Cities worldwide are exploring solutions to address the impact of climate change, reduce pollution, and improve people’s health and well-being. Among many technologies and potential approaches to creating more sustainable urban environments, biochar is emerging as a powerful tool that has the potential to transform urban areas into greener spaces.
What is Biochar?
Biochar is a natural charcoal carbon product made from biomass, or organic waste material, partly combusted without oxygen. The biochar process, called pyrolysis, involves heating organic material to high temperatures, resulting in a stable form of carbon. The quality of the material is determined by what is used in its production, including materials such as manure, corn stalks, or feedstocks, and the temperature at which it combusts. The resulting carbon can exist in the environment for thousands of years, storing carbon and improving soil quality.
Indigenous Amazonians historically used biochar as part of Terra Preta de Indio, a porous topsoil that retains nutrients and water. Today, its usage has expanded beyond soil remediation and improvement; its unique properties, including porosity, carbon content, and high surface area, make biochar an invaluable asset in urban sustainability efforts.
Fighting Climate Change by Sequestering Carbon
A significant challenge facing modern society is the rise in carbon dioxide (CO2) levels in the air, contributing to climate change and global warming. Biochar offers a potential solution by acting as a carbon sink. The creation of biochar reduces CO2 in the atmosphere as the carbon-neutral process of decomposing organic matter becomes carbon-negative. The carbon that plants absorb, grow, and emit upon decay is stabilized by biochar, sequestered out of the atmosphere, and stored in the soil for years.
A study published in Nature Communications found that biochar production could offset around 12 percent of greenhouse gas emissions. Because the process of its creation can be slowed down or sped up depending on the temperature at which it is heated, it may be the fastest and most realistic option for atmospheric carbon sequestration. Converting biomass into biochar stabilizes the carbon, preventing its immediate release. Integrating biochar into urban landscapes, such as parks or green spaces, can store significant amounts of carbon for centuries, reducing the urban carbon footprint.
Reducing Urban Pollution and Enhancing Green Spaces
Urban areas often struggle with pollution in various forms, particularly water and air pollution. Research shows that urban environments account for 75% of global carbon emissions. Fortunately, there are several ways that biochar can be leveraged to help reduce the amount of environmental pollution that occurs in urban locations.
Water Filtration
Due to its porous nature, biochar can act as a filter by absorbing pollutants from the air and water. For example, its use in water filtration systems will capture heavy metals, harmful particles, and other contaminants, improving the environment for city dwellers. Because of biochar’s high absorption levels, biochar filters are improving the efficacy of environmental wastewater treatment.
Additionally, biochar can effectively complement a “sponge city” design concept, where flooding damage is reduced by maintaining natural landscapes and using porous materials. Utilizing natural land patterns along with the porous nature of biochar helps slow water movement during heavy rains and flooding, limiting the amount of destruction that would typically occur.
Green Roofs
Another way charcoal can reduce urban pollution while enhancing green spaces is by incorporating it into climate-change-resilient construction, specifically green roofs. Rooftop gardening is becoming a popular eco-friendly method of reducing rainwater runoff, absorbing harmful gases and particulates, and saving energy consumption. It also improves the area’s natural ecology by providing new habitats for wildlife.
Creating a successful rooftop garden is challenging due to thin soil layers, high temperatures, and limited water, which significantly impact the survival and growth of its plants, shrubs, and flowers. However, applying biochar can improve soil properties and quality, successfully allowing green roofs to enrich urban biodiversity while adding to a city’s aesthetics.
Supporting Urban Green Spaces
The advantages also extend to enhancing urban green spaces. Its application in soil improves water retention and supports microbial life while reducing nutrient loss, making biochar essential to developing urban green spaces such as urban forests, tree beds, parks, and gardens. Increasing green spaces in urban areas contributes to more than just an improved environment; it also improves people’s lives. A paper in The International Journal of Environmental Research and Public Health found that various tree species in urban environments reduce people’s stress, improve mental health and cognition, and contribute to lower crime rates and fewer instances of war.
Biochar carries nutrients to support plant and tree growth and health, making it an ideal addition to municipalities looking to increase treescapes. For instance, Stockholm, Sweden, was one of the first cities to use a biochar-gravel-soil mix to improve the health and survivability of urban trees. The result was younger trees that grew faster and stronger than older ones. A biochar-gravel mix is currently used to support trees growing near pavement, which endangers trees’ health by limiting the amount of oxygen and water to their roots. Biochar’s porous nature means it is resistant to compaction and compression while it retains the water and nutrients urban trees need to survive.
In cities with limited space, biochar can help maximize green spaces’ environmental and aesthetic advantages, ranging from pocket parks to larger green belts. These improved areas support biodiversity while providing residents opportunities to connect with nature amidst the busy city life.
Improving Urban Resilience
The increasing effects of climate change, including more severe and frequent weather events and natural disasters, pose significant dangers to cities. Using biochar can enhance an urban area’s resilience to these risky events. Biochar can bolster a city’s environmental strength in these ways:
- Improving soil health, which allows urban plants and trees to withstand extreme weather conditions, such as droughts or heavy rainfall;
- Improving water retention capabilities contributes to more efficient stormwater management, reducing the risk of flooding and runoff.
These qualities are critical to cities looking to adapt to climate change while minimizing the disruption to urban life.
Paving the Way Forward
Despite its benefits, incorporating biochar into urban planning and sustainability strategies is in its early stages. Municipalities must address potential barriers like production costs, logistical challenges, public education, and lack of awareness. However, recent pilot projects and research studies are proving the feasibility and advantages of biochar, paving the way for its acceptance in environmental conservation.
Cities like Stockholm that have experimented with biochar are observing successful results. Implementing biochar into urban green projects has demonstrated increased soil health and carbon sequestration. Similarly, municipalities using biochar for purifying air and water yield positive outcomes, making biochar a vital component in revolutionizing tomorrow’s cities today.
Moving Toward Greener Urban Environments
As cities grow and confront the challenges of climate change, innovative solutions like biochar provide hope for a greener future. Embracing biochar demands action from communities, businesses, researchers, and policymakers. Through a combined effort, these parties can transform urban cities into pillars of sustainability and resilience for future generations to emulate. Investing in biochar and other green technologies will be increasingly necessary to help ensure the creation of livable and resilient urban areas.
Amanda Winstead is a freelance science and technology writer. You can follow her work online at her website.