Use of Biomass for Heating
Greenhouses in Ontario - Rules* and Best Management Practices
* Take Notice: the relevant legislation relating to the use of
biomass as a source for heat for greenhouse operations supercedes
this Factsheet if any discrepancies arise between them, or if any
regulatory requirement has been omitted herein. This Factsheet is
meant to serve as a guideline only. The reader should consult all
of the relevant Acts and the regulations before taking any decisions
about a greenhouse where the use of biomass as a source of heat
is concerned. This Factsheet has been published as a service for
Ontario greenhouse operations only. Readers use it at their own
risk. The Ontario Government does not accept any liability for any
injuries arising from the use of this Factsheet.
The higher cost of heating a greenhouse using natural gas or oil
has resulted in many growers switching to alternate fuels. This
document describes the opportunities, challenges, regulations and
types of best management practices related to the use and storage
of these alternate fuels.
Fuels for Greenhouse Operations
Traditionally, commercial greenhouse growers have used natural
gas as their primary source of fuel to heat the greenhouse. The
- clean-burning fuel, resulting mainly in carbon dioxide and water
as the final by-products
- ease of initial hook-up and use
- minimal equipment maintenance
- improved boiler technology with increased heating efficiency
- flue gas carbon dioxide available for greenhouse supplementation
- fuel delivered to the farm via a pipeline
Many greenhouse operations using natural gas as their primary source
of heating fuel have used light oil (#2 oil) as a secondary source
of fuel to provide a back-up in case of natural gas supply interruption.
In some situations, a gas supply company may request a greenhouse
operator switch to an alternate fuel source to increase the availability
of natural gas to a residential user during exceptionally cold periods
in the winter. When the price of natural gas increased significantly,
some growers switched to heating with heavy oil (#6 oil). The boilers
were easily convertible to accept heavy oil as a fuel, and growers
had oil storage tanks on site. Despite the lower cost of heavy oil,
there were several disadvantages:
- parasitic losses
- energy required to keep fuel fluid
- increased expense to maintain boilers in efficient working condition
- increased potential of fouling boiler tubes, requiring shut-down
- potential for oil spills, especially during transfer from delivery
truck to storage tanks
- disruption of supply due to delivery failure
- inability to use flue gas carbon dioxide to supplement the greenhouse
Because energy prices for both natural gas and oil have remained
high, more vegetable and flower growers have shifted, or plan to
shift, to the use of alternate fuel sources.
Factors to Consider Before Using Alternate Fuels
Before using alternate fuels, numerous factors should be considered,
including, without limitation:
- fuel source characteristics, including:
- reliability of supply over the long term
- current and future pricing
- quality of fuel (uniformity, thermal value, ash content and
- ease of on-site management of fuel
- transportation system to transfer fuel to the combustion chamber
- combustion chamber and its combustion characteristics
- health and safety considerations
- potential impacts on the natural environment (e.g., particulate
emissions or surface water contamination)
- possible approval requirements from the Ontario Ministry of
the Environment (MOE), such as a certificate of approval
- dispersion modelling of stack emissions
- waste disposal site designation (if required)
- long-term availability of the fuel and pricing
Types of Alternate Fuels
There are many alternate fuels available to heat a greenhouse,
- biomass fuels for incineration (woodchips, sawdust (from fresh-cut,
wood mills, furniture factories, pallets, etc.), construction
and demolition debris (wood-based), energy crops, farm-waste (plant
materials, seeds), food processing waste, pelletized agricultural-
and wood-based products)
- biofuel (biodiesel or ethanol)
- biogas (bio-digestion gas from energy crops, manure and food
by-products, landfill gas, etc.)
Choosing an Alternate Fuel
The factors listed above, as well as the cost and return on investment,
will likely determine which fuel a grower selects. A Certificate
of Approval (C of A) from the Ministry of the Environment (MOE)
is not required for combustors using agricultural waste, biofuel
or biogas. Other alternate fuels may require a C of A based on the
type of fuel, its storage and transportation requirements and its
combustion emissions in an approved combustion vessel (under the
jurisdiction of the Technical Standards and Safety Authority).
Greenhouse production is considered part of the agricultural sector.
This has the following effects:
- Section 9 of the Environmental Protection Act (EPA) does not
apply to any plant, structure, equipment, apparatus, mechanism
or thing used in agriculture. Due to this exemption, greenhouses
do not generally require a C of A for the air discharge from the
combustion vessel used for heating the facility. However, some
monitoring may still be required.
- Part V of the EPA and Ontario Regulation 347 made under the
EPA do not apply to agricultural waste resulting from farm operations.
