Somewhere under a patch of ordinary garden soil, billions of bacteria are quietly going about their work eating organic matter, releasing electrons and, in doing so, producing a weak but constant electrical charge.
For most of human history, that energy simply disappeared into the Earth without anyone noticing. A British startup called Bactree, which emerged from the University of Bath, is trying to change that. The company developed a device it called “Bacteria,” which is a microbial fuel cell in the soil that captures the electrons that bacteria naturally release into the ground and converts them into usable electricity. The technology, founded on the doctoral research of chemical engineer Dr. Jakub Dziegielowski, is designed to be buried and forgotten and then quietly generate power for the next 25 to 30 years without any maintenance at all.
How soil microbial fuel cells harness bacterial electricity from the Earth
The science behind the Bactery device isn’t new in principle, but getting it to work reliably in real outdoor environments was the hard part. Soil microbial fuel cells work by exploiting a group of microorganisms called electrogenics, or exogenous electricity-generating bacteria, which, as a natural byproduct of consuming organic compounds in the soil, release electrons out of their cells. Genera such as Geobacter and Shewanella are among the best-known examples, and are found naturally in soils throughout the world.
The bacterial device captures these freely available electrons using electrodes, an anode buried in the soil to absorb the electrons, and a cathode exposed to the air at the surface. The soil itself simultaneously serves as a fuel source, electrolyte, and medium that carries microbial activity, meaning no membrane, pumps, or complex chemical inputs are required. As a comprehensive review of the mechanisms of microbial fuel cells published in the International Journal of Energy Research explains, bacteria inside these systems metabolize organic substrates through standard biochemical pathways and produce electrons that flow through an external circuit (the same basic principle that underlies all electricity generation, only with microbes doing the work instead of combustion or photovoltaics).The University of Bath team, including Professor Mirella Di Lorenzo, who co-founded Bactery alongside Dziegielowski and Dr Ben Metcalfe, successfully field-tested an early version of this approach in 2019 at a primary school in Icapui, Brazil, where stacked soil fuel cells produced enough electricity to disinfect three liters of water a day.
Bacteria Device Design: Bury it, forget it, collect energy for decades
The practical design of the bacteria unit is part of what makes it so interesting.
The device is roughly the size of a small box about six by six inches, and installation requires nothing more complicated than digging a hole, placing the unit in it with the same soil that came out, and covering it again. Within a few days, a natural biofilm of electroactive bacteria forms inside the reactor, and it begins generating power on its own.According to the University of Bath’s official announcement, the device has an expected lifespan of over 25 years and an expected cost of around £25 per unit with no maintenance expenditure which the company describes as an ‘install and forget’ function.
There are no moving parts, no fuel that needs to be replaced, and it is not weather dependent. Unlike solar panels, which stop producing when the sun goes down, or wind turbines, which need wind, a soil fuel cell works as long as the microbial ecosystem underneath remains active, which isn’t really a concern, since soil bacteria have been doing this for billions of years.Current outdoor prototypes generate about 0.2 watts per square metre, which is modest power but already enough for the agricultural applications the bacteria are initially targeting.
In laboratory settings, Dziegielowski says their systems are already operating at six times that level, and the company has set a goal of reaching 4 watts per cubic meter as a practical standard for wider home use.
Promoting smart agriculture by using clean soil energy first
The direct commercial target of the bacteria is not domestic homes, but farms. Precision agriculture increasingly relies on soil sensors, moisture monitors, and Internet of Things (IoT) devices that transmit real-time data to farmers.
The problem is running all this equipment across large rural areas where cables are impractical, disposable batteries create ongoing waste and cost, and solar panels are weather dependent and require infrastructure for installation.Research published in the journal Frontiers in Computer Science specifically identifies soil microbial fuel cells as a promising clean energy source for exactly these types of outdoor sensor networks, noting their suitability for environments where traditional energy sources are not practical.
The bacteria device is already able to meet the power requirements of low-draw agricultural sensors without any problems, according to Dziegielowski, and the company sees the farm sector as its first major deployment arena before expanding toward residential applications.This technology also appears to have a positive, rather than a neutral, impact on the soil in which it is located. The bacteria reported no depletion of soil quality in their tests, and analyzes suggest that the microbial activity encouraged by the device may benefit the surrounding ecosystem.
Soil, the company says, is a complex, self-sustaining environment that cannot be easily destabilized by the presence of graphite electrodes that withdraw a small portion of the naturally produced electrons.
Can your garden ultimately power your home?
Dziegielowski’s longer-term vision is more ambitious. Speaking to Reuters, he described a scenario in which multiple bacterial devices are installed and linked together entirely underground across a medium-sized residential park.
He said coproduction could offset a significant portion of household electricity bills, and because the system operates year-round regardless of the season or weather, it would complement solar power in a way that addresses solar power’s most obvious weaknesses.A 2024 Northwestern University study, published in the Proceedings of ACM on Interactive, Mobile, Wearable and Ubiquitous Technologies, demonstrated a soil-powered fuel cell that could power fully underground sensors without batteries or solar panels, operate in dry and wet conditions and have comparable, long-lasting technologies.
The research, which ScienceDaily described as a potential alternative to conventional batteries in low-power applications, adds independent academic weight to the direction bacteria are headed.The honest caveat is that the energy density of soil microbial fuel cells remains low compared to large-scale solar or wind power, and going from 0.2 watts per square meter to something that effectively contributes to household energy remains a real engineering challenge. But the basics are sound: bacteria already exist, already produce electrons, and have been doing so without interruption since long before humans started worrying about electricity bills.
Bactery is simply the first company to make a serious commercial attempt to collect for free what the Earth has always offered.