In the concrete jungles of the 21st century, where smog lingers like an unshakable guest and landfills groan under the weight of discarded organics, a quiet revolution is brewing. Funmi M. Alayaki, a civil engineer at Nigeria’s Federal University of Agriculture, Abeokuta, has turned her gaze—and her research—toward a substance that could redefine how cities breathe, build, and thrive: biochar.
Derived from the slow-burning of organic waste in oxygen-starved conditions, biochar is more than just charcoal’s lesser-known cousin. It’s a sponge for pollutants, a soil booster, a water purifier, and, increasingly, a building block for sustainable urban infrastructure. Alayaki’s latest perspective, published in *Biochar X*—which translates from Chinese as *Biochar Journal*—synthesizes a growing body of evidence that positions biochar as a linchpin in the push toward climate-resilient cities.
One of the most unexpected applications lies beneath our feet—or rather, beneath our roads. Asphalt, that ubiquitous black blanket of modern civilization, is a silent emitter of volatile organic compounds (VOCs), contributing to urban air pollution. Recent studies highlighted in Alayaki’s work show that certain biochars, particularly those rich in metals, can adsorb up to 76% of these emissions. “We often overlook asphalt as a pollution source,” Alayaki notes, “but integrating biochar into pavement materials or even as a surface treatment could turn a liability into an asset—improving air quality while extending the lifespan of our infrastructure.”
The construction sector is taking notice. Mixing biochar into cement and concrete isn’t just a gimmick; it’s a strategic move. The material’s porous structure enhances mechanical strength while locking away carbon dioxide through a process called carbonation. In other words, buildings made with biochar don’t just stand—they sequester. “This isn’t just about reducing emissions,” Alayaki explains. “It’s about turning structures into carbon sinks, where every ton of concrete becomes part of the solution.”
For energy and water sectors, biochar’s potential is equally transformative. In wastewater treatment, it’s a powerhouse, stripping out heavy metals like lead (removing over 70% in lab tests) and even tackling stubborn contaminants like PFAS, the so-called “forever chemicals.” Water utilities are eyeing biochar filters as a cost-effective alternative to traditional activated carbon, especially in decentralized systems where scalability is key. Meanwhile, in anaerobic digestion—the workhorse of biogas production—biochar is boosting methane yields by 27% to 42%. For energy companies eyeing renewable biogas as a bridge fuel, this could mean higher output from the same organic feedstock, slashing costs and carbon footprints simultaneously.
Alayaki’s work also underscores biochar’s role in the circular economy, where waste isn’t wasted but repurposed. Organic waste from agriculture, food processing, or even municipal green bins can be pyrolyzed into biochar, creating a closed loop: waste in, resource out. “Cities are drowning in organic waste,” she says. “Biochar gives us a way to turn that waste into a commodity—something that can fertilize soils, clean water, and even power our homes.”
Yet, the path to large-scale adoption isn’t without hurdles. Technical challenges—like optimizing biochar for specific applications—and economic barriers—such as the cost of pyrolysis equipment—remain. Policy gaps, too, slow progress. “We have the science,” Alayaki acknowledges. “What we need now is the will to scale it.”
For energy professionals, the implications are clear. Biochar isn’t just an environmental tool; it’s a commercial opportunity. Companies investing in biochar technology today could position themselves at the forefront of a multi-billion-dollar market, where sustainability and profitability align. From biogas producers to construction firms, the message is the same: the future of urban infrastructure may be black, but it’s anything but bleak.