Cement factories like the one shown here are a major source of climate-warming carbon dioxide. But some of these pollutants can be converted into a new type of fuel. This salt can be safely stored for decades or longer.
       This is another story in a series looking at new technologies and actions that can slow climate change, reduce its impacts, or help communities cope with a rapidly changing world.
       Activities that release carbon dioxide (CO2), a common greenhouse gas, contribute to warming the Earth’s atmosphere. The idea of ​​extracting CO2 from the air and storing it is not new. But it is difficult to do, especially when people can afford it. A new system solves the problem of CO2 pollution in a slightly different way. It chemically converts the climate-warming gas into fuel.
       On November 15, researchers from the Massachusetts Institute of Technology (MIT) in Cambridge published their groundbreaking results in the journal Cell Reports Physical Science.
       Their new system is divided into two parts. The first part involves converting carbon dioxide from the air into a molecule called formate to produce fuel. Like carbon dioxide, formate contains one carbon atom and two oxygen atoms, as well as one hydrogen atom. Formate also contains several other elements. The new study used formate salt, which is derived from sodium or potassium.
       Most fuel cells run on hydrogen, a flammable gas that requires pipelines and pressurized tanks to transport. However, fuel cells can also run on formate. Formate has an energy content comparable to hydrogen, according to Li Ju, a materials scientist who led the development of the new system. Formate has some advantages over hydrogen, Li Ju noted. It is safer and does not require high-pressure storage.
       Researchers at MIT created a fuel cell to test formate, which they produce from carbon dioxide. First, they mixed the salt with water. The mixture was then fed into a fuel cell. Inside the fuel cell, the formate released electrons in a chemical reaction. These electrons flowed from the negative electrode of the fuel cell to the positive electrode, completing an electrical circuit. These flowing electrons—an electrical current—were present for 200 hours during the experiment.
       Zhen Zhang, a materials scientist working with Li at MIT, is optimistic that his team will be able to scale the new technology within a decade.
       The MIT research team used a chemical method to convert carbon dioxide into a key ingredient for fuel production. First, they exposed it to a highly alkaline solution. They chose sodium hydroxide (NaOH), commonly known as lye. This triggers a chemical reaction that produces sodium bicarbonate (NaHCO3), better known as baking soda.
       Then they turned on the power. The electrical current triggered a new chemical reaction that split every oxygen atom in the baking soda molecule, leaving behind sodium formate (NaCHO2). Their system converted nearly all the carbon in CO2 — more than 96 percent — into this salt.
       The energy needed to remove the oxygen is stored in the chemical bonds of formate. Professor Li noted that formate can store this energy for decades without losing potential energy. It then generates electricity when it passes through a fuel cell. If the electricity used to produce formate comes from solar, wind or hydroelectric power, the electricity generated by the fuel cell will be a clean energy source.
       To scale up the new technology, Lee said, “we need to find rich geological resources of lye.” He studied a type of rock called alkali basalt (AL-kuh-lye buh-SALT). When mixed with water, these rocks turn into lye.
       Farzan Kazemifar is an engineer at San Jose State University in California. His research focuses on storing carbon dioxide in underground salt formations. Removing carbon dioxide from the air has always been difficult and therefore expensive, he says. So it’s profitable to convert CO2 into usable products like formate. The cost of the product can offset the cost of production.
       There has been much research into capturing carbon dioxide from the air. For example, a team of scientists at Lehigh University recently described another method for filtering carbon dioxide from the air and converting it into baking soda. Other research groups are storing CO2 in special rocks, converting it into solid carbon that can then be processed into ethanol, an alcohol fuel. Most of these projects are small-scale and have not yet had a significant impact on reducing high levels of carbon dioxide in the air.
       This image shows a house that runs on carbon dioxide. The device shown here converts carbon dioxide (the molecules in the red and white bubbles) into a salt called formate (the blue, red, white, and black bubbles). This salt can then be used in a fuel cell to generate electricity.
