A major development in sustainable architecture has enabled researchers to transform ordinary wood into an advanced thermal reservoir. In this case, lignin is removed from the wood through chemical modification and phase change material is added, creating a new product called a ‘solar battery’, which stores the solar energy collected by a building during the day as latent heat. Traditional solar systems have variables such as intermittency. Yet, due to the nature of the bio-based materials used, the thermal conditions of these solar batteries are stable and release their stored energy long after the sun goes down.This discovery is based on advanced materials science and will allow us to achieve zero carbon emissions when heating our homes or controlling the temperature inside them. Using the natural porous structure of wood, this new technology will provide a bridge between energy harvesting and long-term storage by using the actual walls of our homes as insulated heat batteries.
Wooden solar battery works even in complete darkness
A chemical purification process is being used to create a new type of battery. Researchers at KTH Royal Institute of Technology have successfully removed lignin from wood and filled the pores in the wood with polyethylene glycol (PEG) to create a thermal battery. When the sun shines on the wood and heats it, the peg will melt and absorb a large amount of heat energy to store it. At night, when the temperature drops, the PEG will crystallize and release the stored heat into your home. The total amount of heat that can be stored is approximately 760 kilojoules per kilogram (kJ/kg), meaning that this new building material can function as a climate control system without requiring any electricity.
How wood’s hierarchical structure captures photons
To maximize the absorption of solar radiation, scientists have advanced the concept by embedding plasmonic nanoparticles directly into microscopic channels of wood, according to a story published in Science Advances. These metallic particles have been engineered to resonate with the solar spectrum, effectively trapping photons and converting them into thermal energy with an efficiency rate of up to about 99 percent. The natural hierarchical structure of these wood fibers acts as a light trap, forcing sunlight to bounce repeatedly within the porous channels until it is completely absorbed as heat. This concentrated thermal energy can raise the temperature of the material to more than 82 °C (180 °F) in a matter of minutes. This efficiency makes wood suitable not only for space heating but also for intensive applications such as solar-powered steam generation and water purification.
Decarbonizing the grid with bio-based thermal storage
According to the US Department of Agriculture, residential energy consumption is one of the main sources of carbon emissions, and the use of engineered wood in modern construction can help solve this serious problem. Engineered wood will help buildings reduce dependence on the electrical grid and HVAC systems by becoming a source of passive thermal regulation through thermal mass. It also acts as a carbon sink, trapping atmospheric carbon over the lifetime of the building. Unlike synthetic batteries and mechanical systems that store energy, thermal batteries made from wood are biodegradable. They come from forests managed with sustainability in mind, offering an environmentally conscious option that aligns with the construction industry’s global decarbonization goals.