The Bulgarian water plant transforming waste into power

Getting water to our taps and treating it afterwards accounts for about 5% of the greenhouse gas emissions of many countries. But one water plant in Bulgaria is bucking the trend. Can this be scaled up so the water industry gets to net zero?

From turning on a tap to flushing the toilet, few of us often stop to consider the environmental impact of our water use. The process of providing clean water and treating that water once we’ve used it, however, has a significant carbon footprint. In fact, in many countries, the energy needed to pump and treat our water is thought to add up to around 5% of all greenhouse gas emissions, a figure comparable to the aviation industry.
A few hours after somebody goes to the toilet in Bulgaria’s capital Sofia, what gets flushed away normally ends up at the Kubratovo wastewater treatment plant. Operated by Sofiyska Voda, part of the Veolia group, the plant is one of the most energy-efficient in Europe.
“We collect the wastewater from Sofia citizens. We treat it here so that it’s clean when it enters the river. In the process, we produce biogas. This biogas is then transformed into electricity and heat. The heat is used for our processes and the electricity satisfies the needs of this plant,” Stanislav Stanev, the Technical Director at Veolia Bulgaria, told Euronews.
Every year the Kubratovo plant generates around 24,000 megawatt-hours of electricity and heat energy – enough to power 2,300 homes annually. But what sets the plant apart from other water treatment facilities is the efficiency of its digesters where the biogas is made, explains Stanislav.
’’The difference is the amount of biogas produced. Usually, wastewater treatment plants are producing 50 to 60% of their own needs. And here we cover more than 100% of our needs. We are also saving CO2 emissions, approximately 70,000 tonnes per year.’’
In addition to CO2, wastewater treatment produces a lot of gases like methane, a potent greenhouse gas. Capturing and using these gases through a process called cogeneration prevents their release into the atmosphere, while also enabling them to be harnessed as an energy source.
“This is one of the industries where it’s not impossible to get down to net zero emissions or in fact zero emissions,” explains Diana Ürge-Vorsatz, Vice Chair of the Intergovernmental Panel on Climate Change (IPCC).
“We have many opportunities to use water much more efficiently and to reuse those gases which are now greenhouse gases. All together, this can become net zero, especially if the energy we use for this is coming from renewable energy sources,” she adds.
The Kubratovo plant has already been awarded Gold Standard certification for reducing its emissions but plans are in the pipeline to go further.
Summing up, Stanislav says: ‘’We are just commissioning a new plant which will boost the biogas production by 10 to 15% here, and we’re installing photovoltaics. But it’s not only this plant, we are exchanging with our colleagues trying to inspire the other plants to reach energy self-sufficiency, as this is something that the group is asking us to push forward.’’
Euronews and the European Commission are partnering to promote the EU’s Water Wise campaign, #WaterWiseEU. Our series, Water Matters, and the EU campaign aim to raise awareness about the increasing stress on Europe’s water systems and the need for sustainable water management. Water Matters will delve into various water-related issues, highlighting the importance of protecting nature and ecosystems integral to the water cycle. Through engaging content, Euronews and the European Commission hope we can inspire individuals and communities to become #WaterWiseEU.