       Kazemifar said our best option is to “cut greenhouse gas emissions first.” One way to do that is to replace fossil fuels with renewable energy sources like wind or solar. This is part of a transition scientists call “decarbonization.” But he added that stopping climate change will require a multifaceted approach. This new technology is needed to capture carbon in areas that are difficult to decarbonize, he said. Take steel mills and cement factories, to name two examples.
       The MIT team also sees benefits in combining their new technology with solar and wind power. Traditional batteries are designed to store energy for weeks at a time. Storing summer sunlight into the winter or longer requires a different approach. “With formate fuel,” Lee said, you’re no longer limited to even seasonal storage. “It could be generational.”
       It may not sparkle like gold, but “I can leave 200 tons… of formate to my sons and daughters,” Lee said, “as an inheritance.”
       Alkaline: An adjective describing a chemical substance that forms hydroxide ions (OH-) in solution. These solutions are also called alkaline (as opposed to acidic) and have a pH greater than 7.
       Aquifer: A rock formation capable of holding underground reservoirs of water. The term also applies to subsurface basins.
       Basalt: A black volcanic rock that is usually very dense (unless a volcanic eruption left large pockets of gas in it).
       bond: (in chemistry) a semi-permanent connection between atoms (or groups of atoms) in a molecule. It is formed by attractive forces between the participating atoms. Once bonds are formed, the atoms function as a unit. To separate the constituent atoms, energy in the form of heat or other radiation must be supplied to the molecules.
       Carbon: A chemical element that is the physical basis of all life on Earth. Carbon exists freely in the form of graphite and diamond. It is an important component of coal, limestone, and petroleum, and is capable of chemically self-associating to form a wide variety of molecules of chemical, biological, and commercial value. (In climate research) The term carbon is sometimes used almost interchangeably with carbon dioxide to refer to the potential impact that an action, product, policy, or process may have on the long-term warming of the atmosphere.
       Carbon dioxide: (or CO2) is a colorless, odorless gas produced by all animals when the oxygen they breathe reacts with the carbon-rich food they eat. Carbon dioxide is also released when organic matter, including fossil fuels such as oil or natural gas, is burned. Carbon dioxide is a greenhouse gas that traps heat in the Earth’s atmosphere. Plants convert carbon dioxide into oxygen through photosynthesis and use this process to make their own food.
       Cement: A binder used to hold two materials together, causing it to harden into a solid, or a thick glue used to hold two materials together. (Construction) A finely ground material used to bind sand or crushed rock together to form concrete. Cement is usually made as a powder. But once it gets wet, it turns into a muddy slurry that hardens when it dries.
       Chemical: A substance made up of two or more atoms combined (bonded) in a fixed proportion and structure. For example, water is a chemical substance made up of two hydrogen atoms bonded to one oxygen atom. Its chemical formula is H2O. “Chemical” can also be used as an adjective to describe the properties of a substance that result from various reactions between different compounds.
       Chemical bond: A force of attraction between atoms that is strong enough to cause the bonded elements to function as a unit. Some attractions are weak, others are strong. All bonds appear to connect atoms by sharing (or attempting to share) electrons.
       Chemical reaction: A process involving a rearrangement of the molecules or structures of a substance rather than a change in physical form (e.g., from solid to gas).
       Chemistry: the branch of science that studies the composition, structure, properties, and interactions of substances. Scientists use this knowledge to study unfamiliar substances, to reproduce useful substances in large quantities, or to design and create new useful substances. (of chemical compounds) Chemistry also refers to the formula of a compound, the method by which it is prepared, or some of its properties. People who work in this field are called chemists. (in the social sciences) the ability of people to cooperate, get along, and enjoy each other’s company.
       Climate change: A significant, long-term change in the Earth’s climate. This can occur naturally or as a result of human activities, including burning fossil fuels and clearing forests.
