Carbon capture and storage - one of the most important engineering challenges
Chemical Capture and Underground Dumping (CCS) Offers No Realistic Hope
Conventional thinking holds that chemical capture (by amine scrubbing) followed by underground dumping ("sequestration") is the only possible way to a "clean coal" system. Now that the delusion about "renewables" providing baseload generation in place of fossil fuels has been dispelled, informed people recognize that at least for the next 20 years we are stuck with coal to meet power demand and therefore we have to find some realistic means for post-combustion capture and disposal of CO2 from the world's fleet of pulverized coal plants.
Chemical capture has as much chance of success as flying by flapping mechanical wings. The scaling problem is insurmountable. Although it has worked to separate CO2 in high concentration from natural gas, it can't work for the huge volumes of hot and dirty flue gas with CO2 in low concentration that need to be processed. Chemical capture doubles the consumption of increasingly scarce fresh water at thermal power plants (see http://www.powermag.com/coal/Determining-Carbon-Capture-and-Sequest... ), and the addition of chemical capture to a plant increases fuel consumption by 31%. NOx and SOx in the flue gas are acid precursors, leading to heat-stable salt deposits on the heat exchange surfaces when the solvent is regenerated.
Even if the capture problem could be solved, there remains the problem of what to do with the enormous volumes of CO2. Enhanced oil recovery (EOR) operations using CO2 can only account for a very small portion of it. Many regions, such as the southeastern US, do not have any suitable nearby geological formations. And after the BP blowout the public may be rightly skeptical of assurances that a Lake Nyos disaster from CO2 eruptions can't happen.
The US Government Accountability Office (GAO) is the watchdog for government agencies, including the Department of Energy (DOE) that are in charge of this challenge. In 2008, the GAO raised serious doubts about the feasibility of sequestration (see http://www.gao.gov/products/GAO-08-1080 ). This year, the Economides study (http://twodoctors.org/manual/economides.pdf) concluded that "models that assume a constant pressure outer boundary for reservoirs intended for CO2 sequestration are missing the critical point that the reservoir pressure will build up under injection at constant rate. Instead of the 1–4% of bulk volume storability factor indicated prominently in the literature, which is based on erroneous steady state modeling, our finding is that CO2 can occupy no more than 1% of the pore volume and likely as much as 100 times less" and that therefore geologic sequestration is "a profoundly non-feasible option for the management of CO2 emissions."
The GAO on July 16, 2010, drove what should be the final nails in the coffin of sequestration. See http://www.gao.gov/new.items/d10675.pdf One disturbing finding was that DOE does not have any technology assessment for the elements of a CCS program. Maybe the Carbon Capture Journal might provide a forum for this.
Chemical capture has as much chance of success as flying by flapping mechanical wings. The scaling problem is insurmountable. Although it has worked to separate CO2 in high concentration from natural gas, it can't work for the huge volumes of hot and dirty flue gas with CO2 in low concentration that need to be processed. Chemical capture doubles the consumption of increasingly scarce fresh water at thermal power plants (see http://www.powermag.com/coal/Determining-Carbon-Capture-and-Sequest... ), and the addition of chemical capture to a plant increases fuel consumption by 31%. NOx and SOx in the flue gas are acid precursors, leading to heat-stable salt deposits on the heat exchange surfaces when the solvent is regenerated.
Even if the capture problem could be solved, there remains the problem of what to do with the enormous volumes of CO2. Enhanced oil recovery (EOR) operations using CO2 can only account for a very small portion of it. Many regions, such as the southeastern US, do not have any suitable nearby geological formations. And after the BP blowout the public may be rightly skeptical of assurances that a Lake Nyos disaster from CO2 eruptions can't happen.
The US Government Accountability Office (GAO) is the watchdog for government agencies, including the Department of Energy (DOE) that are in charge of this challenge. In 2008, the GAO raised serious doubts about the feasibility of sequestration (see http://www.gao.gov/products/GAO-08-1080 ). This year, the Economides study (http://twodoctors.org/manual/economides.pdf) concluded that "models that assume a constant pressure outer boundary for reservoirs intended for CO2 sequestration are missing the critical point that the reservoir pressure will build up under injection at constant rate. Instead of the 1–4% of bulk volume storability factor indicated prominently in the literature, which is based on erroneous steady state modeling, our finding is that CO2 can occupy no more than 1% of the pore volume and likely as much as 100 times less" and that therefore geologic sequestration is "a profoundly non-feasible option for the management of CO2 emissions."
The GAO on July 16, 2010, drove what should be the final nails in the coffin of sequestration. See http://www.gao.gov/new.items/d10675.pdf One disturbing finding was that DOE does not have any technology assessment for the elements of a CCS program. Maybe the Carbon Capture Journal might provide a forum for this.
Tags: and, capture, carbon, sequestration
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© 2012 Created by Karl Jeffery.
