by If you’ve ever seen yourself through a thermal camera, you know that your body produces a lot of heat. This is in fact a waste product of our metabolism. Every square meter of the human body emits heat equivalent to approximately 19 matches per hour.
Unfortunately, much of this heat simply escapes into the atmosphere. Wouldn’t it be great if we could use it to produce energy? My research has shown that this is indeed possible. My colleagues and I are discovering ways to capture and store body heat for energy generation, using environmentally friendly materials.
The goal is to create a device that can both generate and store energy, acting as a built-in power bank for wearable technology. This allows devices such as smart watches, fitness trackers or GPS trackers to work for much longer or even indefinitely by harnessing our body heat.
It’s not just our bodies that produce waste heat. In our technologically advanced world, significant waste heat is generated every day, from the engines of our vehicles to the machines that manufacture goods.
Normally, this heat is also released into the atmosphere, which represents a significant missed opportunity for energy recovery. The emerging concept of “waste heat recovery” seeks to address this inefficiency. By harnessing this otherwise wasted energy, industries can improve their operational efficiency and contribute to a more sustainable environment.
frameborder=”0″ allowfullscreen=”allowfullscreen”>
The thermoelectric effect is a phenomenon that can help convert heat into electricity. This works because a temperature difference produces an electrical potential as electrons flow from the hot side to the cool side, generating usable electrical energy.
However, conventional thermoelectric materials are often made of cadmium, lead or mercury. These pose environmental and health risks that limit their practical applications.
The power of wood
But we’ve discovered that you can also make thermoelectric materials from wood, offering a safer, sustainable alternative.
Wood has been an integral part of human civilizations for centuries, serving as a source of building materials and fuel. We discover the potential of wood-derived materials to convert residual heat, often lost in industrial processes, into valuable electricity.
This approach not only improves energy efficiency, but also redefines the way we view everyday materials as essential components of sustainable energy solutions.
Our team at the University of Limerick, in collaboration with the University of Valencia, has developed a sustainable method to convert waste heat into electricity using Irish wood products, particularly lignin, a by-product of the paper industry.
Our research shows that lignin-based membranes, when soaked in a saline solution, can efficiently convert low-temperature waste heat (below 200°C) into electricity. The temperature difference across the lignin membrane causes ions (charged atoms) to move in the salt solution.
Positive ions drift towards the cooler side, while negative ions move towards the warmer side. This separation of charges creates an electrical potential difference across the membrane, which can be harnessed as electrical energy.
Since approximately 66 percent of industrial waste heat falls within this temperature range, this innovation represents a significant opportunity for environmentally friendly energy solutions.
This new technology has the potential to make a big difference in many areas. Industries such as manufacturing, which produce large amounts of waste heat, could see big benefits by converting that waste heat into electricity. This would help them save energy and reduce their impact on the environment.
This technology could be used in a variety of environments, from providing power in remote areas to powering sensors and devices in everyday applications. Its environmentally friendly character also makes it a promising solution for sustainable energy generation in buildings and infrastructure.
The problem with storage
Extracting energy from residual heat is only the first step; Storing it effectively is just as important. Supercapacitors are energy storage devices that charge and discharge electricity quickly. This makes them essential for applications that require fast power delivery.
However, their dependence on fossil fuel-derived carbon materials raises sustainability concerns, highlighting the need for renewable alternatives for their production.
frameborder=”0″ allowfullscreen=”allowfullscreen”>
Our research group has discovered that lignin-based porous carbon can serve as an electrode in supercapacitors for energy storage generated by harvesting waste heat using a lignin membrane.
This process allows the lignin membrane to capture waste heat and convert it into electrical energy, while the porous carbon structure allows the rapid movement and storage of ions. By providing a green alternative that avoids harmful chemicals and dependence on fossil fuels, this approach offers a sustainable solution for energy storage from waste heat.
This innovation in energy storage technology could power everything from consumer electronics, wearable technology and electric vehicles.
Muhammad Muddasar, PhD candidate, School of Engineering, University of Limerick
This article is republished from The Conversation under a Creative Commons license. Read the original article.
