Over the same period, domestic natural gas production has risen by 15 percent, producing a glut that has forced down the gas price by nearly two-thirds. Plentiful, cheap natural gas has crowded out much of the expected growth of renewable energy like wind and solar power, but it has cut domestic consumption of dirtier coal even more sharply.

Electrical generation from wind, solar, geothermal and biomass have expanded to 5.8 percent of the country’s electricity, from 3.1 percent, since Mr. Obama took office, partly because of tax incentives and other support from the administration’s stimulus package. But the expansion of power driven by natural gas has arguably been even more impressive. Cheap natural gas fuels a bit more than 30 percent of American power production, up from just over 20 percent in 2008.

On the stump, Mr. Obama has not been shy in heralding the boom in domestic oil and gas drilling under his watch. Not to be outdone, Mr. Romney has put “energy independence” — including the expansion of hydrocarbon exploration and production, building the Keystone XL pipeline from Canada and removing federal regulations on coal — at the top of his five-point plan to produce millions of jobs.

Certainly the two have different energy visions. Mr. Romney’s proposal to expand state regulatory control over drilling and mining on federal lands would represent a break from government policies dating back to Theodore Roosevelt, in the highly unlikely event that Congress could be coaxed to go along. And the two candidates are on opposite sides of a gaping divide over coal, with Mr. Obama pushing to phase out coal-fired electrical generation while Mr. Romney favors burning more coal to keep mine operations rolling.

But how much does the nation’s energy future depend on who wins the race?

No doubt the nation has several important decisions to make in the next couple of years. Should it limit hydraulic fracturing, the contentious method of blasting water through tight rocks to gain access to oil and gas, with new regulations? Should the federal government aggressively open up more offshore drilling in Alaska’s Arctic and off the coasts of Virginia and the Carolinas? Should it export vast amounts of its new bounty of natural gas, potentially jeopardizing the low price that is currently benefiting domestic consumers and manufacturers? Should the country allow construction of the Keystone XL pipeline, which would secure oil supplies from Canada, but also guarantee the spread of mining for oil sands, which has a higher carbon footprint than most conventional oils? Does coal, the dirtiest fossil fuel, have a future in America?

Either Mr. Obama or Mr. Romney will have to decide along with, of course, the new Congress and in many cases the states. The two candidates and their parties have different constituencies that are tugging them in opposite directions on these questions. But the election will probably matter only on the margins of energy policy. The same cannot necessarily be said, however, about the flip side of energy policy — environmental policy — where a Romney Environmental Protection Administration would probably look very different from Mr. Obama’s.