The Revolutionary Potential of Carbon Capture
Carbon capture and storage (CCS) encompasses a range of technologically advanced processes designed to mitigate the progression of climate change. This approach entails two primary phases: carbon capture, which generally reduces carbon dioxide emissions from large point sources such as fossil fuel power plants, and storage, which involves the secure sequestration of captured carbon in underground geological formations or its utilization across diverse industrial sectors.
While not a permanent solution to cease precautions surrounding fossil fuels, CCS still plays an invaluable role as a transitional technology that can help reduce emissions in carbon-intensive industries and bridge the transition to renewable energy sources.
As the climate crisis intensifies with rising sea levels and extreme weather events, implementing CCS solutions at a pertinent scale is becoming increasingly urgent to hopefully avoid the most catastrophic impacts of climate change.
There are three main approaches that scientists are developing to capture carbon dioxide emissions: post-combustion capture, pre-combustion capture, and direct air capture.
Post-combustion capture involves treating the flue gases exiting a power plant or industrial smokestack to separate and isolate the CO2 content, preventing its release into the open air. Common techniques use chemical solvents that bind to carbon dioxide at certain temperatures and pressures, allowing it to be removed from the treated exhaust.
Specifically amine-based absorption, which employs amines like MEA which bind with CO2 in flue gases. Contact with the amines enables CO2 isolation by compound formation. Heating then regenerates the solvent by releasing captured CO2, allowing it to be reusable again and capture more emissions. This extensively researched amine method separates and stores carbon dioxide from power plant smokestacks.
Pre-combustion capture works by processing the fuel before it undergoes combustion using gasification. This converts the carbon-containing material into carbon monoxide and hydrogen, which are then reacted through the water-gas shift reaction. This separates and concentrates the CO2 before the remaining synthesis gas is burned for power or heat, sidestepping the need for post-treatment.
While useful for large stationary emitters, direct air capture (DAC) is another approach that has recently been gaining traction. Its approach involves pulling carbon dioxide directly from ambient air. This can be accomplished in two main ways: either using chemical gradients to pull CO2 from the air that blows through a carbon-capturing solid or reacting it with solvents that scrub it from broad volumes of air.
Innovative companies are spearheading the establishment of DAC facilities, which are designed to efficiently extract CO2 from the surrounding air on an industrial level. These facilities employ advanced filtration systems to capture the carbon, which is then compressed and transported through pipelines for secure storage or potential utilization in other applications.
Scientists and engineers have been exploring innovative ways to utilize and store captured carbon dioxide for beneficial purposes rather than just keeping it secure underground.
The production of cement is notorious for its egregiously high carbon output with it being responsible for nearly 8% of planet-warming emissions. One approach being researched is substituting a portion of the cement used in concrete production with captured CO2 in its solid mineral form of calcium carbonate. As well as utilizing captured carbon dioxide in the production of cement, studies indicate that this can strengthen the resulting concrete while also reducing the substantial CO2 emissions from cement manufacturing.
Captured carbon dioxide exhibits potential as an aggregate material suitable for constructing foundations and road bases, a layer of material placed on the subgrade serving as a foundation for the road. Instead of releasing CO2 into the atmosphere, innovative construction practices are being developed to incorporate the greenhouse gas into infrastructure projects, thereby enabling its long-term storage. Early projects in Canada by CarbonCure Technologies introduced its enhanced concrete while sequestering carbon long-term in infrastructure.
Innovative advancements are taking place in the field of converting captured CO2, along with sustainably produced hydrogen, into synthetic liquid fuels. This process involves the use of specialized reactors and holds immense potential. By utilizing this transformative approach, it becomes possible to produce drop-in gasoline, diesel, and jet fuels that closely resemble traditional fossil fuels in terms of their benefits.
One study from German climate non-profit Agora Energiewende projected that producing synthetic fuel, with its capacity matching just 10% of today's aviation fuel demand, could utilize over 1.2 gigatons of CO2 per year by 2050. That's equal to roughly a quarter of annual emissions from all US economic activity today.
Importantly, this method also addresses the concern of adding new CO2 emissions to the atmosphere during fuel combustion. Taking into account the diminishing global fuel resources and the tightening of environmental regulations, the widespread adoption of synthetic e-fuels derived from direct air capture has the remarkable ability to significantly reduce our reliance on conventional oil consumption on a large scale.
Spearheading this are companies that are developing scalable technologies to cost-competitively produce carbon-neutral jet fuel and diesel to power heavy transport sectors. If produced globally, synthetic fuel facilities utilizing atmospheric CO2 could sink billions of metric tons of carbon from the atmosphere while securing the future sustainability of vital industries like aviation and shipping.
Although capturing and converting CO2 into liquid fuels faces challenges around efficiency and high production costs, the field of carbon capture continues advancing at a tremendous pace. Researchers and private companies are making breakthroughs that bring these challenges to rest.
To help overcome these hurdles, scientists at several international laboratories have been working on novel methods of converting captured CO2 into a dense, powdered form classified as energy pellets. These synthetic energy pellets are composed mainly of carbon and hydrogen and can be readily transported and stored.
The process involves using renewable electricity to power hydrogenation (using hydrogen gas to reduce compounds by adding hydrogen molecules to carbon-carbon double or triple bonds in hydrocarbon chains through a catalytic reaction) reactions that convert CO2 gas into long chains of solid hydrocarbons at low temperatures while also keeping it cost-competitive.
If further developed, energy pellets present a promising avenue for transforming carbon into a functional commodity. These pellets have the potential to greatly enhance the economic viability of carbon capture projects by facilitating the cost-effective transportation and sale of CO2 in a highly condensed pelletized form.
While carbon capture and storage won't solve climate change alone, it serves an important role in curbing emissions from industries that will be challenging to fully decarbonize like cement production, oil refining, and steelmaking.
CCS buys the world time to combat the inevitable effects of climate change and allows renewable energy technologies to continue advancing to meet more of our needs.
There's no single approach that will work everywhere, which is why developing the full portfolio of CCS technologies is so critical. Entrepreneurs continue exploring new ways to commercialize captured carbon as a product.
While significant progress still lies ahead, the future prospects for carbon capture technologies are distinctly auspicious.