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How do we get energy from natural gas?

Do you know how we get energy from natural gas?
Do you know how we get energy from natural gas?
Hemera/Thinkstock

You've heard the clean-fuel hype. So what's your role? Homeowners and residents account for 21 percent of all natural gas consumption in the U.S. And, if you bought a new home in 2010, there's a 54 percent chance your place runs mostly on natural gas, instead of oil or electricity. Gas is trendy now because it's greener than coal and petroleum.

Each year, technology makes gas more profitable, and green laws encourage it over coal and oil. So how do we get it?

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Several million years ago, plants and animals died at the bottom of then-oceans. Silt and sand hardened over the decaying organic material, trapping it beneath. Cue heat and pressure slow-cooking the remains, and transforming carbon and hydrogen into methane-rich gas, coal and oil. The gas rose through porous rock and hit impenetrable traps -- reservoirs. It collected there till geologists came along.

Geologists know which rock types are likely to contain gas; for instance a sloped surface might be a place where land folded in on itself, creating a dome shape we can see and a gas reservoir below the surface. Using seismic earthquake surveys -- or dynamite -- to explore more surface characteristics, they can also determine stable drilling places.

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Shale reservoirs are worth exploring separately. Shale is fine sedimentary rock, like dried sludge that traps gas well. Since shale has low permeability, the gas can't move to more permeable rocks, making it very expensive to extract. Enter hydraulic fracturing or fracking.

In fracking, workers pump gallons of water, sand and chemicals down a well, and into the rock, which cracks under pressure. Gas escapes, travels through tunnels propped open by the sand, and is collected at the top of the well. Since fracking started a few years ago, North America's reachable gas supply has suddenly exploded. Now the U.S. has a projected 100 years' supply of gas.

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Water and land drills pump gas right to refineries through miles of pipeline. Byproducts (propane, butane and other chemicals) get separated and cleaned for use in other ways. If oil was drilled with the gas, the oil is separated on-site.

Refineries pump pure gas to distributors or storage. The gas might be stored during a whole summer, for instance, before being released to heat homes during an icy winter. To convert gas into electricity, it's burned in a boiler or steam turbine to produce heat and steam energy.

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