Reengineered metasequoia wood generates electricity from water flow while cooling buildings through evaporation, offering a dual-function material tested successfully in real-world cabin trials.
(Nanowerk Spotlight) Keeping buildings cool consumes vast amounts of electricity. Air conditioners dominate the task, but they require constant power, putting pressure on energy systems and raising costs. The need is most acute in hot regions where access to electricity is least reliable. This mismatch drives a search for materials that can regulate temperature without heavy infrastructure.
One promising answer comes from wood, a material better known for strength and warmth than for advanced functionality. Inside wood lie natural networks of microscopic channels that move water from roots to leaves. Researchers have found that these channels can do more than sustain trees. With modest chemical changes, they can be used to lower temperatures through evaporation and generate electricity from water flow.
The physics is simple but powerful. When water evaporates, it absorbs heat and cools the surface it leaves behind. When water flows through very small charged channels, it drags ions with it, creating a voltage. Both processes occur naturally in wood. The challenge has been finding ways to amplify them so that they produce useful results at scales relevant to buildings.
Schematic diagram of the construction and application of a metasequoia wood-based dual-effect platform. a) Preparation of carboxylated modified metasequoia wood chips. b) Operational mechanism of the modified wood chips for power generation and cooling effects driven by water evaporation. c) Application of metasequoia wood-based green dual-effect housing with integrated power generation and energy-saving capabilities. (Image: Reprinted with permission by Wiley-VCH Verlag) (click on image to enlarge)
Metasequoia wood was chosen for its structure. Its channels are tightly packed and square in shape, providing a large contact area between water and surface. This geometry improves both water transport for evaporation and lateral flow for electricity generation. The team enhanced these properties by grafting carboxyl groups—negatively charged chemical groups—onto the channel walls.
The treatment, using citric acid and triethylamine, increased surface charge and made the wood more hydrophilic, meaning it drew in water more easily. Together these changes strengthened capillary flow and raised the voltage produced. Stainless steel mesh electrodes attached to opposite faces collected the current.
Electricity in this system arises from hydrovoltaic generation. As water containing ions flows through charged channels, ions near the surface are dragged along. This separation of charges produces a streaming potential, which shows up as a measurable voltage. Capillary action supplies the pressure needed to keep water moving, while evaporation ensures the flow is continuous. By increasing surface charge and water affinity, the chemical treatment amplified both effects.
The researchers compared several types of wood. Metasequoia delivered the highest electrical output, outperforming elm, Brazilian wood, cottonwood, and masson pine. Elm had too few vessels, Brazilian wood had low density despite large vessels, and cottonwood soaked water efficiently but failed to generate much electricity. Metasequoia’s dense, square-shaped channels offered the best combination of water uptake and voltage production.
Size also mattered. Blocks that were too short became wet on both faces, which weakened evaporation. Taller blocks suffered from higher resistance to water flow and electricity. The best dimensions were about two centimeters in height and four centimeters in length. Devices at this scale produced about 260 millivolts of open-circuit voltage and 1.2 microamperes of short-circuit current, with peak power densities of around 408 microwatts per square meter. These numbers were higher than most earlier biomass-based hydrovoltaic devices.
Performance proved stable in different environments. The devices generated power in seawater, tap water, and even dye-contaminated wastewater, with only modest changes in output. Shifts in humidity and temperature also had little impact. Arrays of several devices could be connected to increase total voltage or current, enough to charge capacitors within minutes. The stored energy powered small electronics such as lamps and calculators.
Cooling was equally effective. With an optimized water flow rate, evaporation reached about 1.37 kilograms per square meter per hour. Surfaces remained roughly six degrees cooler than surrounding air under sunlight. Thermal images showed water-fed panels about ten degrees cooler than dry panels. Inside the cabin, indoor air stayed six degrees cooler during the day and two degrees cooler at night compared with outside conditions.
Field tests in Yangzhou confirmed these results. On May 17, 2025, the cabin roof was fitted with eight connected devices. Voltages remained between 1.58 and 1.63 volts, while the indoor temperature stayed several degrees below ambient. The system maintained performance in high humidity, at elevated temperatures, and under intense sunlight.
Manufacturing is straightforward. The wood is treated with citric acid and triethylamine, rinsed, freeze-dried, and fitted with stainless steel mesh electrodes. The process avoids high-temperature steps, exotic materials, or complex fabrication. The components—wood and steel—are inexpensive, durable, and widely available.
The result is a dual-function material. Modified wood generates steady electrical output suitable for low-power devices while also cooling spaces through evaporation. The science rests on familiar principles, yet the application is new: combining natural structure and simple chemistry to create panels that actively manage heat and produce electricity.
The electrical power is modest, so this approach cannot replace larger energy systems. But the combination of cooling and small-scale electricity could be valuable in off-grid shelters, rural cabins, or monitoring stations. The key point is that the concept works not only in the laboratory but in a real cabin exposed to outdoor conditions. This suggests a future in which building materials themselves contribute to energy and climate management, transforming walls and roofs from passive barriers into active systems that shape the environments we live in.
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