Carbon Mitigation Initiative
CMI

Stabilization Wedges The Wedge from Substituting Natural Gas Power for Coal Power

BAU

  • Activity level(AL)
    • 2.8Gt coal
    • 1400 GW installed capacity and 10,800 TWh output
  • Assumptions
    • Carbon content: 70.7%1
  • Total emissions
    • =2.8*71%=1.98 Gt-C/year

Target

  • Activity level(AL)
    • 1.3 Gt Natural Gas (69,350 Billions of standard cubic feet)2
    • 1400 GW installed capacity and 10,800 TWh output
  • Assumptions
    • Carbon content: 75%
  • Total emissions
    • =1.3*75%=0.98 Gt-C/year

Thus, we derive a wedge.

Comments

The pace associated with this wedge is 28 GW of new natural gas power displacing 28 GW of new coal power every year. At these power plants, 1 GtC/y will be emitted from natural gas instead of 2 GtC/y from coal. The 3x3 matrix for 2054 above would read, after one such wedge: 1 GtC/y from coal to electricity and 3 GtC/y from natural gas to electricity, for a total 2054 emission of 4 GtC/y associated with electricity production, instead of 5 GtC/y. A full second wedge of this kind would not be available.

We can relate a wedge of natural gas to flows through specific large pipelines and LNG tankers:

1 "70.7 percent carbon describes coal equivalent within +/- 2%," according to G. Marland, et. al. (S35) . This percentage is consistent with the bituminous coal atomic ratios of CH0.8O0.1, if the coal is 85%( CH0.8O0.1) and 15% "other", by weight. "Other" might be ash.

2 We assume that the volumetric carbon content of natural gas is 538 gC/Nm3, where Nm3 is "normal cubic meter." We use the equivalence of two gas volumes, both defined at atmospheric pressure, but defined at different temperatures: 1 Nm3 = 37.24 scf, where scf is "standard cubic foot." (The scf is at 60 degrees F, and the Nm3 is at 0 degrees C.) The arithmetic, then, is that 1 GtC/y is 37.24/(538*10-6*365) Bscf/d = 190 Bscf/d. Here, both G and B are one billion, or 109.

The Alaska natural gas pipeline currently under negotiation is to carry about 4 Bscfd. A wedge of flowing natural gas (190 Bscfd, or 1 GtC/y) is equivalent to bringing one Alaska pipeline on line every year for 50 years3.

A wedge of flowing natural gas (190 Bscfd, or 1 GtC/y) is equivalent to 50 large LNG tankers docking and discharging every day4. Current LNG shipments create about one-tenth as large a flow of carbon.

Reference

S35 Marland, G., et. al. 1989. Estimates of CO2 emissions from fossil fuel burning and cement manufacturing, based on the United Nations energy statistics and the U.S. Bureau of Mines cement manufacturing data. Oak Ridge, TN: Oak Ridge National Laboratory, Environmental Sciences Division. Publication No. 3176, 1989.


 
Feedback: cmi@princeton.edu
Last update: February 17 2011
BP Princeton Environmental Institute © 2014 The Trustees of Princeton University
CMI is sponsored by BP.