Well, things are not so simple. Under the best conditions, we may enjoy those benefits, but under more adverse conditions, natural gas can be a greater generator of greenhouse gases than coal, it can wreak massive local environmental destruction, and it can undermine energy efficiency and renewability. And without a strong set of policies to guide natural-gas development, the worst case is far more likely.
Start with climate change: Generating a kilowatt-hour of electricity with a natural-gas turbine emits only about half as much carbon dioxide as generating the same amount at a coal plant. That's pretty good. But unburned natural gas turns out to be a very powerful greenhouse gas: One molecule of leaked gas contributes as much to global warming as 25 molecules of burned gas. That means that if the system for the exploration, extraction, compression, piping, and burning of natural gas leaks even 2.5 percent of the total, it's as bad as coal.
So, how much does the gas system leak? No one knows. Estimates range from 1.5 percent to as much as 8 percent. Even near the low end of that range, gas can be as bad as coal. And whatever the leakage in the U.S. system, it is likely to be far worse in, say, Russia.
This gives us Rule One for smart natural-gas development: No leaks. We have to know for certain that the whole process is tight and will stay that way.
There's more we need to ensure because of the economics of energy systems and how they drive choices in the electricity system. It starts with a basic economic truth: Once a coal-fired plant is built, it is incredibly cheap to run. So, once built, our coal plants run forever. The median age of a coal plant in the United States is 44 years, and fully a third of them were built during or before the Eisenhower administration.
What this means is that when we add new natural-gas power plants to the electricity system, they do not, through pure market forces, displace coal. Instead, they displace other new alternatives, which generally means new renewable energy. If gas is displacing zero-CO2 renewables, well, that's hardly a victory. So, Rule Two: Use gas to shut down old coal.
The final three rules have to do with local environmental conditions. We have all seen the films of people's tap water catching fire after a gas well was put in nearby. That's because of lousy construction: Bad well casings allow gas to leak into an aquifer. They can also allow contamination with fluids used in hydraulic fracturing. Rule Three: Strong standards for wells, with effective monitoring and enforcement.
Then there is the damage that wells can do to the drilling site. Many wells extract brackish water and other nasty by-products, like benzene and toluene, from deep underground, and spill the mixture onto nearby farmlands - literally salting the earth. The water is a large-scale by-product of gas extraction, and, at the request of then-Vice President Dick Cheney's energy task force, it is exempted from any regulations under the Clean Water Act. Rule Four: Don't allow these toxic streams to poison the land.
Finally, choosing where and how to drill is important. Many of the new natural-gas technologies entail massive surface disturbance. Roads, drilling rigs, compressors, pipelines, drainage ponds, and large amounts of heavy equipment are required for each well. And wells are densely placed, sometimes one for every 10 acres. This means that many natural-gas fields are industrial wastelands. After drilling, cattle ranches in the West have been left unsuitable even for cows, never mind wildlife.
We need to zone natural-gas development so that it is kept out of ecologically important areas, and we need strong drilling, operating, and reclamation standards so that gas doesn't become a scorched-earth energy strategy.
Gas can do a great deal for our energy future. But if it is mishandled, it can cause big problems - in land destruction, water quality, and climate change.
Five rules get it right: Don't allow leaky systems; use gas to phase out coal; have sound well drilling and casing standards; don't pollute the landscape with brackish water; and drill only where it is sensible. Let's do this right.
Hal Harvey is the founder of the ClimateWorks Foundation. He was a member of presidential commissions under George H.W. Bush and Bill Clinton, and he serves on an advisory board for the Department of Energy. He wrote this for the Los Angeles Times.