Sunday, February 08, 2009

Shrinking Your Carbon Footprint

Well a deep recession certainly helps to shrink your carbon footprint but perhaps there are other ways to be good "green citizens"? The nice people at PGE offer some clues at that this website; http://www.pge.com/myhome/environment/calculator/assumptions.shtml

Glaeser/Kahn paper on standardized urban carbon footprints

I would like to see PGE think about how to design some research for measuring how different "treatments" such as information provision affect a household's electricity consumption. I have been working on this topic and I would encourage PGE to get in touch with me if this topic interests them.


Carbon Footprint Calculator Assumptions


General Information

Typical PG&E Residential Customer — Monthly Household Energy Use1
Electricity Usage: 540 kilowatt-hours (kWh)
Natural Gas Usage: 45 therms (winter 60 / summer 24)
ClimateSmart Rates1
Electricity: $0.00254 per kWh
Natural Gas: $0.06528 per therm
PG&E Carbon Dioxide (CO2) Emissions Rates2
Electric: 0.524 lbs CO2 per kWh
Natural Gas: 13.446 lbs CO2 per therm

Minimizing Your Carbon Footprint – Estimated Avoided CO2 Emissions

Switch to Compact Fluorescent Light Bulbs
Avoid 34 lbs CO2 per bulb per year
Assumptions:
Compares a 100-watt incandescent bulb to a 23-watt compact fluorescent
Lighting used 2.34 hours per day3

PG&E emissions rate (electric): 0.524 lbs CO2 per kWh
Install an Energy-Efficient Clothes Washer
Avoid 260 lbs CO2 per year
Assumptions:

Avoid up to 15 therms per year and up to 128 kilowatt-hours per year
Based on California Energy Commission-rated Tier 3, 2.65 cubic feet clothes washer supplied by a gas water heater — savings will vary greatly depending upon number of loads and size of washer, whether front- or top-loading, and whether electricity or natural gas is used for water heating
PG&E emissions rate (natural gas): 13.446 lbs CO2 per therm
PG&E emissions rate (electric): 0.524 lbs CO2 per kWh
Purchase an Energy-Efficient Water Heater
Avoid 120 lbs CO2 per year
Assumptions:
Avoid up to 9 therms per year
30 to 50 gallon 0.63 Energy Factor (EF) natural gas water heater — EF is a measure of energy efficiency
PG&E emissions rate (natural gas): 13.446 lbs CO2 per therm
Install High Efficiency Central Furnace
Avoid 1,000 lbs CO2 per year
Assumptions:

Avoid up to 74 therms per year
Based on installation of a more efficient furnace (94% AFUE) to replace a less efficient unit (70% AFUE) of the same size (67.611 kBtuh rating) — AFUE stands for Annual Fuel Utilization Efficiency and is a measure of heating efficiency on an annual basis
PG&E emissions rate (natural gas): 13.446 lbs CO2 per therm


Install Solar Electric Panels
Avoid 3,300 lbs CO2 per year
Assumptions:

Typical residential system is 3-5 kW
18% capacity factor
Operating 8,760 hours per year
PG&E emissions rate (electric): 0.524 lbs CO2 per kWh
Switch to Hybrid-Electric Vehicle
Avoid 2,900 lbs CO2 per year
Assumptions:
12,000 miles per year for average automobile4
Compares hybrid-electric subcompact with comparable vehicle: 2007 Toyota Prius (46 miles per gallon average fuel efficiency) and (non-hybrid) 2007 Honda Civic (29 miles per gallon average fuel efficiency)5
Burning 1 gallon of gasoline produces 19.4 lbs CO26
Average Per Capita CO2 Emissions (Energy and Vehicle Use)
Average Californian
22,941 lbs CO2 per person
Assumptions:

2005 California Per Capita Electricity Usage: 7,032 kWh7
2005 California Per Capita Natural Gas Usage: 422 therms7
California Emissions Rate for Delivered Electricity: 0.879 lbs CO2 per kWh8
Emissions Rate for Natural Gas: 13.446 lbs CO2 per therm9
12,000 miles per year and 21 miles per gallon for average passenger vehicle10
Burning 1 gallon of gasoline produces 19.4 lbs CO26

