Saturday, February 15, 2014

Is Natural Gas Worse than Coal or Diesel?

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A new article in Science (it is behind a paywall, so check out the review of the article in Grist and another review of it here in the New York Times) reviewed 20 years worth of data to demonstrate that natural gas is not as green of a fuel as we thought it was.  Indeed, they found that there s 50% more methane in the atmosphere than previously thought.

Many have looked to natural gas as a partial solution to solving greenhouse gas problems.  Natural gas is largely methane, so when it burns, it produces far less carbon dioxide than other fuels.  As a result, many have looked to natural gas to replace gasoline in cars and coal in power plants.  We've all probably seen the vehicles (particularly buses and government-owned cars) with signs that say "runs on natural gas".

But there's a problem.  Methane is 25 times more potent of a greenhouse gas as carbon dioxide.  So, one molecule of methane does 25 times more damage as a molecule of carbon dioxide.  We have far more carbon dioxide in the atmosphere so the focus on greenhouse gas management has largely been on reduction of fuels like coal and gasoline.

Because methane has not been used widely until recently, we have not really looked at it all that much as a major contributor in fossil fuel use (it has always been looked at in terms of biological production). Indeed, methane use would not be a problem if we had ways to transport and extract natural gas that didn't allow some of it to escape into the atmosphere.  We don't.  According to the authors, we are underestimating the contribution of natural gas to the atmosphere by 25-75% as a result of production and transportation.

I've often thought that we underestimated methane contributions.  It is one of the hardest gases to assess.  It occurs naturally through a variety of biological functions.  Also huge quantities of it are stored underground and are released in highly variable geographic patterns.  Throw in a leaky production and transportation system and things get very complicated fast.  It is a very difficult non-point pollution problem to solve.

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