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Oslo's Sewage Heats its Homes

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Oslo's sewage heats its homes
By Alister Doyle, Environment Correspondent

OSLO, April 7 (Reuters) - In an extreme energy project tapping heat from raw sewage, Oslo's citizens are helping to warm their homes and offices simply by flushing the toilet.

Large blue machines at the end of a 300-metre long tunnel in a hillside in central Oslo use fridge technology to suck heat from the sewer and transfer it to a network of hot water pipes feeding thousands of radiators and taps around the city.

"We believe this is the biggest heating system in the world using raw sewage," Lars-Anders Loervik, managing director of Oslo energy company Viken Fjernvarme which runs the plant, told Reuters. The plant opened this week.

The heat pump, a system of compressors and condensers, cost 90 million Norwegian crowns ($13.95 million) and has an effect of 18 megawatts (MW), enough to heat 9,000 flats or save burning 6,000 tonnes of oil a year.

And experts say sewers could be exploited elsewhere.

"The technology is there, so if the infrastructure is also there, this is a feasible solution in many cities worldwide," said Monica Axell, head of the International Energy Agency's heat pump centre. The agency advises 26 industrialised nations.

She said a bigger heat pump in Sweden, with a 160 MW capacity, exploited heat from treated sewage. And in Finland, a 90 MW plant ran on waste water.

In Oslo, untreated sewer flows -- from toilets, bathtubs, sinks and rainwater from the streets -- runs into the system past a filter that keeps out big objects such as dead rats.

Sewage was flowing into the system at 9.6 Celsius (49.28 Fahrenheit) on Friday and coming out at 5.7 Celsius after heat is extracted with a refrigerant.

The energy in turn goes to warming the water in the 400 km (250 mile) pipe system, fed to offices and homes, to about 90 C from a temperature of 52 C when it reaches the sewerage plant. Other plants, burning industrial waste, also heat the water.


Similar heat pumps can be run on any stable source of water -- in Paris the Seine River is tapped to run air-conditioning systems. Sea water can also be exploited.

Sewer power is less polluting than burning fossil fuels but more than renewable energy like wind power. About a third of the heat energy comes from electricity to drive the system and the other two-thirds is the heat from the sewer.

"Oil prices have an impact on investment willingness, but more important is the ratio of fuel price and electricity price," Axell said. "A high fuel price and a low electricity price is a strong driver to invest in heat pump technology."

Among other sewage energy projects worldwide, U.S. scientists are looking to exploit sewage-eating bacteria to generate electricity.

"The microbial fuel cell work is going well, but we still are not out of the lab on this technology," said Bruce Logan of Pennsylvania State University.

In Oslo, a problem is that the flow in the sewers is irregular -- Monday mornings between 4-6 a.m. are especially dry because people go to bed early on Sunday. But at weekends, the flow is good.

"When people have been out to parties there's a lot of beer going into the sewer," said Oyvind Nilsen, the project manager for the Oslo plant.

At the opening ceremony for the plant, Oslo mayor Per Ditlev-Simonsen was given a new toilet seat for his office. "It will be an inspiration," he said.
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They are actualy going to be seting this up in the Vancouver Olympic village and maybe the the future comunity around it which will house 15,000 people.
FEATURE-Britain starts digesting as biogas catches on

LONDON, July 30 (Reuters) - Medieval alchemists tried in vain to find a way to turn lead into gold, but modern technology is rediscovering a more ancient transmutation -- turning trash and sewage into energy.

Biogas -- created from waste, sewage, manure, grass and even pig remains has become an increasingly popular source of environmentally friendly energy in Europe and Asia.

Another name for methane, biogas as a source of electricity cuts mankind's contribution to global warming by burning this potent greenhouse gas, otherwise released into the atmosphere.

"It makes us self-sufficient in power and it is low carbon and makes use of waste resources... It's purely driven by the green agenda," said farmer Owen Yeatman, a public promoter of biogas systems at his Dorset, southwest England farm.

Fed maize from his farm, the 750,000 pounds ($1.51 million) system will produce enough gas both to maintain it and heat around 450 houses.

Germany leads the world with around 70 percent of the global market and produced 1,100 megawatts of electricity from biogas last year, enough to supply over a million homes, said German biogas plant developers Biogas Nord.

Britain, which wants to raise its share of renewable energy, only produced around one-25th of this, according to Germany's Agency of Renewable Resources.

Like liquid biofuels -- used to power cars -- biogas involves generating energy from organic matter. It has the same structure as natural gas and is transported the same way.


Biogas is not new. There is anecdotal evidence it was used for heating bath water in Assyria during the 10th century BC and in Persia during the 16th century AD, according to the University of Adelaide's Web site 'A Brief History of Biogas'.

It captured the attention of 13th-century adventurer Marco Polo in China, where he noted covered pots of sewage stored to generate energy -- and earned a mention by 17th-century writer Daniel Defoe.

Now environmentalists hail biogas on two counts: it prevents methane created by decaying organic matter from entering the atmosphere in its pure form, and is renewable.

It is generated in two main ways: by putting organic waste in sealed containers, or by capturing gas emitted by landfill waste dumps.

Million-dollar complexes that have canisters acting as mammoth compost bins produce most of Europe's biogas, through the process known as anaerobic digestion.

But almost all Britain's biogas comes from landfills, and is often converted into electricity.

"We are now capturing the majority of gas that landfills produce," said Michael Walker, Policy Director of the Environmental Services Association (ESA), which represents the British waste management industry.

Landfill gas makes up a quarter of British renewable energy, the ESA said, giving electricity to some 900,000 households. The rest comes from wind, solar, water, geothermal and a tiny share from anaerobic digestion.


Britain's low position on the biogas ladder is not surprising -- the crowded island only recycles around 15 percent of its household waste. That's far less than most European countries like top recycler the Netherlands at around 60 percent.

But Britain is being forced to go the renewable route. The European Union set a target of increasing renewable energies to 20 percent by 2020 in last year's Energy Review.

It now stands at 2 percent in Britain, the country's Renewable Energy Association (REA) says. The EU as a whole sources 6.5 percent of its energy from renewables, with Latvia the highest at 47 percent, the EU says.

Germany builds around 1,000 digesters a year, Yeatman said, and Scandinavian countries and Austria, Canada and Australia are also devotees of the system.

Though biogas makes up a tiny proportion of renewables, some countries are surging ahead with it -- many public buses in the Stockholm region run on biogas, the EU says.

"If we go further down the carbon-saving route -- which is the government's avowed intention -- there is no doubt that the carbon saving is very impressive," said REA's Head of Biofuels Clare Wenner.
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If shit can grow my food, it can keep me warm. That's smart thinking.
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