OSLO, Capital of Norway, is a city that imports garbage. Some comes from England, Ireland and from neighboring Sweden. It even has designs on the American market.

A trash incinerator. Roughly half of Oslo and most of its schools are heated by burning garbage.

“I’d like to take some from the United States,” said Pal Mikkelsen, in his office at a huge plant on the edge of town that turns garbage into heat and electricity. “Sea transport is cheap.”

Oslo, a recycling-friendly place where roughly half the city and most of its schools are heated by burning garbage — household trash, industrial waste, even toxic and dangerous waste from hospitals and drug arrests — has a problem: it has literally run out of garbage to burn.

The problem is not unique to Oslo, a city of 1.4 million people.

Across Northern Europe, where the practice of burning garbage to generate heat and electricity has exploded in recent decades, demand for trash far outstrips supply.

“Northern Europe has a huge generating capacity,” said Mr. Mikkelsen, 50, a mechanical engineer who for the last year has been the managing director of Oslo’s waste-to-energy agency.

Yet the fastidious population of Northern Europe produces only about 150 million tons of waste a year, he said, far too little to supply incinerating plants that can handle more than 700 million tons. “And the Swedes continue to build” more plants, he said, a look of exasperation on his face, “as do Austria and Germany.”

Stockholm, to the east, has become such a competitor that it has even managed to persuade some Norwegian municipalities to deliver their waste there.

By ship and by truck, countless tons of garbage make their way from regions that have an excess to others that have the capacity to burn it and produce energy.

“There’s a European waste market — it’s a commodity,” said Hege Rooth Olbergsveen, the senior adviser to Oslo’s waste recovery program. “It’s a growing market.”

Most people approve of the idea. “Yes, absolutely,” said Terje Worren, 36, a software consultant, who admitted to heating his house with oil and his water with electricity. “It utilizes waste in a good away.”

The English like it, too, though they are not big players in the garbage-for-energy industry. The Yorkshire-based company that handles garbage collection for cities like Leeds, in the north of England, now ships as much as 1,000 tons a month of garbage — or, since the bad stuff has been sorted out, “refuse-derived fuel” — to countries in Northern Europe, including Norway, according to Donna Cox, a Leeds city spokeswoman.

A British tax on landfill makes it cheaper to send it to places like Oslo. “It helps us in reducing the escalating costs of the landfill tax,” Ms. Cox wrote in an e-mail.

For some, it might seem bizarre that Oslo would resort to importing garbage to produce energy.

Norway ranks among the world’s 10 largest exporters of oil and gas, and has abundant coal reserves and a network of more than 1,100 hydroelectric plants in its water-rich mountains. Yet Mr. Mikkelsen said garbage burning was “a game of renewable energy, to reduce the use of fossil fuels.”

Of course, other areas of Europe are producing abundant amounts of garbage, including southern Italy, where cities like Naples paid towns in Germany and the Netherlands to accept garbage, helping to defuse a Neapolitan garbage crisis.

Yet though Oslo considered the Italian garbage, it preferred to stick with what it said was the cleaner and safer English waste. “It’s a sensitive question,” Mr. Mikkelsen said.

Garbage may be, well, garbage in some parts of the world, but in Oslo it is very high-tech.

Households separate their garbage, putting food waste in green plastic bags, plastics in blue bags and glass elsewhere. The bags are handed out free at groceries and other stores.

The larger of Mr. Mikkelsen’s two waste-to-energy plants uses computerized sensors to separate the color-coded garbage bags that race across conveyor belts and into incinerators.

The building’s curved exterior, with lighting that is visible from a long distance to motorists driving by, competes architecturally with Oslo’s striking new opera house.

Still, not everybody is comfortable with this garbage addiction. “From an environmental point of view, it’s a huge problem,” said Lars Haltbrekken, the chairman of Norway’s oldest environmental group, an affiliate of the Friends of the Earth. “There is pressure to produce more and more waste, as long as there is this overcapacity.”

In a hierarchy of environmental goals, Mr. Haltbrekken said, producing less garbage should take first place, while generating energy from garbage should be at the bottom. “The problem is that our lowest priority conflicts with our highest one,” he said.

“So now we import waste from Leeds and other places, and we also had discussions with Naples,” he added. “We said, ‘O.K., so we’re helping the Neapolitans,’ but that’s not a long-term strategy.”

Maybe not, city planners say, but for now it is a necessity. “Recycling and energy recovery have to go hand in hand,” said Ms. Rooth Olbergsveen, of the city’s waste recovery agency. Recycling has made strides, she said, and the separation of organic garbage, like food waste, has begun enabling Oslo to produce biogas, which is now powering some buses in downtown Oslo.

Mr. Haltbrekken acknowledged that he does not benefit from garbage-generated energy. His home near the center of town, built about 1890, is heated by burning wood pellets, and his water is heated electrically. In general, he said, Friends of the Earth supports the city’s environmental goals.

Yet he added, “In the short-term, it’s better to burn the garbage in Oslo than to leave it in Leeds or Bristol.”

But “in the long term,” he said, “no.”