Bad digestion

Municipality must wade through a minefield of risks and potential issues as it seeks to regulate proposed anaerobic digester plant

Anaerobic digesters, such as the one proposed for the edge of the village of Wellington, have had a mixed experience in Ontario. This is in spite of the fact the province pays a lofty premium for electricity that is generated from biogas and has made generous upfront investments to assist farmers to turn their waste into energy.

WHAT IS PROPOSED?
Anaerobic digesters (ADs) are closed, oxygen-free containers in which organic materials are introduced and allowed to decay. As the material breaks down it produces a mix of methane and oxygen dioxide called biogas. The biogas is siphoned off and then used to fire a boiler or furnace, which drives a generator that in turn creates electricity.

Bob Hunter, a landowner north and west of Wellington, was at a committee of council last week seeking its support for a plant that would process farm waste along with municipal waste in an AD facility on the edge of the village limits— across from a former vegetable processing plant on Belleville Road.

FOUL ODOUR
His proposal raises many questions about how such a facility will manage odours and other emissions, as well as runoff from waste and organic material storage, and disposal of digestate—the byproduct of this process. It raises further questions about the municipality’s ability to regulate such a facility.

Most of the farm-based ADs approved in Ontario so far are located in rural areas situated well away from neighbours and population centres. Even so, the Association of Professional Engineers of Ontario has warned that the province’s requirements related to storage, structural siting of ADs and the provisions for the treatment for minimizing odours are “too vague and could cause irresolvable conflicts.”

Ontario’s initial farm-based AD regulatory framework was designed to process farm waste only. But the rules have eased as farmers struggled to make their facilities profitable. Many now process other offfarm organic materials in including municipal waste. This is what Hunter proposes.

But with so few comparable facilities the municipality will have a difficult time properly assessing issues of odours, emissions and runoff mitigation—particularly in one potentially located so close to an urban area. Its challenge is further complicated by the fact that an approved subdivision plan will see homes constructed to within a few dozen metres of the proposed digester plant.

POOR EXAMPLE
In Newmarket, one of the first anaerobic digesters to be built in North America was mothballed in 2009 after years of litigation between the town and the operator.

“The odours are significant, and they are causing people to leave their places of work and school due to illness,” said Newmarket Mayor Tom Taylor in 2005. “Local residents are unable to use their outdoor yards to the full extent and enjoyment because of the ongoing odour problems.”

A court ordered the facility closed until it found a solution to the odour problems and fined the operator $155,000. But by then nearly a decade had gone by.

The Ontario Ministry of Agriculture, Food and Rural Affairs supports the development of ADs but warns of potential pitfalls, noting the operation and control of such facilities is complex and must be managed diligently. The Ministry also notes the ADs are still new in Ontario and, as such, regulations and insurance approvals may take longer than expected. The Ministry also warns care must be taken in designing and managing biogas systems to deal with the moisture, sulphur compounds and other minor gases found in biogas. The good news for the municipality is that the waste diverted to such a facility isn’t regulated by provincial waste regulations but is treated as a nutrient and managed under the much less stringent rules of the Nutrient Management Act.

Germany has about 3,000 farm-based ADs, yet producers continue tostruggle to make them economical even with feed-in tariffs.

As the keynote speaker to the Confederation of European Waste-to-Energy Plants observed last month ,despite the benefits of the concept, there remain significant problems including emissions, low public acceptance, high costs, long lasting legal conflicts and low energy efficiency.

Moving from concept to acceptable methods of profitable practice continues to challenge the sector, though well-established in Europe. It likely poses a greater challenge to jurisdictions such as this one that have never been asked to review such a proposal before.