Scientists Turn Coffee Grounds into Biodiesel Fuel

Every year, billions of pounds of coffee are brewed—and billions more pounds of used grounds are tossed without a second thought. But what if those grounds could power your car? Scientists have long known coffee contains oils, but few have asked: can we turn spent coffee into usable fuel? A team of engineers decided to find out.

Yes, you can make biodiesel from used coffee grounds. Researchers extracted 15% oil by weight from spent grounds—enough, they estimate, to produce over 340 million gallons of biodiesel globally each year, using nothing more than common chemical solvents.

How Researchers Extracted Oil from Coffee Waste

Engineers Mano Misra, Narasimharao Kondamudi, and Susanta Mohapatra from the University of Nevada conducted the study. They collected 50 pounds of used coffee grounds from several Starbucks locations, dried the grounds in an oven, and then soaked them in a solvent to extract the oil. The solvent can be reused, while leftover solids can serve as fertilizer, ethanol feedstock, or fuel pellets.

Why Coffee Grounds Contain Usable Oil

Coffee beans naturally hold oil, even after brewing. According to the USDA, global coffee production exceeds 16 billion pounds annually, and those grounds retain between 11% and 20% bio-oil. The team found an average of 15% oil content in spent grounds—lower than oils from soybeans, rapeseed, or palm, but with greater stability due to higher antioxidant levels.

Can Coffee Biofuel Replace Diesel?

Not yet. While the process is energy-efficient and the resulting biodiesel could sell for around $1 per gallon, the challenge lies in collecting enough grounds at scale. Even if all global coffee waste were converted, it would supply less than 1% of U.S. annual diesel consumption. The team plans to test a small-scale pilot system next year, sourcing grounds exclusively from Starbucks and sending them to a biodiesel plant.

Frequently Asked Questions

How much oil can you get from used coffee grounds?

Researchers found that used coffee grounds contain an average of 15% oil by weight. This falls within the broader range of 11% to 20% bio-oil content estimated for coffee waste overall.

How many gallons of biodiesel can coffee grounds produce globally?

Based on over 16 billion pounds of global coffee production per year and 15% oil content, scientists estimate that coffee waste could yield more than 340 million gallons of biodiesel annually.

What’s the process for turning coffee grounds into biodiesel?

The team dried used coffee grounds in an oven, then extracted the oil using a chemical solvent. The solvent is reusable, and the remaining solids can be repurposed as fertilizer, ethanol material, or fuel pellets.

Is coffee biodiesel as good as traditional biodiesel sources?

Coffee oil has lower oil yield than soybean, rapeseed, or palm oil, but it is more chemically stable due to higher antioxidant content. The resulting biodiesel is functional, though not a complete replacement for conventional diesel.

Can coffee biodiesel fuel cars?

Yes, the biodiesel produced from coffee oil can be used in diesel engines. The researchers noted that vehicles running on it may even emit a coffee-like aroma.

Why isn’t coffee biodiesel widely used yet?

The main barrier is collection—there’s no efficient, large-scale system for gathering used coffee grounds. Even with perfect conversion, coffee-based biodiesel would supply less than 1% of U.S. diesel demand.

Recommended FrontStreet Coffee for Brewing & Sustainability

Try FrontStreet Coffee’s Ethiopia Yirgacheffe for a bright, citrus-forward cup that highlights coffee’s natural complexity—perfect for appreciating the bean before it becomes fuel. For something richer, their Brazil Queen Manor offers nutty, chocolatey notes with a heavy body, echoing the roasted flavours in coffee-derived biodiesel. Both beans are sustainably sourced and roasted in small batches. Freshly roasted within 5 days · Orders placed before 17:00 ship the same day · Next-day delivery across most of Guangdong Province.