       Decarbonization: refers to the intentional transition away from polluting technologies, activities, and energy sources that emit carbon-based greenhouse gases, such as carbon dioxide and methane, into the atmosphere. The goal is to reduce the amount of carbon gases that contribute to climate change.
       Electricity: The flow of electrical charge, usually resulting from the movement of negatively charged particles called electrons.
       Electron: a negatively charged particle that usually orbits the outer region of an atom; it is also the carrier of electricity in solids.
       Engineer: Someone who uses science and mathematics to solve problems. When used as a verb, the word engineer refers to designing a device, material, or process to solve a problem or unmet need.
       Ethanol: An alcohol, also called ethyl alcohol, that is the basis for alcoholic beverages such as beer, wine, and spirits. It is also used as a solvent and fuel (for example, often mixed with gasoline).
       Filter: (n.) Something that allows some materials to pass and others to pass, depending on their size or other characteristics. (v.) The process of selecting certain substances based on properties such as size, density, charge, etc. (in physics) A screen, plate, or layer of a substance that absorbs light or other radiation or selectively prevents some of its components from passing.
       Formate: A general term for salts or esters of formic acid, an oxidized form of a fatty acid. (An ester is a carbon-based compound formed by replacing the hydrogen atoms of certain acids with certain types of organic groups. Many fats and essential oils are naturally occurring esters of fatty acids.)
       Fossil fuel: Any fuel, such as coal, petroleum (crude oil), or natural gas, that was formed over millions of years inside the Earth from the decaying remains of bacteria, plants, or animals.
       Fuel: Any substance that releases energy through a controlled chemical or nuclear reaction. Fossil fuels (coal, natural gas, and oil) are common fuels that release energy through chemical reactions when heated (usually to the point of combustion).
       Fuel cell: A device that converts chemical energy into electrical energy. The most common fuel is hydrogen, the only by-product of which is water vapor.
       Geology: An adjective describing everything related to the physical structure of the Earth, its materials, history, and the processes that occur on it. People who work in this field are called geologists.
       Global warming: A gradual increase in the overall temperature of the Earth’s atmosphere due to the greenhouse effect. The effect is caused by increasing levels of carbon dioxide, chlorofluorocarbons, and other gases in the air, many of which are emitted by human activities.
       Hydrogen: The lightest element in the universe. As a gas, it is colorless, odorless, and extremely flammable. It is a component of many fuels, fats, and the chemicals that make up living tissue. It consists of a proton (the nucleus) and an electron orbiting it.
       Innovation: (v. to innovate; adj. to innovate) An adjustment or improvement to an existing idea, process, or product to make it newer, smarter, more efficient, or more useful.
       Lye: The general name for sodium hydroxide (NaOH) solution. Lye is often mixed with vegetable oils or animal fats and other ingredients to make bar soap.
       Materials scientist: A researcher who studies the relationship between the atomic and molecular structure of a material and its overall properties. Materials scientists may develop new materials or analyze existing ones. Analyzing a material’s overall properties, such as density, strength, and melting point, can help engineers and other researchers select the best materials for new applications.
       Molecule: A group of electrically neutral atoms that represents the smallest possible amount of a chemical compound. Molecules can be made up of one type of atom or different types of atoms. For example, the oxygen in air is made up of two oxygen atoms (O2), and water is made up of two hydrogen atoms and one oxygen atom (H2O).
       Pollutant: A substance that contaminates something, such as air, water, people, or food. Some pollutants are chemicals, such as pesticides. Other pollutants can be radiation, including excessive heat or light. Even weeds and other invasive species can be considered a form of biofouling.
       Potent: An adjective that refers to something that is very strong or powerful (such as a germ, poison, medicine, or acid).
       Renewable: An adjective referring to a resource that can be replaced indefinitely (such as water, green plants, sunlight, and wind). This contrasts with non-renewable resources, which have a limited supply and can effectively be depleted. Non-renewable resources include oil (and other fossil fuels) or relatively rare elements and minerals.