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. It’s not that Swedish decision-makers foresaw the need to safely dispose of garbage when they started building a countrywide network of district heating plants a generation ago, but it turned out to be a fortuitous move when public concern over trash in landfills prompted the country to rethink its garbage-disposal policies. Today putting waste on the trash heap is banned, which means that municipalities have to sort, recycle and, yes, burn, their residents’ garbage. As a result, waste now constitutes 19 percent of the fuel used by district-heating plants, which heat half of Sweden’s households and also use biomass such as leftover tree branches from the logging industry. That makes Sweden the world leader in energy generated from garbage; it is followed by, in order, the Czech Republic, Denmark, Norway and Finland. Using garbage for energy neatly solves the issue of excessive reliance on landfills while at the same time helping address residents’ energy and heating needs. And as Sysav, Renova and district-heating operators are owned by the cities they serve, they have an obligation to use waste. Not that it’s a heavy burden: The energy companies get the resource for free and sell the resulting heat and electricity. Measured by the volume of garbage used to produce energy, the United States — not surprisingly, given its much larger population — tops the list, with 29 million tons. Still, that’s just 12 percent of the waste generated by Americans. This is how the waste-to-energy process works: After recyclable content has been removed, the garbage is placed in incinerators that produce heat or energy, which is then transported to nearby homes. From the ashes, small pieces of metal, which do not burn, are separated and recycled, while those of porcelain and tile are sifted to extract gravel, which is used in road construction. The remaining one percent goes into landfills. And though garbage-infused smoke sounds highly poisonous, thanks to electric filters that give the particles a negative electric charge, in Sweden the smoke is almost entirely nontoxic carbon dioxide and water, which are cleaned again before release. “I know that district heating means they burn garbage, but it’s not something I pay any attention to,” says Göteborg resident Karin Fjellander. “The thing about district heating is that it’s supposed to be green, so if the smoke was poisonous I don’t think they’d keep doing it.” Because waste in landfills generates methane, a concentrated form of CO2, the Swedish municipal association estimates that every ton of imported garbage — which would otherwise have been decomposing in landfills — saves 1,100 pounds of CO2 equivalent. Even if ships were to travel specifically to deliver this garbage, the trade would still end up a net positive for the environment. “You wouldn’t believe how many emails we get every week from people offering us garbage,” says Weine Wiqvist, CEO of Avfall Sverige. For now, Sweden imports its trash mostly from Britain and Norway. According to Löwhagen, “But since our trading partners pay us to dispose of their garbage, we prefer to say that we’re exporting a service” — waste disposal. Either way, Sweden’s garbage needs are skyrocketing: According to Avfall Sverige, the country will import 1.5 million tons of waste this year and 2.3 million tons in 2020. But with recycling rates increasing, the European Union has advised its member states to start building district-heating facilities that can also produce energy. Delegations from various countries including Poland, India and China now regularly visit Sweden to learn about garbage heat and energy.