Evaluating AERMOD and Wind Tunnel Derived Equivalent Building Dimensions

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Evaluating AERMOD and Wind

Tunnel Derived Equivalent

Building Dimensions

A&WMA’s 109th Annual Conference and Exhibition

New Orleans, LA

June 22, 2016

Abstract #1015

Sergio A. Guerra, Ph.D.; Ron Petersen, Ph.D., CCM

CPP Inc., 2400 Midpoint Drive Suite 190, Fort Collins, CO 80525


Outline

• Background

• Classic EBD Method

– Wind Tunnel-Derived EBD

• Experimental Method

– AERMOD-Derived EBD

• Evaluation of WT and AERMOD Derived EBD

• Conclusions


Building Downwash


Building Profile Input Program

(BPIP)

Figure created in BREEZE ® Downwash Analyst

BREEZE is a registered Trademark of Trinity Consultants, Inc.


PRIME

AERMOD’s Building Downwash Algorithm

• Used EPA wind tunnel data

base and past literature

• Developed analytical

equations for cavity height,

reattachment, streamline

angle, wind speed and

turbulence

• Developed for specific

building dimensions

• When buildings outside of

these dimensions, theory falls

apart


Long Buildings with Wind

at an Angle

Figure created in BREEZE® Downwash Analyst

BREEZE is a registered trademark of Trinity Consultants, Inc.


AERMOD/PPRIME

Overestimates

Downwash

Reality

Summary of Needed Updates to

PRIME


BPIP Diagnostic Tool

http://bit.do/cppwind-BPIPDiagnosticLikely Overprediction Factor for each Flow Vector

Source 1


ComplianceCompliance

CPP’s EBDCPP’s EBD

BPIP Diagnostic

ToolBuilding Geometry

Meteorological Data

Terrain Data

AERMET

AERMAP

Operating Parameters AERMODOther Inputs

Building

Inputs

BPIP Diagnostic Tool


• Equivalent Building Dimensions (EBDs) are the dimensions (height, width, length and location) that are input into AERMOD in place of BPIP dimensions to more accurately predict building wake effects

• Guidance originally developed when ISC was the preferred model –

– EPA, 1994. Wind Tunnel Modeling Demonstration to Determine Equivalent Building Dimensions for the Cape Industries Facility, Wilmington, North Carolina. Joseph A. Tikvart Memorandum, dated July 25, 1994. U.S. Environmental Protection Agency, Research Triangle Park, NC

• Determined using wind tunnel modeling

What is EBD?


Classic Approach

Wind Tunnel-Derived EBD


Measure Ground-level

Concentrations

Data taken until good fit and max

obtained

Automated Max GL Concentration Mapper


Measure Ground-level Concentrations

With Site Structures Present

Tracer

from stack

Max ground-level concentrations measured versus x


Measure Ground-level Concentrations w/

Various EBD in Place of Site Structures

Tracer

from stack

Max ground-level concentrations measured versus x


Selecting and Equivalent Building


Summary of Approved Projects• Studies conducted and approved using original guidance for ISC

applications– Amoco Whiting Refinery, Region 5, 1990

– Public Service Electric & Gas, Region 2, 1993

– Cape Industries, Region 4, 1993

– Cambridge Electric Plant, Region 1, 1993

– District Energy, Region 5, 1993

– Hoechst Celanese Celco Plant, Region 3, 1994

– Pleasants Power, Region 3, 2002

• Studies conducted using original guidance for AERMOD/PRIME

applications – Hawaiian Electric (Approved), Region 9, 1998

– Mirant Power Station (Approved), Region 3, 2006

– Cheswick Power Plant (Approved), Region 3, 2006

– Radback Energy (Protocol Approved), Region IX, 2010

• After 2011 EPA Clearinghouse Memo

– Chevron 1 (Study Approved), Region 4, 2012

– Chevron 2 (Study Approved), Region 4, 2013

– Confidential Project (In process), Region 4, 2015

– Confidential Project (In process), Region 10, 2016


Experimental Method

AERMOD-Derived EBD Approach


AERMOD-Derived EBD• Step 1: Wind Tunnel Study to Establish

Maximum Ground-Level Profile Mapping with

the No Site Structures Present Case


AERMOD-Derived EBD• Step 2: Adjust AERMOD Inputs for the No Site

Structures Present Case


AERMOD-Derived EBD• Step 3: Wind Tunnel Study to Establish Max.

Ground-Level Profile Mapping with Site

Structures Present


AERMOD-Derived EBD• Step 4: AERMOD-Derived EBD


Comparison between

Wind Tunnel and AERMOD-Derived

EBDs


Comparison of WT-derived and

AERMOD-derived EBD profiles


Conclusion

• Adjustments to key parameters in the *.sfc

and *.pfl meteorological files can be used to

get better agreement between WT and

AERMOD MGL concentrations for the no site

structures present case

• After these adjustments the AERMOD-EBD do

not match the Wind Tunnel-EBD


Conclusion

• Discrepancy suggests that AERMOD is not

suitable to evaluate EBDs derived from WT

observations

• Wind Tunnel-derived EBD are still the

preferred method to replace BPIP-generated

ones


PRIME2 Advisory Committee

Subcommittee of the Atmospheric Modeling and

Meteorology Committee (APM) of the Technical Council

of the Air and Waste Management Association (AWMA).

The two purposes of this committee include to:

1. Provide a technical review forum to improve the

PRIME building downwash algorithms

2. Establish a mechanism to review, approve and

implement new science into the model for this and

future model improvements


Ron Petersen, PhD, CCM Sergio A. Guerra, PhD

[email protected] [email protected]

Mobile: +1 970 690 1344 Mobile: + 612 584 9595

CPP, Inc.

2400 Midpoint Drive, Suite 190

Fort Collins, CO 80525

+ 970 221 3371

www.cppwind.com @CPPWindExperts

Thanks!

Engineering

Evaluating AERMOD and Wind Tunnel Derived Equivalent Building Dimensions