Oops Natural Gas's CO2 footprint could be higher than Coal

Forbes has an article that accounts for Natural Gas through its life cycle, not just in consumption.

Traditionally, we use emission numbers just for the power plant itself, that is, how much CO2 does a coal plant emit in producing a kWhr of electricity versus a gas plant versus a wind turbine, etc. These numbers have some emissions from other parts of the plant life-cycle such as construction and mining, as these dominate the emissions for energy sources like nuclear, hydro and wind which emit no GHG during operation.

Until now, the average equivalent grams of CO2emitted per kWhr produced has been calculated as 975 gCO2/kWhr from coal; 600 gCO2/kWhr from natural gas; 90 gCO2/kWhr from hydro; 55 gCO2/kWhr from solar; 15 gCO2/kWhr from wind, and 15 gCO2/kWhr from nuclear (Parliamentary Office of Science and TechnologyGHG from Power Plants).

One calculation that has stirred debate is that the natural gas number is as high as 1200 gCO2/kWhr.

However, new studies by Robert Howarth and associates at Cornell University (GHG Footprint of Natural GasNational Climate Assessment; thanks to atomikrabbit for pointing me in this direction) provide emissions data from the entire natural gas life-cycle. Their results bump this number for gas from 600 gCO2/kWhr to over 1,200 gCO2/kWhr, making natural gas the largest emitter of GHGs in electricity generation. On the other hand, Howarth and company have been challenged by others that say their numbers are too high (BusinessWeek), particularly Lawrence M. Cathles, also of Cornell. Cathles contends that gas is still better than coal with respect to global warming. Even if Cathles is correct and 600 gCO2/kWhr is still the number for gas, it’s not that much better than coal compared to ther energy sources like hydro and nuclear.

For those of you have just switched to a power generation mix that has more natural gas than coal, you may be stuck again.  And, your carbon footprint may be much bigger than you thought.