Paula Gant A renewable fossil fuel? Naturally.

Last week, Senator Ben Nelson, D-Nebraska, introduced a bill that would extend renewable fuel tax credits to cover the production of biogas, or renewable natural gas.  AGA President David Parker released a letter  commending the senator and the bill’s co-sponsors for their action to help increase cost-effective production of a renewable fuel.  But some may wonder – what exactly is “renewable” natural gas?  How can a fossil fuel be renewable?

Here’s the scoop.  Natural gas is comprised primarily of methane, which can be produced through two different natural processes.  Traditional natural gas comes from methane that forms underground by geologic pressure over millions of years – this is the process that makes it a conventional fossil fuel.  Renewable natural gas, on the other hand, is comprised of methane that is being produced and released continuously from the decomposition of organic materials found in places like swamps, manure bins, and landfills.  Once purified and upgraded, both sources of methane can be used as the same fuel we know and rely upon to heat water, cook food, and warm our homes and businesses.

So what’s so great about renewable natural gas?  Plenty. Let’s consider the following points.

A vat of liquid cow manure at the Vintage Dairy Biogas Project. The gas produced is injected into PG&E’s pipeline, where it will be shipped to a power plant in Northern California.

It’s abundant. A 1998 U.S. Department of Energy study estimated that, worldwide, between 25 and 37 quadrillion Btu of methane (between 25 and 37% of annual energy usage in the U.S.)  is released each year into the atmosphere due to natural decomposition of organic material.  The study predicts that 6% of all natural gas used in the U.S. could be displaced by encouraging production of naturally occurring renewable natural gas.

It’s clean. When burned for energy, biogas has the same low-carbon properties as natural gas, but with an added unique benefit.  When captured for conversion into renewable natural gas, methane that would otherwise have entered directly into the atmosphere ultimately is combusted resulting in the release of a much less-harmful greenhouse gas.  In other words, the heat-trapping (or greenhouse) effect resulting from burned methane is less potent than that resulting from directly-released methane, so capturing these gases for biogas production is a positive step towards global warming mitigation.

It’s versatile. Once biogas is purified to pipeline quality standards, it can be used in place of traditional natural gas.  Whereas other renewable fuels, such as ethanol, can require the construction of new infrastructure in order to bring them to our everyday lives, biogas can be distributed and used wherever natural gas is used.

Thanks to relentless technological progress, doors are opened daily to new sources of fuel for our energy-intensive lifestyles.  What is it that makes an energy source renewable?  In the case of renewable natural gas, it can be sustainably produced as a product of our waste-producing (landfills, agricultural processes and animal farms) lifestyle.  Now that’s efficient.

As with other “renewable” energy sources, renewable natural gas is not yet ready to displace large amounts of fossil fuels, but it does have serious potential as a alternative fuel source.  And you thought natural gas was just a boring fossil fuel option.

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