Carbon capture technology is used to capture and store carbon and it is the process of capturing waste carbon dioxide (CO2), transporting it to a storage site, and depositing it where it will not enter the atmosphere.
Carbon capture technology is designed to capture CO2 emissions from the combustion of fossil fuels. It can absorb 85-95 percent of CO2 emissions in the atmosphere.
How Does Carbon Capture Work?
Capturing CO2 is most effective at point sources, such as large fossil fuel or biomass energy facilities, natural gas electric power generation plants. When we talk about carbon capture, there are three things we need to focus on:
- Capturing CO2 from emissions or from the atmosphere and making it transportable.
- Transporting CO2 to places that can use it or sequester it.
- Sequestering or otherwise using the CO2.
Capturing carbon from emissions or the atmosphere typically uses things called sorbents, which are typically ceramic filters that allow smaller O2 and NOx molecules through, but capture larger CO2 molecules. This is fairly inefficient in practice, but very modern and expensive sorbents achieve 95% capture in laboratory settings.
The sorbents then go through another cycle which causes them to emit the captured CO2 in a controlled way where it can be captured. Corning’s ceramic sorbents, for example, are dunked in 100 degree Celsius water.
This process involves powering fans to push the gases through the sorbents, then a mechanical process of moving the sorbents to the release mechanism, then more energy to cause the sorbents to release the CO2. This isn’t energy-efficient, it’s actually fairly energy-intensive.
When transported by pipeline, CO2 is typically transported as a gas. When transported by truck or rail car, CO2 is typically liquified by refrigerating it and keeping it cold. This process of refrigeration is energy-intensive as well.
While there are a lot of CO2 pipelines in the USA, for example, none of them run from coal or gas plants to places that use large volumes of CO2. As a result, any discussion of carbon capture runs into the logistical nightmare of vastly increasing the number and length of CO2 pipelines.
Sequestering or using CO2
The vast majority of CO2 is used in enhanced oil recovery fields where the CO2 is pumped underground in order to liquify sludgy oil and push it to the other end of the oil field where it can be pumped out.
Any carbon captured from coal or natural gas plants would almost certainly be used to pump even more carbon out from underground in the form of oil to be turned into petroleum or diesel.
Another form of sequestration is mineral carbonation, which pumps carbon into seams where other chemicals it will bond with exist so that it turns into a solid have no economic value except getting rid of the carbon. Pumping carbon into disused mines and other underground sinks without enhanced oil recovery benefits also has no economic value except getting rid of the carbon.
Examples of Carbon Capture Technology
Scientists are exploring new ways to remove and store carbon from the atmosphere using innovative technologies. Below are a few carbon capture techniques that have the potential and have been explored.
Direct Air Capture
Climeworks and Carbon Engineering for example capture carbon dioxide directly out of the atmosphere. This helps remove the large quantities of CO2 emitted in the past that remains trapped in our atmosphere.
Carbon Engineering builds Direct Air Capture facilities using a potassium hydroxide solution to bind with the CO2 molecules drawn in by the fans, that will capture one million tons of CO2 per year each – which is equivalent to the work of 40 million trees. The air is released back into the atmosphere with much lower – although typically not zero – carbon dioxide levels.
Biochar is charcoal that is produced by pyrolysis of biomass in the absence of oxygen. According to studies is believed that biochar can be used as a solution to the CO2 problem. When the plant is left to compost, it produces CO2, but if it is turned into biochar, and then added to soil, can absorb CO2.
Researchers have estimated that sustainable use of biochar could reduce the global net emissions of carbon dioxide, methane, and nitrous oxide by 12%.
Turning Carbon into Fuel
Researchers in collaboration with the U.S. Department of Energy’s National Renewable Energy Laboratory have directly converted carbon dioxide from the air into methanol at relatively low temperatures. They discovered a metal carbide nanoparticle (a compound of carbon and metal) that can convert CO2 into fuel.
Their work was published in the Journal of the American Chemical Society.
CO2 Capture by Microalgae
An alternative to geochemical injection would instead be to physically store carbon dioxide in containers with algae or bacteria that could degrade the carbon dioxide. Using this bacteria would prevent the overpressurization of such theoretical carbon dioxide storage containers.
Many research studies have shown a positive impact of growing microalgae under high concentrations of CO2, and reporting increased carbon bio-fixation and biomass productivity
Organisms that produce ethanol by fermentation generate cool, essentially pure CO2 that can be pumped underground.
Liquefied CO2 is injected into wet concrete and chemically reacts with calcium ions released from cement to form solid, nano-sized calcium carbonate particles that become permanently bound within the concrete.
CarbonCure manufactures technology for the concrete industry that introduces recycled CO₂ into fresh concrete to reduce its carbon footprint without compromising performance.
This method involves injecting carbon dioxide, generally in supercritical form, directly into underground geological formations. Oil fields, gas fields, saline formations, unmineable coal seams, and saline-filled basalt formations have been suggested as storage sites.
Turning Carbon to Rock
In Iceland, a team of international researchers has successfully demonstrated that CO2 emissions can be pumped underground and altered chemically to form solid stone. The successful experiment took place at the Hellisheidi geothermal power station, about 30 kilometers from the the Icelandic capital of Reykjavik.
In this process, CO2 exothermically reacts with available metal oxides, which in turn produces stable carbonates. The economics of mineral carbonation at scale are now being tested in a world-first pilot plant project based in Newcastle, Australia. New techniques for mineral activation and reaction have been developed by the GreenMag Group and the University of Newcastle.
Turning Carbon into Fibers
Dr Stuart Licht of George Washington University has developed a novel method to economically convert atmospheric carbon dioxide directly into highly valued carbon nanofibers.
The nanofibres have multiple industrial uses for industrial and consumer products that included replacing metal in cars and airplanes, wind turbines, battery manufacturing, and construction.
“We calculate that with a physical area less than 10% the size of the Sahara Desert, our process could remove enough carbon dioxide to decrease atmospheric levels to those of the pre-industrial revolution within ten years,”Dr Licht said.
Researchers at KIT have developed a way to convert carbon dioxide into graphene, using a copper-palladium catalyst. It uses CO2 as a carbon source, giving it the potential added benefit of removing this harmful gas from the atmosphere. Graphene has the potential to be widely used but currently is used to create screens for smartphones and other tech devices.
We need to recycle all our wastes to prevent pollution, recover necessary materials and get the hydrocarbons we will still need in a primary solar and wind energy system. Chemicals, grid reserve generators fuels, and air and sea long distances will all need hydrocarbons fuels for a while.