Sunday, March 09, 2008

Progress Report on Carbon Dioxide Capture and Storage

By Paul Calhoun

http://environmentalhelp.typepad.com

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 the North Sea where Norway's StatoilHydro strips carbon dioxide from natural gas with amine solvents and disposes of this carbon dioxide in a deep saline aquifer. Since 1996, Sleipner has stored about one million tons of CO2 a year. A second project in the Snohvit gas field stores 700,000 tons per year.

The Weyburn project is currently the world's largest carbon capture and storage project. Started in 2000, Weyburn is located on an oil reservoir discovered in 1954 in Southeastern Canada. The CO2 for this project is captured at the Great Plains Coal Gasification plant in Beulah, North Dakota, which has produced methane from coal for more than 30 years. The first phase finished in 2004 and demonstrated that CO2 can be stored underground at the site safely and indefinitely.

Future Projects

A major Canadian initiative called the Integrated CO2 Network (ICO2N) is a proposed system for the capture, transport and storage of carbon dioxide (CO2). ICO2N is an alliance of 15 largest Canadian industrial companies and the Canadian Government. The Alliance has been in existence for two years.

The ICO2N alliance has the stated objective to be the “world Leader in the implementation of Carbon Dioxide Capture and Storage.” Its goal is to remove 60% of Alberta CO2 emissions and also to enhance oil recovery from mature oil fields. The first phase of operation is planned in 2012-2015.

In October 2007, the Bureau of Economic Geology at The University of Texas at Austin received a 10-year, $38 million subcontract to conduct the first intensively monitored, long-term project in the United States studying the feasibility of injecting a large volume of CO2 for underground storage. The project is a research program of the Southeast Regional Carbon Sequestration Partnership (SECARB), funded by the National Energy Technology Laboratory of the U.S. Department of Energy (DOE). The SECARB partnership will demonstrate CO2 injection rate and storage capacity in the Tuscaloosa-Woodbine geologic system that stretches from Texas to Florida. The region has the potential to store more than 200 billion tons] of CO2. Physical work started in late 2007.

FutureGen was a US government project announced by President Bush in 2003 to build a near zero-emissions coal-fueled power plant to produce hydrogen and electricity while using carbon capture and storage. In December 2007, Mattoon Township, Coles County, Illinois was chosen as the site for the plant from among four finalists in Illinois and Texas. Sadly, on January 29, 2008the Department of Energy announced it was withdrawing funding from FutureGen, effectively terminating the project. The Department of Energy has stated that the demonstration was canceled because costs had escalated to $1.5 Billion and it did not believe a demonstration of the technology was now needed. The DOE has asked for existing power plants to submit proposals to be fitted for CCS to be up and running in the 2015-2016 timeframe.

Carbon Dioxide Capture Research

The capture of carbon dioxide is the most expensive component of the technology and is receiving the focus of the world researchers. UCLA’s researcher, Omar Yaghti, has developed ZIF materials which can absorb 80 times their weight in carbon dioxide. After absorption, the material can be decompressed and the CO2 released.

Research at the University of Texas in Austin, led by Professor Gary Rochelle, has developed a chemical process that will absorb carbon dioxide and release it when boiling the mixture. There are many other examples of these new technologies in research to capture carbon dioxide and for sure many others to be demonstrated.

Summary

Carbon Dioxide Capture and Storage is a well demonstrated technology that is ready for large scale implementation. The cost of scrubbing exhaust gases or the pre burned fuel and the CO2 Gs compression will raise the energy costs between 40 to 60% over the unscrubbed and storged CO2 technology. There are scores of researchers working to develop materials that can absorb the CO2 gas in the smokestack and avoid the energy cost of scrubbing. These developments are at a minimum of seven to ten years away. We had best encourage this development, because it will be 10 to 15 years before their implementation after they are begun.

2 comments:

Chris said...

The International Test Centre for CO2 Capture has been functioning at the University of Regina for over 20 years. It is run in conjunction with the public company HTC Purenergy, listed on the TSX Venture exchange.

The university recently announced that it's received $240 from the federal government to pursue a clean coal project with CCS.

Read more about it here:

http://www.uregina.ca/news/releases/2008/february/27.shtml

gasification said...

you have given many things regarding coal like combustion gasification and many more...coal is a prefect energy resource where many countries are generating income and power.