Uses for Leftover Coffee

Coffee’s place at the top of the flavor heap (or at least near it) is tough to contest. Which makes it all the more ironic that every day, Americans throw away thousands of pounds of used—but still flavorful—coffee grounds.

While you wouldn’t reuse them for another cup of coffee, what most people don’t realize is there are at least a dozen worthwhile destinations for those grounds (not to mention unfinished coffee).

In-house Recycling
If your coffee (and your desire for coffee) has cooled to room temperature, simply cap it and refrigerate it for a few hours. Few people enjoy tepid coffee, but almost everyone loves it iced, especially during hot summer months. You can also use leftover coffee to make everything from mocha frosting to chipotle mole sauce for your fried eggs.

Better yet, leftover coffee grounds have enjoyed a recent renaissance in recipes for cookies, cakes and even spice rubs for steak.

Let’s Get Practical
Coffee grounds are actually one of the most versatile substances sitting in your kitchen, and have a myriad of household uses. To start with, they have amazing deodorizing power—stick a bowl in your fridge or freezer to neutralize all the lingering smells that have accumulated from storing food through the winter months. Possibly the most creative repurposing idea is to use them in an easy, DIY all-natural pesticide—the insects don’t like the acids contained in all coffee beans, but your flowers and plants don’t mind at all. In fact, the grounds contain a fair amount of nitrogen and you can also use them as fertilizer.

For the more adventurous, they can also be used to make homemade soap (your skin actually absorbs the caffeine while you shower), candles (for that lovely fresh-roasted coffee scent) and as a super-natural body scrub (it turns out coffee grounds have just the right level of abrasiveness for some heavenly-scented skin exfoliation).

If you don’t have the energy for a DIY project, it’s always a sustainable choice simply to compost your used coffee grounds—they’re just plants after all, and they provide a nice balance for the fruits and vegetables you’re likely tossing in around them.

The Science of Leftover Coffee Grounds
Advanced bioscience is taking coffee grounds in some truly incredible directions. A company called UTZ Certified is helming a project that generates energy through treating wastewater from industrial-scale coffee mills. The project is headquartered in Latin America, which produces 70% of the world’s coffee, and the company is seeing significant improvement in reducing climate change and converting the wastewater into natural biogas, which then can be used to power households and coffee plants.

In London, a new start-up company at the heart of the green energy movement called Bio-bean has developed a process that converts the waste materials from brewing coffee into a type of biofuel that can actually power vehicles and homes. This in turn leads to less reliance on conventional fossil fuels to supply energy.