image: Leveraging the inherent advantages of bio materials, bio hydrovoltaic technology has progressively advanced from structure-oriented material engineering (non living hydrovoltaics) to biofunction driven design (living hydrovoltaics). Based on the origin and properties of biological materials, bio hydrovoltaic materials can be classified into three primary categories: microbial based, plant based, and animal based hydrovoltaic materials.
Credit: ©Science China Press
Scientists are opening a new chapter in sustainable energy with bio-hydrovoltaic technology, which harnesses water’s natural phase transitions to generate electricity. A team led by Professor Shungui Zhou at Fujian Agriculture and Forestry University has published a review in National Science Review that explains how bio-hydrovoltaic technology has evolved from static, non-living materials such as wood and cellulose into dynamic, living bio-hydrovoltaic systems, with the potential to transform the landscape of renewable energy. The technology directly converts low-grade thermal energy within the Earth’s water cycle into electricity through interactions between biological materials and water.
The researchers classify bio-hydrovoltaic systems into two major categories. Non-living hydrovoltaics use static biological materials like wood, paper, and microbial protein nanowires to harvest energy from spontaneous water evaporation and moisture absorption. Living hydrovoltaics represent a paradigm shift, leveraging dynamic biological processes such as plant transpiration and microbial metabolism to achieve more efficient energy conversion with strong self-regulation. Living hydrovoltaic systems offer unique advantages. Plants generate electricity during natural transpiration while also purifying the air. Microorganisms can survive in extreme environments and produce power using hydrovoltaic energy. These biological generators are inherently eco-friendly and biodegradable, and they require far less maintenance than synthetic alternatives.
The review divides hydrovoltaic materials into three main categories based on biological origin. Microbial-based hydrovoltaic materials, including bacteria and algae, feature self-healing capabilities, environmental adaptability, and potential for genetic engineering. Plant-based hydrovoltaic materials, the most extensively studied, possess natural pore gradients and directional transport channels that facilitate water movement and energy conversion, while also being low-cost and abundant. Animal-based hydrovoltaic materials, though less explored, show great promise due to excellent biocompatibility and mechanical properties. Hydrovoltaic technology operates through multiple mechanisms. Water-evaporation-induced electricity generation delivers the highest voltage output. Moisture-induced generation provides stable performance in humid environments. Droplet-induced systems offer the highest instantaneous power. Recent advances demonstrate the coupling of multiple mechanisms, for example combining hydrovoltaic effects with photovoltaic and piezoelectric energy conversion to enhance overall efficiency.
Living hydrovoltaic systems are especially promising for distributed energy applications. Plants can form natural electricity-generating networks across landscapes, while microbial communities can establish self-sustaining energy ecosystems that also support environmental remediation. These systems show strong resilience and can adapt to changing conditions through biological regulation. Current applications span self-powered wearable sensors, environmental monitoring devices, distributed energy systems, and medical implants. Researchers have demonstrated hydrovoltaic devices capable of charging smartphones, supplying continuous power to sensors for months, and enabling self-powered environmental monitoring in remote areas. The technology is particularly promising for Internet of Things scenarios where traditional batteries are impractical. Despite rapid progress, challenges remain. Present hydrovoltaic devices typically produce lower power than conventional solar panels, but their ability to operate continuously in all weather provides a complementary advantage. Material stability, scale-up costs, and the optimization of biological processes require continued research.
Looking ahead, the researchers outline three transformative directions. “Hydrovoltaic internet” envisions distributed networks of bio-hydrovoltaic generators connected via smart grids to deliver resilient, decentralized energy. “Hydrovoltaic intelligence” integrates artificial intelligence and machine learning to optimize biological energy conversion and enable adaptive, self-regulating systems. “Hydrovoltaic ecology” focuses on building zero-carbon energy systems that also advance environmental restoration and ecosystem health. The team emphasizes the need for interdisciplinary collaboration combining synthetic biology, materials science, and device engineering. For example, genetic engineering could improve microbial energy conversion efficiency, while deeper understanding of plant physiology may unlock new applications for vegetation-based power generation. This research marks an important step toward sustainable energy solutions that coexist harmoniously with natural ecosystems rather than replacing them. As global demand for clean energy continues to grow, bio-hydrovoltaic technology offers a pathway to distributed, environmentally friendly power that can complement existing renewable technologies.