Progress Report on Carbon Dioxide Capture and Storage
Progress Report on Carbon Dioxide Capture and Storage
Once again we in the USA have been chided by President Bush for being addicted to foreign oil. President Bush was speaking to the March 5, 2008 Washington International Renewable Conference, a meeting of global energy officials. He told the attendees, “we gotta get off oil, America has got to change its habits.” He went on to say, “It should be obvious to all, demand has outstripped supply, which makes prices go up.”
He is right; we are addicted to oil. We complain about the gasoline and electrical prices, while eighty five percent of us believe that global warming is real and caused by humans. We have not broken the chains of driving our cars or heating our homes in energy inefficient ways. This is mainly because we are not offered affordable alternative energies to break these addictions. The major bet of President Bush is on ethanol, but we are now seeing escalating food prices as our corn goes to fuel production, and now it is projected to be as contaminating as gasoline. Its saving grace is that it keeps our dollars in the USA.
President Bush can hardly take credit for promoting renewable energies when he has held up incentives like production tax credits and refuses to cap carbon dioxide emissions. President Bush reiterated his call for a global cap on carbon dioxide, the main gas behind global warming, but said the United States should not act until nations like China and India do as well. It is actions like these that make one wonder if we will ever break the chains of addiction.
We are currently a second-tier player in the adoption of alternate energies, and we need government incentives to move us to the top tier. We will have a new administration in January 2009 that will, hopefully, be more supportive of alternative energies. It is a good bet that their first moves will be a “cap and tax” bill but should include incentives to help the solar, wind and geothermal industries. It will take time for the alternate energies to gain traction. This means that we will be dependent on coal as an electrical generation fuel for much longer than we would like.
We will need to stop or reduce carbon dioxide pollution if we are to use coal for a longer period when oil becomes more scarce and out of affordable reach. This brings us to the questions of the readiness of the highly touted Carbon Capture and Storage (CCS) technology. The premise sounds great to enable and maintain a quality of life that we are used to and desire.
An overview of the CCS technology is quite simple. The carbon dioxide is captured from the fossil fuels before burning or in the smokestack. The CO2 is conveyed by pipes or perhaps converted to a solid at the generation site. The captured gas is then compressed and buried in a reservoir to preclude its escape into the atmosphere.
CO2 Capture
Post Combustions Capture: The effluent gases from a fossil fuel generating plant can be scrubbed to remove the CO2 and captured for transport to the intended reservoir.
Pre-Combustion Capture: The fossil fuel is partially oxidized before combustion. The resulting CO2 can be captured in a relatively pure exhaust stream.
Oxy-Field Combustion:The fuel is burned in oxygen instead of air. To limit the resulting flame temperatures to levels common during conventional combustion, cooled flue gas is recalculated and injected into the combustion chamber. The flue gas consists of mainly carbon dioxide and water vapor, the latter of which is condensed through cooling. The result is an almost pure carbon dioxide stream that can be transported to the sequestration site and stored.
These capture technologies are well understood and examples of their use can be pointed out today. The cost of these techniques, however, will be high. There will be additional capital costs to install the technology. Depending on the capture technology, the energy cost to power the capture techniques can add 10 to 40% additional energy costs. The cost of the energy could be two times what we know today.
Conveyance of the CO2 Gas
This technology is, very simply, pipes which will convey the CO2 gas from the generation plant to the reservoir for storage.
The Reservoir
Here we have an abundance of proposals, but none have been proven on a large-scale demonstration. The proposals range from caverns in the earth to the ocean. The proposal is to compress the CO2 gas and then store it as a gas or react it into a carboneous mineral such as limestone for storage. It is estimated that this procedure will add another 30 to 40% onto the cost of energy in addition to the capture of the gas.
Storage Projects in Operation
There are several CO2 storage projects in operation. Sleeper is the oldest project (1996) and is located in
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