AWARD OF EXCELLENCE / ENVIRONMENTAL REMEDIATION Harvest Energy Garden
Juror Comments: "By allowing waste to be turned into a resource on a large scale, this project sets an example for other locations."
Juror Comments: “By allowing waste to be turned into a resource on a large scale, this project sets an example for other locations.”
Metro Vancouver is
implementing an organics waste ban from landfills by 2015. As the largest local composter, Harvest Power needed a new, innovative technology to process co-mingled food and yard waste.
Opus DaytonKnight coordinated the design and construction of the Harvest Energy Garden in Richmond, B.C. using a new digestion technology developed in Germany. This innovative facility — the first in North America — processes 30,000 tonnes per year of organic waste, generating 8,000 MWh of renewable electrical energy.
Developed in Germany by Grossmann Ingenieur Consult GmbH (GICON), the digestion technology is new and transformative because of its ability to accept high solids organic material such as mixed food and yard waste. It also produces high quality biogas in the range of 70 – 80% methane and high quality, nutrient rich compost.
Food waste is a difficult material to process, but is high in energy. The process employed at the Harvest Energy Garden extracts the energy and turns this odorous waste into highly beneficial resources. This plant, located on York Road north of Blundell Road, demonstrates the first use of the technology to process food and yard waste.
What’s the difference?
The facility has been designed to completely contain the handling of raw food waste. The receiving and pre-processing areas are enclosed, and the digestion processes are entirely sealed. After digestion, the spent food waste composts easily with low odour emissions.
The process optimizes the production of biogas. The two main process steps in the conversion of organic material to biogas are hydroloysis and methanization. Typically these processes take place in parallel in completely mixed tanks. In this facility the steps are separated, and optimal conditions for each process are created. It requires very little energy to operate compared to alternative technologies.
In this Lower Mainland area, residential food waste is collected as mixed food and yard waste while commercial food waste is concentrated and contaminated. For standard anaerobic digestion, these organic waste streams must be liquefied and heavily preprocessed to remove contaminants. The plant is capable of processing these waste streams as solid material with minimal pre-preprocessing.
Waste is first percolated
The food waste is first tipped into a large receiving hall for processing prior to being fed into the anaerobic digestion process. Air in the receiving hall is extracted and passed through a dedicated biofilter to remove odours, vapours and VOCs.
Pre-processing consists of shredding the food waste and removing large contaminants. The material is then blended and stockpiled into one of 10 large percolation tunnels, which is then sealed. Warm water is percolated through the organic matter, and recycled over several days, “leaching” out the biodegradable organic components which become concentrated in the recycled liquid.
A side stream of concentrated liquid is continuously fed to the methane digesters. After percolation, the digested matter is removed from the percolator and composted.
Energy for 800 homes
The process is very energy efficient: after a percolator is filled, the only process step is the pumping of liquids, which allows a high level of control and optimization. Recycling retains heat energy in the system. The process is currently exceeding gas production and quality estimates.
The energy produced is sold to local markets and is enough to meet the annual energy requirements of 800 single family residences. The estimated annual greenhouse gas (GHG) reduction attributable to the plant is 23,000 tonnes of CO2, and this benefit accumulates annually.
Deceptively simple to describe, the project integrated German technology, American management and Canadian engineering. The Harvest Energy Garden in Richmond presents an environmentally sustainable alternative for managing the large volumes of organic waste generated in large urban areas. cce
Harvest Energy Garden,
Harvest Power Canada
and Gicon GMBH
Award-winning firm/main consultant for substation, odour control/subconsultant
to Gicon GMBH for biogas plant:
Opus DaytonKnight Consultants (Seamus Frain, P.Eng.; Tjandra Tjondrotekodjojo, P.Eng.; Goran Vranic, P.Eng.; Bengul Kurtar, P.Eng.; John Boyle, P.Eng.; Harlan Kelly, P.Eng.)
ISL Engineering & Land Services (civil); FWD (fire protection); DA (architect);
Schenke Bawol (energy centre electrical)