Every day, some 300 trucks arrive at a plant outside the city of Göteborg on the west coast of Sweden. They carry garbage, but they are not there to dump the cargo. Instead, they deliver it to the plant’s special ovens, which burn it, providing heat to thousands of local homes.

“The only fuel we use is waste,” says Christian Löwhagen, a spokesman for Renova, the local government-owned energy company operating the plant. “It provides one-third of heat for households in this region.” Across Sweden, 950,000 homes are heated by trash; this lowly resource also provides electricity for 260,000 homes across the country, according to statistics from Avfall Sverige, Sweden’s national waste-management association.

With Swedes recycling almost half (47 percent) of their waste and using 52 percent to generate heat, less than 1 percent of garbage now ends up in the dump. “Sweden has the world’s best network of district heating plants” — essentially large ovens that use a variety of fuels to generate heat, which is then transported to consumers’ homes through a network of underground pipes — “and they’re well-suited for use of garbage,” says Adis Dzebo, an energy expert at the Stockholm Environment Institute. “By contrast, in many other countries the heat and electricity infrastructure is based on gas or other fossil fuels, so it’s not economical to start building plants that utilize garbage.”

Here’s the problem: Swedes (as well as Germans, Danes, the Dutch and Belgians) have become so good at recycling that there’s no longer enough garbage to meet the heating plants’ needs. Sweden now has to import the trash that most other countries are trying to dispose of — some 800,000 tons in 2014, up from 550,000 tons in 2010, according to Avfall Sverige.

Last year Renova brought in 100,000 tons of foreign garbage, mostly from Britain, in addition to the 435,000 tons supplied by Swedish municipalities. In Stockholm, energy provider Fortum also imports garbage, and in the southern city of Malmö, the Sysav energy company brought in 135,000 tons of waste from Norway and Britain last year, according to the company’s communications director, Gunilla Carlsson. That’s an almost 100 percent leap from the year before.

“We try to stay up to date on where well-sorted garbage is available,” says Löwhagen. “We only use waste where all recyclable bits have been taken out. In Europe, enormous amounts of garbage are put in landfill, so we’re doing other countries a favor by taking care of it for them.” In order to minimize cost and environmental impact, companies try to get a cheap ride for their garbage on ships going to Sweden that would otherwise have empty holds.