Average American
32,607 lbs CO2 per person
Assumptions:

2005 United States Per Capita Electricity Usage: 12,347 kWh7
2005 United States Per Capita Natural Gas Usage: 504 therms7
United States Emissions Rate for Delivered Electricity: 1,363 lbs CO2 per kWh8
Emissions Rate for Natural Gas: 13.446 lbs CO2 per therm9
2004 United States Per Capita Vehicle Usage: 464 gallons per person7
Burning 1 gallon of gasoline produces 19.4 lbs CO26
Average Global Person
8,750 lbs CO2 per person11
Sources
PG&E’s ClimateSmart program, authorized by the California Public Utilities Commission in Decision 06-12-032

PG&E’s ClimateSmart program, authorized by the California Public Utilities Commission in Decision 06-12-032 — The most accurate measure of emissions from power generation involves calculating the emissions from each plant operating in the portfolio of generating assets for each hour of the day and year, and this can vary considerably by time of day, year, and with seasonal variations in weather.

To avoid this complex approach, it is common to approximate emissions from electric usage through the use of an average emissions rate such as the California Public Utilities Commission (CPUC)-approved ClimateSmart electric emissions rate of 0.524 lbs CO2 per kWh — This reasonable approximation is based on the average emissions rate for PG&E’s electric portfolio, consistent with the emissions rate that is independently certified and registered each year with the California Climate Action Registry (see www.climateregistry.org). The CPUC-approved ClimateSmart natural gas emissions rate is 13.446 lbs CO2 per therm.


Database for Energy Efficient Resources, California Public Utilities Commission and California Energy Commission


Emission Factors (EMFAC) Model 2007 Version 2.3, Average Annual Mileage from Air Basins in PG&E Service Territory

U.S. Environmental Protection Agency, 2007 Miles-Per-Gallon Updates

U.S. Environmental Protection Agency, Overview: Pollutants and Programs Average Carbon Dioxide Emissions Resulting from Gasoline

California Energy Commission.

U.S. Environmental Protection Agency eGRID (Updated April 2007)

California Energy Commission (CEC): Inventory of California Greenhouse Gas Emissions and Sinks: 1990 to 2002 Update, Page A-24, CEC-600-2005-025, June 2005. The average emissions rate for customer use of natural gas is 11.7 lbs CO2 per therm. For comparability purposes for this calculator, we use the CPUC-approved ClimateSmart rate of 13.446 lbs CO2 per therm, which includes both customer use and distribution of natural gas.

Emission Factors (EMFAC) Model 2007 Version 2.3

World Resources Institute Climate Analysis Indicators Tool Version 3.0 (2002 Emissions Data), which is based on:
U.S. Department of Energy, Energy Information Administration 2004. International Energy Annual 2002
International Energy Agency. 2004. CO2 Emissions from Fuel Combustion (2004 Edition)
Marland, G., T.A. Boden, and R. J. Andres. 2005. Global, Regional, and National Fossil Fuel CO2 Emissions — in Trends: A Compendium of Data on Global Change — Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn., U.S.A.
Population Division of the Department of Economic and Social Affairs of the United Nations Secretariat, 2005 — World Population Prospects: The 2004 Revision
Return to Carbon Calculator

3 comments :

tom steenburgh said...

david mckay makes a complete set of similar calculations in a great book called "sustainable energy without the hot air." you can download it for free at

http://www.withouthotair.com/

i've wanted to replicate his work for the us market, but i haven't had time.

tom

Estimate Carbon Footprint, Carbon Offset Estimation. said...

You have given important information. Today
Global Carbon Emissionsis the biggest problem for environmental health.But many institutes are working on
Carbon Reduction Projects to
Reduce Co2 Footprintwhich will provide better ways to tackle.

Dan said...

I believe your number of "United States Emissions Rate for Delivered Electricity: 1,363 lbs CO2 per kWh" is incorrect, just like in PG&E's document. EPA says this (it's per megawatt not kilowatt):

http://www.epa.gov/solar/energy-resources/refs.html