R&D PULSE
WASTE FOR ENERGY
A new study highlights the thermochemical properties of horse manure—and suggests biowaste can provide an efficient means of energy generation in oxygen-free environments.
Written by Kayt Sukel
FOR DECADES, Ryoichi S. Amano, the Alan D. Kulwicki faculty fellow in mechanical engineering at the University of Wisconsin-Milwaukee, has been interested in renewable energy generation, doing research on everything from wind to wastewater. Now, he and his research team are looking at a prominent source of biowaste as a potential renewable energy source: manure.
“This is something that is very available. It contains a lot of protein and lots of contents that produce syngas,” he said. “So, manure is very effective as an energy source. It is easy to obtain. Instead of wasting it, we can convert it into a useful form of energy.”
In a new paper published in the ASME Journal of Energy Resources Technology, Amano and colleagues, including his doctoral student Mohamed Maache, used experimental and mathematical modeling to elucidate the thermochemical conversation of horse manure and its potential for heat and power generation.
While this paper focused on horse manure, the lab is looking at multiple types of animal waste, from chickens to sheep, Maache said. And by understanding their unique thermochemical properties, particularly the effect of the heating rate of thermal cracking, or the process of using heat and pressure to break down hydrocarbon molecules into smaller, more usable molecules, engineers may be able to hit two birds with a single stone.
“We must manage all this waste. We can’t just keep dumping it because we will get to a point where there is too much and it will sneak into the water supply,” he said. “If we can use it to generate energy, we can solve both problems.”
The team used pyrolysis at eight different heating rates between 5 °C per minute to 40 °C per minute. They noted that increasing the heat slowed the thermal degradation of the manure’s contents including hemicellulose, cellulose, and lignin. In addition, the slowest heating rates do allow for a complete reaction, offering gradual increases in energy production.
While Amano said this is not the first time a research group has looked at the energy generating potential of biowaste, he said the technology had not been sufficient in the past to develop adequate syngas.
From left: Mohamed Maache, Cheikh Kada, Ryoichi Amano, and Kada Kada. Photo: Ryoichi Amano
“The good thing about pyrolysis is that we do not need any oxygen to burn it.”
–Ryoichi Amano, professor of mechanical engineering at the University of Wisconsin-Milwaukee
A graphical abstract from “Experimental and Mathematical Investigation of Thermochemical Conversion for Horse Manure,” published in the ASME Journal of Energy Resource Technology.
“We are seeing effective results so far,” he said. “But we need to improve controlling the temperature, controlling the process time, and controlling the amount of waste against the air. But the good thing about pyrolysis is that we do not need any oxygen to burn it. This means that this kind of energy generation is not only useful here but could also be used somewhere in space.”
The team also learned, when comparing different types of animal manure, that each may require different temperatures and processing to most efficiently break them down into syngas. Because of this, the most efficient energy generation may be via a combination of different types of animal waste, or even a hybrid block that uses a combination of manure and crop waste, Amano explained. But that remains to be seen. The lab plans to test electrolysis conversion to see how it would perform, Maache added.
“Basically, it would just be using anode and cathodes, connect them to a battery, make a circuit, and then generate hydrogen using the biowaste,” Maache said. “Many people use water to do this, but we may be able to optimize it using this kind of biomass.”
Amano hopes to continue this work to develop efficient, effective means of generating energy from common biowaste.
“This is a very important renewable energy source,” he said. “For years, I have worked on gas turbine and other types of combustion, which use fuel from oil, coal, and natural gas. But we need to find ways to make useful energy from other things. We could use this waste, which is plentiful, especially in farmland, to do that.”
Kayt Sukel is a technology writer and author in Houston.
© 2025 The American Society of Mechanical Engineers. All rights reserved.