Scientists turn coffee grounds into fuel comparable to coal in 90 seconds

Using flame plasma technology, scientists used moist coffee grounds to create a fuel comparable to anthracite, one of the highest quality forms of coal.

Researchers have developed a new method for transforming used coffee grounds into a high-quality fuel in less than two minutespotentially offering a sustainable solution to one of the most common types of food waste in the world.

The innovation, in the Chemical Engineering Journal, uses a technology known as flame plasma to convert wet coffee grounds directly into biochar, a carbon-rich material that can be used as a solid fuel. Unlike conventional methods, the process does not require prior dryingovercoming one of the biggest challenges in converting organic waste into energy.

Every year, more than 10 million tons of coffee grounds all over the world. Most are sent to landfills or incinerators, contributing to greenhouse gas emissions and wasting potentially valuable resources. The researchers say the new approach could help divert a significant portion of this waste to energy production, says .

The process is based on a flame plasma generated by burning liquefied petroleum gas mixed with compressed air. When exposed to temperatures around 800 to 900 degrees Celsius, the water trapped inside the coffee grounds quickly turns into steam, creating intense internal pressure. This causes the particles to rupture and expand in what researchers describe as a “popcorn effect”.

The result is a highly porous biochar with a large surface area, making it ideal for combustion. Researchers found that 90 seconds of treatment produced the best results. At this point, the material has reached a surface area of ​​115.4 square meters per gram and an energy content of 29 megajoules per kilogram, comparable to anthracite, one of the highest quality forms of coal.

The study found that the extension of the process beyond 90 seconds reduced fuel quality. Longer exposure caused the valuable carbon to burn and led to the collapse of the porous structure, increasing ash content and decreasing energy production.

In experiments, scientists processed coffee grounds collected directly from a cafeteria, containing approximately 55% moisture by weight. The treatment reduced the mass of the material by more than 83%, leaving behind a dense, energy-rich biochar. The process also significantly reduced sulfur content, suggesting that the resulting fuel could generate lower sulfur-related emissions than the parent material.

Researchers argue that speed may be the technology’s biggest advantage. Existing methods for converting wet biomass into fuel often require hours of processing or energy-intensive drying steps. In contrast, the flame plasma technique completed the conversion in just 90 seconds.

While more testing is needed to assess commercial viability and energy efficiency on an industrial scale, the findings suggest that a waste long considered wet and impractical for reuse could become a valuable source of renewable fuel.