In addition, approval under Part V of the EPA is not required
for the use of waste wood as a fuel, unless large volumes of the
waste are stored. Agricultural waste and waste wood have different
exemptions. Therefore, greenhouses combusting these materials
do not require a C of A for waste management from the MOE. A greenhouse
operation that accepts other kinds of waste (as defined in the
Environmental Protection Act and Regulation 347 made under the
EPA) may be required to obtain a C of A. Any mixing of these wastes
with an exempt material (such as agricultural waste) may also
require a C of A. Note that even if an approval is not required,
a greenhouse operation must not cause an adverse effect (defined
below) or violate other environmental regulations.
Under the EPA, adverse effect means one or more of:
- impairment of the quality of the natural environment for any
use that can be made of it
- injury or damage to property or to plant or animal life
- harm or material discomfort to any person
- an adverse effect on the health of any person
- impairment of the safety of any person
- rendering any property or plant or animal life unfit for human
- loss of enjoyment of normal use of property
- interference with the normal conduct of business
For more information about C of A requirements, please contact
the Environmental Assessment and Approvals Branch (EAAB) at 416-314-8001
in Toronto, 1-800-461-6290 outside Toronto, or by e-mail at EAABgen.firstname.lastname@example.org.
As of December 2006, applicants for a C of A for a Waste Disposal
Site must complete the following sections of their application unless
otherwise expressly instructed in writing by the MOE:
- facility description
- property location
- storm water management
- property ownership and description
- existing land uses
- proposed site plan and operation specifications
- proposed maximum volume of materials
- volume calculations
- biomass boiler description and operating specifications
- pre-processed material quality control
- hours of operation
- description of material movement on-site
- material storage time
- fencing and site security
- proposed record-keeping
- vehicle movement on-site
- facility maintenance and training
- financial assurance and liability assurance
- contingency plan
- emergency response plan
- notification of neighbours
- notification of municipality
- municipalities may have zoning restrictions requiring rezoning
to accommodate a waste disposal site as an agricultural use
- posting a financial assurance
- emission and dispersal modelling
Some key points to note are:
- notification of neighbours
- notification of municipality. Municipalities may have zoning
restrictions requiring rezoning to accommodate a waste disposal
site as an agricultural use.
- posting a financial assurance for the implementation of remedial
action if necessary
- lead time to obtain a C of A
- C of A details. Each C of A is specific to the initial submission
request. Any changes to the fuel source, hours of operation, etc.,
will require an amendment to the C of A. It is best to apply for
all foreseeable options when obtaining a C of A.
Storage of Biomass
When storing biomass, greenhouse operators should consider, without
limitation, the following:
- Biomass is bulky and requires large storage facilities.
- Biomass has a higher moisture content. There is more shipping
weight and lower heating efficiency with biomass.
- Biomass will absorb moisture if left in the open. In most cases,
when the outer layer of the pile is wet, the interior of the pile
remains relatively dry.
- Biomass may spontaneously combust under the wrong conditions:
- Material was too wet when piled.
- There is a large variation in particle size, creating pockets
of trapped air.
- Compacted materials prevented heat dissipation from the
- There is a potential for odours when fuel source breaks
- There is a potential for wind-blown dust and debris off
the storage piles.
- There is a potential for runoff or leachate from the storage
facility. This must not be allowed to reach surface or groundwater
in a manner that will impact the environment.
Storage structures constructed to store biomass must comply with
the Building Code Act requirements, and with requirements of the
Fire Marshal. The size of the storage must be adequate to house
the amount of fuel stored. Ideally, the storage facility should
be located close to the boiler room to ease fuel delivery to the
combustion vessel. It should be located on a solid surface to allow
easy all-weather access for delivery trucks (as well as emergency
vehicles). The storage site should be graded to manage and capture
surface water. These must be specified on the C of A application
(if required). To prevent contamination of the surface and groundwater,
the storage facility should be located away from drains, drainage
ditches and watercourses and on an impervious floor to prevent potential
leachate contaminating the groundwater. For setback distances, see
the Best Management Practices publications Manure Management, Order
No. BMP16, and Water Wells, Order No. BMP12, and the Environmental
In most cases, outside storage is necessary. A C of A (if required)
or Regulation 347 could limit its size. Best management practices
for storing the biomass fuel should include/consider, without limitation,
- Keep piles less than 8 m in height.
- Do not use machines to compact material. Do not build up piles
by driving loaders or dozers onto the fuel pile.
- Limit pile size to less than 1,000 m3/ pile.
- Maintain fire breaks of at least 6 m between piles (Source:
Ontario Fire Marshal's Office).
- Provide easy access for emergency vehicles in all weather conditions.
- Ensure fire hydrants or a large volume of available water are
in close proximity to biomass storage area.
