Sunshine and sewage seen to power our cities of the future

Outside the cities, where land is cheapest, solar power stations will find a niche, feeding power into the metropolis.

As solar power costs have fallen due to economies of scale, an initially subsidized power source is becoming viable in some places.

“In countries like Spain, southern Italy and Greece, the cost of energy from solar is already, or will soon be, at parity with the cost of electricity from the grid,” said Winfried Hoffmann, president of the European Photovoltaic Industry Association.

“Germany is less sunny so it will take longer, but it will reach parity by 2016 at the latest,” he added.

But where Brisbane gets about 2,790 hours of sunlight a year, Lille gets about half that, as moist air sweeps in from the North Atlantic. So Lille is focusing hard on waste.

Biogas — the fuel that will power some Lille buses — is actually an ancient energy source. It captured the attention of 13th-century adventurer Marco Polo in China, where he noted covered pots of sewage stored to generate energy, and it earned a mention by 17th-century writer Daniel Defoe.

Lille is also looking at that option.

“We're studying the possibility of getting biogas from sewage sludge at one of the city's two sewage treatment plants, and that has the potential to do at least 150 more buses,” said Hirtzberger.

“Potentially, one could run the entire bus system with biogas from sewage and rubbish. This would be typical of most cities in Europe.”

Other cities, such as Malmo, Sweden, use waste to heat and power buildings. In Malmo, 50 percent of heat is produced from its 550,000 tons of waste a year — a level that could be replicated in most north European cities, said Richard Bengtsson, project manager of E.ON Nordic, which developed Malmo's heat and power system.

“Waste is an interesting fuel due to the fact that you don't have to pay for it,” said Bengtsson. “You get paid to take care of it.”

Malmo owes much of its success to an existing network of pipes to carry heated water from the Sysav plant direct to homes and businesses — a highly efficient system most popular in eastern Europe known as “district heating”.

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