Semra Bakkaloglu

Semra Bakkaloglu did not start out chasing methane. She took a double major in chemical and environmental engineering at Middle East Technical University in Turkey, won a Fulbright to do a master's at Clemson on cleaning water with superfine activated carbon, then spent three years as a process engineer at a Turkish petroleum refinery, in charge of the wastewater plant and the greenhouse-gas reporting. That refinery job is where the climate side caught her, and she went on to a PhD at Royal Holloway, University of London, as a Marie Curie fellow, measuring methane leaking out of landfills and wastewater plants across Europe. She is now a research associate at Imperial College London's Sustainable Gas Institute.

Semra Bakkaloglu became interested in biogas the day she caught a methane plume drifting off a biogas plant during a mobile measurement run. Biogas and biomethane are sold as climate solutions, renewable gas made from manure, sewage sludge and food waste, so a leak is a genuine question mark over the whole pitch. Methane matters here because, as she points out, it traps about 27 times more heat than CO2 over a century, which means a small leak undoes a lot of the climate benefit. And until her study, nobody had added up the emissions across the entire supply chain, from the feedstock to the digestate, the leftover slurry, at the end.

So Semra Bakkaloglu and her colleagues combined every measurement they could find into one assessment, published in the journal One Earth in 2022, and the number came out uncomfortable. The International Energy Agency had put biogas and biomethane supply-chain methane at about 9 megatons a year. Her team's upper estimate came to around 18.5 megatons, so when you line those up, the real figure could be roughly double the official one. The gap is not spread evenly, and that turns out to be the most useful part: the top 5% of sources cause about 62% of the emissions, the super-emitters, and the worst single stage is the digestate, the leftover slurry that too often sits in open storage because nobody was watching it.

Here is why Semra Bakkaloglu does not read as a doom merchant. If a handful of super-emitters cause most of the problem, then most of the problem is fixable, and the fix is not exotic: continuous monitoring, leak detection and repair, better-trained operators, more automation, the same discipline the oil and gas industry adopted over decades. Her read on why biomethane leaks more than fossil gas is basically an investment story, a young, fragmented, under-monitored industry that has not yet put capital into the boring plumbing of catching its own leaks. Catch them, and you cut emissions by most of that 62% while keeping the renewable energy. It is the same tension Kunal Shah picked up when he cited her work on turning wastewater plants into carbon-negative fuel factories, and you can see how Leviathan tracks where that water-and-energy capital actually flows.

“In the paper, we estimated that the top 5% of these emissions can cause the 62% of total emissions. If we just fix these super emitters, we directly reduce our emissions by 62%. And they can easily be detected and they can easily be fixed.”

Semra Bakkaloglu is, in the end, the rare researcher who can stand in a wastewater plant and talk about the atmosphere in the same breath, which is exactly the bridge the biomethane industry needs as it scales.