Carbon dioxide in Earth's atmosphere initial carbon dioxide in the atmosphere of the young Earth was produced by volcanic activity, modern volcanic activity releases only 130 to 230 megatonnes of carbon dioxide each year. These natural sources are nearly balanced by natural sinks, physical and biological processes which remove carbon dioxide from the atmosphere. For example, some is directly removed from the atmosphere by land plants for photosynthesis and it is soluble in water forming carbonic acid. There is a large natural flux of into and out of the biosphere and oceans. In the pre-industrial era these fluxes were largely in balance. Currently about 57%
Carbon dioxide removal funded by Bill Gates, is developing a process to capture carbon dioxide using a solution of potassium hydroxide mixed with some water at their pilot plant. They hope to create and sell synthetic fuels at a cost of $100 a ton. Among the technologies studied for direct air capture (DAC), the use of aqueous hydroxide sorbents is one of the most promising approaches. In this process, CO from the air is chemically dissolved into NaOH(aq) solution as NaCO; the NaCO is then reacted with solid Ca(OH), which regenerates the solvent and produces CaCO crystals; lastly, heat is applied to the