- Greenhouse Growers Explore New Energy-Conserving Measures
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- By Jeffrey Carter
Ontario Correspondent
- Greenhouse growers across the Great Lakes region have been left scrambling in the wake of a major increase in the price of natural gas. Drilling activities have increased dramatically and an eventual price decline is expected but energy experts like Terry Rochefort of Canada’s National Energy Board are not sure when that will come. Meanwhile, greenhouse growers are finding ways to cut costs and many have switched to alternative fuels.
Rochefort and several other speakers talked about energy saving measures at a greenhouse growers meeting held earlier this year in Leamington, Ontario.
Bunker C fuel, a low-grade diesel, is becoming the fuel of choice in some regions but there are problems. There have been complaints in Leamington that Bunker C fuel contains higher levels of contaminants and is difficult to burn properly. The fuel needs to be pre-heated to 180 to 205°F prior to entering the combustion, according to Lorne Smith of Waterloo Manufacturing Ltd., and the deposits that are left can be difficult to remove.
Cole Cacciavillani of CF Greenhouses at Leamington is sticking with clean-burning natural gas. That keeps his neighbors happy and he’s still able to save a substantial portion of his energy costs. The system recovers heat that otherwise would escape through the boiler smokestacks. The pay back period, even without government incentive programs, is conservatively estimated to be three years, Cacciavillani said.
In essence, a heat exchanger is installed around the smokestack with a hot water heating loop extended to the greenhouse. The resulting “low grade hot water” has a temperature range between 82 and 113°F. The hot water is circulated in its own loop. The harder the boiler is working, the more energy is saved. For producers with steam-heat systems, there’s an added benefit: the piping system allows for railed harvesting which also reduces labor.
Three industry representatives, Nick Holubowsky of Cravo Equipment Ltd., Gary Dekker of VRE Greenhouse Systems, and John Walters of Ludvig Svensson Americas, spoke about thermal curtain systems for greenhouses. They became popular in the 1980s when the last energy crunch occurred. Walters said they provide, depending on the design, a 20 to 70% savings during the evening period when the curtains are drawn.
The curtains are reflective, made from an aluminum cloth material. There are designs intended to provide shading and designs intended primarily to reduce energy costs. The latter should provide a sealing action and should be drawn at night time, trapping the heat from the sunlight and reducing heat lost from steam and hot water heating systems. The cost of systems providing higher energy savings are around a dollar per square foot of greenhouse, Walters said.
Boiler maintenance can also save a greenhouse operator energy. Larry Smith, of Waterloo Manufacturing, provides solid advice. He said greenhouse producers should make sure their boilers are properly set up. For example, a boiler with the incorrect outlet nozzle size can have its efficiency dramatically reduced.
In addition, boiler operators should ensure the mixture of fuel to oxygen is correct. This can be adjusted according to results from a monthly or quarterly analysis of combustion efficiency.
Smith said operators should know the correct flow of water or steam for their boiler along with the correct pressures.
Shalin Khosla, a greenhouse researcher with Ontario’s Ministry of Agriculture, said producers should temper their expectations. While a combination of energy-saving technologies may result in higher overall savings, it’s “realistic” to base business plans on savings between 10 to 15% of your current energy costs.
