Free tools Windows power users keep installed
One-click scans. No signup required.
A 2022 study introduced a way to measure thermogalvanic cells’ heat-to-electricity efficiency using measured heat flow and electrical output. It reports results for both the electrolyte and the complete device, but it does not establish one universal efficiency for water-based cells or show that the technology is commercially ready. The study is a likely match for the headline’s subject, though the original headline’s source and date are not confirmed. Chemical Science (2022)
What water-based cells do
Thermogalvanic cells, also called thermocells, generate electrical power when their electrodes are held at different temperatures. Electrochemical reactions in the electrolyte respond to that temperature difference, producing a voltage and, when connected to a circuit, electrical output. They are being studied as a way to harvest low-grade heat, including heat that would otherwise be wasted.
“Water-based” describes the electrolyte in some designs, not a single standardized cell. Different chemical compositions and device architectures produce different electrical and thermal behavior, so one cell’s result cannot be treated as the performance of the whole category.
What the new measurement method changes
To calculate efficiency, researchers need to know both the electrical power produced and the thermal power passing through the system. Earlier approaches estimated heat flow through the electrolyte using a conductive heat-transfer model. Maria A. Trosheva, Mark A. Buckingham, and Leigh Aldous instead measured heat flux alongside electrical output, then calculated efficiency for the electrolyte and for the complete thermogalvanic device. Their 2022 paper in Chemical Science describes the method.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
#1 Best Overall
The two boundaries answer different questions. An electrolyte-only result concerns the active material; a complete-device result accounts for heat passing through the assembled cell. The latter is more relevant to evaluating a device as built, because heat can flow through parts beyond the electrolyte. Directly measuring that flow also avoids relying on a modeled estimate for this key part of the calculation.
The paper’s phrase “genuine efficiency” refers to this measurement approach. It is not proof that a thermocell is commercially useful, cost-effective, or competitive with other technologies.
Rank #2
- POTATO BATTERY KIT - This STEM science kit teaches kids about electricity with the components they need to build a DIY potato clock with voltmeter. Easy-to-follow instructions let kids get started right away, all they need is two potatoes!
- COIN POWERED FLASHLIGHT - The science experiments for kids in this kit continue with an amazing penny flashlight. Kids will construct a battery with the included "coins" and see the electric circuit come to life when they turn on the flashlight.
- ASTOUNDING SCIENCE EXPERIMENTS - This combination of STEM labs give kids the chance to learn about electrical engineering in a fun, hands-on, and memorable way. This is a great science gift for any curious kid that loves to build and explore!
- SO MUCH TO LEARN - Not only will kids make a battery and a complete electrical circuit, they'll also learn why these things work. Our detailed learning guide provides fascinating insight into the science of electricity, circuits, and more.
- AWARD-WINNING PRODUCTS - Blue Marble, winner of the Toy Association's prestigious Toy of the Year Award, proudly develops products that foster education, imagination, and creativity, with a U.S. support team to ensure a stellar experience!
Why performance figures from different studies cannot be ranked as one efficiency
Several studies report promising results for related electrochemical systems, but they use different materials, architectures, conditions, and metrics. Voltage, power density, and efficiency are not interchangeable. The figures below provide context, not a head-to-head ranking.
| Study and system | Reported result | How to interpret it |
|---|---|---|
| 2018 aqueous ferri/ferrocyanide system modified with guanidinium and urea | Seebeck coefficient increased from 1.4 to 4.2 mV K⁻¹; temperature-insensitive power density increased from 0.4 to 1.1 mW K⁻² m⁻². A prototype module demonstrated 3.4 V open-circuit voltage at an 18 K temperature difference. | These are results from a separate electrolyte and prototype study, not measurements produced by the 2022 efficiency method. Nature Communications (2018) |
| 2019 gas-containing electrolyte thermogalvanic cell | Reported power density of 4 W/m² at a 30 K temperature difference. | A different architecture and test condition; its power-density value is not directly comparable with the 2018 normalized metric. ACS Energy Letters (2019) |
| 2020 thermogalvanic hydrogel battery demonstration | Reported a 20 °C battery temperature reduction and retrieval of 5 μW electricity at a 2.2 C discharge rate. | A distinct battery demonstration, not an efficiency result for the 2022 measurement method. ACS (2020) |
| 2025 water-formation device | Reported converting nearly 30% of surrounding heat under standard conditions and a temperature-insensitive maximum power density of approximately 33.55 mW m⁻² K⁻². | A separate device and study. The reported efficiency and power-density metric should not be treated as directly comparable with thermogalvanic-cell figures without aligning definitions and test conditions. Royal Society of Chemistry (2025) |
What a useful efficiency claim needs to tell you
When evaluating a reported result, look for the measurement boundary and the conditions, not just a headline number.
Do these 3 things before closing this tab:
1Clear out junk files and repair common Windows errors2Scan for outdated or missing drivers - takes under a minute3Repair Windows errors before they cause bigger problems- Efficiency boundary: Is the value for the electrolyte alone or the assembled device? Was heat flux directly measured or estimated with a model?
- Temperature conditions: What were the hot- and cold-side temperatures, and what temperature difference was maintained?
- Electrical metric: Is the result an efficiency, a Seebeck coefficient, open-circuit voltage, or power density? Check the units and normalization before comparing values.
- Design and application: Is it a laboratory cell, a prototype module, or a system demonstrated on a particular heat source? A prototype result does not establish commercial availability.
These checks matter especially for waste-heat applications, where the temperature difference and thermal losses in the installed system can differ from laboratory conditions.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Does this mean water-based cells can power everyday devices?
The cited studies establish experimental progress, including improved electrolyte performance and several device demonstrations. They do not establish that a consumer thermogalvanic product is commercially available or that the reported laboratory results will translate directly into useful power in everyday settings. The 2022 contribution is a way to measure efficiency more directly, helping researchers assess and design cells; it is not itself a finished power source.
Quick Recap
Rank #4
- Used Book in Good Condition
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
