Methane Capture and Use:
Current Practices vs. Future
Possibilities
Methane Capture and Use: Current Practices
Today’s primary use of capture Methane from a landfill or
digester is Electrical Power Generation by internal
combustion engine (turbine or reciprocating) typical
installation consist of the following major components:
– Gas compression equipment for gas field extraction and
compression to 2-3 psig
– Internal Combustion Engine is usually a reciprocating engine
that manufactured for numerous other commercial applications
with some enhancements to run on landfill or digester gas.
– Engine is coupled to synchronous generator.
– Electrical power controlled and connected to the grid via
common electrical switchgear with some additional controls for
load control.
– Electrical substation consisting of station transformer (stepping
up to utility distribution voltage and well as utility tie breaker (at
distribution voltage.
Methane Capture and Use: Current
Practices
Why is electrical power generation the preferred choice?
– Financially feasible in most areas of the country.
– Proven technology that is relatively simple with a system that is
comprised of common everyday components.
– Operation fits in well with day to day operation of a landfill.
– Low risk compared to alternatives
Other common current practices:
– Direct fired heating examples: leachate evaporation, asphalt
plant, space heating
– Steam production for various commercial and industrial
processes.
Methane Capture and Use: Current
Practices
Current state of landfill methane to energy
development
– Market is mature; almost all large landfills have
projects or are committed to projects.
– Most opportunities today involve landfills with 1000
SCFM or less of gas.
– In cases where there is REC market and or high
electrical energy cost smaller power plants once
thought to be unfeasible are now feasible.
– Changing landscape of the energy market opens new
possibilities for methane use.
Methane Capture and Use: Future
Possibilities
Conversion of LFG to pipe line quality gas
– Different technologies used:
membrane separation process
pressure swing adsorption
absorption process using a liquid solvent
– Benefits
Delivery of renewable energy to anyone within the natural
gas transmission and distribution network.
Eliminates some emissions issues associated with
conventional combustion and power generations.
Extraction and isolation H2S is possible with pressure swing
adsorption.
Extraction of CO2 for commercial sale
Methane Capture and Use: Future
Possibilities
Conversion of LFG to pipe line quality gas
– Challenges:
High capital cost for equipment
Financial Feasibility is limited to large scale projects
Very limited number current operating applications;
technology still developing
Location has to be in close proximity to natural gas pipeline
Uncertainity natural gas market
High parasitic for conversion and compression
CO2 is only suitable for industrial application not food market
due impurities and stigma associated with LFG
Methane Capture and Use: Future
Possibilities
Conversion of LFG to CNG for use in vehicular
applications
– Technologies similar to LFG to pipeline quality with
additional compression equipment and storage
– Benefits
More commercial vehicles available with CNG option
A small landfill with 250 SCFM of 50% could displace over a
1000 gallons of # 2 diesel fuel.
Cleaner fuel for commercial vehicles.
Extraction and isolation H2S is possible with pressure swing
adsorption.
Extraction of CO2 for commercial sale
Methane Capture and Use: Future
Possibilities
Conversion of LFG to CNG for use in vehicular
applications
– Challenges:
High capital cost for equipment
Financial Feasibility is limited to large scale projects
No current commercial operating applications; technology still
very early in developing
Storage
Vehicles available.
Regulatory issues exist in many states
High parasitic for conversion and compression
CO2 is only suitable for industrial application not food market
due impurities and stigma associated with LFG
Methane Capture and Use: Future
Possibilities
Combine Heat and Power
– Technologies are similar to straight power generation with heat recovery
for heating and cooling.
– Benefits
With net metering small CHP projects 500 kW or less make very good
financial sense.
Inexpensive energy source for electricity, heating and cooling for industrial or
commercial real estate development in close proximity to a landfill.
Total thermal efficiency approaching 85% are possible.
Small scale possibilities
– Challenges
Net metering
Electrical interconnect.
Island operation
Location must have loads (electrical and heat) in close proximity of landfill.
Methane Capture and Use: Future
Possibilities
Other Possibilities
– Conversion to methanol or ethanol
– Fuel Cells
– Hydrogen Production