Nevada Statewide Greenhouse Gas Emissions Inventory and Projections, 1990 to 2030
Nevada Statewide Greenhouse Gas Emissions Inventory and Projections, 1990 to 2030
3.
3.1
Electricity Generation
Overview
GHG emissions associated with electricity generation have long accounted for a significant fraction of
Nevada's total emissions and the amount of GHGs released (overwhelmingly CO2, but in smaller
amounts CH and N2O) depends on the type and quantity of fuel consumed during the production of
electricity. Historically, Nevada's generation mix has been largely dependent on coal, a high carbon
content fuel, but this has been changing over the past decade as the state's aging coal-fired power
plants are retired and replaced with natural gas-fired power plants. Natural gas has about 55 percent
the carbon content of coal per unit of useful energy. Thus, as Nevada's generation mix has begun to
include more natural gas, Nevada has had less GHG emissions in spite of producing more electricity.
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Historical emissions were calculated using two methods. From 1990 to 2009 emissions were calculated
using the SIT. The SIT depends on information from the Energy Information Administration State Energy
Data System (EIA-SEDS) to perform its calculations. The EIA-SEDS provides fuel consumption estimates
for the electricity generation sector at the state level by calculating fuel consumption at a multi-state
level and distributing the results back to the states. The fuel consumption estimates (the EIA-SEDS
data) are then each multiplied by a specific emission factor that depends on the fuel type and the GHG
being estimated. From 2010 to 2013 emissions were determined using the methodologies of EPA's
Emissions & Generation Resource Integrated Database (eGRID). 13 This database is a comprehensive
source of data on the environmental characteristics of almost all electrical power generated in the
United States. Unfortunately, eGRID is not updated on an annual basis. So instead of using eGRID
directly for every year, the data sources that eGRID depends on were used to estimate GHG emissions
when eGRID data was not directly available.
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Projected emissions were determined by considering the emissions from Nevada's existing fleet of
generating facilities (their expected usage, remaining useful life, etc.) and then adding to that the
expected emissions of new generating facilities that are expected to be added to the state's fleet by
2030. New facilities were determined using regulatory filings submitted by Sierra Pacific Power
Corporation (SPPC) and Nevada Power Company (NPC), collectively NV Energy. As a requirement to
operating in the state, NV Energy has to submit Integrated Resource Plans and Energy Supply Plans to
the Public Utilities Commission of Nevada (PUCN) every 3 years for both SPPC and NPC. These
documents provide information as to when NV Energy is expecting to put into service new units and
what types of units it expects them to be. Knowing when a unit is expected to go into service, what type
11 Ibid, p 3-6.
12 This method does have drawbacks such as possible errors in the distributions resulting in under/overestimates
of emissions.
13 When information was unavailable, CH4 and N2O emissions (minute contributors to total sector emissions) were
still determined using the SIT.
14 https://www.epa.gov/energy/egrid (accessed October 2016).
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