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HWANGE (The Citizen Bulletin) — In Zimbabwe, a significant portion of electricity is produced from thermal power stations such as the one in Hwange, where coal is used as fuel. This process generates a substantial amount of waste, classified into three types: fly ash, bottom ash, and coal dust waste. Disposal of coal dust waste poses challenges as it can harm local livelihoods.
However, communities in Hwange are discovering that coal dust waste can be used to produce bricks or blocks for low-cost construction. These blocks are made by mixing fly ash, cement, sand, and water, while traditional clay bricks are made from natural clay, water, and sand. Using fly ash, a by-product of thermal power plants, makes these bricks an eco-friendly option by reducing waste material disposal.
The fired clay brick industry has a significant environmental footprint. Large quantities of fertile topsoil and clay are required to prepare traditional kilns, and a considerable amount of coal is needed for firing. Additionally, traditional kilns occupy vast land areas, rendering the sites unfit for agriculture after abandonment.
In Hwange, the brick-making industry is largely unregulated and unorganized, with many small-scale manufacturers using outdated production technologies. This has led to environmental degradation, local air and water pollution, and contributions to global climate change.
The rapid depletion of arable land in Zimbabwe is a pressing concern. Due to the adverse environmental impacts of traditional brick-making, transitioning to cleaner and greener alternatives is essential. One such alternative is the use of fly ash bricks. Once considered waste, fly ash is now seen as a valuable resource. Communities are recycling coal dust waste to fabricate energy-efficient bricks.
Allan Twalumba, a young entrepreneur, is turning coal waste like duff and fly ash into bricks. His environmentally friendly approach prevents deforestation for fuel in the brick-making process.
“I run a company called Twalumba Bricks, which uses coal waste to make bricks. These coal mining companies don’t care about the waste they produce, which becomes a hazard to the community and livestock,” says Allan. “At Twalumba Bricks, we focus on sustainable development in line with SDG 12, which promotes responsible consumption and production. We mix clay and coal waste to make our bricks.”
The high demand for bricks in construction has led to clay poaching and illegal brick molding, with authorities often clashing with residents. Allan, who employs eight youths, sells his bricks for 5 cents each, with 10,000 bricks translating to US$500.
For his innovative efforts, Allan won USD$20,000 in an international environmental innovation and sustainability youth competition.
“Last year, I was among the top 30 game-changers. We are expecting US$20,000 for Twalumba Bricks, which we won in a competition on brick-making innovation for youths. About 50 youths participated, but only 30 were selected,” he says.
“Once we receive the money, we plan to purchase a brick molding machine from China that can produce 40,000 bricks in two days.”
Shepherd Sibanda, another brick molder, has also adopted the use of coal waste, particularly fly ash, on a small-scale trial basis.
“I’m working near the power station’s ash dams, where I access fly ash and mix it with clay to make bricks. As a builder, I found that fly ash bricks are lighter and stronger, reducing plastering costs by 30 percent. Additionally, using fly ash productively reduces pollution of water, air, and soil. This is a new concept for us, but the lack of regulation makes it challenging.”
Shepherd Sibanda, a brick molder
Studies show that using fly ash in brick production helps mitigate the problem of waste dumping and provides a reliable solution to environmental pollution. Fly ash bricks do not require heating, cutting down emissions from coal completely. They are lighter and more robust than standard clay bricks. A mix of 50% fly ash and 50% clay produces bricks with high compressive strength, low thermal conductivity, and minimal water absorption.
For Hwange, where illegal brick molders are widespread, adopting fly ash in brick manufacturing would conserve water quality around the kilns. Traditional kilns lower the water table, hinder groundwater recharge, and increase surface runoff and evaporation, negatively impacting agricultural productivity.
The Hwange Local Board (HLB) and the Environmental Management Authority (EMA) have tried to regulate the industry by mandating cleaner technologies, but these efforts have not effectively addressed the environmental and social challenges sustainably.
Producing fly ash bricks through an energy-free process saves emissions, conserves topsoil, and limits greenhouse gas emissions, helping tackle climate change.
Climate change advocate Daniel Sithole commended using waste coal in brick-making, arguing that it is more environmentally friendly than conventional clay bricks.
“As a climate change advocate, I recommend fly ash bricks. From an environmental perspective, using coal waste in brick molding is beneficial as it repurposes waste material. However, the environmental friendliness is compromised when bricks are burnt using coal.”
Sithole, also the executive director of the environmental organization Green Shango, emphasized the need for regulated brick molding associations or consortiums to rehabilitate the environment.
“While using coal waste in brick molding utilizes waste material, burning coal for brick firing negates much of the potential environmental benefits. We need to push towards finding alternative materials.”
He adds that adopting fly ash bricks as an innovative and sustainable building material offers significant advantages over traditional clay bricks, particularly in reducing fly ash pollution in the Ingagula residential area near the Hwange Thermal Power Station.