, according to Li. Later, when Formate is passed through a fuel cell, it can generate electricity. Furthermore, if the electricity used to produce the Formate was generated from solar, wind or hydropower, then the electricity produced by the fuel cell will be an environmentally-friendly form of energy. Li asserts that in order to expand the use of this innovative technology, it is crucial to locate ample geological reservoirs of lye. He is currently examining a form of rock known as alkali basalt (pronounced AL-kuh-lye buh-SALT), which, when combined with water, transforms into lye.

Future fuel

This illustration depicts a house that is powered by CO2. There is a device shown in the front that is capable of converting CO2 molecules, which appear as red-and-white-bubble molecules, into a Formate salt. The Formate appears as blue, red, white, and black bubbles. This salt can be utilized to generate electricity via a fuel cell.

    Kazemifar suggests that the most effective way to address the issue is to "reduce greenhouse gas emissions" by switching to renewable energy sources like wind or solar power. This process is referred to as decarbonization. However, he notes that a comprehensive approach is necessary to combat climate change. He explains that carbon capture technology, such as the one developed by the MIT team, is essential in areas that are difficult to decarbonize, such as steel and cement plants. Additionally, the MIT group believes that combining their new technology with solar and wind power would be advantageous. Unlike traditional batteries that store energy for a few weeks, the Formate fuel can be used to store energy from the summer sun until winter or even longer. Li explains that the possibilities with Formate fuel are endless, as it can be used for generations. Moreover, Li points out that although it may not be as flashy as gold, he can still leave his children a substantial inheritance in the form of 200 tons of Formate.

References

Allen, L. (2024) Pollution Power? A new device turns carbon dioxide into fuel, Science News Explores. Available at: https://www.snexplores.org/article/device-turns-carbon-dioxide-fuel-chemistry.