While the development of alternative energy with renewable sources and reduced environmental impact has been the focus of scientific research for the past decades, our world today still operates on conventional fossil fuels, generating vast quantities of CO2 and releasing it to the atmosphere. Efforts in the research for mitigating these CO2 emissions are crucial in minimizing environmental damage before a better alternative is discovered.
Carbon capture and sequestration is currently the most extensively studied and well understood method for reducing CO2 emissions from large point sources. Various technologies have been developed to capture and sequester CO2 from power plants and other emission sources. Carbon capturing technologies varies from conventional post-combustion carbon scrubbing units to oxy-fuel combustion and chemical looping combustion which are newly investigated territories. The sequestration stage of the process has been the most debated part of the CCS topic. This is mainly due to concerns with CO2 leakage from the sequestration sites over time. Research and testing of the sequestration technologies to reduce the risk of leakage is one of the key components of the development and implementation of CCS processes.
One of the main spot for CO2 sequestration research is here in Austin, TX. Two years ago, October 2007, “The Bureau of Economic Geology at The University of Texas at Austin has 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 carbon dioxide”. This project focuses mainly on geo-sequestration technologies for CO2 in brine reservoirs. Compared with ocean storage and mineral storage, the brine reservoirs have the advantage of availability and large potential volume of storage. It is hoped that the research in sequestration will lead to the development of well-selected, designed and managed geological storage sites potentially store CO2 for millions of years and retain over 99% of the injected CO2 over 1,000 years [2 wiki].
This project is the phase 3 of the Frio brine sequestration pilot testing directed by the Bureau of Economic Geology (BEG) here at UT. The original field experiment was proposed in 2002.  The goal was to conduct a small-scale CO2 injection experiments at a geologically isolated site with suitable brine formations. Subsequent monitering of the movement of CO2 and the interaction between injected CO2 and the brine/sandstone were the main focus of the experiment . It was hoped the phase 2 tests will demonstrated the feasibility of injecting CO2 into brine reservoirs, as well as generating data towards understanding the behavior and mobility of CO2 cloud post injection, thus lead way to future large scale testing.
The testing site was chosen at Liberty County northeast of Houston. CO2 was provided from the nearby power generation plants and was injected over a period of 100 days, followed by a one year period of observation and data collection. It was the first of these kind of tests ever conducted in the U.S. . Data collected during the one year monitoring period provided valuable information on the post injection condition of brine reservoir as well as the movement pattern of injected CO2 cloud. While concerns were raised on the acidification and mineral leaching observed during the experiment, the overall assessment was rather confirming . More importantly, the success of these first round of experiment lead way for the subsequent testing conducted in 2006 and the long-term project received in 2007.
CCS is currently a much debated area not only due to concerns with the science of the technology, but also its economic feasibility. It is often argued that all of our efforts and capitals should be invested in developing new sources of energy to replace carbon based fuels all together. Therefore, CCS, which is and effort that potentially minimizes the damage of this “lost-cause” fuel source, should be abandoned along with it. However, since it’s doubtful that fossil fuel will be replaced overnight by any of the alternative energy currently under investigation, CO2 is still being emitted from these fossil fueled power plants daily. The question is how much economic and research efforts we are willing to pay for the environmental impact of these emissions.