While the scale of envisaged need for CO2 disposal far exceeds today's uses, they do demonstrate the possibility. Safety and permanence of disposition are key considerations in sequestration.
IEA member governments spent less than $400 million per year on CCS up to 2008, but the total then jumped to over $1 billion from 2009 to 2013, before falling sharply in 2014.
In 2012 this was about 6.6% of their total energy research, development and demonstration (RD&D) expenditure.
The share of CCS in fossil fuel RD&D expenditure increased significantly, from around 20% in 2008 and 2009 to over 50% in 2010-13.
Research on geosequestration is ongoing in sevaral parts of the world.
The main potential appears to be deep saline aquifers and depleted oil and gas fields.
In both, the CO2 is expected to remain as a supercritical gas for thousands of years, with some dissolving.
In 2016 it was reported that Iceland had trialled pumping CO2 and water into hot underground rocks and turning it into limestone over about two years.
Large-scale storage of CO2 from power generation will require an extensive pipeline network in densely populated areas. This has safety implications.
Given that rock strata have held CO2 and methane for millions of years there seems no reason that carefully-chosen chosen ones cannot hold sequestered CO2.
However, the eruption of a million tonnes of CO2 from Lake Nyos in Cameroon in 1986 asphyxiated 1700 people, so the consequences of major release of heavier-than-air gas are potentially serious.