An amazing thing has happened over the last five years. Against all expectations, American emissions of carbon dioxide into the atmosphere, since peaking in 2007, have fallen by 12%, back to 1995 levels. (As of 2012. US Energy Information Agency). How can this be? The United States did not ratify the Kyoto Protocol to cut emissions of greenhouse gases below 1997 levels by 2012, as Europe did.
Was the achievement a side-effect of reduced economic activity? It is true that the US economy peaked in late 2007, the same time as emissions. But the US recession ended in June 2009 and GDP growth since then, though inadequate, has been substantially higher than Europe’s. Yet US emissions continued to fall, while EU emissions began to rise again after 2009 (EU). Something else is going on.
The primary explanation, in a word, is “fracking.” In fourteen words: the use of horizontal drilling and hydraulic fracturing to recover deposits of shale gas.
One can virtually prove that shale gas is the major factor behind the fall in US emissions. Natural gas, especially when burnt in combined-cycle gas turbine power plants, emits only half as much greenhouse gas (GHG) as coal. Ten years ago domestic natural gas production appeared to be reaching its limits; the industry was so sure of this that it made big investments in terminals to import Liquefied Natural Gas (LNG). Yet the fracking revolution has increased the supply of natural gas so rapidly since then that LNG facilities are being expensively converted to export. Clean natural gas occupies a rapidly increasing share of the generation of electric power. It has come largely at the expense of coal’s share. Within power generation, natural gas is up 37% since 2007, while coal is down 25%. As a result, natural gas has drawn close to coal as the number one source of US power — unthinkable a short time ago. Renewables have been rising, but still constitute only 5% of power generation in the US. This is less than hydroelectric and far less than nuclear, let alone coal or gas.