Biomethane : Dr. Semra Bakkaloglu: "The biogas industry has moved past the denial phase"

Your research identified significant methane leakage from biogas facilities. Since publishing, what positive responses have you seen from the industry?

Since my study in 2022, the industry has moved past the 'denial phase' and is now focused on proactive mitigation. Operators are much more open to having their emissions measured; they want to know exactly where the leaks are happening and how to fix them. There has been a visible increase in transparency and a real surge in monitoring technology. Ultimately, the industry is realising that methane leakage isn't just an environmental issue—it's a loss of profit and a risk to damage their climate credentials.

You identified "super-emitters" in your research. What makes these facilities different, and what solutions exist to address the issues?

Super-emitters are typically a small number of sites responsible for a disproportionate amount of total emissions (the "heavy tail" of the distribution). 

It is rarely about the technology type and more about operational management, such as operational instability like frequent start/stop, foaming. Common culprits include pressure relief valves (PRVs) stuck open, poorly maintained digester covers, or inefficient flare systems.

The good news is that super-emitter behaviour is highly preventable. Regularly monitoring the site provides the opportunity for frequent inspection and the quick repair of point sources. Additionally, installing proper gas-tight covers helps to significantly mitigate emissions from digestate storage.

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Your research showed leakage at multiple stages. Which stage offers the best return on investment for leak prevention

The best ROI is typically where leaks are high-rate, easy to access, and cheap to fix. My research suggests two primary areas:

1. Digestate storage covers and fittings: These are among the highest contributors and are generally easier to access, though installing or replacing covers can be more capital-intensive than a simple valve or seal repair.
2. The digester: This is where the gas is most concentrated. Even a tiny hole in a membrane can lead to massive methane losses.

Additionally, the upgrading phase (such as water scrubbing or membrane separation) offers a high return. By capturing the 'off-gas' and recirculating it back into the system, operators can recover significant volumes of product that would otherwise be vented, turning a potential emission into a sellable asset.

What monitoring technologies or approaches were particularly effective at detecting leaks in your research?

The most effective approach is layered, following a 'detection, visualisation, and quantification' workflow:

1. Screening tools to find hotspots quickly: Mobile surveys, site walkdowns, and downwind screening are excellent for initial detection. Using relatively inexpensive handheld gas detection instruments helps identify leaks at the equipment level.
2. Optical Gas Imaging (OGI): An OGI camera is essential for visualising the exact source of a leak, such as a loose flange, a degraded seal, or a hairline crack in a membrane.
3. Flux measurements for quantification: To report emissions in mass units (e.g., kg/h), we use tracer gas release or modelling-based approaches. These allow us to understand the site's true climate impact.

This 'detection + quantification + decision' framing has now become the standard for best-practice guidance across methane detection technologies.

Intermittent emissions are challenging to detect. What monitoring strategy works best—continuous monitoring, periodic surveys, or a combination?

Intermittent emissions are notoriously difficult to capture because they are often event-driven. While continuous monitoring is the gold standard, it can be capital-intensive. Therefore, a hybrid strategy is currently the most practical and cost-effective approach.

We can quantify plant-level emissions (top-down) in kg/h using vehicle-based or drone-mounted sensor campaigns. To complement this, OGI cameras allow us to identify and quantify component-level leaks (bottom-up).

Ideally, continuous monitoring should be deployed—at least during critical operational windows like feed loading, engine startups, or shutdowns—to catch super-emitter events and build an accurate emission profile of the asset. In the long term, moving toward periodic surveys makes emission reporting far more robust than relying on generic emission factors, which often underestimate the real climate impact.

This hybrid approach prevents small, intermittent failures from evolving into persistent, super-emitter-scale problems.

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What's a realistic leakage rate that well-designed, properly managed facilities can achieve?

While many older or poorly managed sites currently show rates around 3–6%, my research indicates that well-designed, modern facilities can achieve much lower levels. With the rigorous application of current monitoring and LDAR (Leak Detection and Repair) programs, a leakage rate of below 1% of total methane production is a realistic and achievable target for the industry.

What specific design features or operational practices consistently appear in low-leakage facilities?

You know, when we look at the low-leakage facilities, the sites that are really getting it right. They usually have three things in common.

First, they don't leave any part of the process open to the atmosphere. They use gas-tight, double-membrane covers, particularly on the digestate storage. A lot of people forget that even after the main digestion is done, the leftover material is still producing methane. The best sites catch every last bit of it.

Second, they’ve mastered their CHP engine performance. We often talk about 'methane slip' at the exhaust, and these sites tackle that head-on. They might install a Regenerative Thermal Oxidizer (RTO) or use advanced exhaust gas treatments to make sure no unburnt methane escapes into the atmosphere. Those are really the two biggest 'leakage hotspots' sorted right there.

And finally, it’s just about good housekeeping and stability. They’re obsessed with the health of their digester. They optimise the process to maximise the CH₄ yield while working hard to avoid foaming, which is a nightmare for sensors and valves. They also keep a very close eye on their gas holder levels. By keeping the pressure stable and the measurements accurate, they avoid those accidental 'burps' or venting events that happen when a system gets overwhelmed. It’s a mix of great engineering and really disciplined daily management.

Since your 2022 study, what promising developments have you seen in detection technology or operational practices?

Since my 2022 study, the biggest shift I’ve seen isn't just new tech, but how that tech is finally moving from small pilots into real-world, everyday use.

We’re seeing a new generation of continuous methane sensors that are much cheaper and more accurate than what we had just a few years ago. But the real 'game-changer' is that they’re finally being integrated directly into SCADA systems. This means an operator doesn't have to check a separate app; the leak alerts pop up right on their main control screen alongside their temperature and pressure data.

On a larger scale, we’ve seen remote sensing really mature. Whether it’s drones, aircraft, or satellites, the transparency is at an all-time high. Even though a lot of these systems—like MethaneSAT, for example—were originally designed for the oil and gas sector, the 'trickle-down' effect for the biogas industry is huge. It’s becoming much harder for 'super-emitters' to go unnoticed when we have an 'eye in the sky' providing that kind of data. It’s a very exciting time for accountability in the sector.

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What percentage of methane leakage is preventable with current, commercially available technology?

Recent studies demonstrate that high emission sources can reduce emissions by 46–62% with the best available technologies. 

Can the biogas industry maintain its climate advantages while scaling up rapidly?

The short answer is yes, but it only works if we adopt a 'Measurement-First' mindset from the start. If we try to scale up using the old 'build it and forget it' model—where we just assume everything is airtight because it’s new—we run a massive risk. High methane intensity could actually negate the carbon-neutral benefits that make biomethane so attractive in the first place. We can’t afford to let that happen.

However, if we couple this rapid growth with mandatory LDAR protocols and digital monitoring from day one, it’s a completely different story. We also need the right regulatory and market incentives that reward measured performance rather than just theoretical goals. If we do that, biogas isn't just a renewable natural gas; it remains one of our most powerful, credible tools for a truly circular economy.

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