Decommissioning On-Farm Biogas Systems
Table of Contents
This Factsheet examines the special features for decommissioning common on-farm biogas systems and operations. Figure 1 shows an on-farm biogas process flow. Consult an engineer if your biogas system has features not discussed here.
Read this Factsheet together with OMAFRA Factsheet, Decommissioning and/or Recommissioning Existing Nutrient Storage Structures, Order No. 12-061, which describes important dismantling and demolishing methods for nutrient storage tanks and transfer systems, including:
The process of decommissioning a multi-part system, like a biogas system, is broken down into several steps:
Identify potential risks prior to decommissioning to help prevent potential impact on public health or the environment. When planning the decommissioning, consider the following:
At the time of decommissioning, the biogas system may still contain a variety of input and digestate materials. An input is a material prior to any pre-treatment and digestion. Digestate is a material after pre-treatment (if necessary) and digestion. See Nutrient Management Regulation O.Reg. 267/03, as amended, for definitions of the input and digestate materials.
General Precautions for Pumping Out Liquids
Biogas systems are designed to produce and capture gas. Proceed with caution when emptying the digester vessels and other tanks to avoid encountering an explosive or toxic gas mixture.
If uncertain about the risks, consult an engineer with biogas system experience to develop a safe plan for pump-out.
See the OMAFRA Factsheet, Hazardous Gases, Order No. 04-087, for further information on managing hazardous gases.
Managing Materials During Decommissioning of an On-Farm Biogas System
Fully remove and properly manage all materials (including water used for clean-up) from the digester system when decommissioning, as described below.
Input on-farm anaerobic digestion material
Input off-farm anaerobic digestion material
Note: While, in some circumstances, there are regulatory exemptions when bringing these materials to the biogas system, when sending them off-farm, they are considered to be waste and should be hauled by a licensed waste hauler.
Digestate agricultural source material
Note: If at least half the inputs to an on-farm biogas system are "on-farm anaerobic digestion materials," and they do not contain sewage biosolids or human body waste, the digestate can be considered an "agricultural source material" for the purpose of land application.
Digestate non-agricultural source material (NASM)
Note: While, in some circumstances, there are regulatory exemptions when bringing non-agricultural source materials (NASM) to the biogas system, when sending them off-farm they are considered to be waste and should be hauled by a licensed waste hauler.
Dismantle and demolish on-farm biogas system structures and equipment as described below.
Storage tanks, digester
Gas storage roof/dome
Components affected by desulphurization (build-up of crystallized sulphur)
Mixers, pumps and other mechanical equipment
Emergency flare and over-under pressure relief valve
Note: Only remove these valves when there is no chance that gas pressure could still build up in the container protected by the valve.
For more details, see the OMAFRA Factsheet, Decommissioning and/or Recommissioning Existing Nutrient Storage Structures, Order No. 12-061.
In most cases, the biogas system site is restored as agricultural or farmstead land. The OMAFRA Factsheet, Decommissioning and/or Recommissioning Existing Nutrient Storage Structures, Order No. 12-061, provides recommendations for dealing with below-ground components and ground surface restoration, and for safely disposing of structural materials on or off the farm. Where the site is within the footprint of the farmstead or where equipment was mostly or all above ground, it may be satisfactory to remove the equipment, tanks or structures without any further site restoration. Also, some equipment or structures may be re-purposed for other farmstead needs once other biogas system components have been removed.
Throughout the entire process of dismantling and decommissioning on-farm biogas systems, take care that the work is done safely. Follow applicable law when handling materials both on and off the farm. Information in this Factsheet will not override other requirements. For example, biogas systems that are approved under the Environmental Protection Act, 1990, as a renewable energy generation facility must follow the requirements of the Ontario Ministry of the Environment (MOE) document, Technical Guide to Renewable Energy Approvals, for guidance on preparing the Decommissioning Plan Report.
For more information:
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