Carbon capture is a process in which carbon dioxide is extracted from emissions, classically the flue gases produced at large facilities like power plants. By capturing carbon before it can be released, carbon capture reduces the amount of CO2 being released into the atmosphere, thereby reducing some of the damage believed to be caused by carbon emissions. Growing concerns about rising carbon dioxide levels in the early 21st century led to some interest in carbon capture as a technique which could be used to manage carbon emissions.
This process is part of a procedure known as carbon capture and storage or carbon capture and sequestration (CCS). In this process, the trapped carbon is transported to a site where it can be stored. CCS primarily focuses on underground storage sites, which could potentially be located directly beneath carbon dioxide-producing facilities for convenience.
Some serious criticisms have been raised about carbon capture. The process can be very expensive, whether the CO2 is recovered from flue gases after combustion or extracted before combustion as part of a chemical process. The cost of carbon capture makes it impractical for companies concerned about operating expenses, especially since consumers may be reluctant to have the costs passed on to them. Installing equipment to trap carbon can also be a costly and time consuming process.
Once captured, CO2 also presents a storage problem. If storage facilities leak, the carbon dioxide would be allowed to escape into the atmosphere, defeating the purpose of capturing the carbon in the first place. Leaks can also be dangerous to animals; natural CO2 leaks from sites like volcanoes have killed people and animals in several regions of the world, and presumably large man-made CO2 deposits could do the same thing.
Some researchers have suggested that trapped carbon dioxide could be processed for reuse, with the storage being a temporary solution rather than a permanent one. However, processing can be expensive and time consuming, and it's not clear how useful and affordable the resulting products would be. For example, CO2 can be repurposed into fuels through a lengthy process, but the fuel might be cost-prohibitive.
People have also suggested that investing in carbon capture technology distracts the public from the real concern, which is reliance on fossil fuels. By investing in alternative fuel technologies, governments and the public might be better served in the long term by reducing situations in which carbon dioxide is emitted, rather than trying to mitigate emissions as they occur.