All things environmental

Musings about the environment and all it touches, from education to city planning

The Jenfelder Au project in Hamburg

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Water and energy flows in Jenfelder Au..follow the flush

Water and energy flows in Jenfelder Au..follow the flush

Here’s something else that caught my eye when I was in Hamburg recently: the new Jenfelder Au development, which will derive some of its energy from wastewater.

A bit like the famous Vauban neighbourhood in Freiburg, Jenfelder Au is a re-development of an old army base, and like Vauban, solar energy and energy efficiency are prominent features. But the comparisons stop there: Jenfelder also embodies a brand-new approach to water management and energy generation. (Okay, okay, there is another difference: Jenfelder Au is still in development…just you wait, though!)

A view of part of the complex

A view of part of the complex

The project, a complex for 700 households laid out on over a 35 ha area (flat as much of Hamburg), has prominent water features: ponds, a basin, ditches with cattails and what have you. These are the core of the green infrastructure of the project: basically, when it rains, water is not rushed through storm drains, rather it is absorbed and released gradually by the vegetation and the basin, which can hold over 5000 m3 of runoff. Hamburg has embarked on an ambitious green infrastructure initiative (green roofs, new parks and infiltration areas, etc.) and Jenfelder Au should be a showcase for these.

But this isn’t what is really unique: rather, it’s the whole wastewater-energy nexus of the development. The way modern cities deal with waste (flushing them down with copious dilution water) means that there is little useful that can be done with them, since they are so diluted. Centralised wastewater treatments plants make biogas out of the sludge they remove, but that is usually barely enough to power the plants themselves, with little energy left-over. But if the waste weren’t so diluted, much more energy could be generated.

This is the approach that Jenfelder is following. All toilets are on a vacuum system, so that only about one litre of water is used per flush. This is expected to save about 7300 litres of fresh water per year per person (that’s a non-negligible 12,500 m3 per year). The vacuum system will convey the waste to an anaerobic digester. The digester will produce biogas that will generate both heat and electricity for the complex.

The overall plan, with the water features highlighted

The overall plan, with the water features highlighted

The biogas system (with combined heat and power) is expected to produce 100 kW of electrical power and 135 kW of thermal power, enough to supply 30% of the heating needs and 50% of the electricity. The rest of the energy will come from a commination of solar panels and a geo-exchange heat pump system.

All in all, the system is expected to reduce by 500 tonnes per year the amount of carbon dioxide that would have been emitted in a conventional residential development of that size.

Because the wastewater treatment system is decentralised, the proponents expect to develop systems that would recover nitrogen and phosphorus from the digested sludge, as well as preventing the release of micropollutants (such as pharmaceuticals) to the environment.

You have to give it to the Germans: they don’t do things half-way, and don’t mind trying new systems. They may well be rewarded for it: the Australian government has taken a keen interest in the water-saving and power system developed at Jenfelder Au, and may well purchase the rights to the technology.

More info can be found here, here, here, here, here, and here.  Or just look up anything related to the International Building Exhibit (IBA, in German) in Hamburg – you’ll be amazed what they’ve come up with.

HWC_kreise_engl

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5 Responses

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  1. […] systems that save water while allowing for energy recovery (a system being built in the Jenfelder Au development in Hamburg, for instance). Unfortunately, most of his material consists of drawing lessons from failed […]

  2. […] development complex that gets part of its energy from human waste,  in Hamburg, Germany, called Jenfelder Au, to be com pleted next […]

  3. […] to investigate, but in more detail, some of the things I already wrote about: the Algae House, Jenfelder Au, and other stuff, as well as a bunch more (the EnergieBerg, the energy bunker, HafenCity) that make […]

  4. […] bad for a smallish plant that serves about 7% of metro’s population.  It’s not quite Jenfelder-like technology, which  could supply about thirty times that many homes.  By hey, it’s a welcome […]

  5. […] much at an airport has used them on planes, so that takes care of the freak-out factor. And then, Jenfelder Au style, the concentrated sewage could be digested into producing biogas for electricity and […]


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