Published December 2004
Ninety percent of the world's energy is derived from fossil fuels. Emissions of CO2 have risen from 20.7 billion tonnes of CO2 in 1990 to 24.1 billion tonnes in 2002, a rise of over 16%. Hence, the Kyoto protocol and attempts to slow and ultimately reverse the increase in emissions of greenhouse gases will have profound economical and geopolitical effects. However, so have the potential effects of global warming. This creates strong interests and lobbies both against and for the implementation of Kyoto.
Given this, there has been increasing interest in the capture of CO2 and its subsequent sequestration. Options for disposal of CO2 after capture include storage in former oil and gas fields, injection into coal seams to liberate sorbed methane, ocean disposal, or saline aquifer injection. Fixation of CO2 by reforestation and changes in agricultural practice, while relatively cheap, can only offset a small part of the projected CO2 emissions for the next century.
Given this, there has been increasing interest in the capture of CO2 and its subsequent sequestration. Options for disposal of CO2 after capture include storage in former oil and gas fields, injection into coal seams to liberate sorbed methane, ocean disposal, or saline aquifer injection. Fixation of CO2 by reforestation and changes in agricultural practice, while relatively cheap, can only offset a small part of the projected CO2 emissions for the next century.
Geological storage of CO2 by injection into saline aquifers appears the most practical, in terms of capacity and widespread geographical availability, but this method means that the stored CO2 will be underground in supercritical phase for centuries. The potential of a catastrophic release of CO2 if such underground reservoirs were created is still being quantified. C
Currently favored options for CO2 capture at the power plant include post-combustion CO2 removal, pre-combustion CO2 capture with temperature-swing regeneration. Our report includes conceptual designs and costs for the use of amine solvents for both post-combustion CO2 removal and pre-combustion removal of CO2 by reforming and water-shift reaction with natural gas-fired combined cycle generation (NGCC). Our estimated costs for both methods are above those by previous researchers who have examined this topic. This reflects a more conservative design strategy in our concept of the processes, a higher natural gas price, as well as a higher efficiency penalty for CO2 capture in our scenarios.
The technologies for CO2 capture, with the exception of the ultimate sequestration of CO2, are proven technologies, largely borrowed from other chemical processes (such as ammonia and hydrogen production) which could easily be implemented in the short to medium term. This technology creates a path where a fossil fuel, natural gas, can continue to play a major role in power production but CO2 emissions can also be drastically reduced, without imposing an unconscionable economic price. We would predict a window between 2020-2030 where the technology might be used. Earlier than this window, we would expect that CO2 emissions credits would be unlikely to at a price where the use of the technology would be economically justified.
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