Researchers propose heating homes with manure

TORONTO Researchers at an Ontario university say farm manure could be a viable source of renewable energy to heat homes.

University of Waterloo scientists say they are developing technology to produce natural gas from manure so it can be added to the existing energy supply system for heating homes and powering industries.

The proposal would eliminate harmful gases released by naturally decomposing manure when it is spread on farm fields as fertilizer.

They say it would also partially replace fossil natural gas, a significant contributor to global warming.

Chemical engineering professor David Simakov says the technology could be viable with several kinds of manure, particularly cow and pig manure, as well as at landfill sites.

In addition to being used by industries and in homes, the researchers say renewable natural gas could replace diesel fuel for trucks, another major source of greenhouse gas emissions.

“There are multiple ways we can benefit from this single approach,” Simakov said Thursday in a statement. “The potential is huge.”

To test the concept, researchers built a computer model of an actual 2,000-head dairy farm in Ontario that collects manure and converts it into biogas in anaerobic digesters.

Some of that biogas is already used to produce electricity by burning it in generators, reducing the environmental impact of manure while also yielding about 30 to 40 per cent of its energy potential.

Researchers want to take those benefits a significant step further by upgrading, or converting, biogas from manure into renewable natural gas.

That would involve mixing it with hydrogen, then running it through a catalytic converter. A chemical reaction in the converter would produce methane from carbon dioxide in the biogas.

Known as methanation, the process would require electricity to produce hydrogen, but that power could be generated on-site by renewable wind or solar systems, or taken from the electrical grid at times of low demand.

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 fertilizer, the Waterloo researchers said.

“This is how we can make the transition from fossilbased energy to renewable energy using existing infrastructure, which is a tremendous advantage,” said Simakov, who collaborates with fellow chemical engineering professor Michael Fowler.

The modelling study showed that a $5-million investment in a methanation system at the Ontario farm would, with government price subsidies for renewable natural gas, pay for itself in about five years, the researchers said.