A typical power plant is a tangle of pipes and large metal cylinders enclosed in concrete walls coated with drab paint. Its furnaces burn dirty fuel and pump out noxious gases.
Amager Bakke in Copenhagen is not your typical power plant. Designed by architect Bjarke Ingels, the power plant’s roof doubles as a ski slope and a hiking trail. The longest bit of flat surface becomes an 85-meter (280-foot) climbing wall. At the very top of the building, one of the highest points in the city, there’s even a restaurant and bar.
The public is encouraged to tour the power plant, which burns waste instead of fossil fuel. The city’s municipal councils paid $670 million to build Amager Bakke, which began operating in 2017. Burning up to 400,000 tons of waste per year, it produces electricity to power 60,000 homes and heat 160,000 homes. Its state-of-the-art technology ensures that there’s nothing noxious coming out the chimney. And that’s crucial, because it hopes to attract more than 300,000 visitors each year.
Most countries in the world have waste incinerators, and Amager Bakke shows that they need not be tucked in a corner and kept out of reach for the general public. “It’s supposed to start a dialogue about waste,” says Patrik Gustavsson, CEO of the Amager Bakke Foundation, which runs the ski slope. “People don’t know what happens to the waste after they dump it in their bin.” Such a dialogue is crucial in a world where environmental problems from waste to climate change are affecting our daily lives.
For the last 100 years, the city of Copenhagen has been supported by district heating. Residents simply pay a utility company to access hot water through a large network of pipes. That means, however, that the power plants heating the water need to be fairly close to the city. In countries that don’t have this system, heat comes from burning natural gas or oil in a boiler or using electricity to run some kind of heat pump—all from within the comforts of their home.
When a coal power plant called Amagerværket was first built in 1971, it was outside the city of Copenhagen, far away from any residential areas. But during its time in service, the city’s population grew by 30%, sprawling into the former outskirts—and putting Amagerværket closer to residential areas. The municipal corporations that own the power plant decided that they needed to replace Amagerværket with a power plant that would be safe, wouldn’t produce harmful emissions, and wouldn’t be an eyesore.
Ingels won the competition to design the power plant and proposed a ski slope that sits on top of the power plant’s roof. The 44-year-old Danish architect is known for VIA 57 West, a residential building in New York City that looks like a sailing ship from across the Hudson. Construction of Amager Bakke—named quite literally for being in the “Amager” region of Copenhagen and sporting a hill, or “Bakke”—began in 2013. It’s also called CopenHill.
Around that time, the city’s leadership adopted ambitious climate goals. By 2025, Copenhagen aims to be carbon neutral. If it succeeds, it would be the first capital city in the world to do so. Amager Bakke fell in line with those goals. Rather than burning fossil fuels, the utility that owns the power plant decided that the power plant would burn household waste instead.
Amager Bakke is a 24-hour operation, but its functions—mixing the trash it collects, dumping it in the furnace, and collecting the ash produced—are almost all automated. No more than two people are needed to run it, says Signe Josephsen, who runs Amager Bakke’s visitor center. The operations are funded by the bills the residents pay for energy and waste collection.
I got a tour of the power plant in September. As Josephsen and I walked from the visitor center to the furnace, the stench of garbage grew stronger. She pointed to various parts of the power plant shouting to speak over the hum of the machinery. That’s the boiler, that’s the emissions scrubber, that’s the generator, she told me but they were all hidden behind large sheets of metal.
When we got inside the control room where an operator sat in front of a computer, the hum came to a standstill and the stench almost went away. That place existed in case the workers had to manually manage the garbage. One of the four walls of the room was made of clear plastic, and it was slightly disorienting to see so much trash but not smell it. Josephsen and I stayed there for a good few minutes—just staring. Oddly, I felt at peace watching a robotic arm grab hundreds of kilos of garbage in one go and feed it to the furnace.
After the tour, we rode the elevator a few hundred feet up to the roof; the ski slope was under construction, and there was no whiff of trash at all.
Amager Bakke claims to have one of the world’s cleanest incinerators. Scrubbing equipment removes most of the sulfur and nitrogen emissions from the exhaust before being dumped in the chimney. The furnace is capable of burning anything you put in it, says Josephsen. Practically, however, that means the waste burned is that which can’t be recycled.
That’s not to say the facility is totally emissions-free. The power plant has no plans to retrofit carbon-capture technology, which can scrub out carbon dioxide that can then be stored underground. It could, however, choose to burn only biomass. That would technically make it carbon-neutral power plant—it’ll still emit carbon dioxide, but because the biomass was created by capturing carbon dioxide from the air, burning it simply return that carbon dioxide back to the air.
