Landfill Gas 101
HALTON REGION
Public Works - Waste Management Services
May 15, 2014 – MWA Spring Workshop, Hockley Valley Resort
Presented by: Art Mercer, Supervisor of Landfill Operations
Today’s Topics
•
Background on Halton Region
•
Sources of Methane
•
The How, What & Why of Landfill Gas (LFG) Systems
•
Development of Halton’s LFG Collection, Flaring & Utilization System
•
Gas Collection Components
•
Utilization Facility Components
•
Project Costs and Results
•
Lessons Learned
Halton Region
The Halton Waste Management
Site is located in Milton, Ontario
• Population ~ 525,000
• On Lake Ontario between Toronto &
Hamilton
• 4 Local Municipalities :
Burlington, Halton Hills, Milton & Oakville
• Landfill ~ 75,000 tonnes of garbage per
year
• Remaining site life is until 2044 at
current fill rates
Major Sources of Methane
Emissions…
Agriculture
Globally, domestic livestock are the primary source of methane
which is produced as part of their normal digestive process
Environment Canada (2013)
Major Sources of Methane
Emissions…
Environment Canada (2013)
Major Sources of Methane
Emissions…
Landfills
• Anaerobic decomposition of buried
organic waste produces landfill gas
• Landfill gas is composed primarily of
methane (CH4 ) and carbon dioxide
(CO2) which are greenhouse gases
• CH4 has 21-times the global warming
potential of CO2 *
• Canadian landfills account for 20% of
national methane emissions *
Landfill Gas Composition
O2 N2
H2 H20 Trace
CO2
CH4
* Environment Canada (2013)
The
How, What & Why of Landfill Gas Systems
How do you capture Landfill Gas?
•
Use vacuum pressure within the landfill to collect the LFG before it
escapes to the atmosphere
What can you do with captured Landfill Gas?
• Flare it to destroy the methane (good choice)
• Use the combustion energy for power generation instead (better
option)
Why collect Landfill Gas at all?
• GHG emissions reductions for landfills
• Offset use of non-renewable fossil fuels (if utilized for electricity
generation)
• Reduce odours and potential for off-site impacts
• Regulations now make it mandatory to collect LFG in Ontario (2010)
Development of the Halton Landfill Gas
Collection, Flaring & Utilization System
Phase 1 COLLECTION FACILITY - (Constructed
2006)
• Halton Region installed wells within landfill and
constructed a flare station
• Landfill gases were then vacuumed from the landfill
to the enclosed flaring system for burning
Phase 2 UTILIZATION FACILITY - (Constructed
2007)
• Partnership was struck between Halton Region and
Oakville Hydro in 2004 for development
• Oakville Hydro installed two 1-Megawatt engines
(GE-Jenbacher) running exclusively on LFG
captured and provided by Halton Region in 2007
• Facility has capacity to generate enough “green
power” to provide electricity for up to 1,500 homes
(2-MW)
• Electricity is sold to Ontario Power Authority under
purchase agreement with Oakville Hydro and
distributed by the local utility, Milton Hydro
Gas Collection Components
(Phase 1)
1) Vertical Wells – installed in deep waste in closed landfill areas
2) Horizontal Collection Trenches – Installed within waste during filling
3) Headers & Laterals – Transmit gas from landfill to Blower Building
4) Condensate Sumps – Collect moisture along header pathways
Gas Collection Components
Vertical Extraction Wells
•
Wells are drilled into waste
•
Consist of perforated vertical piping
surrounded by porous granular materials
•
Well-head allows volume of gas extracted
to be regulated
•
Applying vacuum pressure to the well
creates a collection “zone-of-influence” of
up to 30 metre radius
•
Wells are spaced out to achieve full
coverage for optimal capture of the landfill
gases
Gas Collection Components
Gas Extraction Hardware
Perforated horizontal collection pipe installed in waste
Gas Extraction Hardware
Solid-walled Lateral piping
Gas Extraction Hardware
Solid-walled large diameter perimeter Main Header piping
Gas Extraction Hardware
Condensate sump riser with internal pump and buried discharge
Collection meets Utilization
Utilization Facility Components
Components
•
Condensate Trap
•
Moisture Separator
•
Condenser-Chiller Loop
•
Blowers
•
Main Flare (Enclosed)
•
Gas Treatment (Carbon
Filter)
•
Purge Flare (Candle-stick)
•
Generators
“Make the Green Power”
Project Costs and Results
•
Halton’s LFG collection system required initial investment of $3.4-Million in 2006 for 21Vertical Wells, 5-Horizontal Collection Pipes, Blowers, Flare and peripherals
•
Two well-field expansions of $0.25-M (2009) and $0.75-M (2013). System now consists
of 80 gas collection points
•
Oakville Hydro invested $4.1-Million to construct the power generation facility in 2007,
includes two 1-MW gen-sets and peripheral equipment
•
Currently collecting 250 – 500 cubic feet per minute of LFG (varies seasonally)
•
99% of LFG collected is utilized for power production on site, generating revenue
through OPA standard offer program (2007)
•
Halton Region achieved voluntary early-action acknowledgement for compliance with a
2010 Regulation 347 Amendment requiring all landfill’s containing > 1.5-million m3 of
waste to have a LFG collection system installed
Lessons Learned
• Differing requirements for Collection and Utilization can create
challenges, e.g. volume of gas for environmental controls –vspower generation/revenue
• Revenue sharing plans (contracts) should be targeted to provide
sufficient income to cover operating costs for all partners
• Horizontal collection piping is subject to flooding from perched
leachate conditions which “choke off” the gas flow, therefore are
not recommended for this climate
• Vertical wells can also partially fill with liquid. Pumping it out
improves gas capture, although this does increase costs of
collection
Lessons Learned
(Cont’d)
• Scrutiny of collection system designs before construction can
help reduce operational issues such as unnecessary Confined
Spaces and other H&S issues (e.g. in-ground chambers for well
heads, chambers for condensate sumps)
• Study of waste composition, density and moisture content can
help to maximize gas capture and improve well field design
• Due to the variability of landfill factors, need to ensure that
experienced consultants and operators are hired who are familiar
with unique design and operation challenges of LFG systems
THANK
YOU!
QUESTIONS?
Contact
Art Mercer, Supervisor of Landfill Operations
905-825-6000 x 8207, art.mercer@halton.ca