This article is a brief description of carbon offsetting through projects related to landfill methane. It is for someone intending to offset their carbon footprint, providing the basics for how these projects achieve carbon offsetting, what carbon accreditation auditors look at when evaluating them, and issues commonly associated with them.

For preparatory reading, and links to other articles in this Carbon Offsetting series, see articles below:

Carbon offsetting & Net Zero emissions

Since the global warming phenomenon was first confirmed in the 1990s, the need to scale back greenhouse gas emissions has been known.

Greenhouse gases have increased at an unprecedented rate in planetary history, driven by mankind’s burning of fossil fuels within a relatively short period of time. The increased heat trapped by the added greenhouse gases have begun to change the balance of climate systems, some of which lead to the release of even more greenhouse gases (e.g. forest fires, permafrost melts).

In 2015, the Paris Agreement saw the nations of the world agree that global warming needs to be kept below 2 degrees above pre-industrial global temperatures (aiming for no more than 1.5 degrees to avert the worst effects of climate change to vulnerable nations).

Net zero carbon emissions is not about that.

You may notice a growing number of companies pledging to be ‘net zero’ or have ‘net neutral’ carbon emissions. Invariably this will involve changing the way their businesses operate so that they emit less carbon. And, if there are any carbon emissions left over, they have to be offset.

However, without needing to be particularly good in math, you would realise that even if all businesses are net neutral from now on, we would still not be in carbon balance. The greenhouse gases already in the atmosphere now will continue to heat the earth, and climate change that is already underway will release other greenhouse gases from natural reserves.

So this is why I say upfront that going net zero is not about solving climate change. Additional things have to be done over and above that. Going net zero is about not making the problem worse, so that it isn’t harder and harder to solve.

Carbon offsetting verification standards

Carbon projects rely on carbon accounting to qualify as carbon offsetting. (Jargon cheat sheet article link is at the top). Like financial accounting, you need audits to make sure the carbon accounting is honest. Unlike financial accounting, which has been around for longer, carbon accounting is still being tweaked, since is it still a relatively new discipline. That this is still going on, does not mean that carbon accounting is inherently untrustworthy, or that it isn’t essential.

Carbon projects may be fully dedicated to a company intending to meet their own net neutral targets (e.g. Qantas’ reforestation project), or generate credits which can be bought by other companies or individuals like you and I. The latter are usually managed by carbon offsetting service providers, such as Terrapass.

We can rely on audits carried out by the service providers to be assured that projects are managed to standards submitted to the United Nations Framework Convention on Climate Change (UNFCCC). Examples include the Gold Standard, and the Verified Carbon Standard.

Landfill methane carbon offsetting projects

Ok, that’s the context for why carbon projects exist, and what carbon offsets are supposed to be used for. This article will cover landfill methane capture projects that qualify for carbon credit funding.

Garbage truck on collection day to landfill

Why do landfills produce methane?

The oldest method of getting rid of waste from human habitations, is to bury it underground. As population density increased, centralised waste collection came about, and with it, the invention of the landfill.

A landfill is basically a massive hole dug in the ground. Waste is simply dumped in, and when it is full, it gets buried. More modern versions are more engineered; for example, by adding liners at the bottom to prevent groundwater from being contaminated by leachate (basically, ‘garbage juice’). This is called a sanitary landfill.

When landfills are full, they usually get turned into open air spaces like parks. Buildings are rarely built on them until much later, due to harmful gases generated by garbage decomposition.

One of these landfill gases is methane. This happens because municipal waste has a lot of organic content, such as food scraps and garden waste. Because you’re basically just dumping all the garbage together, there isn’t a lot of oxygen inside a landfill. It gets used up as the garbage rots, yet the bottom part of a landfill doesn’t get airflow (and more oxygen) from the top. The garbage will then rot in a different way, called ‘anaerobic’.

How do landfill methane projects combat climate change?

‘Normal’ (aerobic, i.e. with oxygen) decomposition produces carbon dioxide. This is what happens in compost piles and on the forest floor.

