Carbon capture and sequestration: off to slow start
By Jeff Ryser
December 8 - Mitigating the impact of carbon dioxide emissions by capturing CO2 and burying it has always been an audacious concept. In practice it is also proving to be expensive and therefore slow in adoption.
CCS, as the idea is broadly known in the power industry to describe carbon capture and sequestration or storage, has taken some hits.
When American Electric Power announced in mid-2009 that it would try its hand at CCS, many within the power industry and government believed it was the right company stepping forward at the right time.
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The Columbus, Ohio-based AEP is not only one of the US’ largest utilities with a total of 5.3 million electricity customers, but 25,000 MW of its total 38,000 MW of capacity is coal-fired, giving it one of the largest coal fleets in the US. The approximately 130 million metric tons of carbon dioxide emitted each year from AEP’s plants makes it one of the country’s single largest CO2 emitters. (See a map of the major carbon sequestration projects in the US.)
The big utility made its decision to pursue CCS at about the time the US House of Representatives approved cap-and-trade legislation that some thought presaged mandatory CCS for big emitters. That legislation died on the vine, but AEP pursued CCS anyway.
In the past two years AEP worked with the French engineering firm Alstom in isolating a 20-MW slip stream of flue gas at its 1,300-MW coal-fired Mountaineer facility in West Virginia.
It spent almost $120 million capturing just 50,000 metric tons of CO2 and burying a mere 37,000 metric tons of the greenhouse gas.
When the company looked at the prospects of spending an additional $670 million — albeit with a $334 million pledge from the US government — to capture and bury 1.5 million tons a year of CO2 from a 235-MW slip stream of flue gas, it balked.
On July 14, Michael Morris, AEP’s chairman and CEO, said the company would take a pass on the government’s funding and put on hold the commercial-scale phase of its high-profile CCS project at the Mountaineer facility "until the economic and policy conditions create a viable path forward.”
AEP was mostly satisfied with the amount of power Alstom’s chilled ammonia process consumed during the pilot phase. This so-called parasitic loss that is associated with the capture of CO2 has been a concern to many who have worked on the design side of the technology.
AEP’s primary concerns were part economic and part political. The company concluded that state regulators had not allowed the company to pass on its costs to ratepayers because Congress never declared CCS mandatory. The company also was not able to find any partners from the private sector to join it in taking on the higher cost of the larger project.
Capturing and burying how much carbon?
For AEP the two-year test of CCS proved to be a technical success, but it did not provide a revenue stream the company could borrow money against. Testing a process that could act as a retrofit on a large number of existing coal-fired facilities was a key part of the AEP trial, as Alstom saw it.
In June, AEP said it anticipated spending between $6 billion and $8 billion complying with new Environmental Protection Agency regulations. It expected to retire nearly 6,000 MW of coal-fired capacity and upgrade or install new emission reduction equipment on 10,100 MW. AEP said it has spent $7.2 billion on emission controls and retrofits on its plants since 1990.
According to the Energy Information Administration, the US has about 1,400 coal-fired units at 600 facilities with a net summer capacity of almost 315,000 MW. A typical 500-MW coal plant burns 1.4 million tons of coal each year.
EIA says 73% of all coal-fired capacity was at least 30 years old at the end of 2010. EIA also calculates that there are about 400 coal-fired generators, representing about 140,000 MW, that have scrubbers already installed. Most carbon capture processes require a scrubber.
Meanwhile, the EPA on August 4 said it was proposing new rules to exclude from EPA’s hazardous waste regulations CO2 streams that are injected for geologic sequestration in wells designated for this purpose under the Safe Drinking Water Act. The agency said it was proposing the exclusion “as part of the agency’s effort to reduce barriers to the use of CCS technologies.”
But AEP’s brief experience with CCS generated a key conclusion: at substantial cost and effort the company managed to bury a pittance of all the CO2 that the company, along with a vast number of others, produce in the US and around the globe.
While AEP considered expanding its CCS project from 37,000 metric tons to capture 1.5 million metric tons of CO2 per year, starting in 2014, the EIA reported in July that in 2010 the US power sector emitted about 2.27 billion metric tons of CO2, with 1.99 billion metric tons coming from the burning of coal.
Total US annual emissions of CO2 in 2010 was 5.63 billion metric tons, while worldwide the total was just under 31 billion metric tons.
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