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Garbage powers Vienna

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Vienna may well be the champion of waste tourism – that is, as a place where one can see interesting and curious things related to waste management.

The visitor can tour Vienna’s sewers; the city offers frequent tours in English and German.  Vienna has an interesting sewer system, sure, but the main attraction of the sewers is that they were used as a set of the movie The Third Man with Orson Wells.  (Like Berlin, Vienna was divided in zones after the war, and the sewers were used by spies operating between the west and the Soviets.) The sewers end up at the Simmering wastewater treatment plant.  The plant itself is not included in the tour, which is too bad; with its recent upgrades, the tertiary-treatment plant has reached energy self-sufficiency, a performance that very few such plants reach (the one in Hamburg, Germany, being another).

But garbage may be the main attraction.  Vienna incinerates its waste, and two of its four incinerators are famous for their architecture.

The Spittelau plant finds itself in coffee table art books.  The original plant was built in 1971, but this is not what the visitor sees, because it was destroyed by a fire in 1987 (there is a certain irony in this).  Vienna’s mayor at the time, Helmut Zilk, decided to rebuild a new incinerator on the same location, to take advantage of the direct connections to the network heating grid.  The new plant, of course, was to use the best air purification technology available.  But Zilk also decreed that it should also be artistic, with an innovative architecture.

The design was given to artist Friedensreich Hundertwasser. Hundertwasser, a committed environmentalist, was at first reluctant to take on the work. It took his friend the environmentalist Bernd Lӧtsch to convince him to proceed. Lӧtsch told the artist that the plant would have the best emissions control technology, that burning the garbage would provide heat for 60,000 apartments, and that the city needs a garbage-incinerating plant even with the greatest efforts to avoid garbage.

Hundertwasser’s Spittelau plant

The result is a unique-looking plant, a tourist attraction, but one that produces 120,000 MWh of electricity, 500,000 MWh of heat for district heating, as well as recovering 6,000 tonnes of iron.  The city boasts that

its colourful façade, the golden ball on the chimney, roof greenery and planted trees have made the new Spittelau unmistakable and a Viennese landmark on a par with St Stephen’s cathedral and the Riesenrad Ferris wheel.

The Pfaffenau plant is Vienna’s newest, and while not as showy as Spittelau, it also got architectural kudos.  Architect Snezana Veselinovic explains:

We did not consider the technical facilities separately but incorporated them through the design of the facades and the roofscape. The materiality is calm, reduced: clear building volumes of exposed concrete, orange folding doors, planted flat roofs.

The Pfaffenau plant

It’s more than just a pretty design, obviously. The city boasts of its four-step flue gas cleaning system, which

consists of an electrostatic filter, a twin-phase wet scrubbing processes, an activated charcoal filter and a denitrification plant. The result is rock-bottom emission levels.

In contrast, the boxy Simmeringer Haide plant is unlikely to win architectural awards (though it is painted in bright colours).  But the plant processes yearly 100,000 tonnes of household waste and 225,000 tonnes of sewage sludge – it shares its location with the city’s main sewage treatment plant.

The facility also processes 110,000 tonnes of commercial and industrial waste – including hazardous waste.  That’s right, hazardous waste.  Except for explosive of radioactive waste, the city abides by its philosophy that its own waste should be processed within the city.  Needless to say, the pollution control system is remarkable.  Complete combustion of regular waste is done in four 950C fluidized bed burners, while hazardous waste is incinerated in two rotary kilns at a temperature of 1200C, after which

the clinker arising from rotary furnace lines is abruptly cooled in a water bath from over 1,200 °C to outside temperature levels. This procedure seals the clinker, preventing toxic heavy metals from escaping. The clinker is thus rendered harmless and can then be used in the construction of landfill sites.

What is remarkable is how the whole things works as an integrated system.  Household waste, industrial waste, and sewage sludge all contribute to the supply of heat and electricity for the city.  A full 328,000 households, as well as 6400 large buildings, get their heat and hot water from the district heating system, a remarkable network of 1169 kilometers of pipes that run under city streets.

The Simmeringer Haide plant

In summer, the demand for energy is lower (hot water mainly), and incineration supplies about one half of the demand. In winter, of course, heating needs are higher, but incineration still supplies a full third of the requirements.  Some of the waste can be stored to meet peak needs; up to 2600 tonnes of waste that has been compacted in large bales (one cubic meter or so), shrink-wrapped to prevent odors, can be stored for later use to balance the seasonal demand.

Since 2009, district cooling has also been provided; the cooling division of the Spittelau plant provides cooling to some large-scale facilities as Vienna General Hospital, a university, and office buildings via refrigeration pipes.

 

Yes, there is more to Vienna than schnitzels, much more.  But what still comes as a surprise is the extent of environmental responsibility shown by the city: waste is minimized, and any waste is dealt with locally, not exported out of the city.  Not only that, but waste is used to heat and power the city.  Vienna is proud of its record, rightfully so.  They even designed a chatbot who answers questions about the whole process.  She’s called BotTina (groan).

 

You can get more details here, here or here.

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Written by enviropaul

January 24, 2019 at 12:41 pm