In Sweden, Trash Heats Homes, Powers Buses and Fuels Taxi Fleets

New York Times

By Amy Yee

September 22, 2018

In a cavernous room filled with garbage, a giant mechanical claw reaches down and grabs five tons of trash. As a technician maneuvers the spider-like crane from a control room high above, the claw drops its moldering harvest down a 10-story shaft into a boiler heated to more than 1,500 degrees Fahrenheit. All around, a fetid odor emanates from plastic trash bags discarded by hundreds of thousands of homes.


The process continues 24 hours a day to help fuel this power plant run by Tekniska Verken, a municipal government company in Linköping, a city 125 miles south of Stockholm. It is one of Sweden’s 34 “waste-to-energy” power plants. Instead of burning coal or gas, this power plant burns trash.

“We don’t look at it as waste,” said Klas Gustafsson, vice president at the company. “We use the energy content of waste as much as possible.” Four tons of garbage contains energy equivalent to one ton of oil, 1.6 tons of coal, or five tons of wood waste, according to Tekniska Verken.

Sweden is known for dramatically reducing its trash sent to landfills. Less than 1 percent of household waste in this Scandinavian country finds it final resting place in landfills, according to Avfall Sverige, the Swedish Waste Management and Recycling association. About 49 percent of household waste is recycled. And roughly 50 percent of garbage is incinerated in power plants like this one. Here, heat is transformed into steam that spins turbines to generate electricity much like conventional power plants that burn coal or gas.

Trash accounts for a small portion of Sweden’s overall power supply; hydro and nuclear energy generate about 83 percent of Sweden’s electricity and wind another seven percent.

But garbage supplies much of the heating during cold months for the country’s nearly 10 million residents. Energy from trash equals the heating demand of 1.25 million apartments and electricity for 680,000 homes, according to Avfall Sverige.

Conventional power plants typically feature large cooling towers that dissipate excess heat, so only about 40 percent of energy is fully used. The trash-powered plant in Linköping — which both generates electricity and heats water for home and commercial use — harnesses 90 percent of total energy . This supplies hot water for bathrooms, kitchens and central radiator heating.

This centralized system of “district heating” warms many buildings in Sweden. The system was built over decades of planning starting in the late 1950s“This is not something you do overnight,” said Ronny Arnberg, project manager at IVL Swedish Environmental Research Institute in Stockholm.

Sweden is not “special smart,” he added when it comes to developing new energy technologies. Instead, the country is “extremely lucky to be one of the most developed countries in the world” that can afford to build and manage big infrastructure initiatives, he said.

Trash-burning plants do have their drawbacks, such as creating emissions just like conventional power plants fueled by natural gas and coal.

However, methane generated from organic waste in landfills is reduced. This is important. Methane is about 72 times more potent as a greenhouse gas than carbon dioxide in the short-term.

Between 2002 and 2005, Sweden banned organic and combustible waste (such as paper) in landfills. This is a marked change compared to four decades ago. In 1975 every person in Sweden recycled 18 kilograms (about 40 pounds) of waste per person compared to 162 kilograms (357 pounds) in 2016. Back then, each person also produced 197 kilograms (430 pounds) of trash that was landfilled compared to 3 kilograms (6.6 pounds) in 2016, according to Avfall Sverige.

Along with reducing landfill, proponents say using trash as an energy supply also reduces burning fossil fuels such as coal, gas and oil, which are extracted from the earth and shipped around the world using even more fossil fuels.

Tekniska Verken estimates that its trash-burning operations last year avoided emitting the equivalent of 467,000 tons of carbon dioxide.

“Waste-to-energy is a reasonable short-term solution,” said Owen Gaffney, director of international media and strategy at the Stockholm Resilience Centre, which conducts environmental research. “It is less carbon intensive than coal and it uses resources more efficiently than simply putting them in landfill where they would decompose and release greenhouse gases anyway.”

Along with heat and electricity, Tekniska Verken produces methane biogas from 100,000 tons of food and organic waste each year. This biogas runs more than 200 city buses in the county, as well as fleets of garbage collection trucks, and some taxis and private cars, said the company.

