Unaccounted gas amounts to nearly 2% of US greenhouse gas emissions

Putting together data from here and here.

These documents show:

-Over the last five years the US total annual unaccounted for gas averaged 247 billion cubic feet, which translates to 123 million metric tons of equivalent CO2 (according to my process for calculating shown here for Massachusetts).

-The total US GHG emissions were 6,633 Million Metric Tons.

123/6633 = 1.9%

Greenhouse Gas Potential from leaking Natural Gas in Massachusetts

Here is my calculation for the Greenhouse Gas Potential from the 8 billion cubic feet of natural gas (methane, or CH4) lost each year in the state of Massachusetts:

Convert to cubic meters: 8 x 10^9 ft^3 x 0.028 m^3/ft^3 = 2.26 x 10^8 m^3 CH4

or, 2.26 x 10^11 liters of CH4

assume (accepting a bit of temperature and pressure error) 22.4 liters per mole for an ideal gas at standard temperature and pressure.

2.26 x 10^11 liters x 1 mol/22.4 liters = 10^10 moles CH4

use 1 mole CH4 = 16 grams

10^10 moles CH4 x 16 grams/mol = 1.6 x 10^11 grams CH4

use CH4 25X the Greenhouse Gas Potential of CO2
(ref: http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter2.pdf)

= 4.0 x 10^12 g eCO2 = 4 Million Metric Tonnes equivalent CO2 per year in Massachusetts in lost natural gas.

This is about 4-5% of the total state greenhouse gas emissions inventory
(ref: http://www.mass.gov/dep/air/climate/ghg08inv.pdf)

Infrastructure for Idiots

Ever seen these road markings? If you start looking you'll see them everywhere on our streets. Here's what it means: A natural gas pipeline is in-line with the axis of the double arrow (about 5 feet belowground). In this case, the pipe is 8" diameter cast iron (CI). These markings come from the utility in response to dig safe requests, when someone needs to dig and wants to avoid hitting a pipeline.

So if the utility can mark our streets, shouldn't we be able to mark where the leaks are too?