Potential Capacity for Geologic Carbon Sequestration in the Midcontinent Rift System in Minnesota

摘要

Increasing concern about climate change has necessitated the assessment of ways to reduce greenhouse gas emissions, while concurrently increasing our preparedness for climate change and variability. For example, in 2007, the Minnesota Legislature set goals to reduce our emissions 15% by 2015, 30% by 2025, and 80% by 2050. These reductions can be achieved by reducing combustion of fossil fuels, and by reducing other activity that generates greenhouse gases. Changes in land use can induce increased storage of carbon in soil and vegetation, thus facilitating terrestrial sequestration of emissions from the full range of sources, including vehicle emissions. In the case of stationary sources of carbon dioxide (CO2) emissions, however, such as the coal-fired electrical generating stations, ethanol plants, and other stationary sources that make up over one-third of Minnesota CO2 emissions, the technology to capture CO2 is available, pending developments in methods and costs. The likely fate of CO2 captured from stationary sources would be storage by geologic sequestration, also known as carbon capture and storage, by injection into underground geologic formations where it can be stored for long periods of time to prevent its escape to the atmosphere. This method is in the early deployment phase worldwide, but estimates indicate it may permit 15 to 55% of the emissions reductions needed to avoid dangerous levels of climate change. In addition, analyses indicate that achieving these reductions will be less costly if geologic carbon sequestration is an option. Another geologic technique is mineral carbonation, in which CO2 is reacted with material from mining, producing mineral products for disposal or use in construction. While Minnesota has favorable geology for this option, the method is not fully developed and the costs remain high.