- Develop a "Fire safety plan" document for both indoor
and outdoor storage. Review the document with the local Fire Department
and with staff.
- Establish a no smoking policy. Post "No Smoking" signs
in clear, visible locations around the fuel storage site, and
enforce the policy.
- Invest in appropriate portable fire extinguishing equipment
or other control measures (contact local Fire Chief).
- Erect fencing to limit access to storage site and to prevent
- Install security lighting.
- Landscape around the perimeter of the site using berms, trees
and fences to improve the visual aspects of the site and to minimize
wind-blown dust/particles and odours.
- Use infrared thermography to assist in identifying hot spots
to mitigate the risks of spontaneous combustion.
- Grade land to manage surface water runoff.
- Locate site on impervious soils to minimize leachate entering
Spontaneous combustion in biomass can usually be prevented by following
- Store only dry or seasoned fuel.
- Prevent segregation of particle sizes in the piles by forming
the piles with an inclined conveyor.
- Store in small piles.
- Keep piles low.
- Use oldest fuel first.
- Monitor temperatures within the piles regularly, using infrared
thermography, if available.
There are two types of ash:
- ash remaining in the combustion chamber
- fly ash (ash collected from the cyclone and smoke stack)
Ash generated from an agricultural activity is exempt from Part
V of the EPA and Ontario Regulation 347. However, ash must be disposed
of responsibly after the combustion of biomass. Ash remaining in
the combustion chamber may be disposed of in landfill or incorporated
into the soil as a soil amendment. Fly ash can be considered hazardous
and should be disposed of in a facility approved to receive this
type of waste. If the material remaining in the ash chambers is
composed of more than 10% unburned fuel, it should be disposed of
at a landfill site.
Rising fuel costs may make burning of alternate fuels a viable
option for some greenhouse operators. Careful consideration of the
information provided above is necessary to determine if alternate
fuels will work for you. All greenhouse operators are responsible
for ensuring that their choice of fuel does not cause an adverse
affect on the environment.
If a greenhouse operation accepts any waste, other than 100% agricultural
waste resulting from farm operations or wood waste, it may require
a Certificate of Approval - Waste Disposal Site from the Ontario
Ministry of the Environment. Please note that Regulation 347 does
prescribe some conditions for the use of waste wood and that these
must be followed to ensure that a Certificate of Approval is not
required in relation to the use of the waste wood. It is a violation
of the EPA to accept non-exempted waste at a site that has not been
Agricultural waste - waste, other than sewage, resulting
from farm operations, including animal husbandry and, where a farm
operation is carried on in respect of food packing, food preserving,
animal slaughtering or meat packing, includes the waste from such
Biomass - materials organic in origin that can be used as
fuel (e.g., wood, straw, stover, husks, grains and even manure and
biodegradable wastes that can be burned as fuel).
Biofuel - fuel derived from biomass, including liquid and
gaseous fuels such as ethanol and biodiesel, produced from agricultural
products such as corn, soybeans, flaxseed, canola and sugar cane.
Energy crop - crop grown for the production of fuel wherein
the whole plant is used or processed for this purpose.
Processed organic waste - waste that is predominantly organic
in composition and has been treated by aerobic or anaerobic digestion,
or other means of stabilization, and includes sewage residue from
sewage works that is subject to the provisions of the Ontario Water
Wood waste - waste:
- that is wood or a wood product, including tree trunks, tree
branches, leaves and brush
- that is not contaminated with chromated copper arsenate, ammoniacal
copper arsenate, pentachlorophenol or creosole, and
- from which easily removable hardware, fittings and attachments,
unless they are predominantly wood or cellulose, have been removed
Wood waste does not include:
- upholstered articles
- articles to which a rigid surface treatment is affixed or adhered,
unless the rigid surface treatment is predominantly wood or cellulose
Waste biomass - organic matter that is derived from a plant
or an animal, that is available on a renewable basis and that is
- waste from harvesting or processing agricultural products or
- waste resulting from the rendering of animals or animal by-products
- solid or liquid material that results from the treatment of
wastewater generated by a manufacturer of pulp, paper, recycled
paper or paper products, including corrugated cardboard
- water from food processing and preparation operations
- wood waste
This Factsheet was written by Shalin Khosla, Greenhouse Vegetable
Specialist, OMAFRA, Harrow, and Helmut Spieser, Engineer, Field
Crop Conditioning and Environment, OMAFRA, Ridgetown. It was reviewed
by Veronica Pochmursky, Patrick Spezowka, and Trevor Robak, Ministry
of the Environment, and Wayne Brown, Greenhouse Floriculture Specialist,
OMAFRA, Vineland, and Don Hilborn, Engineer, OMAFRA, Woodstock.