The Global CCS Institute, which is based in Canberra, has reported that since its previous survey a year ago, five carbon capture and storage projects have been canceled, one reduced in size and seven postponed, while three have been added.

The leader in capture and storage is the United States – mostly because of the use of carbon dioxide for stimulating the flow of oil out of old wells. The American program for capturing carbon dioxide from power plants is lagging.

However, two interestiing new approaches to carbon dioxide storage have been proposed.

Replace Methane with Carbon Dioxide

A research team led by Andres Clarens, an assistant professor at the University of Virginia, has published a paper which estimates the amount of carbon dioxide that could be stored in hydraulically fractured shale deposits after the methane gas has been extracted.

The team estimates that pumping carbon dioxide into the Marcellus Shale deposit alone, as methane is extracted by fracking, could store about 10 to 18 gigatonnes of carbon dioxide – that's about 50% of the US carbon dioxide emissions expected to be produced from stationary sources between 2018 and 2030. There are several other large shale formations that could provide additional storage.

Profeeor Clarens says that knows that the environmental movement opposes hydraulic fracturing because of possible risks to ground and surface waters but he thinks that this type of extraction is inevitable in many places and it is important to develop new strategies for handling the environmental implications.

Despatchable Geothermal Power Using Carbon Dioxide

Meanwhile researchers at Ohio State University, the University of Minnesota and Lawrence Livermore National Laboratory have proposed using carbon dioxide storage as part of a new type of geothermal power plant.

The power plant would consist of three concentric rings of horizontal wells deep underground. Inside those rings, pressurised carbon dioxide, nitrogen and water would circulate separately to draw heat from below ground up to the surface, where the heat can be used to turn turbines and generate electricity.

The underground geothermal formation could store the hot, pressurized carbon dioxide and nitrogen and release the heat to the surface power plant when electricity demand is greatest – complementing wind or solar power plants when the the wind is not blowing and the sun is not shinnig.

The researchers estimate that a 10-mile-wide system of concentric rings of horizontal wells situated about three miles below ground produced as much as half a gigawatt of electrical power.