Posted on: July 2019

Eleanor Eaton, WATEF network

Green Energy from Black Water: The Hamburg Water Cycle

About the author:

Eleanor Eaton is the Project Coordinator for the Water Efficiency Network (WATEF) at the University of Bath.


This year’s study trip takes us to Hamburg, to see how HAMBURG WASSER are building innovative wastewater management technology into a new residential district: the Jenfelder Au. 

HAMBURG WASSER is the water and wastewater specialist in the Hanseatic city of Hamburg, providing both water and wastewater services through one company. In addition to providing safe water and wastewater disposal at the highest quality for the residents of Hamburg, the company also uses its know-how to provide customized solutions for the water supply and waste management needs of the surrounding cities and municipalities in the metropolitan region. 

The HAMBURG WATER Cycle is a unique wastewater concept that combines wastewater treatment and energy directly in the residential district. The beacon project reduces the emission of CO2 and helps to close material cycles. With more than 800 residential units connected, the Jenfelder Au is the largest residential district in Europe, where energy from wastewater is recovered in this way and made available to the neighbourhood. 

Here is more information about the HAMBURG WATER Cycle, taken from a recent press release

The foundation of the HAMBURG WATER Cycle is the separation of three wastewater streams. Black water from the toilet, grey water from showering and washing and rainwater are collected and treated separately. The most important element is the black water treatment. The wastewater from the toilet is routed via a 3.7-kilometer vacuum network to a depot built by HAMBURG WASSER in the industrial park of Jenfelder Au. In the fermenter located there, the black water ferments together with co-substrate and biogas is produced. A combined heat and power plant converts the biogas into electricity and heat. In this way, around 450,000 kilowatt hours of electricity and 690,000 kilowatt hours of heat are generated each year. In terms of average Hamburg consumption, this corresponds to the electricity requirement of 225 households in Hamburg and the heat requirement of 70 households.1 

"With the HAMBURG WATER Cycle, we have done real pioneering work at HAMBURG WASSER. By treating wastewater directly in the neighbourhood, we not only reduce CO2 emissions. The entire system is self-sufficient and we provide heat and electricity to the neighbourhood..." 

"With the HAMBURG WATER Cycle, we have built a demonstration plant for further projects of this kind throughout Europe. In addition, today's commissioning opens up a new field of research. Together with scientific partners we can investigate important questions in the Jenfelder Au; among other things, how micro pollutants in wastewater can be eliminated. " 

(Nathalie Leroy, Managing Director of HAMBURG WASSER.)  

"Climate change presents us with major challenges - including drinking water supply and disposal. Thanks to HAMBURG WASSER, we are well prepared for extreme summers like 2018. But climate change requires us to adapt our infrastructure and water resource management to this challenge. With HAMBURG WATER Cycle, HAMBURG WASSER sets the course for the wastewater disposal of the future. Thanks to the technical innovation that we are developing for the first time on a large scale in the Jenfelder Au, the municipal company is making a decisive contribution to achieving our climate goals. CO2 emissions are reduced, water saved and energy produced. That pays several times for climate protection"  

(Jens Kerstan, environmental and energy donator of the Free and Hanseatic City of Hamburg.)    

In addition to energy production, the low water requirement of the system is a highlight of the HAMBURG WATER Cycle. While conventional toilets use between six and nine litres per flush, the consumption of the vacuum toilet is only one litre. This makes the concept interesting also for regions with less water. 

The HAMBURG WATER Cycle can also vary on its scale of implementation. The most crucial feature is the separation of wastewater streams and the subsequent energy recovery from wastewater. In the neighbourhood of Jenfelder Au, a feature is added, rainwater, which extends the creative possibilities of urban- and landscape-planners. In the open space design, rainwater becomes a creative element.

The Jenfelder Au stormwater management concept decouples the rainwater flow from the sewer network, allowing the water to flow over the natural landscape back to the local waters. The landscape and urban planning concept is made possible through the use of open channels which allow rain to flow through streams and waterfalls to retention basins which are in the form of attractive ponds and lakes. Thus, the appearance of the residential area is enhanced, and the flood protection is optimized as the retention basins are designed to provide further storage potential in case of heavy downpours.

The development and expansion of the HAMBURG WATER Cycle was funded by the Federal Ministry for Economic Affairs and Energy, Federal Ministry of Education and Research and funds from the Life + Program of the European Union. 

This study trip has been postponed - more information to follow


1.  Calculation basis: For the calculation, Hamburg assumed an average household size of 1.8 persons with an average power consumption of 2000 kilowatt hours and a heat energy requirement of 10,000 kilowatt hours per year.   

Images copyright Hamburg Wasser.