Biomass as a greenhouse energy source is not new.
Biomass as a greenhouse energy source is not new. Commercial greenhouses in British Columbia have used wood waste since at least 1986. Growers use what would otherwise be waste materials, saving money (compared to using natural gas and propane) and, more recently, develop their carbon-offset status. Some installations also benefited from Scientific Research and Experimental Development (SR&ED) tax credits.
Burner technology developments have allowed growers more flexibility. For example, Bio-Fuel Technologies has burners that mean “growers have the versatility to burn the fuel that’s available at the least cost, whether it is coal, wood, corn, manure, walnut shells, coconut shells, food wastes or agricultural wastes.”1 Further, research is very close to solving the next critical step: developing commercially available systems that enable CO2 to be cleanly harvested from the exhaust gasses of burning biomass for use in the greenhouse.
Growers not content with being at the mercy of waste availability from other industries are now developing their own biomass supplies. Last year, Greenhouse Canada reported on Dean Tiessen, (“New Energy Farms Group”), who plans to provide sufficient renewable biomass to heat 37 acres of tomatoes from his own (and contracted out) plantings of miscanthus. Pyramid Farms’ greenhouse operation consumes about 28,000 tonnes of wood waste per year. Growing its own biomass means this fuel supply is no longer a short-term solution to a long-term problem. New Energy Farms provides material for about 3,000 acres of contract grown miscanthus, which is “both economically profitable and environmentally friendly,” according to Tiessen, who found that willow and poplar don’t match the heat output or growth of miscanthus. In the U.S., Plainview Growers (a large Allamuchy, N.J., propagator of ornamental plugs and seedlings), is among the first “Biomass Conversion Facilities” under the USDA “Biomass Crop Assistance Program” (BCAP) planning to convert grasses, straw and corn stover to a self-sustaining pelletized fuel to heat seven acres of greenhouses.2
Growers are also developing other biofuels, such as willow. As reported in Greenhouse Canada (October 2011), Luc Verrier has the first system in Quebec that can use either wood waste or willow, and he plans to harvest his first (10-hectare) willow crop in 2013, meeting the energy needs of his 2,500-square-metre vegetable greenhouse.
These are all terrific projects, to be commended for their commitment to reducing dependency on non-renewable fuels.
However, detractors argue that the best use of any biomass material is to compost it and build soil rather than just burn it. This viewpoint often comes from thinking that using land for fuel production rather than food production is unquestionably non-sustainable.
On the other hand, supporters argue that there are essentially two kinds of biomass: woody and non-woody. Since animals rarely eat woody biomass, this can justifiably be sustainably converted into biofuel. Perhaps even better (as long as it doesn’t take land away from producing edible crops) is the use of fast pyrolysis to turn woody biomass into liquid fuels (“biomass gasification”). The “waste” of this process (biochar), can be used to vastly improve soils, so providing fuel and soil building in one process. Willow, being woody biomass, is an ideal candidate for this, and as seen previously, produces enough growth from a short three-year crop cycle if coppiced (a practice used in Europe for many decades).
Arguments for/against fuel versus food production are put forth passionately from both sides. But producers seeking some kind of “justification” might consider certification by the “Roundtable on Sustainable Biofuels” (RSB). This reviews compliance on several aspects of operation such as size, practices and local context, to provide a global, recognized and verifiable standard. RSB certification is recognized by the European Union (since July 2011), and applies to both operators and products. Certifiable products include:
- Biomass that can be processed into biofuel or energy.
- Processed biomass (e.g., straight vegetable oil, SVO).
- Biofuels such as bioethanol.
- Any mixture of biofuels mixed together.
Essential to certification is that all operators must evaluate the food security situation in their region – biofuels cannot be certifiably produced in a food-insecure region (except under specific provisions). The RSB currently has about 130 members from 35 countries, including companies producing fuels through processes such as creating bioethanol from starch-rich wastewater from wheat milling flour plants. For more information, check out the RSB website at www.rsb.org .
1 Delilah Onofrey, ‘Plainview Growers’ Biomass System And Alternative Fuels Are Funded By Grants,’ Greenhouse Grower, February 2009.
2 Tanya Brown, U.S. Department of Agriculture Biomass Crop Assistance Program, April 2011.
Gary Jones is chair of production horticulture at Kwantlen University, Langley, B.C. He sits on several industry committees and would welcome comments at Gary.Jones@Kwantlen.ca.
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