Beyond Emissions: The Future Conversion of CO2 as a Fuel Source

1. Carbon dioxide, Fossil Fuels: Ancient Carbon, Modern Impact

CO2, or carbon dioxide, is widely recognized as a significant contributor to global warming. Plants and trees, collectively known as biomass, play a crucial role in the carbon cycle by utilizing CO2, sunlight, and water to produce food. However, when these plant-based fuels, such as wood, are burned, CO2 is released as a byproduct. This process can potentially balance the net CO2 in the atmosphere if managed sustainably. Unfortunately, the unsustainable use of biomass fuels is a major cause of excess CO2, exacerbating global warming.

The Future Conversion of CO2 as a Fuel Source

Fossil fuels, another significant source of CO2, also originate from ancient biomass. Formed over millions of years under high pressure and temperature conditions in the Earth's crust, these fuels represent sequestered carbon from a bygone era. When burned, they release vast amounts of CO2 that had been stored for millennia, significantly increasing atmospheric CO2 levels.

The cycle of CO2 involves its transformation from ancient carbon to biomass and eventually to the fuels we rely on today. This energy use, however, comes with the environmental cost of re-releasing CO2 into the atmosphere.

To address this challenge, researchers have proposed innovative solutions to capture and store CO2, utilizing it as a feedstock for chemicals and other products, including fuels. This approach not only reduces the amount of CO2 in the environment but also helps mitigate global warming, providing a sustainable and beneficial use of CO2 for humanity.

Read: Researchers utilized tea waste to produce hydrogen fuel

2. Facts of Increased CO2 on Nature:

CO2 emissions increased by 2.7% annually, 60% higher since 1990.
IPCC: Greenhouse gases could raise temperatures by 1.1°C to 6.4°C.
To limit warming to 2°C, CO2 emissions must drop 50%.
Increased CO2 and warming could disrupt ecosystems, causing 15-40% species extinction.

3. Why Convert CO2 to Fuels?

Converting CO2 back into fuel will reduce global warming. Here's the logic behind it: Whenever carbon-based fuels are used for energy, CO2 is inevitably released. If we can convert that released CO2 back into fuel, the net CO2 evolution would become zero. This means that the amount of CO2 released would be equal to the amount converted back into fuel. This cycle of releasing CO2, converting it back into fuel, using it again, and then converting it back into fuel would continue indefinitely.

4. How Can CO2 Be Transformed into Fuel?

The fuels used in transportation include gasoline, which has a carbon chain range from C5 to C11, aviation fuel with a carbon chain range from C8 to C16, and diesel with a carbon chain range from C10 to C20. To produce these fuels, we simply need to convert CO2 into these hydrocarbons.

4.1 Synthetic Conversion of CO2 to Fuels

Various photocatalysts, metal catalysts, electrolytic techniques, and even enzymes are utilized to directly convert CO2 to fuels. In synthetic conversion, two methods are generally utilized:

a. Indirect Transformation: This approach involves converting CO2 to CH3OH (methanol) first, followed by transforming CH3OH into gasoline or diesel.

Methanol to Gasoline

Methanol to Diesel

b. Direct Transformation: This approach involves converting CO2 to CO via the Reverse Water-Gas Shift (RWGS) reaction, followed by hydrogenation of CO with H2 via Fischer-Tropsch synthesis to produce various fuels.

4.2 Biological Conversion of CO2 to Fuels

In this process, plants and microorganisms first convert atmospheric CO2 into biomass (carbohydrates, lipids, and proteins) through photosynthetic or non-photosynthetic methods. This biomass is then further transformed into fuels, also known as biofuels, such as bioethanol using synthetic approaches.

5. Current challenges for CO2 to fuel conversion

Cost Effectiveness: Ensure that CO2 conversion technologies are economically viable and competitive with older approaches.

Implementation at Industrial Scale: Overcoming hurdles while scaling up CO2 conversion technologies for wider industrial application.

Development of New Catalysts with Increased Efficiency: Researching and developing catalysts to improve the efficiency and selectivity of CO2 conversion processes.

Nutrients for Plants: Addressing the demand for adequate nutrients in CO2 bioconversion systems, particularly plant-based processes such as algae culture.

CH4 Production from CO2: Managing CO2 stability and the potential for methane (CH4) generation, which present obstacles in obtaining optimal product selectivity.

Read: Innovative or Sustainable solutions for Plastic pollution in 2024

6. Future perspectives

The growing amounts of CO2 in the atmosphere provide a huge challenge that must be handled. Converting CO2 into fuel is a possible alternative, and there is now active study in this field. Many governments are actively promoting this study inside their respective countries, urging industry to implement carbon capture and storage efforts. It is not unreasonable to expect that in the next decade, we will have modern technology for converting CO2 into fuel, which will also be employed on an industrial scale. As we approach 2050, this method is likely to be fully applied.