Your Cheese Habit Is Now a Battery

You probably don’t think about “waste” when you’re eating a slice of cheddar. But the cheese industry has a massive environmental secret: for every one pound of hard cheese produced, about nine pounds of liquid whey are left behind.

This isn’t just water. This leftover “acid whey” is an environmental nightmare, an organic-rich sludge that can starve rivers of oxygen if dumped. For decades, dairies have paid to have it trucked away or spent energy processing it into protein powders. But what if there was a better way?

What if we could use this waste to generate power?

A new study published in the journal Fermentation in April 2025 details a wild proof-of-concept: turning raw cheese whey directly into electricity using a “bacteria battery.”

Meet the Microbial Fuel Cell

The technology is called a Microbial Fuel Cell, or MFC. It’s a bio-electrical device that harnesses the metabolism of bacteria to create an electrical current.

It’s simpler than it sounds. Think of it like a normal battery, but with a living “bio-anode”:

  1. The Anode (Negative Side): This is where the magic happens. You have a chamber filled with cheese whey (the “fuel”) and a community of bacteria. The bacteria “eat” the organic pollutants in the whey.
  2. The “Exoelectrogens”: As part of their metabolic process (literally, “breathing”), these special bacteria, known as exoelectrogens, need to get rid of electrons. In a normal pond, they’d dump them onto oxygen or minerals in the water. But in an MFC, they are incentivized to dump them directly onto a conductive anode (like a piece of carbon).
  3. The Circuit: Those harvested electrons now flow out of the anode, through an external wire (where you can power something, like an LED), and over to the cathode.
  4. The Cathode (Positive Side): The electrons arrive at the cathode and combine with protons (which migrated from the anode) and oxygen (from the air) to create the most harmless byproduct of all: plain water.

The result? The bacteria get to “eat” the pollutants, and you get electricity as they do. It’s waste treatment and power generation rolled into one.

The 2025 Whey-to-Power Experiment

While MFCs have been around for a bit, using them on raw, messy, industrial-grade cheese whey is new territory. That’s what a team of researchers in Peru set out to do.1

They built a set of 800 mL microbial fuel cells, hooked them up, and poured in raw whey from a local dairy. The results, tracked over 18 days, were impressive for a first run.

First, the “power” specs: The cells produced a peak voltage of over 800 mV and a maximum power density of $1.585 \text{ mW/cm}^2$.2 While that won’t charge your phone (yet), it’s a solid proof-of-concept. The team showed that by stacking just a few of these cells in series, they could generate over 2.14 V 2—enough to power small sensors.

Second, the “waste” specs: This is arguably more important. In just over two weeks, the “bacteria battery” had eliminated 70% of the chemical oxygen demand (COD).3 In simple terms, it took a potent, toxic pollutant and made it 70% cleaner.

The Microbial “Who’s Who”

The researchers didn’t just measure the power; they used metagenomic analysis to see which microbes were doing all the heavy lifting.2

The “workforce” was dominated by two main groups: Bacteroidota (48%) and Proteobacteria (30%).

This pairing is key. The Bacteroidota are known as expert “degraders” 64—they excel at breaking down the complex, tough organic molecules in the whey. The Proteobacteria, on the other hand, are the “engineers”.65 This phylum includes famous exoelectrogenic bacteria that are superstars at transferring electrons to an anode.

But the most interesting discovery was a bonus. The analysis also found microbes like Caproiciproducens.2 This bacterium is known for something very specific: it produces caproate (or caproic acid) 67, a valuable medium-chain fatty acid.

This suggests the MFC is doing a “bacterial double-dip.” One group of bacteria is breaking down whey into valuable biochemicals (like caproate), and a second group is eating that waste and turning it into electricity.2 It’s a bio-refinery and a power plant in one.

The Circular Creamery

This research is a big deal because it flips the script on dairy’s environmental footprint.2

Cheese-making is an energy-intensive business, requiring a lot of power for pasteurization, heating, and cooling.54 This new research points toward a future “circular creamery”: a dairy where the waste from cheese-making is funneled into an array of MFCs, which in turn generate electricity to help power the facility.

It transforms a dairy’s biggest liability—its waste—into its biggest asset. And it all happens thanks to a few trillion hungry bacteria, ready to turn your cheese habit into a clean battery.

References

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  • Energy and nutrient recovery from municipal and industrial waste and wastewater—a perspective - Oxford Academic, accessed November 17, 2025, https://academic.oup.com/jimb/article/doi/10.1093/jimb/kuae040/7840386
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