That’s all in theory. In practice, producing and transporting that biomass also generates carbon dioxide, which means the process is unlikely to be carbon neutral. Consider the emissions profile of different fuel types:
Amager Bakker might be forced to burn biomass anyway. As Danish citizens produce less waste and recycle more, Denmark has been struggling to find enough waste to burn in its 28 waste-to-energy power plants. At least some of the waste being burned is imported from countries like the UK, which don’t have enough incinerators of their own.
Amager Bakke is so unique that there’s no guarantee that visitors will come in the numbers expected. “The whole enterprise will stand or fall with the number of visitors,” Gustavsson admits. If it succeeds to run commercially, it will be yet another gleaming achievement in Denmark’s quest towards sustainability. If it fails, it will be yet another example of how hard it is to make people interested in energy issues.
The experiment is on.
Gustavsson hopes to lure people to the power plant by providing for a fun experience. The first people to ski on CopenHill got their turn in December 2018. It took nearly two years after the power plant began operation to get the ski slope running, and even today only some parts of it are fully functional. So far about 1,500 people have used the ski slope, which is fewer than the numbers expected to come in a similar period after the slope is fully operational this spring.
Born in Stockholm, Gustavsson, like many of his fellow Swedes, grew up skiing. That’s not as common for the Danes. “Many people coming here would be experiencing skiing for the first time,” he says. To make sure the experience was as good as he could make it, Gustavsson got help from Copenhagen’s ski clubs on designing the track and choosing the right material for the ski floor. The Danes who do know skiing could become the ambassadors for CopenHill.
Even for those who have skied before, though, the experience at Amager Bakke is strange. The ski slope does not have any snow. It’s not even white. It’s made of green-blue plastic laid atop a field of grass, which holds the earth underneath together and keeps the plastic sheets intact. Skiers (they do wear skis) glide down the small blades of plastic sticking out of the sheet, which are coated with silicone oil to provide a low-friction glide.
For those not into skiing, there’s a hiking trail alongside the slope. Gustavsson got help from the city’s running clubs to weigh in on the design of the hiking trail. Those who embark on the short jaunt, step on hand-casted concrete that has a peculiar bounce, to give hikers an experience more reminiscent of walking on dirt than if they just stepped on to hard concrete.
Amager Bakke’s creators hope it will be as much an education center as it is a ski slope and entertainment hub. The glass lift that takes visitors to the restaurant has only two stops: ground floor and the rooftop. But as the visitors climb up nearly 100 meters, they can see the innards of the power plant. The idea is that it would make people curious to find out more.
If their interest is piqued, they’ll learn how the city sorts out its waste, what happens to the different bits, what is burned in the power plant, and why the emissions produced are safe to breathe in. There is something powerful about the idea of knowing where your power comes from, says Ulrik Kohl, a member of the Copenhagen’s city council and a part of its Technology and Environment committee.
Kohl invited me to his home to talk about Amager Bakke and the city’s climate goals. After coffee, we walked to the back door of his fourth-story flat and climbed up a few stairs. Out in the distance, I could see Amager Bakke and its shiny metal chimney. But Kohl was more interested in a wind turbine near it.
“Every time it turns, I make money,” Kohl says. Copenhagen residents can buy shares in some of the many wind turbines dotted around the city—a structure of ownership that’s becoming common in Scandinavian countries. This way, the profits made are reinvested in a community, rather than accrue in the investors’ accounts of those who may not even live in Copenhagen. Crucially, Kohl knows that his share, however small, is helping to cut emissions.
To be sure, Copenhagen has already done more to curb emissions than most cities in the world. After the city’s population fell in the 1970s and 1980s, it has grown by nearly 50% since 1990. At the same time, the city has cut its emissions by 40% compared to the levels in 1990. Climate action, among other measures such as promoting cycling and electrifying public transport, have helped Copenhagen become one of the world’s most livable cities.
Reducing an entire city’s emissions to be carbon neutral, however, is a much bigger challenge. Most of the reductions are going to come from cleaner energy to power and heat homes and buildings. But others, such as cutting emissions from cars, will come from buying carbon offsets. That’s an imperfect solution, if achieved, but it will still be more than what most cities have done.
Getting there requires more than politicians with a unified vision—it also demands the support of Copenhagen residents who will bear the burden financial burdens of climate action. Amager Bakke wants to be a catalyst to make that change happen.
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