Neutralizing Carbon Emissions With Recycled Batteries

Carbon dioxide (CO₂) emissions have steadily increased due to industrialization and human activities, exacerbating climate change concerns. Recent efforts to convert CO₂ into valuable products like fuels and chemicals have faced challenges such as low CO₂ concentration, energy-intensive conversion, unviable conversion systems, and unwanted byproducts.

Recently, a Chinese-led team achieved a milestone by developing a method to harness CO₂, the primary greenhouse gas. This article explores CO₂'s impact on the atmosphere, the obstacles encountered in harnessing the gas, and the implications of the latest research. 

 

Carbon emissions. Image used courtesy of Pexels

 

Carbon Dioxide and a Stable Climate

Carbon dioxide absorbs and traps heat energy in the Earth's atmosphere. When sunlight reaches the Earth's surface, some energy is absorbed and re-radiated as heat. CO₂ molecules in the atmosphere absorb this heat energy, preventing it from escaping back into space and effectively warming the planet. 

Despite being present in a very small fraction (0.04%) of the atmosphere, CO2 is essential for maintaining a stable climate. However, burning fossil fuels and deforestation, have significantly increased the concentration of CO₂. The Met Office, the meteorological service of the U.K., has warned that atmospheric CO₂ levels are projected to increase more rapidly than the trajectory necessary to align with the 1.5°C global warming threshold by 2024.

 

Greenhouse effect portrayed. Image used courtesy of Wikimedia Commons

 

Even within the shift toward renewable energy sources, fossil fuels continue to play a substantial role in power generation. The considerable CO₂  emissions resulting from these activities present an opportunity. If efficiently captured, they could potentially replace some or all of the 45 million metric tons per year emitted from natural sources.

However, the primary obstacle hindering carbon capture and conversion techniques is their substantial energy demand. Methods like adsorption and reduction require significant energy input, posing a major challenge to their widespread implementation.

 

A Major Breakthrough in Carbon Dioxide Conversion

A Chinese-led team from the University of Auckland and Wuhan’s Huazhong University of Science and Technology (HUST) has recently devised an electrolysis system capable of converting CO₂ into formic acid with over 93% efficiency. 

Electrolysis entails decomposing CO₂ bonds and combining them with hydrogen to yield valuable hydrocarbons like formic acid, methanol, and ethanol. Traditionally, alkaline feedstock serves as the electrolyte, yet it generates undesired by-products such as carbonates, which can accumulate on equipment, impairing efficiency and longevity. 

To solve this issue, the key innovation is the utilization of electrolytes sourced directly from spent lead-acid batteries, representing a sustainable and eco-friendly alternative. The recycling procedure for used batteries is energy-intensive and complex, requiring incineration before extracting lead ions. Although lead is a hazardous heavy metal due to its toxicity, it is an effective catalyst in converting greenhouse gases. Repurposing these materials reduces waste and contributes to environmental conservation. 

 

Lead-acid batteries awaiting recycling. Image used courtesy of Sandia National Laboratories

 

Notably, the team’s process was proven to operate continuously for at least 5,000 hours without a major decrease in output efficiency. Moving forward, the team aims to further develop the technology for industrial use, potentially revolutionizing carbon-intensive industries and aiding decarbonization efforts.

 

Path to a Sustainable Future

According to the research team, expanding this process to an industrial scale may encounter operational hurdles like device overheating, according to the researchers. However, they aspire, through ongoing exploration, to transcend formic acid production, aiming for derivatives like ethylene. This compound, dubbed "the world's most important chemical," holds promise for diverse sectors, from textiles to antifreeze, fostering optimism for further advancements in CO₂ utilization.