Nevada Greenhouse Gas Inventory and Reference Case Projections

FINAL Nevada GHG Inventory and Reference Case Projection
CCS, July 2007
Appendix I. Inventory and Forecast for Black Carbon
This appendix summarizes the methods, data sources, and results of the development of an
inventory and forecast for black carbon (BC) emissions in Nevada. Black carbon is an aerosol
(particulate matter or PM) species with positive climate forcing potential but currently without a
global warming potential defined by the IPCC (see Appendix J for more information on black
carbon and other aerosol species). BC is synonymous with elemental carbon (EC), which is a
term common to regional haze analysis. An inventory for 2002 was developed based on
inventory data from the Western Regional Air Partnership (WRAP) regional planning
organization and other sources. This appendix describes these data and methods for estimating
mass emissions of BC and then transforming the mass emission estimates into CO 2 equivalents
(CO 2 e) in order to present the emissions within a GHG context. Data from the WRAP for their
2018 forecast inventory were also analyzed to assess the changes in future year BC emissions.
In addition to the PM inventory data from WRAP, PM speciation data from EPA’s SPECIATE
database were also used: these data include PM fractions of elemental carbon (also known as
black carbon) and primary organic aerosols (also known as organic material, or OM). These data
come from ongoing work being conducted by E.H. Pechan & Associates, Inc. (Pechan) for EPA
on updating the SPECIATE database. 108 These new profiles have just recently been released by
EPA. As will be further described below, both BC and OM emission estimates are needed to
assess the CO 2 e of black carbon emissions. While BC and OM emissions data are available from
the WRAP regional haze inventories, CCS favored the newer speciation data available from EPA
for the purposes of estimating BC and OM for most source sectors (BC and OM data from the
WRAP were used only for the nonroad engines sector). In particular, better speciation data are
now available from EPA for important BC emissions sources (including most fossil fuel
combustion sources).
After assembling the BC and OM emission estimates, the mass emission rates were transformed
into their CO 2 e estimates using information from recent global climate modeling. This
transformation is described in later sections below.
Development of BC and OM Mass Emission Estimates
The BC and OM mass emission estimates were derived by multiplying the emissions estimates
for particulate matter with an aerodynamic diameter of less than 2.5 micrometers (PM 2.5 ) by the
appropriate aerosol fraction for BC and OM. The aerosol fractions were taken from Pechan’s
ongoing work to update EPA’s SPECIATE database as approved by EPA’s SPECIATE
Workgroup members.
After estimating both BC and OM emissions for each source category, we used the BC estimate
as described below to estimate the CO 2 e emissions. Also, as described further below, the OM
emission estimate was used to determine whether the source was likely to have positive climate
forcing potential. The mass emission results for 2002 are shown in Table I1.
108 Version 4.0 of the SPCIATE database and report is expected to be finalized during the Fall of 2006 and will be
provided via EPA’s web site (http://www.epa.gov/ttn/chief/emch/speciation/index.html).
Nevada Division of 73 Center for Climate Strategies
Environmental Protection
www.climatestrategies.us