Ontario Power Generation’s (OPG) Atikokan Generating Station (GS) is now operating on biomass, making it the largest electrical power plant in North America fuelled by 100% biomass.
“Atikokan GS is a unique addition to our clean energy portfolio as it provides dispatchable, renewable energy that can be used when the power system needs it,” said OPG’s president and CEO, Tom Mitchell.
“The biomass conversion and solutions developed for the Atikokan GS are cutting edge and OPG is at the forefront of this innovative technology. The project is the first of its kind in Ontario and will bring economic benefits to northwestern Ontario for years to come,” he added.
OPG has fuel supply contracts in place with two companies in northwestern Ontario -- Rentech Inc. and Resolute Forest Products Canada. Each will supply 45,000 tonnes of wood pellets annually for a total of 90,000 tonnes. Having two suppliers enhances reliability of supply. Both suppliers have employment arrangements with local Aboriginal communities. Transportation contracts are also in place.
The Atikokan GS is a former coal-fired electrical facility. The conversion project got underway in mid-2012 with ground preparation and the construction of two silos, each 44 metres tall and 21 metres in diameter. Each silo can store up to 5,000 tonnes of wood pellets. Modifications to the boiler and a new distributed controls system were also required. As well, new truck receiving and transfer infrastructure was built.
Pellets are received from self-unloading, rear discharge trucks that have their own discharging system built into the trailers. A new receiving system transports the pellets to the large storage silos by conveyor belt and a bucket elevator. When needed for production, the pellets are delivered to the plant on a first-in, first-out basis from the silos via conveyor belts and a second bucket elevator. Once inside the powerhouse, the pellets are pulverized and fed into the boiler, much the same way as coal was previously. Due to the similar heat content of lignite coal and wood pellets, the Atikokan boiler design was an ideal candidate for fuel conversion. All 15 burners were replaced with Doosan Mark IV biomass burners. New ash transport systems have also been installed.
The Pembina Institute conducted a Biomass Sustainability Analysis in 2011 that included climate change implications of electricity generation using biomass fuel. The report identified that harvesting biomass for electricity production is sustainable. A biomass program using wood pellets at a rate of two million tonnes per year is possible with no systemic decline in forest carbon stocks over time. This, together with Ontario’s sustainable forest management planning process and practices, means OPG’s biomass program can satisfy the United Nations Framework Convention on Climate Change (UNFCCC) definition of renewable biomass.
All OPG thermal generating stations have now ceased burning coal.