Rhea’s step in the fight against greenhouse gas emissions
Rhea won two prizes last Thursday. This is the result of her reporting of her research into laughing gas emissions in wastewater treatment plants.
With a press of a large black button, Rhea Kapoor (23) opens the door to the REMO Lab, the renewable molecules laboratory at Zernike Campus. The researcher, who hails from Delhi (India), completed her Master’s degree in Renewable Energy this year. Her dissertation focused on nitrous oxide, also known as laughing gas. And she certainly has reason to laugh, this June 18, the day on which she not only won the second prize in the Entrance Student Award but she was also crowned the very first winner of the Entrance Research Award.
Everyone knows high CO₂ emissions are a problem, but did you ever hear of the N₂O danger?
Rhea attributes the awards to her report on a series of studies into reducing nitrous oxide emissions in sewage treatment works.
‘Laughing gas sounds fun, but it’s a potent greenhouse gas. It’s 250 to 300 times more potent than carbon dioxide.’ Almost everyone knows that high carbon dioxide (CO₂) emissions are a problem. But very few people know about the dangers of nitrous oxide. Ever heard of N₂O?
‘That’s because it’s less prevalent in the atmosphere than CO₂, water vapour and methane, the better-known greenhouse gases. But nitrous oxide still accounts for around ten per cent of the greenhouse effect. What’s more, nitrous oxide emissions appear to be on the rise.’
‘It surprises me that there are hardly any regulations governing nitrous oxide emissions’
During the treatment of sewage, nitrous oxide can be released when the nitrogen compounds present in the water, such as ammonia, are removed by bacteria. ‘These bacteria are very sensitive to changing conditions. Under ideal operating conditions, nitrous oxide should not be produced. The problem is that even small formation rates in wastewater lead to large emissions due to large volumes of operation 24/7.’
Wastewater treatment plants are not the biggest emitters of nitrous oxide (that dubious honour goes to the chemical industry, agriculture, and waste and fossil fuel incinerators), but there is certainly no harm in tackling that source. Rhea: ‘It surprises me that there are hardly any regulations governing nitrous oxide emissions. And there’s certainly no question of taxing these emissions. Given how harmful it is, it seems to me that’s only a matter of time. For that reason alone, it’s important to devise methods now to reduce emissions.’
It takes a lot of time and effort, since I started in February, I’ve hardly left the lab
Electrolysis is a way of breaking down compounds of the chemical composition. And that is the subject of her final-year project and the award winning paper she and Jorrit Reede wrote on the topic: NO More! Reducing Nitrous Oxide Emissions in Wastewater via Ammonia Electrolysis. ‘Jorrit is responsible for the lab setup and the research design. My strength lies in carrying out the experiments themselves. I’m a hands-on type of person,’ she says, standing in front of a lockable, transparent chamber full of hoses and glass tubes. The processes taking place inside are monitored via a computer device that processes data. ‘It’s precision work. It takes a lot of time and effort. Since I started here in February, I’ve hardly left the lab.’
Still, Rhea couldn’t always stay indoors. One of the unique aspects of this research was that it actually used waste water. ‘We collected it from the treatment plant in Garmerwolde. Just in jerrycans.’ Rhea points to a large fridge in the corner of the lab. ‘That’s where we store them, at a constant temperature. During the experiments, we can see how it behaves under different conditions. For the experiments, we could also have used pure ammonia, NH3, that’s actually standard practice. But we wanted to see if and how we could adapt the electrolysis for everyday use.’
Electrolysis via platinum produces a stable result, as was also evident in our tests with wastewater
It was already clear beforehand that it is possible to electrolytically split ammonia into nitrogen and hydrogen. ‘The best way to do this is by passing an electric current through platinum. This produces a stable result, as was also evident in our tests with wastewater. But platinum is rare and very expensive. That’s still manageable in our laboratory setup, but if we scale up to the level required for a real treatment plant, it becomes unaffordable. That’s why we’re looking for alternatives to platinum.’
Rhea is no longer a student. She works, just like Jorrit, under the guidance of professor Joàn Teerling at EnTranCe in Groningen. ‘It’s quite strange, really, because I’d actually imagined a future for myself in Germany. I did my bachelor’s degree in Bremen. It was only when I was looking for an interesting master’s programme that Groningen came into the picture. And now I’ve got a one-year post here. I’d quite like to do a PhD here as well.’