Farm manure to renewable natural gas system developed
Scientists in Canada are working on technology to produce renewable natural gas from manure. This gas could be used for heating homes and powering industries, while also eliminating harmful gases released by decomposing manure spread on farm fields and used as fertiliser.
According to the University of Waterloo researchers involved in the new study, this renewable natural gas could also reduce dependence on fossil natural gas, and even replace diesel for trucks in the transportation sector.
“There are multiple ways we can benefit from this single approach,” said University of Waterloo’s David Simakov, professor of chemical engineering, in a press release. “The potential is huge.”
According to Simakov and colleagues, their technology could be viable with cow, pig and other manures, as well as landfill waste.
The innovative concept was tested using a computer model of a 2,000 head dairy farm in Ontario. This farm collects manure and converts it into biogas with anaerobic digesters.
Some of that biogas is already burnt in generators to generate electricity. This reduces the manure’s environmental impact while yielding between 30-40% of its energy potential.
The University of Waterloo researchers decided to build on this process through converting the biogas into renewable natural gas in a process known as methanation. This involves mixing it with hydrogen before running it through a catalytic converter. A reaction in the converter produces methane from the carbon dioxide present in the biogas.
"This is how we can make the transition from fossil-based energy to renewable energy using existing infrastructure, which is a tremendous advantage," said Simakov.
Key to the process’ renewable credentials is the fact the electricity required to produce the hydrogen could be generated by wind or solar systems on site. “The net result would be renewable natural gas that yields almost all of manure’s energy potential and also efficiently stores electricity, but has only a fraction of the greenhouse gas impact of manure used as fertiliser.”
Simakov collaborated with Waterloo professor of chemical engineering Michael Fowler on the study, which has been published in the International Journal of Energy Research.