Carbon Mineralization: From Natural Analogues to Engineered Systems

Abstract

Carbon mineralization sequesters CO2 by reaction of alkaline earth metal bearing silicate and hydroxide minerals with CO2 to form stable carbonate minerals. Seifritz (1990) proposed harnessing this natural process as a method for sequestration of anthropogenic CO2. It was first studied in detail as an industrial process by Lackner et al. (1995), which is often referred to as “mineral carbonation.” Much of this early research aimed to capitalize on the globally abundant natural deposits of ultramafic and mafic rocks, which are rich in alkaline earth metals, in addition to the long-term stability of the resultant carbonate minerals (Lackner et al. 1995). More recently, other process routes have been investigated that rely on feedstocks other than naturally occurring minerals (e.g., industrial wastes) as a source of cations for carbonate precipitation. Therefore, we use the more general term “carbon mineralization” to refer to any process that sequesters CO2 as a solid carbonate phase. The main advantages of carbon mineralization as a CO2 storage method are that the reactions are thermodynamically favored, the carbonation processes can be readily controlled and manipulated, and the resulting product is benign and stable over geological time. We begin this review with an overview of the fundamental processes that are relevant to carbon mineralization, which provides a basic framework in which to understand CO2 sequestration strategies based on carbon mineralization. We next discuss natural analogues to engineered systems, focusing on (1) exhumed hydrothermal systems in peridotite that have formed listvenite (magnesite + quartz) and soapstone and (2) shallow subsurface peridotite weathering processes and related alkaline springs that form carbonate veins, surficial travertine deposits, and hydromagnesite–magnesite playas. The propensity to form carbonate minerals in these ultramafic terranes reflects the thermodynamic instability of Mg-silicate minerals in the presence of CO2. …