You’ve seen the advertisements for RNG CNG and LNG.  The acronyms avoid using the chemical name for the gas which is Methane.  You’ve heard “Natural” gas used for decades as part of a concerted marketing effort and more recently you’ve even heard it called “Clean Natural gas” as if they needed to simplify for us that it is good and not bad.  Here we drift from history into marketing and for decades you and I have been soaking in this greenwash.

Greenwash you will recall is where a company makes claims that their practices or products are more environmentally safe/ clean / friendly than they really are.  Canada is beginning to implement and enforce laws against greenwashing because it deceives the public, creates goodwill for companies that are doing bad things and confuses the topic so that it is hard to make good decisions and have the market lead us to solutions that benefit our society. (ok that last one was a bit passionate) 🙂

First of all.  Lets do the acronyms. (RNG, CNG, LNG)
RNG – Renewable Natural Gas is a new term for something old.  It used to be called “bio-gas”.  Now you know.  It means that it was collected from a landfill or some other facility that causes organic matter to decompose without the presence of oxygen. Anaerobic digestors do this and the anaerobic break down of these organic materials produces methane (marketed to you as “natural gas”). Methane from landfills can be captured, refined, and injected into natural gas pipelines as RNG

CNG – Compressed Natural Gas means they take methane and run it through a compressor and put it in a tank.  The buses that burn methane have stickers saying CNG.  Sometimes with marketing that says “Clean Compressed Natural Gas Vehicle”.  Again the “clean” and “natural” might be a bit of marketing that have slipped in there.  They compress it (which takes some energy) because the gas itself would require a huge tank otherwise (same size as the bus?) So this is sensible.

LNG – Liquified Natural Gas is interesting.  Again because the transportation cost is high for uncompressed gas, they need it to take up less space.  Turns out if they refrigerate it to negative 160 Celsius (yes that is very cold) then it becomes a liquid.  They can put it in those big round tanks on ships and sail it across the ocean.  Where it must be rewarmed before it can be used.
Where do they plan to get all the energy for refrigeration and rewarming? (looks around for an energy source) well generally they will burn some of the gas.  It would be silly to make a polluting gas less polluting by consuming available renewable electricity right?

Today lets focus back on RNG.  You see mention of it on your garbage collection trucks. (Yes there is a connection there)
Marketing like “this truck runs on table scraps” are catchy and sound like the energy is fun and almost free.

• When there is organic waste (like food scraps, yard trimmings, paper) which decompose anaerobically (without oxygen) in landfills, it produces methane (CH₄) and carbon dioxide (CO₂).

• Normally, landfills are significant sources of fugitive (leaking) methane emissions unless this gas is captured and either flared or used for fuel.

• RNG qualifies for renewable energy credits, carbon offset schemes, and low-carbon fuel standards, especially in jurisdictions like California and Canada.

• These financial incentives create a market pressure to treat methane not as pollution but as a commodity.

First lets consider the alternatives.

What is the alternative to harvesting biogas? 
1. Probably the best alternative is that we reduce food waste and other organic waste going to the dump. We consume less, we waste less. That cuts costs for us, reduces our air pollution and more.
2. I think the worst alternative is that we have that same methane production but we just vent it to the atmosphere and don’t capture it. That is pretty bad.  Arguably burning the methane and producing the CO2 is less harmful as a greenhouse gas.  The process is innovative in that we can make a useful fuel from what might previously have just been considered “waste”. 
3. Another alternative is that we don’t bury the organic products and we compost them.  This produces high quality soil and returns nutrients to farmland to boost productivity (food security / financial viability) without the need for (as much) chemical/synthetic fertilizer.  Your local city is probably supporting the collection of compostable separate from garbage, and this diversion, not only allows for the organics to avoid a trip to the dump, it avoids most of the methane that might be produced in that way.  

4. Flaring methane – this means 80x less pollution than just letting it leak, but there is useful energy there that isn’t being used/sold.
So we have at least 4 alternatives to RNG here.  Some seem greener, but none seem as financially lucrative for the gas company.

Is RNG green?
Is RNG cleaner? more sustainable?  Well according to a scientist friend I consulted.  It all depends. We had quite a lengthy conversation about the ways that biogas can be done poorly, resulting in not just GHG pollution but also damage to water quality, the land and more.  I won’t relate ALL of that conversation but one of the small parts is this.  How far is the material being transported for the bio-gas? And is that transportation zero pollution?  (imagine diesel trucks driving around collecting the organic materials…  Yes, now you get the idea. )  It might be renewable if we only look at a little piece of the puzzle, but taken together it is a much more complex discussion than the marketing will allow.  I won’t dive into that detail, but we’ll stay at the summary level for readability. (You’re welcome)

How do you make sure that YOUR gas is renewable
…and not the dirty polluting kind that comes out of the ground through mining?  You don’t.  The idea is that RNG gets mixed in with everything else.  RNG skips the mining part of the process for getting a polluting gas to your home for you to burn.  That in itself might be positive as long as you don’t consider the alternative. We’ll come back to that.
Since you can’t differentiate between RNG and mined (usually fracked) methane, why is it being marketed to you as clean?  It is accounting.  They are putting some RNG into the gas pipes and are willing to charge some customers a premium for that amount of gas.  As long as they are ethical and don’t sell the RNG amount twice this seems reasonable. Methane is methane is methane after all. 

What about your gas purchasing habits? 
If you are convinced that your methane is somehow more sustainable or ethical than the fracked gas your neighbour uses, you are more likely to keep buying it.  Your purchase of RNG supports the overall business model of a gas network that is distributing fracked methane.  And you still pollute at your house just as much as your neighbour.  That hot water tank, or stovetop (please read https://unnaturalgas.org ) or “high efficiency” furnace all produce CO2 and other pollutants.  It is the reason that your furnace has a chimney to the outside rather than venting into your living space.  (that pollution is deadly)  If they mixed in 1% or 2% RNG with your fracked gas, they could SAY it was a “renewable natural gas mix” or some such nonsense.  They could start convincing you that there was a little bit more good in the gas than there was in the past.

What about the Landfill?
Now lets talk about what to some is an industry best practice and to others will seem to be a dirty secret that your gas company hasn’t mentioned to you.  There is growing concern that some landfill operators might manage waste streams or landfill conditions to boost methane production, rather than minimize emissions overall. Practices that may contribute include:

• Deliberately burying high-organic waste instead of composting or diverting it.

• Moisture addition (sometimes called “bioreactor landfills”) to enhance anaerobic activity and speed up methane production.

• Deep and fast burial of organics to suppress aerobic decomposition, pushing waste into anaerobic states more quickly.

This could result in more methane being generated than would naturally occur, particularly compared to practices like composting or aerobic digestion which emit far less methane.

And lets stop and look at the word renewable.  If it requires waste, garbage (including sorting collection and long-term storage) is it renewable? no.  It is not.  Not renewable like the wind and sun that blow and shine each day, not renewable like things that grow back.  It literally is not renewable because it has to be constantly fed artificial feedstock. Garbage that is poorly sorted and contains organic material.

Climate Consequences;

Even if methane is captured, landfill gas systems only capture 60–90% of the methane at best—often less. The rest leaks into the atmosphere, where methane is over 80 times more potent than CO₂ over 20 years.

So while capturing landfill methane is better than letting it leak, designing systems to produce more methane (instead of minimizing waste or preventing its creation in the first place) is a deeply flawed climate strategy.

What does this mean for us as consumers of energy?
1. We are swimming in a sea of marketing that selectively frames RNG as good and clean and something which is worth paying a premium price for.