A leader in CHP
Rosa Flora partnered with Toromont Power Systems in 1992 to develop a customized CHP system with the ability to provide electricity for electrical loads and thermal energy for warming the greenhouse when natural light isn’t enough. “I think we are unique in that we started with CHP 22 years ago, so we are familiar with the technology and what needs to happen to make it work,” says operations manager Ralph DeBoer, a partner in the business and son-in-law of the founders. “To realize some of the economies of scale with CHP, you do need to be a certain size, and we certainly qualify for that.”.
Rosa Flora installed the two G3516 generators in 1992. Each produces 800 kW of electrical energy, and 1 MW of useable thermal energy. The net result is a system that is around 80 percent efficient in converting natural gas energy into useable heat and power, a much higher number than can be achieved via separate electricity and boiler utilities.
“Those engines are still running today, and the kilowatts that we make are used to offset the cost of electricity that we would normally purchase from our electric utility, the Ontario Power Authority,” DeBoer says.
In early 2011, the grower commissioned two G3520Cs, which each produce 2 MW of electricity and deliver approximately 3 MW of thermal energy to support greenhouse heating needs. Together the four generators supply a total of 5.6 MW of power.
“The real advantage for us as greenhouse growers with CHP equipment is during the coldest months of the year, when the heat is worth the most to us,” DeBoer says. “We will generally run the generators from mid-August to mid-April. We do have a thermal load in the summer, as well, to de-humidify the greenhouse.”
The heat from the generators is recovered through jacket water, exhaust, lube oil, and after-cooler recovery. The captured heat is used to send hot water directly into the greenhouse and heat it. If the heat is not used immediately, it is stored in insulated hot water storage tanks, which act as a thermal battery for use in the evening. Heat from the generator sets is captured through jacket water, exhaust, lube oil and after-cooler recovery. If the heat is not used immediately, it is stored in insulated hot water storage tanks, which act as a thermal battery for use in the evening.
Rosa Flora purchased two additional G3520C generators from Toromont Power Systems in 2014, which is part of another 4 MW CHP plant. The new CHP plant supports a contractual arrangement with the Ontario Power Authority, where Rosa Flora sells the electricity it generates back to the grid and use the heat from the generator to warm its greenhouses.
“As a fresh cut flower grower here in Ontario, one of the drivers to investing in CHP is that over the last few years, the power prices from the grid have continued to rise,” DeBoer says. “With the stability that we hope to see in natural gas pricing, CHP can become more and more attractive to us as a grower that uses heat and electricity, and purchases natural gas.”
Given the exacting conditions required to grow fresh cut flowers, the proper combination of heat, light and moisture must be present at all times. “CHP ensures that our greenhouses stay warm,” DeBoer says. “It’s one more tool that we have when it’s 20 below and the wind is blowing at 50 mph—we have combined heat and power units that we can fire up to heat the greenhouses. In addition to biomass and natural gas boilers, it’s one more added level of security.” Additionally, in the event of a power outage on the main grid, the CHP system can be used as standby power until utility power is restored.