Natural gas, in many ways, is a tough form of energy to beat.

It's currently cheap, it comes from the U.S., not the Mideast, and when compared to coal or petroleum -- it looks like a cleaner alternative. Natural gas prices have settled in at about $4 per million BTUs and seem to be holding at that price, based, in part, from the enormous U.S. reserves like those in the Marcellus Shale.

Methane, or natural gas, also emits approximately half of the greenhouse gases of coal. The actual greenhouse gas emissions vary by the source of the fuel and age of a power plant, but gas generally wins by a wide margin. More importantly, gas doesn't emit the same amount of particulate matter.  In California and Texas, some companies are harvesting it from cow manure, a carbon-neutral alternative that cuts down on farm waste.

Natural gas accounts for 21 percent of U.S. power now, but that figure might rise to 40 percent by 2035, according to consulting and construction giant Black & Veatch. Gas can also be used to smooth out the power output fromsolarand wind farms.

On the negative side, shale gas, obtained through hydraulic fracturing, is becoming an increasingly contentious issue. Some see natural gas as a coal replacement, a transition fuel as we move towards renewables, and a potential way to power much of our transportation -- freeing the U.S. from reliance on imported oil.  Others see fracked natural gas as another air-polluting fossil fuel with horrific potential to damage our aquifers.

T. Boone Pickens claims that the United States has natural gas reserves that are equivalent to 700 billion barrels of oil and it is his personal crusade to move that ocean of natural gas into the American transportation sector.  He claims to have already spent $62 million on this quest, known as the Pickens Plan. Pickens wants compressed natural gas to be part of our transportation fuel mix -- starting with trucks and fleets.

Hydraulic fracturing, or "fracking," involves blasting through rock with a mix of water, sand and a chemical cocktail used to split the shale formation and free the trapped gas. The process produces an enormous amount of waste water, referred to as "produced water," that must be treated and transported.

Vikram Rao, former CTO of Halliburton and the current Executive Director of RTEC (Research Triangle Energy Consortium), said that the shale gas supply "is the most important energy event in the U.S. since the discovery of Alaskan oil." Rao sees the water transport and contamination issue as solvable. Others see the water problem as an entrepreneurial gold mine.

Dan Reicher, Executive Director, Steyer-Taylor Center on Energy Policy and Finance, Stanford University, said, "We need the combination of natural gas, renewable energy and energy efficiency," adding "We need to build this bridge between natural gas and renewables."

Even the President likes it. "Some folks want wind and solar. Others want nuclear, clean coal, and natural gas," President Obama said during his State of the Union Message. "To meet this goal, we will need them all, and I urge Democrats and Republicans to work together to make it happen."

But natural gas prices are tied to some extent to the the price of oil. And shale deposits tend to yield big quickly but deplete quickly as well. Are we just tying our future to a commodity that might zoom in price?

And what about government incentives? Will natural gas siphon off the funds for emerging technologies?