Matt Damon's new film Promised Land is stoking the controversy over fracking, the shorthand for natural gas production using hydraulic fracturing and horizontal drilling. The film pits a big natural gas production company against economically stressed farmers in a Pennsylvania community who are being offered lots of money to permit drilling on their land. To illustrate the alleged evils of fracking, an environmental activist sets a model farm on fire in an elementary class. The film has gotten decidedly mixed reviews for its dramatic appeal and its characterization of the costs and benefits of fracking.

In fact, natural gas production in the United States is way up due to fracking. The process of fracking, which involves pumping water laced with sand and some small amounts of chemicals under high pressure into deep underground shale formations, has enabled drillers to release vast quantities of trapped natural gas. Thanks to fracking, shale gas production has grown from 1.3 trillion cubic feet (tcf) in 2007 to 7.8 tcf in 2011. According to the projections of the Energy Information Administration (EIA), U.S. natural gas production will rise from 23 tcf in 2011 to 33 tcf in 2040 and almost all of that increase will be due to shale gas production. In his 2012 State of the Union speech, President Obama cited estimates that the U.S. has enough natural gas to last 100 years. That estimate has been questioned, but even if it's off by a few decades, there's still plenty of natural gas to burn.

Environmental activists, who once hailed natural gas as the bridge fuel to the renewable energy future, have turned with a vengeance against it. Originally, activists who worried about man-made global warming produced by burning fossil fuels that emit carbon dioxide favored fracking because burning natural gas produces about half the carbon dioxide emitted by coal. However, local and national environmental groups have turned decisively against shale gas based on both not-in-my-backyard concerns and the fear that cheap natural gas undermines the economic case for solar and wind power.

Let's look first at some of the benefits of shale gas production. Natural gas is outcompeting coal as a cheap fuel for producing electricity and the result is that U.S. carbon dioxide emissions are down sharply to a level last seen around 1992. In addition, a study comparing the costs and benefits of coal with those of conventional and shale gas in the February 2013 issue of Energy Policy finds that burning natural gas produces far less in the way of air pollutants like sulfur dioxide, nitrogen oxides, soot, and mercury. The authors conclude that a shift from coal to gas would "reduce the overall likelihood of health problems affecting the nervous system, inner organs, and the brain."

Shale gas production in 2010 supported 600,000 jobs and that is projected to grow to 870,000 by 2015 and contribute nearly $120 billion to the overall economy. In addition, shale gas production is revitalizing a number of U.S. manufacturing sectors including the steel, chemical, and fertilizer industries. Thanks to cheap shale gas, Canada's TD Bank estimates that American residential consumers will save around $75 billion in home heating and electricity costs in 2013, the equivalent to about $650 per household.

So what about the downsides of shale gas production cited by environmental activists? Their first claim is that the beneficial reduction in carbon emissions that results from burning natural gas instead of coal is completely offset by the leakage into the atmosphere of much more powerful greenhouse gas methane from shale gas wells. In fact, on a 100 year time scale, the global warming potential of a molecule of methane (natural gas) is 21 times greater than that of a molecule of carbon dioxide. Over a 20-year period, methane is 72 times worse than carbon dioxide. So clearly it is important to figure out just how much methane is escaping from wells. Naturally, activists eagerly highlight studies that find very high levels of fugitive natural gas emissions, while shale gas boosters embrace studies that find low levels of escaping methane.

This fierce battle over shale gas methane heated up with the publication of a paper in Climate Change in 2011 by Cornell University environmental biologist Robert Howarth and his colleagues. The researchers concluded [PDF] "3.6% to 7.9% of the methane from shale-gas production escapes to the atmosphere in venting and leaks over the life-time of a well." If these estimates are right that would mean shale gas production results in more global warming than burning coal does. In 2012, Cornell University geoscientist Lawrence Cathles found that Howarth's estimates for fugitive methane emissions were much too high and were actually in the range of 1 to 1.5 percent.

More recently, scientists, measuring atmospheric methane near Denver, Colorado and the Uinta Basin in Utah, estimate that the amount of methane escaping wells is on the high side, 4 to 9 percent respectively. Before activists jump on the anti-fracking bandwagon for a joy ride the Environmental Defense Fund's chief scientist Steven Hamburg notes that while the Colorado and Utah studies are "valuable snapshots of a specific place on a specific day, neither is a systematic measurement across geographies and extended time periods." Consequently, Hamburg warns, "For this reason, conclusions should not be drawn about total leakage based on these preliminary, localized reports [emphasis in original]."



In the meantime, researchers at the Massachusetts Institute of Technology have published a new study in Environmental Research Letters assessing fracking emissions in 2010 which concludes, "[I]t is incorrect to suggest that shale gas-related hydraulic fracturing has substantially altered the overall GHG (greenhouse gas) intensity of natural gas production." In other words, fracked wells are no worse than conventional wells when it comes emitting methane into the atmosphere. In any case, concern about fugitive emissions should decline since new regulations require drillers to adopt "green completion" techniques that capture natural gas before it can escape from new wells.

The other big but more localized environmental concern is that fracking might pollute water both on the surface and in drinking wells. Of course, any industrial activity can go awry and so water pollution can occur. Lots of water is used in fracking and some 10 to 30 percent of it flows back to the surface as "production water" that must be dealt with. This production water contains some of the chemicals used to dope the water injected into the wells as well as naturally occurring salts and low levels radionuclides. Flowback water is now often being recycled [PDF] for use in fracking new wells although must be treated to remove contaminants.

Contamination of drinking water wells by fracking was dramatized in the dishonest documentary Gasland in which a homeowner in Colorado used a cigarette lighter to cause his running faucet to flame up. As it happens, an analysis by the Colorado Oil and Gas Conservation Commission found that the natural gas in that homeowner's well was from natural sources and was not related to fracking [PDF] as claimed in Gasland.

Gasland also highlighted claims by some residents of Dimock, Pennsylvania that fracking had contaminated their well water. The U.S. Environmental Protection Agency (EPA) has now sampled drinking water wells that served 64 homes. In July 2012, the agency reported finding no contaminants related to fracking, although 5 wells did have elevated levels of naturally occurring hazardous substances such as manganese.

An initial EPA study did find that water wells in Pavillion, Wyoming were likely contaminated with chemicals associated with fracking; however, that agency finding continues to be contested by pro-fracking proponents. A peer-reviewed study of the EPA's testing results is supposed to be released later this year. If Pavillion is the only confirmed example of contamination out of thousands of wells drilled each year, then it cannot be the case that fracking is a particularly hazardous activity with regard to well water.

One other area of concern is land disturbance caused by fracking. The February 2013 Energy Policy study notes that with regard to the amount of energy produced per land area both conventional well-drilling and coal mining disturb far more land than does fracking. Since fracking uses horizontal drilling, many more well-heads can be crowded into a relatively small area.

Promised Land offers a false choice between rural purity and virtuous poverty on the one hand and industrial degradation and rapacious greed on the other. Fracking poses some risks, to be sure, but the evidence suggests that they can be effectively managed in such a way that the environmental and economic benefits greatly outweigh the costs.