Research Trends in the Valorisation of Potato Peels for Fermentative Biohydrogen Production: A Bibliometric Analysis (2015-2025)

Every day, the global food industry generates mountains of waste. Among the most common byproducts are the skins peeled from potatoes during processing. Traditionally, these peels are treated as trash, often sent to landfills where they rot and release greenhouse gases, or burned, which adds to air pollution. Yet, hidden within this discarded material is a potential energy source. Potatoes are rich in starch, a type of carbohydrate that certain microscopic organisms can break down. When these microbes feast on the sugars released from the potato skins, they produce a gas called hydrogen. This hydrogen is a clean fuel that, when used, releases only water, offering a way to turn a waste problem into a source of renewable energy. The challenge for scientists has been to figure out how to do this efficiently and on a large scale, moving beyond simple experiments to create a system that could actually power homes or industries.

A team of researchers from the Durban University of Technology in South Africa recently took a fresh look at how the scientific community has approached this challenge over the last decade. Instead of running new experiments in a lab, they performed a comprehensive review of existing studies published between 2015 and 2025. They used a method called bibliometric analysis, which is essentially a way to map out the landscape of scientific research by looking at who is publishing, where, and what topics are gaining the most attention. By examining 24 specific studies that focused strictly on making hydrogen from potato peels, the researchers pieced together a clear picture of how this field has grown and where it is heading.

The story of this research is one of steady growth. In the early years of the study period, from 2015 to 2020, the field was in its infancy. Scientists were primarily asking basic questions: Can potato peels actually work as food for these microbes? Is it even possible to get hydrogen from them? During this time, only a handful of papers were published each year, mostly focused on proving that the concept was feasible. However, a significant shift occurred after 2020. The number of studies began to climb, with the highest number of publications appearing in 2021, 2022, and again in 2025. This surge suggests that the scientific community has moved past the "can we do it?" phase and is now deeply engaged in the "how can we do it better?" phase. Researchers are no longer just testing if the process works; they are actively trying to make it faster, more efficient, and more reliable.

Geographically, the effort to solve this puzzle is concentrated in a few key regions. China emerged as the most productive country, publishing the highest number of studies. However, when looking at the impact of the work—measured by how often other scientists cite these papers in their own research—South Korea stood out as having the most influential contributions. India and Poland also made significant contributions, while South Africa, the home of the authors of this review, established itself as a leading voice in the field from an African perspective. This distribution highlights that while the problem of potato waste is global, the scientific solutions are currently being driven by nations with strong investments in renewable energy and waste management technologies.

As the research matured, the focus of the work shifted in a very specific direction. In the beginning, studies were heavily focused on the biology of the process: understanding the microbes, the enzymes they produce, and the chemical makeup of the potato skins themselves. Over time, the conversation changed. The most recent studies are less about the biology alone and more about the engineering. Scientists are now concentrating on building better systems to hold the microbes and the potato waste, optimizing the conditions inside these systems, and using advanced computer models to predict how to get the most hydrogen out of every batch. The keywords that appear most frequently in the latest papers are no longer just about the potato or the bacteria; they are about "bioreactors," "optimization," and "process intensification." This indicates a field that is growing up, moving from the benchtop of a university lab toward the design of industrial-scale machines.

The researchers also identified four main themes that dominate the current conversation. The first is the actual production of hydrogen and how to make the process stronger. The second is the fine-tuning of dark fermentation, a specific type of biological reaction that happens without light, which has become the preferred method for this task. The third theme involves the microscopic details: how the microbes eat, how enzymes break down the starch, and how to characterize the potato waste itself to get the best results. The fourth theme is the hardware: the design of the tanks and reactors where this magic happens, and how to measure the yield to ensure it is worth the effort. These four areas are deeply connected, showing that progress in one area, like better reactor design, often depends on understanding another, like how the microbes behave.

Despite the excitement and the clear progress, the authors of this review are careful to note that the technology is not yet ready for the world to use on a massive scale. Almost all the work reviewed so far has been done in small laboratory settings. While the results are promising, there is a significant gap between a small experiment in a lab and a large factory that can process tons of potato peels every day. The studies show that it is possible to get hydrogen, and that we can improve the amount we get, but the jump to commercial success requires more than just better science; it requires better engineering and economic planning. The researchers suggest that the next step is to build pilot plants—medium-sized test facilities—to see if the process holds up under real-world conditions. They also point out that the most promising future lies in "biorefineries," where the potato peels are not just used for hydrogen, but are processed to create multiple valuable products at once, such as fertilizers or other chemicals, making the entire process more profitable and sustainable.

This review serves as a roadmap for where the science has been and where it needs to go. It confirms that turning potato peels into clean fuel is a viable and growing field of study, driven by a global need to find sustainable energy sources and manage waste better. The path forward is clear: move from small-scale experiments to large-scale demonstrations, integrate the process into existing food industries, and continue to refine the technology until it is robust enough to be a standard part of our energy future. The potato peel, once a simple piece of trash, is now being seen as a key ingredient in a cleaner, more circular economy, but getting there will require patience, investment, and the continued collaboration of scientists and engineers around the world.