Can We Cut CO2 Emissions by Capturing and Valorizing Them?
The future of decarbonization may involve capturing carbon dioxide (CO2) with specific technologies and then using it to create valuable products and materials. While it might seem unbelievable, it is indeed possible.
Climate change poses significant threats to nature and people worldwide, affecting health, food security, and water supplies. Our planet has already warmed by 1.3C compared to pre-industrial times due to greenhouse gas emissions from human activities. Despite global efforts to limit warming to 1.5C, we are far off track, and every fraction of additional warming exacerbates climate change impacts.
In 2024, CO2 emissions from energy use increased by 0.8% to record levels, pushing atmospheric CO2 levels to their highest point ever. Fossil fuel combustion is the primary driver of this increase, while emissions from some industrial activities have decreased. Despite reductions in advanced economies, global CO2 emissions continue to rise due to increasing emissions in developing countries. The most polluting sectors are energy combustion, transport, and industrial processes.
Ecosystems like forests, soils, wetlands, and oceans act as carbon sinks, absorbing CO2 through biological and physicochemical mechanisms. Protecting and restoring these natural sinks is crucial, as their degradation can turn them from carbon absorbers to sources. However, natural systems alone cannot offset all anthropogenic emissions, which is where engineered solutions come into play.
Carbon Capture Technologies
Carbon capture is not a single solution but a range of technologies that work at various scales and stages of development. Current research focuses on making these technologies more efficient, using less energy, and adapting them to different types of emissions.
Some technologies capture CO2 from industrial sources before release, primarily at high-emission facilities like power plants, cement kilns, refineries, and chemical manufacturing sites. These facilities produce flue gas, a mixture of gases including CO2, nitrogen, and water vapor. Specialized separation techniques, such as chemical absorption, are used to prevent CO2 from entering the atmosphere.
Chemical absorption involves passing flue gas through a solvent containing amines, which selectively bind to CO2 molecules, effectively scrubbing them from the gas stream. The remaining gases are released, while the concentrated CO2 is trapped for transport and storage.
Other technologies extract CO2 directly from the atmosphere using liquid solvent systems or solid sorbent systems. These systems can capture CO2 from low atmospheric levels and address a broader range of sources.
CO2 Valorization Strategies
CO2 valorization involves turning it into a valuable resource rather than simply removing it. Despite its chemical stability and difficulty in transformation, advancements in chemistry, biology, and energy systems are opening up new possibilities.
Energy
CO2 can be converted into stored energy, such as fuels, using chemical, electrical, or biological processes. However, these processes require vast amounts of energy, making them viable only if the energy comes from clean, low-carbon sources like solar or wind power.
Construction
CO2 can also be used in construction materials by reacting with minerals to form stable compounds that lock carbon away for decades. While promising, challenges related to material supply, costs, and industrial integration persist.
Bio-based Products
Microorganisms, algae, and enzymes can convert CO2 into valuable products through natural biological processes like photosynthesis or metabolism. By using CO2 for growth, they produce biomass rich in proteins, fats, carbohydrates, and pigments, which can be processed into animal feed, biofertilizers, biostimulants, food ingredients, or functional compounds for cosmetics and pharmaceuticals.
Plastic Alternatives
One of the most promising bioproducts derived from CO2 are biopolymers, which can replace conventional plastics. Polyhydroxyalkanoates (PHAs) are a type of biodegradable plastic naturally produced by microorganisms. Certain bacteria can synthesize PHAs using CO2 as the ultimate carbon source.
PHAs are of great interest due to their environmental benefits and versatile material properties. They can be used for packaging, agricultural films, disposable items, and medical devices while being fully biodegradable, making them a powerful alternative to fossil-based plastics.
The BETA Technological Center is actively working on this challenge within the European project CERNET. The project demonstrates that producing PHAs from CO2 helps close the carbon loop by transforming a greenhouse gas into a long-lasting, value-added material.
Viability and Scalability of PHAs Production from CO2
While certain microorganisms can use CO2 and gases like hydrogen and oxygen to grow and store PHAs, laboratory studies show that large-scale production is challenging. These microbes grow slowly on CO2 and require complex gas systems and vast amounts of energy. Additionally, the process is still more expensive than traditional plastics, although it can be more environmentally friendly with renewable energy.
Despite the strong potential of CO2-based PHAs, further improvements are needed before widespread adoption.
Final Thoughts
Capturing and valorizing CO2 offers a promising pathway to reducing emissions while creating valuable products like fuels, construction materials, and biodegradable plastics. However, many challenges remain, particularly in energy use, microbial growth, and cost. These technologies, combined with renewable energy, natural carbon sink protection, and individual actions, could play a crucial role in achieving a low-carbon future.
For more information, visit: 3 Carbon Capture Technologies We Must Scale Up to Meet Net Zero.
