Michael Deru ASHRAE Albuquerque, NM June 30, 2010 Better Green House Gas Calculations for Buildings NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.
Better Green House Gas Calculations for Buildings. Michael Deru ASHRAE Albuquerque, NM June 30, 2010. NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC. Why?. - PowerPoint PPT Presentation
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Michael Deru
ASHRAE
Albuquerque, NM
June 30, 2010
Better Green House Gas Calculations for Buildings
NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.
Why?
Source: Energy Information Administration, Emissions of Greenhouse Gases in the United States 2008
17.6%
19.2%
35.6%
27.6%
36.8%
Equals emissions from India
Calculating GHGs is Easy, right?
Step 1: Find a GHG calculatorStep 2: Plug in your energy useStep 3: Done, next project
But,
Which GHG calculator should I use?
Where do the numbers come from and what do they mean?
A survey by Texas A&M found 48 GHG calculators and large differences between them
0
1,000
2,000
3,000
4,000
5,000
6,000
1
Emiss
ions
(m
etric
tonn
e)1 State CO2e (+ precombustion)
2 State CO2
3 NERC Subregion CO2
4 State CO2e
4 State CO2e (elec. only)
5 National CO2 (elec. only)
GHG Calculator Comparisons
Credit: Michael Deru, NREL
Potential Issues in Building GHG Calculations
• Finding and interpreting emission factors• Regional variations in electric grid• Transmission and distribution losses• Time of day variations• Life-cycle emissions• On-site fuel combustion• On-site renewable energy• Accounting for electricity exports• Accounting for energy and CO2 offsets
Where do GHG Emissions Come From?
Combustion
CO2, CH4, N20Leakage
CFC, HFC, SF6
Scope-1 Emissions
Combustion
CO2, CH4, N2O
Precombustion
CH4, CO2, N2O
Scope-2 Emissions
Leakage
SF6
Scope-3 Emissions Typically only combustion emissions are
accounted for
Credit: Michael Deru, NREL
Global Warming Potential• GWP compares the ability to trap radiant energy in the
Total Average of CAISOTotal Min of CAISOTotal Max of CAISO2
Recommendations
• Clearly define the project scope• Use eGRID subregion or larger region data • Include T&D losses• Include precombustion emissions• Don’t forget on-site combustion and refrigerant
leakage (if applicable)• Use time-of-day factors to evaluate load
shifting and renewable energy
Conclusions
• Can’t get exact GHG emissions• Hopefully, we can get close and understand
whether they are going up or down• Nation wide hourly and time of use emissions