Photovoltaic-Diesel System for Electricity Supply
By Emmanuelle Brière
February 2013
The installation of a photovoltaic-diesel mini-grid in British Columbia’s Nemiah Valley has reduced fuel needed to generate electricity by approximately 25%.
The community of Nemiah Valley is located 250 km north of Vancouver, BC, 100 km from the closest electrical power grid. Because of its remoteness, it relies on diesel “gensets”, or sets of generators, to produce electricity. However, the cost of producing electricity from those gensets is approximately 10 times higher than the cost of producing it from a power plant that is part of an integrated electrical network.
Researchers at Natural Resources Canada’s (NRCan) CanmetENERGY have collaborated with the Xeni Gwet'in First Nation in the Nemiah Valley to test the viability of a hybrid photovoltaic (PV)-diesel mini-grid to help reduce electricity cost. To achieve this, the partners first studied ways to improve the efficiency of the genset in place, and then installed a system of PV solar panels.
“The improvements we have made to the genset, combined with the addition of the PVs, have resulted in savings averaging 26,000 litres of fuel per year, which is a 25% reduction,” announced Sophie Pelland, photovoltaics researcher at NRCan’s Varennes Research Centre. “We have also observed a decrease in greenhouse gas emissions of approximately 73 tonnes, equivalent to taking 21 cars off the road.”
A More Efficient Genset
The Nemiah Valley genset initially consisted of three 95-kW diesel generators, which supplied 22 homes and a commercial zone containing a daycare, health centre, gas station and other amenities. However, like most remote communities, generators are oversized in comparison to their energy demands, in anticipation of an eventual increase in electricity demand.
This practice leads to significant losses of efficiency. “Although the community’s energy needs are relatively low, it is common practice to maintain generators at a baseload of approximately 30% in order to prevent premature wear,” explains Dave Turcotte, researcher in renewable energy integration at CanmetENERGY. “Therefore, most remote communities use an additional load or dump load to ensure a baseload for the generator. The dump load is activated when the generator’s load drops below 30%; the resultant energy is lost.”
To avoid this loss of energy and the associated overconsumption of fuel, researchers at CanmetENERGY recommended replacing one of the three diesel generators with a smaller one. “The new 30-kW generator takes over at night and on weekends, eliminating non-critical loads in the commercial zone, which were previously maintained during those periods,” Dave explains.
Solar Energy as a Complementary Energy Source
After fixing this deficiency in the existing diesel mini-grid, CanmetENERGY and the Xeni Gwet’in Nation added PV solar panels to help lower the community’s electricity costs and provide researchers with the opportunity to study a PV-diesel mini-grid.
“The relatively small load of this community’s original grid allowed for a much higher photovoltaic penetration than in large-scale centralized grids,” added Sophie. The 27.36 kW of PV installed represents approximately 36% of the grid’s peak load, and supplies 11% of the users’ yearly electricity needs.
“The Xeni Gwet’in have been considering using a renewable energy source like solar energy for some time to lower their fuel consumption,” Sophie continues. “This was the perfect opportunity to design a hybrid system for the first time and to evaluate its performance. We also thought that the demonstration project would be very useful for other remote communities facing the same challenges.”
The results of this demonstration project have been shared as part of a collaboration with the International Energy Agency.
For more information, visit the CanmetENERGY and IEEE Web site.
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