Carbon Emission Intensities

There are several fractions that quantify carbon emissions. In general, we want to minimize the amount of carbon dioxide released, while maximizing the services delivered (electricity, transportation, heat, or others). These are also called emission intensities.

• Carbon Intensity of Electricity
  • Mass of carbon released per unit of electricity delivered to the grid
• Carbon Emissions from Fuel Burning
  • Carbon released divided by heat energy released
  • also called carbon intensity of combustion
• Electricity plant efficiency
  • ratio of electrical energy out to heat energy input
• Carbon Intensity of Transportation
  • Mass of carbon released per passenger mile of transportation

Carbon Intensity of Electricity

Note some of these are for technologies and some are averaged over a supply of electricity.

Coal-fired electricity carbon intensity (EIA)	2.21 lb CO2 / kWh
Natural Gas electricity carbon intensity (EIA)	0.91 lb CO2/ kWh
PG&E electricity carbon intensity	0.524 lb CO2 / kWh
Sonoma Clean Power Clean Start	98.8 lb CO2 / MWh
Sonoma Clean Power EverGreen	46.0 lb CO2 / MWh

Carbon Intensity of Combustion

Coal carbon intensity of combustion	210 lb CO2/MM BTU
Natural gas carbon intensity of combustion	120 lb CO2/MM BTU
Natural gas carbon intensity of combustion (EPA)	0.0549 MT CO2/Mcf

Power Plant Efficiencies

Coal plant efficiency	30–45%
Natural gas plant	42%
Natural gas combined cycle	60%

Transportation

Van Pool	0.22 lb CO2/passenger-mile
Heavy Rail Transit	0.22 lb CO2/passenger-mile
Light Rail	0.36 lb CO2/passenger-mile
Bus Transit	0.64 lb CO2/passenger-mile
Private auto	0.96 lb CO2/passenger-mile

Source: DOT Report

Units

Common units of energy for carbon intensities are the kilowatt-hour, megawatt-hour, and gigawatt hour.

Note that:

• 1 MWh = 1000 kWh
• 1 GWh = 1000 MWh

3 MWh \frac{1000\; kWh}{1\; MWh} = 3000\; kWh

A common unit of mass for carbon dioxide emissions is the metric ton.

• 1 metric ton = 1000 kg