The entire process is on display in the company’s trash sorting facility where garbage bags whiz by on conveyor belts. Digital censors detect the special green bags for organic waste. They are batted aside by machines onto another conveyor belt to be trucked to a nearby biogas plant. Machines rip apart plastic bags and organic waste is filtered into a massive metal vat. This biogas digester will create methane that is eventually refined, scrubbed of carbon dioxide and then distributed to Linköping’s fuel stations.

As mixed bags of trash move along a conveyor belt, digital censors detect the special green bags for organic waste and push them onto another conveyor belt to be trucked to a nearby biogas plant. Credit: Casper Hedberg for The New York Times

Tekniska Verken is building a factory to liquefy biogas, making it easier to store in metal tanks and to distribute and sell.

However, garbage-fuelled power plants are not a clean energy source. Some opponents claim these power plants are a “false solution” that greenwashes dirty incineration. “The process of burning trash is inherently polluting. You can put state-of-the-art pollution controls on an incinerator in the same way that you can a coal plant, but that doesn’t make the facility clean,” said Leah Kelly, senior attorney with the Environmental Integrity Project, a nonprofit based in Washington D.C.

Flue gases leave behind heavy metals and other toxins that comprise about 4 percent of residue, according to a report from Avfall Sverige.

This must be cleaned out during periodic maintenance and disposed of safely. Flue gas residue from Tekniska Verken’s power plant is stored in an abandoned lime mine in Norway. Another residue called slag, composed of the remnants of glass, porcelain, gravel and other material can be used to cover landfills and build roads.

Critics also warn that these power plants discourage reducing and recycling waste, and also detract from investment in renewable energy such solar and wind.

Yet Sweden is increasing recycling. The country recycled about 1.4 million tons of waste in 2011 and 1.6 million tons in 2015.

“It’s important to work hard on recycling. It’s crucial because otherwise waste-to-energy is blamed for the problem of ‘feeding the beast,’” said Weine Wiqvist, chief executive of Avfall Sverige.

The country is also ramping up wind and solar capacity as part of its aim to be 100 percent renewable energy by 2040 and to have net zero greenhouse gas emissions by 2045.

As lofty as those goals sound, Sweden is on track to meet them, said Mr. Gaffney of Stockholm Resilience Center. “That’s entirely realistic,” he observed.

Along with its domestic production, Sweden also imports trash from Norway and the UK each year to fuel power plants. These countries pay Sweden to accept their trash because it can be cheaper than paying landfill taxes. Mr. Wiqvist said Sweden did not run out of garbage to burn, but more plants were built to use available fuel.

Waste-to-energy is not just thriving in Sweden. Japan already incinerates up to 60 percent of its solid waste. China has more than doubled its waste-to-energy capacity between 2011 to 2015, according to a World Energy Council report.

Burning trash for energy seems particularly practical for large, developing nations that lack modern trash disposal systems where garbage poses a massive environmental and health threat.

In developing countries, trash is typically carted to mountain-like dumpsites where methane causes fires. Such sites often lack the concrete or plastic linings found in modern ‘sanitary landfills’ and can leach toxins into soil or water supplies. Garbage dumpsites are also serious hazards for poor people who scavenge recyclable material by hand.

Yet setting up waste-to-energy plants in a developing country is particularly challenging — if not outright unviable. They are more expensive to build because of costly flue gas filters and must be carefully regulated.

In the 1980s, waste-to-energy plants in developed countries emitted hazardous dioxins. Since then, better technology and strict regulation have reduced annual dioxins, from 10,000 grams in 1987 to 10 grams in 2013, a reduction of 99.9 percent, according to the World Energy Council report. In the U.S., dioxins from trash incinerators has dropped by 90 percent since 1987 according to the U.S. Environmental Protection Agency.

Another issue is that developing countries with warm climates wouldn’t need central heating. But Mr. Arnberg pointed out that heat could instead be harnessed in a different way. For example, heat could power industry such as nearby paper mills or food processing plants or factories set up nearby. It could also power central cooling systems.

Building large, effective infrastructure projects require good governance and sound business practices. Waste collection needs organized infrastructure and logistics. These traits are more challenging to achieve in developing countries. And importantly, citizens need to be educated about proper disposal of waste.

“If you have citizens who don’t how to use the system, it doesn’t matter how much you invest,” said Arnberg of IVL, who has consulted for energy projects around the world.

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