Stockholm Pursues Climate Holy Grail: a Fossil Fuel-Free Future — Part 3: Clean Heat

By John J. Berger, PhD, an energy and environmental policy specialist based in the San Francisco Bay Area, who is currently working on a new book on resolving the climate crisis.

Early Climate Efforts

STOCKHOLM, SWEDEN—How did Stockholm’s energy transition begin? To properly answer that question, I went to talk with Gustaf Landahl, the head of the city’s Environment and Health Administration.

Gustaf Landahl, Head of Stockholm’s Environment and Health Administration. Courtesy of City of Stockholm.

Landahl has been at the vortex of the planning and implementation of Stockholm’s carbon-cutting since the beginning two decades ago. Currently his team is also in charge of climate assessments for the city.

The tall, sandy-haired civil engineer and environmental planner began tackling climate issues in 1994 while working in Stockholm’s City Planning Administration where the focus was on land use planning and urban master plans. He first became engaged with climate issues out of concern over urban sprawl.

That concern led him and other planners to examine the financial implications of alternative land use patterns. Through their analysis, they arrived at a conclusion that was to have a major impact on the city, its growth pattern, and its environmental footprint.

They discovered that curbing sprawl by concentrating new development within the municipality would not only have economic and tax benefits for the city—and social benefits for the public—but would benefit the environment by reducing CO2 emissions.

At about that time, Landahl moved to the city’s Environment and Health Administration where he proposed that the city should develop a climate strategy to help set the city’s overall priorities. As part of that then-novel undertaking, he and other staff began considering different cost-effective measures to reduce CO2 emissions.

With some help from technical consultants, they examined the city’s energy use—for heating, transport, and power—and they calculated the emissions that were being created, sector-by-sector, process-by-process.

Waste to Energy

That meticulous analytical effort led to the adoption of all kinds of new technologies and processes for tamping down fossil fuel-based emissions. For example, Stockholm’s sewage sludge is now biodigested, and the methane gas produced is blended with natural gas. The “biogas” blend—70 percent biogas, 30 percent natural gas—is now available at gas stations throughout the city for cars that can run on methane.

The sewage produced by 100 people can generate enough methane to fuel a car. Once methane production is increased by adding organic waste from households, such as food waste, planners calculate that it will only take the waste of 60 people to fuel one car.

Stockholm is currently building a biogas grid. (The south and west of Sweden already have a natural gas grid to which biogas is added.) The city is also interested in the potential for producing biogas from forestry and agricultural residues, which can be heated and gasified.

By 2020, the city hopes to collect at least 70 percent of Stockholm’s food waste for biogas production. A facility for sorting food waste for biogas production is planned in the city’s Högdalen district.

Transit Efficiency

The climate plan has also led to efficiency improvements in the city’s public transit system. Schedules on all modes of public transit are coordinated to minimize waiting times. All bus and rail lines meet at the central train station, linking all public transit.

All final stops on the city’s rail lines have park-and-ride facilities so travelers beyond the city limits can reach the city’s outskirts by car and then transition there to public transit. (A more complete description of Stockholm’s transportation challenges and responses can be found in Part 4 of this series.)

Landahl is optimistic about the many potential benefits the climate plan can produce for the city, and he sees no economic downside to the city’s vigorous effort to drive down its greenhouse gas emissions.

“We’ve had wonderful growth,” he remarked. “We are the quickest growing capital in Europe at the moment.” People and companies want to move to Stockholm, he said. Stockholm’s service sector is growing, “and still we are managing to bring down the emissions.”

“So there’s no connection between economic growth and reducing emissions more than possibly a positive one. Moreover, by working on emissions-reduction technology, “you can create services and products in which other cities in other part so the world will be interested.” “Stockholm has a very low emission per capita but very high GDP per capita,” he added.

Sharing Heat

Schematic of Fortum Värme’s cooling service for Interxion data center. The cooling service provides chilled water. Interxion then returns it at 75°F or more. A heat exchanger, mixer, and a circulation pump are all that is needed. The recovered heat enters large heat pumps at Fortum Värme’s plant and is sent on to be shared with thousands of customers on Stockholm’s district heating network. Interxion.

Stockholm has a vast district heating system with 1,800 miles of underground heat pipes that supplies four-fifths of the city’s heating needs. The technology has been in use in the city since shortly after World War II. The current system captures waste heat from power plants and industries to share it with homes, businesses, and more than 10,000 large buildings.

