GHG BACT Analysis
Deanna L. Duram, P.E., C.M.
August 4, 2011
Air & Waste Management Association
Southern Section Meeting
trinityconsultants.com
Outline
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EPA Guidance and 5-Step Process
Differences from traditional BACT
approach
Highlight a biomass case study
throughout
EPA BACT Guidance
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Case-by-case determination
Performed by applicant; approved by agency
EPA recommends 5-Step top-down BACT evaluation
process
Emission limits achievable considering…
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Economic impacts
Environmental and energy impacts
EPA guidance materials
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PSD and Title V Permitting Guidance for GHGs
White Papers on GHG Control Measures
On-Demand Video Training Materials, including sample BACT
assessments
Enhanced RBLC
5-Step Top-Down BACT Process
Step 0 – Define the Source
 Step 1 – Identify available control options
 Step 2 – Eliminate technically infeasible options
 Step 3 – Rank options by control effectiveness
 Step 4 – Evaluate most effective controls and
emission limits achievable
 Step 5 – Select BACT
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Step 0 – Define the Source
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Applicant defines goals, objectives, purpose,
and basic design
Source definition generally provides key
design elements that are not under
consideration through the BACT process
Define in permit application
Permit issuer must discern which design
elements are inherent to that purpose and
objectives and which may be changed for
pollutant reductions
Step 0 Case Study
New Combined Heat and Power System at
existing
pulp and paper mill
 620 MMBtu/hr bubbling fluidized bed boiler
 40 MW Steam turbine generator
 Biomass combustion (bark, mill residuals)
 Natural gas for startup burners and some load burning,
< 250 MMBtu/hr
 Installation allows for shutdown of 1 coal/oil/gas power
boiler; removal of coal/oil from a second power boiler,
retaining only gas combustion
 Objective is to generate renewable energy to replace
fossil fuel energy on site and for potential sale to the
utility grid
Step 1:
Identify
Available
Control
Options
(1/2)
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Identify all control technologies available
to the source, including:
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Inherently lower-emitting processes and
designs
Add-on technologies
Control methods applied at similar
emissions sources
Feasible combinations of these
technologies
Considers facility-level impacts
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No off-site impacts considered, technology
must represent emissions reduction at
facility
Step 1:
Identify
Available
Control
Options
(2/2)
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Not required to include options that
“fundamentally redefine the nature of the
source”
No clear guidance re: which technologies
redefine nature of source
Fuel type as BACT? EPA guidance
considers:
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Cleaner versions of primary fuel
Increased usage of secondary fuel
Alternative fuel for which source is not already
configured
EPA guidance leaves door open for stricter
interpretations by permitting authority
Use relevant white papers as starting point
Step 1 Biofuel Considerations
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EPA Guidance
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Potential carbon neutrality (based on life-cycle of biofuel) not
considered
At facility-level, CO2 emissions from biofuels similar to fossil fuels
Biofuels must represent emissions reduction at facility level to be
considered viable GHG BACT option
Biogenic carbon deferral
3/21/2011: EPA proposes deferral of GHG permitting
requirements for CO2 emissions from biogenic sources
 EPA issued guidance for determining BACT for bioenergy
production
 Promulgated 7/20/2011
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Effective immediately for delegated states
SIP approved states may incorporate into rules
Step 1 Energy Efficiency
Considerations (1/2)
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EPA BACT guidance stresses importance of energy
efficiency
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Construction of new facilities
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Primary Step 1 option(s) for combustion sources
GHG BACT evaluated on facility-wide basis, including energy
efficiency
Evaluate emissions from non-emitting, energy consuming
equipment
Modification to existing facilities
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BACT applies to new or modified emission unit, not necessarily
to energy consuming equipment
EPA guidance still encourages permitting agencies to consider
energy efficiency
Step 1 Energy Efficiency
Considerations (2/2)
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EPA guidance recommends benchmarking
evaluation
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Collectively assess small energy saving measures by
benchmarking efficiency of new unit of similar design
EPA resources to support benchmarking
analyses
ENERGY STAR program
 Sector-specific tools, Energy Performance Indicators
(EPIs), etc.
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Step 1 CCS Considerations
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Carbon Capture and Storage (CCS)
One of primary distinctions between traditional BACT and
GHG BACT
Per EPA, consider CCS in Step 1 for large CO2 emitters,
sources emitting high-purity CO2 streams
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Hydrogen production
Ammonia production
Natural gas processing
Ethanol production
Ethylene oxide production
Cement production
Iron and steel manufacturing
Even if non high-purity CO2 stream, may need to include as a
“possible” control option
Step 1 Case Study
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CCS
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Efficient Boiler Design
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Technology selection of BFB boiler over other designs
Redefining source?
Lowest Carbon Fuel
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High-purity stream? Not on EPA list
Limited industrial applications
Consideration of back-up fuels as primary (natural gas)
Source redefining concerns – not evaluating any other fuel
possibilities
Energy Efficiency Options
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Number of options in EPA guidance documents
New boiler – state of the art
Step 2:
Eliminate
Technically
Infeasible
Options
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Is technology available?
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Reached licensing and commercial
development stage
Compliance with BACT limit
demonstrated at similar facility
Is technology applicable based on
physical, chemical, and engineering
principles?
