Unless many nations act, today’s fossil fuel activities will impact the earth–ocean–atmosphere system long into the future. The International Panel on Climate Change Synthesis Report presents information about the troubling implications of delayed action, and the Stern Review considers social ramifications. One of the portfolio of technologies now available to reduce emissions from our existing fossil fuel–based infrastructure is Carbon Capture and Storage, or CCS.
CCS involves (1) capturing CO2 from emitters; (2) compressing the CO2 to liquid-like form; (3) transporting it to a qualified site; and (4) injecting it into a deep geologic environment where it will be permanently stored in isolation from potable water, the land surface, and the atmosphere. Rather than release carbon into the atmosphere, CCS effectively closes the loop: carbon extracted from storage in geologic accumulations as fossil fuel is returned as CO2 to long-term storage in geologic systems.
Almost all roadmaps to reduce CO2 emissions have shown that, without CCS, adoption of technologies that reduce emissions decreases and the cost of reducing emissions increases. In addition to mitigating emissions from all types of fossil fuel (coal, oil, natural gas), CCS may also be the best option for handling CO2 emitted from other industrial sources, including processing natural gas; producing feedstocks for plastics; preparing fertilizer; and manufacturing iron, steel, and cement. In the quest for negative emissions, CCS could be used on biomass fuel and to dispose of CO2 captured directly from air.
At the Bureau of Economic Geology at The University of Texas at Austin (UT), our team of researchers and students at the Gulf Coast Carbon Center test, validate, and optimize geologic storage of CO2 as part of CCS. Our research is designed to systematically probe questions and concerns about CCS, including: What limits the capacity of the subsurface to accept CO2? Will CO2 spill out or will injection overpressure the system and cause unacceptable seismicity? Where is the best location to inject? How do we test before, during, and after injection to determine if the system is performing as planned? If an error in engineering or operation is made, what could happen to protected resources? How can we quickly and effectively detect and mitigate any error? How much monitoring is enough? This work is undertaken so that CCS is researched as carefully and methodically as other new societal products (for example, medicine, infrastructure, vehicles) to ensure proper performance.
We conduct field studies to assess diverse aspects of geologic storage for CCS, from optimization of site selection to monitoring the response of the subsurface reservoir to CO2 using geophysical and geochemical methods. We have studied the impacts of CO2 injection on rocks at depths of more than 10,000 ft as well as on groundwater and soil at depths of only a few feet. We have worked at locations as close as our university’s field lab and as far away as Australia. To create robust and transparent outcomes, we collaborate with researchers from all over the United States and the world, learning from the best technologists and sharing what we discover with global energy consumers.
We find, in agreement with our colleagues, that CCS is technically ready to go today. CO2 capture, transportation, and injection are mature technologies. Injection can be conducted safely and with a high certainty that storage will be effective. The risks of CCS to humans and ecosystems, groundwater, and the atmosphere are lower than the risk of inaction on climate change. And the tools to manage risk are also mature and available; the U.S. EPA already has in place regulations to require proper site selection, engineering, and sustained monitoring. Geologically appropriate space within porous rocks is of sufficient volume to accept CO2 at the scale needed to play a key role in reducing emissions.
The missing step that limits progress is the willingness of energy consumers to act to mitigate CO2 created during combustion. As consumers of goods and fresh water, we demand and pay for proper processing and recycling or disposal of trash and wastewater. We need a similar commitment to capture and recycle or dispose of the products of fossil-fuel combustion.
CCS can also incentivize a host of other mitigation practices. Starting mitigation of available and relatively low-cost fossil fuels provides economic motivation for other CO2 reduction activities, including conservation, efficiency, and switching to low-carbon alternatives.
Global climate change has consequences for agriculture, infrastructure, political stability, and environmental and public health. With CCS, meaningful, verifiable, technically feasible, and permanent reductions in atmospheric greenhouse-gas emissions can be achieved in the short term and will be less costly than if we don’t use CCS. We stand at a crossroads: atmospheric emissions will either continue to increase, or we can act now to reduce them.
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Dr. Susan Hovorka is the Principle Investigator of the Gulf Coast Carbon Center, Bureau of Economic Geology at The University of Texas at Austin. She is a sedimentologist who works on fluid flow in diverse applications, including water resource protection, oil production, and waste storage. She has led a team working geologic storage of CO2 since 1998, with a focus on field studies, monitoring, and capacity estimation.