Autumn leaves on the forest floor

Carbon dioxide is a greenhouse gas which drives global warming, but this kind of decomposition is more or less carbon neutral. In simple terms, it’s just returning carbon within the body of the (newly deceased) plant or animal. The cycle is relatively short term, and balanced.

However, anaerobic decomposition produces methane, which has a higher greenhouse gas effect than carbon dioxide. Since old-style landfills are not sealed (because it would also be dangerous if the gases build up inside), the methane escapes and makes its way into the atmosphere.

Therefore, if you retrofit old landfills to extract the methane instead, this would make a big difference. The methane can then be used in industry processes so that it doesn’t become a greenhouse gas. Additionally, if the methane is used to generate electricity that would otherwise be supplied by fossil fuels, that’s a second way that a landfill methane project helps.

Which landfill methane projects are also carbon offsetting projects?

All landfills generate methane. However, not all landfill retrofits are carbon offsetting projects.

A carbon offsetting project gets to earn carbon credits. It can then sell the carbon credits to companies or people who wish to offset their carbon emissions to reach carbon neutrality.

Depending on where the landfill is, you can sell the methane. To qualify as a carbon offsetting project, the landfill methane project has to demonstrate that it needs the carbon credit funding, i.e. the sale of extracted methane alone is not enough to make the retrofit commercially attractive.

Clean Development Mechanism (CDM) methodologies for landfill methane

Landfill methane projects are among the more straightforward carbon offsetting projects. There are only so many things that could happen with the extracted methane. You either sell it to consumers as natural gas, burn it for electricity or heat, or flare it. The carbon offsetting benefit is the difference in warming potential between the landfill methane and any carbon dioxide produced from its destruction.

In addition, prevailing regulations and policies are relevant. For example, there may be regulations requiring retrofits to capture landfill methane for other reasons, or policies encouraging waste-to-resource investment. Only methane extraction that is over and above legal compliance counts for carbon offsetting.

Credible carbon offsetting certifiers generally refer to methodologies submitted to the UNFCCC. The one for landfill methane covers all of these scenarios.


How much difference does it make to fix the landfill methane problem?

Global methane sources. [Source: International Energy Agency]

As you can see from the figure, landfill methane (‘waste’) accounts for 11% of total methane emissions, at most. Why then, was it among the earliest carbon offsetting project types?

The answer lies in the fact that landfills, by nature, are a concentrated source. This makes it an easier project to design. Sure, you would only solve 10% of the problem, but removing methane makes a big difference.

Secondly, whatever carbon emissions reduction that can happen earlier, makes a bigger difference. Authorities in charge of waste and landfills are not in a position to do the big transport and power plant projects. But that doesn’t mean they don’t have things within their remit that can make a difference too.

US style corporate management promotes senior managers who see staff in terms of their job grade, like parts in a machine. So if two people happen to be in the same job grade, therefore they must be interchangeable.

As a kind of LOTR fan, I have to nitpick the phrasing and clarify that the reason why the One Ring was the least dangerous with a hobbit, is because hobbits just want to live life and get along, ie hobbits aren’t tempted to “rule them all”.

Project examples:

  • Landfill/waste methane projects around the world; UNFCCC.


I would like to acknowledge Gold Standard and Verra for responding with information and resources that facilitated the writing of portions of this article.

An important part of the Paris Agreement is recognition that countries must have the freedom to choose the combination of methods for how they meet their climate ambitions, because each nation has vastly differing circumstances. A solution that doesn’t make sense to one country – however large and influential – may be perfect for another. Would carbon credits help fund upgrades to old landfills in your country?

Article explaining how to understand landfill methane types of carbon offsetting projects

2 Responses

  1. Karee says:

    Very thoughtful information gathered here. So many things we don’t even think about, but need to be brought to the forefront. Thank you for sharing your thoughts with us!

    • Teja says:

      You’re welcome and thanks for commenting! In this Carbon Offset series I wanted to explain that it’s not so much that any one thing that’s a source of greenhouse gas is ‘bad’. The problem is that though each thing might be sustainable or at least tolerable at a certain scale, when we multiplied it by a billion, it stopped being sustainable.

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