Per EPA, absence of a commercial
guarantee for GHG emissions not
sufficient to eliminate option from
consideration
Step 2 CCS Considerations
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Must consider technical feasibility of each step
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If any step infeasible, CCS considered technically infeasible
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Capture, transport and storage
Low-purity stream?
Space
Right-of-ways
Access to storage reservoir
May suffice to demonstrate difference between CCS
considerations at applicant’s facility and demonstrated CCS
Many state agencies prefer to monetize everything (eliminate
from Step 4 instead)
Step 2 Case Study
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CCS
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Boiler design
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Addressed supercritical steam design (greater than 3,200
psig operating pressure) as infeasible for this boiler size
Fluidized bed, suspension, stoker, and pile combustion
feasible options
Lowest carbon fuel
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Low-purity stream?
No available storage/pipeline
Use of natural gas feasible
Efficiency options
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Feasible
Step 3:
Rank
Remaining
Control
Options
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Ranked by effectiveness of control
Traditionally presented as:
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For GHG, EPA advocating efficiencybased control effectiveness
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Percent pollutant removal
Controlled emission rate
Reduction in emissions over time
Consider thermal efficiency by using
emissions per unit of output (rather than
per unit of fuel input)
Must rank logical combinations of the
technologies
Can be challenging given variety of
iterations on energy efficiencies
Step 3 Case Study
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Compared boiler efficiencies
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In this case, ranked based on energy efficiency –
fluidized bed is the clear choice
What if proposing to install a new stoker boiler with
a lower energy efficiency?
Is this an area an agency can look at – redefining
the source?
Did not do a straight comparison between
remaining options
Proceeded to Step 4 with a BFB boiler, and
lowest carbon fuel and energy efficiency
options to be reviewed
Step 4:
Evaluate
Most
Effective
Controls
(1/3)
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Ranked by effectiveness of control
Traditionally presented as:
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Percent pollutant removal
Controlled emission rate
Reduction in emissions over time
Top-down – Start with most effective
control option
Consider economic, environmental, and
energy-related impacts
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BACT typically focuses on economic
considerations
But EPA guidance suggests other
collateral impacts increasingly important
for GHG BACT
Step 4:
Evaluate
Most
Effective
Controls
(2/3)
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Economic considerations
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No cost effectiveness threshold ($/ton CO2e)
in EPA guidance
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Evaluated on a per ton CO2 equivalent basis
instead of per ton individual GHG
EPA guidance considers average cost
effectiveness and incremental cost of adding
compatible control technology
Work Group’s Interim Phase I Report identifies
cost effectiveness range from $3-$150/ton
CO2e
Additional local economic factors (new for
GHGs)
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High control cost relative to project cost
Potential movement to overseas production
Local job losses
Step 4:
Evaluate
Most
Effective
Controls
(3/3)
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Additional considerations
Direct energy costs (e.g. combustion
sources)
 Indirect energy usage (e.g. purchased
electricity)
 For CCS, consider parasitic load
 On-site and off-site environmental
implications (e.g., life cycle of biofuels)
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Step 4 Case Study
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Environmental benefits of project
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Natural gas is a non-renewable fuel
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Combustion of plant residuals - Identified by EPA as a CH4 control
measure for on-site landfills, so used that logic as a benefit for the
project
Significant reduction in coal generated power on-site
Reduction in wastewater through scrubber removal
Off-site benefit – generation of renewable energy, sale of
renewable energy to grid, likely displacing fossil-fuel generated
electricity
Higher costs than biomass
Biomass carbon-neutrality? Recent EPA guidance – biomass
combustion is BACT
State of the art energy efficiency options for new unit
Step 5:
Select
BACT
(1/2)
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Select BACT based on most efficient
control option or combination of options
not eliminated by Step 4
Permitted BACT standards vary
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Emission limits (output basis, accounting for
energy efficiency)
Averaging time periods
Equipment specifications
Work practices
Associated monitoring, recordkeeping, and
reporting
EPA advocates BACT limits with longer
averaging periods to address GHG
emissions and load variations inherent in
combustion equipment
Step 5:
Select
BACT
(2/2)
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May include work practices such as an
Environmental Management System
(EMS) focused on energy efficiency
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ENERGY STAR provides guidance
BACT limit may include implementation of
energy saving measures identified by EMS
EPA’s Sample GHG BACT assessments
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Municipal solid waste landfill
Natural gas-fired boiler
Hydrogen plant at petroleum refinery
Coal-fired electricity generating facility
Kiln at a cement plant
Natural gas compressor station
Gas-fired combined cycle power plant
Step 5 Case Study
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Proposed BACT limit based on vendor provided data
0.45 lb CO2e per lb steam on a 12-month rolling average
basis
Anticipated CEM for monitoring for CO2, and subsequent
calculations for CH4 and N2O
Since application submittal, EPA released biomass
deferral proposal and bioenergy GHG BACT guidance
State agency was considering a range of options, even
having mentioned the possibility of “good combustion
practices” as BACT
Stay tuned...
Questions
Deanna L. Duram, P.E., C.M.
Trinity Consultants
(678) 441-9977
dduram@trinityconsultants.com