“LNG is clearly not a renewable fuel.” — Gov. David Ige, Feb 4, 2016

At first glance, this might seem like a reasonable statement.

Doesn’t LNG mean “liquefied natural gas,” and isn’t natural gas a fossil fuel?

And aren’t fossil fuels by definition non-renewable?

Well, yes and no.

Natural gas is mostly methane, and methane from a natural gas well is definitely a fossil fuel.

But methane from other sources is renewable — even though it is chemically identical to the methane from a natural gas well.

Methane is generated by all kinds of natural, renewable processes.

The natural decay of agricultural wastes or sewage generates methane.

Ruminant livestock, notably cows, burp up surprising quantities of methane.

And when we are feeling “gassy” — the well-known Bean Effect — humans also emit methane.

According to the EPA, more than half of all methane emissions in the U.S. are from renewable sources, such as agriculture and waste treatment.

Worldwide, agriculture is by far the largest source of methane emissions. Methane emissions are tracked because they are a greenhouse gas. Carbon dioxide (CO2) is the most important greenhouse gas in terms of volume. But molecule-for-molecule, methane is 25 times more powerful than CO2 in heating the planet.

Therefore, capturing and burning any methane that would otherwise escape into the atmosphere not only produces energy, but also slashes the contribution to global warming.

In the U.S., more than 1,500 wastewater treatment plants generate and capture methane and use it to provide electricity and heat to their operations.

Almost 300 livestock and dairy operations now produce and capture methane from their wastes. These are joined by about 650 projects that capture methane from landfills, and many others that are producing gas from food processing plants and field agriculture wastes.

Hawaii already recognizes “biogas” as a renewable fuel, and two significant biogas projects are under development.

In addition, HawaiiGas has issued a request for proposals for supplies of “renewable natural gas” to blend into its pipeline system.

Despite the profusion of names, “biogas,” “renewable natural gas” and “biomethane” are all just methane.

In California, steps have been taken to add “biomethane” to the natural gas pipeline system, and allow credits for use of it in the state’s Renewable Portfolio Standard. This involves some treating of the biogas so it meets the specification of pipeline gas. But once it is in the pipeline, it is all mixed together. There is no way to distinguish the renewable methane from the non-renewable methane.

In the future, we can expect more methane production from renewable sources, and more methane capture from both renewable and non-renewable sources.

One of the climate change problems we face is the melting of permafrost and permanent lakes in the Arctic, where large amounts of methane are locked into and under the ice.

It’s not obvious if this should be classed as “fossil fuel” methane or as biogenic methane. What is certain is that capturing it rather than letting it evaporate into the atmosphere would greatly slow global warming.

So, at present the governor is right: LNG today is clearly not renewable.

But as more biomethane is incorporated into natural gas pipeline systems, things won’t be clear at all.

Exactly the same infrastructure can be used for LNG, whether it is 100 percent fossil fuel, 100 percent bio, or any ratio in between.

Choosing to import LNG does not automatically commit the state to a long-term non-renewable alternative.