Turning cement into a power plant with bioinspired materials

When we think about cement, we usually picture sidewalks, bridges, or the walls of skyscrapers that are solid, gray, and lifeless. But according to new research, the very material holding up our buildings could also power them. In a paper published in Science Bulletin, a team of researchers from Southeast University in Nanjing, together with collaborators in Japan and South Africa suggests exactly that. The researchers developed a bio-inspired “thermoelectric cement” that not only supports buildings but also harvests energy from the everyday temperature differences around us. This breakthrough could help reshape the future of architecture, bringing us one step closer to self-powered buildings.

Although we don't think about it often, buildings are hungry beasts. From heating and cooling to lighting and appliances, they account for about 40% of global energy use and roughly a third of all carbon emissions. Even before a building is finished, producing construction materials like cement already burns through massive amounts of energy. Now, consider the walls of a house or the pavement of a road. They’re constantly exchanging heat with the environment, absorbing sunlight during the day, radiating it at night, or cooling under a chilly breeze. What if we could capture just a fraction of that wasted energy?

That’s where thermoelectric materials come in. These are substances that can generate electricity when exposed to a temperature difference, like if one side is heated by the sun and the other cooled by shade. Traditionally, these materials are expensive, fragile, or made of toxic elements. Using them in construction has been impractical. But the researchers behind this new study had an idea. What if cement itself could become a thermoelectric generator?

Nature, as usual, had a solution. If you slice open a plant stem, you’ll see layers of channels that move water and nutrients efficiently. Some of these pathways can even selectively “trap” certain ions while letting others flow freely. This difference in ion movement creates the electrical potential in living tissues. The team borrowed this principle to redesign cement. They created a cement-polyvinyl alcohol composite (CPC), where thin layers of cement are interlaced with hydrogel (a water-rich polymer similar to what you might find in contact lenses). CPC works with the cement layers containing calcium ions that naturally want to move under a temperature gradient. The hydrogel layers then act like “highways” for hydroxide ions, which zip along faster. At the interface where cement meets hydrogel, calcium ions get “selectively immobilized" (essentially trapped) while hydroxide ions keep moving. This difference in speed between ions is key. It creates a much larger voltage than cement alone could ever produce.

How much better is this new cement than previous attempts? The numbers are extremely different. Ordinary cement has a tiny Seebeck coefficient (a measure of thermoelectric efficiency) of about –0.62 mV/K. The new CPC material reached –40.5 mV/K, more than 60 times higher. Its performance metrics (power factor and figure of merit) were five to six times better than any cement-based material reported so far. And unlike many other experimental thermoelectric materials, CPC is cheap, safe, and strong. In fact, the layered design not only improved energy harvesting but also boosted the cement’s mechanical toughness by up to 875% compared with ordinary cement.

That means this could realistically be poured into walls, bridges, or roads. The team built small test modules to show how CPC could work in practice. Blocks of CPC connected in series generated nearly three-quarters of a volt when exposed to a modest temperature difference. This energy was stored in capacitors, tiny energy banks, that successfully powered an LED light. In larger-scale tests, the CPC acted both as a generator (capturing heat differences) and as a supercapacitor (storing the energy for later use). This dual functionality (harvesting and storing energy in the same material) is especially exciting. Imagine a future building where the very walls are both the power source and the battery.

If adopted widely, bio-inspired thermoelectric cement could transform how we think about energy in cities. We could think about smarter infrastructure like bridges, pavements, and dams could generate electricity from daily temperature swings. Even self-powered buildings, like houses might power their own sensors, lighting, or communications without external wiring. Even using cement itself as the energy harvester avoids the need for expensive, toxic materials is incredibly sustainable. Distributed energy generation in walls and roads could also support the shift toward renewable power.

The main challenges here are scaling up production, integrating CPC into existing construction standards, and optimizing real-world performance. These challenges are still ahead. But the concept of turning the most mundane material of modern civilization into a silent, ever-present power source, is one step closer. The idea that our walls, pavements, and bridges could act like giant batteries or solar panels would have sounded like science fiction just a decade ago. But with innovations like this, it’s inching closer to reality.

If you want to learn more, the original article titled "Bio-inspired thermoelectric cement with interfacial selective immobilization towards self-powered buildings" on Science Bulletin at https://doi.org/10.1016/j.scib.2025.03.032.