Carbon Capture
By Addison Zhang
In addition to renewable energy sources and better storage, carbon capture is crucial to decarbonization and often viewed as the only practical way to achieve deep decarbonization in the industrial sector. Contrary to popular belief, carbon capture, utilization and storage (CCUS) technology has been developed and even deployed in the U.S. in the 1970s. However, CCUS usage remains far short of the 2050 Net Zero goal. Support for lower-cost industrial applications, investment in CO2 transport and storage infrastructure, and finding new commercial users are crucial in scaling up CCUS technologies.
Origin
The earliest CCUS facilities were natural gas processing plants in the Val Verde area of Texas which developed technology to separate carbon dioxide out of concentrated streams using chemical solvents. The captured CO2 was then transferred then injected into local depleted oil fields to enhance oil recovery. Only starting in the 1980s, carbon capture technology was studied for climate mitigation on a small scale. Since these early projects, CCUS deployment has expanded to more regions and more applications including pumping CO2 into greenhouses to boost plant growth. However even today, there are only under 30 commercial CCUS facilities in operation around the world which capture 40 million tons of CO2 every year.
Capture Technology
The most typical technology is post-combustion which uses chemical solvents to remove carbon dioxide out of the flue gas from fossil fuel combustion. There are also pre-combustion carbon capture technology and oxyfuel capture - which requires fossil fuel combustion in pure oxygen (rather than air) so that the exhaust gas is CO2-rich. Currently, the most advanced capture technologies are chemical absorption and physical separation. Other newer technologies include membrane separation - polymeric or inorganic devices (membranes) with high CO2 selectivity that only allow CO2 to pass through, chemical looping and calcium looping - where the calcium or chemical interacting with CO2 are used in two reactors sequentially and repeatedly in a loop.
Promising Uses
Theoretically, CO2 can be made into any kind of fuel or chemical that is based on petroleum. However, the capture and reuse process can be complex and expensive that emits more CO2 than it captures over its lifetime or simply can not compete with fuel products. Due to CO2’s nature being a stable and non-reactive molecule, it needs significant energy to react and form chemicals. Overcoming this means finding products that don’t need this energy boost, or finding less energy-intensive ways to convert CO2. There have been many efforts to encourage research on the use of captured CO2. For example, the X Prize Foundation launched a $20 million competition to award technologies that use the most CO2 to create products with the most economic value. Both winning teams developed technology relating to cement production.
Today, recaptured CO2 is primarily used to produce fertilizers and for enhanced oil recovery. Other commercial uses of CO2 include food and beverage production, cooling, water treatment, and greenhouses. Some new uses include chemical production, building materials, or even transforming carbon emissions into algae biofuels. Moreover, as many see hydrogen as the clean fuel of the future, the process where natural gas is reformed into hydrogen and carbon dioxide - where the CO2 is captured then stored - could be the lowest cost option for hydrogen production that is nearly emission free.
“McKinsey & Company estimates that by 2030, CO2-based products could be worth between $800 billion and $1 trillion, and the use of CO2 for producing fuel, enriching concrete and generating power alone could reduce greenhouse gas emissions by a billion metric tons yearly. The Global Carbon Initiative projects that, with the proper incentives, by 2030 the overall CO2 based product industry could utilize seven billion metric tons of CO2 each year—about 15 percent of our current global emissions.”