The city’s utility, Fortum Värme (co-owned by Fortum, the Finnish energy company), intends that district heating in the city will be climate- and resource-neutral by 2030 through the use of fuel that is either entirely renewable or waste-derived. It now heats about 80 percent of all the floor space in the city.

Most of the homes not served by the system are in the suburbs and are directly or indirectly heated by electricity. About 40 percent have bedrock heat pumps. Every kilowatt of electricity used by these heat pumps produces about four units of heat. Since 1995, two-thirds of Stockholm’s private homes have reduced their energy use by at least 50 percent by switching to heat pumps.


“Only a few oil furnaces are left and they will be phased out by 2040. . . . No one buys a new one,” Landahl said.

The Case for District Heat

District heating has many advantages for consumers. “It is cheaper than oil heating on a fuel comparison basis,” Landahl said. “Moreover, oil furnaces required a large oil storage tank and a furnace room. The area once devoted to the tank and furnace can instead be repurposed, sometimes as a spare room. Moreover, the furnace no longer needs to be maintained or periodically upgraded.”

The building’s entire heating system does not have to be replaced to employ district heat. A heat exchanger simply connects the district heating system to the building’s original heating system. “This is a much smaller and simpler technology,” Landahl said.

Ulf Wilkstrom, Fortum’s Sustainability Manager. Courtesy of Fortum Varme

Sustainability Manager Ulf Wikström —a calm yet intense, balding man with horn-rimmed glasses—manages Stockholm’s district heating system for Fortum Värme, the local utility.

“What people don’t know,” Wikström said, “is that quite a big part of the district heating is produced [from] energy recover[ed] from wastewater coming from households and industries in Stockholm. . . . it’s a very good energy source.” The heat is extracted from the wastewater by electric heat pumps that deliver four times as much energy as they use.

Overall, about 90 percent of the heat provided by the district heating system comes from renewable energy sources. The other 10 percent is derived from fossil fuels.

Most of the emissions reductions that Stockholm has achieved since 1990 has been due to the adoption and expansion of its district heating network which largely replaced oil heating in the city. Sweden’s carbon tax helped accelerate the adoption of district heating.

The next largest emissions reduction came as a result of the replacement of oil heating with geothermal heat pumps. The amount of oil used for heating in Stockholm fell 94 percent. Replacing diesel buses and other fossil-fueled vehicles with renewably fueled vehicles reduced the city’s emissions by another 10 percent.

Energy Arbitrage

Interxion’s data centre in northern Stockholm. Courtesy of Interxion

Because Fortum Värme’s engineers view heating and cooling as part of a unified system rather than as isolated processes, they are able to take advantage of energy resources that would otherwise be wasted.

Thus Stockholm encourages businesses with significant cooling needs, such as large data centers, to sell their surplus heat to Fortum Värme. “We . . . recover exhaust energy from facilities [to which] we supply district cooling,” Wikström said.

One megawatt of heat continually exported from a data center will generate a revenue steam of $200,000 a year to the center, according to Jonas Collet, Fortum’s Värme’s Head of Media Relations.

The company’s heat recovery system where the excess heat produced by the company’s cooling system is recovered by Fortum Värme and used to heat thousands of homes. Courtesy of Interxion

As noted, by dint of a city council resolution, Stockholm is committed to becoming fossil-fuel free by 2040. “We are now making a plan for how to phase out the coal,” Wikström added, “so [Fortum Värme] will go totally fossil-fuel free within 10 years.” Meanwhile, Sweden is attempting to make all cars independent of fossil fuels nationwide by 2030, and that of course will also affect Stockholm. (See “Stockholm Pursues Climate Holy Grail: a Fossil-Fuel-Free Future—Part 2; Stubborn Emissions” for more about the city’s plans for reducing its transportation emissions.)

In Part 4, the next installment of this series, the city’s efforts to increase the use of public transport, bicycles, and walking are discussed along with other measures Part 5, the final installment includes a profile of two of Stockholm’s notable ecodistricts, Hammarby Sjöstad and Stockholm Royal Seaport.



This article is the third of a five-part series on Stockholm’s energy transition originally published on The Huffington Post and republished with permission


John J. Berger, PhD is an energy and environmental policy specialist who has produced ten books on climate, energy, and natural resource topics. He is the author of Climate Peril: The Intelligent Reader’s Guide to Understanding the Climate Crisis and Climate Myths: The Campaign Against Climate Science. He is currently at work on a new book about climate solutions.

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The contents of this article reflect the personal opinions and interpretations of the author and do not necessarily represent the views of ICLEI – Local Governments for Sustainability.