Fat, oil and grease. Every restaurant produces FOG, as it is known. While some grease can be reused, a great deal of FOG is washed down the drain. If it is not trapped in grease interceptors it can clog and corrode sewage system arteries and cause raw sewage to back up. That's why building codes throughout the industrialized world require that FOG-trapping grease interceptors be installed on commercial and industrial buildings.
However, trapped FOG must still be collected or it will back up into sewers. This often happens because building owners don't want to pay to have FOG collected and municipalities don't always enforce the rules.
Interceptors are drained by companies like Woodbridge, Ontario-based Organic Resource Management Inc. (ORMI). An average of once a month, ORMI services more than 8,000 commercial, industrial and institutional customers in Ontario, Quebec and British Columbia. Originally, ORMI processed FOG and dumped it in landfill sites. As governments began to look for ways to reduce landfill volume, ORMI began to look for ways to recycle FOG.
Since 1990, the company has been recycling almost 100 per cent of the FOG it collects by converting it into compost to be used on farm fields. After the Walkerton, Ont. disaster, in which animal waste contaminated water tables and killed several residents, "people started to get nervous about spreading material on fields, even though the compost is safe," says Charles Buehler, ORMI CEO and Chairman.
ORMI looked for other options and discovered something Europeans have known for decades: FOG can be added to animal manure and fed into anaerobic digesters that convert such waste into biogas for use in the generation of electricity. The electricity can be sold to the hydro-electric grid.
Anaerobic digestion is a renewable energy processes in which micro-organisms break down biodegradable material without using oxygen. The process eliminates 98 per cent of the pathogens in manure so the digestate, as the processed waste is called, can be used as clean compost. Adding FOG to animal waste can double the production of electricity, according to European studies and studies conducted at the University of Guelph.
Paul Klaesi, an anaerobic digester pioneer and president of AgriEnergy Producers' Association of Ontario (APAO), operates an anaerobic digester at Fepro Dairy near Cobden, Ontario. The digester cost $2.5-million to build. Using 15 cubic metres of manure a day produced by his 300 dairy cattle, and with the help of FOG supplied by ORMI, the Fepro digester generates 500 kW of electricity per hour, 24 hours a day, seven days a week "without relying on wind or sun," Klaesi says. Considering the average home in Ontario consumes 1000 kW of electricity per month, the digester can light up a small town.
ORMI pays a tipping fee to Fepro and will receive a portion of revenue for the additional energy the FOG enables Mr. Klaesi to sell to the grid. Mr. Klaesi sells about 90 per cent of the energy the digester produces to the grid; the digester uses about 10 per cent of the energy it produces to run. Mr. Klaesi feels that if the Ontario government were truly supporting of anaerobic digesters as a renewal energy source, it would let him buy back the energy requited to run the digester at discount rates instead of paying "full retail" for it, which limits his return on investment.
"The Ontario government is supportive of anaerobic digesters," says Chris Duke, program analyst, with the Ontario Ministry of Agriculture, Food and Rural Affairs. It sees anaerobic digesters as a way to treat animal waste, produce renewable energy and assist in rural development. He says the rules for anaerobic digesters, including the cost of electricity to run them, are under review with the goal of streamlining the approval process and getting more digesters up and running. "We've gone up three flights of stairs in a short period of time" when it comes to approving and supporting anaerobic digesters as a renewable energy source, including sharing up to 40 per cent of the cost, up to $400,000, of building them.
Anaerobic digesters seem like the ideal way to purify and reuse animal waste, FOG and other materials such as fruit and vegetable waste produced by grocery stores. However, there are only seven operational digesters in Ontario, with another 24 under development, as well as a few under development in Alberta and one in PEI - nowhere near the number required to treat all the animal waste and FOG that feeding industrial societies produces.
Buehler would like to see more digesters built so ORMI can recycle more FOG. Digesters lower the cost of recycling FOG and expand the company's capacity to process it. "We're limited in terms of how much material we can handle," he says. Digesters would let the company collect and recycle more FOG and enter a new market - collecting waste produce from grocery stores.
In fact, if oil prices continue to climb, there might come a day when companies pick up FOG for free because the material will become an important, and profitable, source of hydro-electric energy production.
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