Disposal or long-term storage of CO2 is the final step in carbon management. Although the cost of storage accounts only for a small portion of the total cost(2), it may well be the most difficult step in the chain of CCUS. The challenge will grow over time as the volumes that will need to be stored grow rapidly. At present the world is releasing about 8.5 Gt/year of carbon into the environment. As mentioned before, storage volumes over the century could easily amount to several thousand Gt of CO2. Many different technologies have been suggested for long-term CO2 storage. These include storing CO2 in the ocean, in geological formation (Figure 3), and through mineral sequestration, which involves the formation of solid carbonates from CO2 and minerals. Power plant designs and CO2 storage are usually very distinct operations. The goal of the power plant operator is to deliver a stream of concentrated CO2, which typically will have to be pipelined to the site of disposal. Any capture scheme can be combined with any disposal scheme. There are a few exceptions in which the sorbent used in the power plant is directly disposed of. While the CCS technology is still too new to settle on a single approach, any storage option that would be useful beyond small niche markets must possess the following properties: have a large capacity, be safe, be environmentally benign, and guarantee the long-term stability of storage. Storage lifetime constraints will become more stringent over time. With an introduction of the utilization portion of the carbon management scheme, this area of research requires rapid and efficient technological development while building up the scientific foundations for the future. Thus, we propose the RCN-CCUS to address this challenge.
1) Usually disposal of the sorbent is either too costly or defeats the purpose of CCUS. For example, lime sorbents are made from limestone and in their production produce more CO2 than they bind. Thus, they would not store any net CO2 if they were used only once.