Department of Design

Helsinki Biochar Project

The City of Helsinki explored the practical pathways for improved carbon sequestration, circular waste systems, and thriving urban vegetation via increasing the use of biochar on selected demonstration sites across public green structures. During years 2022-23, different kinds of organic waste materials were tested as potential feedstocks for manufacturing local biochar. The project was set out to spread awareness about the benefits of, and providing practical know-how of using biochar among the city administration and citizens.
A concptual cycle of the experimental process of the Helsinki Biochar Project

Biochar to reach a climate-neutral city

The city of Helsinki has set an ambitious program to be carbon neutral by 2030, and all means necessary need to be taken to achieve that goal. Emissions are being cut throughout the city and to reach the target, 20 % of emissions, equalling to 702 kt CO2- eq., can be compensated. By 2040, the city will offset all remaining emissions through carbon sinks located within the city´s geographical boundaries, which is where biochar is needed

In addition to a means to sequester carbon, biochar has potential to play a role in climate adaptation strategies. Biochar can be added as a soil amendment changing the absorption capacity and structure of the soil. Increasing the capacity of urban soils to be more resilient to extreme weather events, such as storms and prolonged periods of drought, could potentially serve as one of multiple means for urban climate adaptation.

a pile of biochar at HSY
Banner of urban biochar trials

Experimental pilot sites in Helsinki public green spaces

In total, the project promoted the planning and setting-up of ten specific test sites that explored the use of biochars in public parks in different ways. The aim was to learn from the planning phase, logistics and handling of biochar-based solutions. Further, a goal was to learn locally about the effects that using biochar has on the vegetation and the surrounding soils. Many pilot sites are systematically being monitored by the city after construction.

Banner of citizens participating in biochar trials

Citizen engagement in biochar related activities

Because biochar is still a relatively unknown material, the Helsinki Biochar Project aims to increase the awareness of citizens on the potential of biochar. In order to do so, the project strives to set up a series of trials in the Helsinki metropolitan area to demonstrate the various stages of the biochar cycle to citizens, ranging from showcasing the production of biochar from local waste streams, how it works as a means to sequester carbon and finding engaging ways to utilise the material as a climate adaptation tool. The goal of the Helsinki Biochar Project is to demonstrate that converting local waste streams into responses to climate change is not just a distant process for decision makers only, but can be an engaging capability-building activity for citizens as well.

Banner of exhibition boxes for the Helsinki Biochar Project

Public events related to the Helsinki Biochar Project

Helsinki biochar tour
Past events

Biochar tour 
The Biochar Tour was organised on the 6th of september 2023together with one of the garden coordinators at the Lapinlahden Lähde community garden. The goal of the tour was twofold: 1) to inform the participating citizens of the citizen engagement trials on the larger scope of the project, and 2) to bring in members from the steering team to facilitate knowledge exchange between professional experts and citizens.

Temporary banner image
Past events

Biochar. In the City?
On the 16th of March had a public discussion about the role of biochar in the climate work of cities. The project responsibles, Mikko Jalas (Aalto) and Susanna Kankaanpää (Helsinki) presented their current views and answered to questions from the public. The event was a part of NODUS Talks continuum at the Helsinki Design Museum and its recording can be viewed on Aalto Youtube channel.

Graphic design. On the right side of the visual there is a volcanic landscape with beautiful rocky pathway towards a mountain. Left side of the visual is fading to black. On the top left corner: Sustainability Science Days text is displayed with Swear Display font, and Aalto University and Helsinki University logos below on the left hand side of the visual.
Past events

Join us on the upcoming Sustainability Science Days 2023 in the session "Scaling Up Urban Carbon Sinks with Urban Green Infrastructure". The Sustainability Science Days is an international, multi-day conference organised jointly by Helsinki Institute of Sustainability Science (HELSUS) and Aalto University on 23 - 26th of May 2023.

The session brings together climate, material, soil and social scientists; landscape architects and urban planners; practitioners and businesses; and municipalities and governmental bodies. The aim is to bring forward academic knowledge and practices on the conditions and current ways of scaling up urban carbon sinks and developing carbon smart Urban Green Infrastructure for development of municipal strategies and decision-making, planning, as well as construction and maintenance practices. 

The Helsinki Biochar Project builds on previous collaboration projects on biochar

Carbon Lane -project

Carbon Lane (CarLa) is an EIT Climate-KIC funded project which takes place during 2019. The project explores practical carbon drawdown solutions for urban green areas

Illustration of a tree in soil with details of roots, carbon, nutrients

Hiilipuisto - Carbon Park

Hiilipuisto project launches scientific monitoring of biochar-based planting soils and develops sustainable practices in the green building sector.

Kuva: Esko Salo
City of Helsinki
Aalto University
Helsinki Region Environmental Services HSY
VTT Technical Research Centre of Finland Ltd

Project responsibles

  • Susanna Kankaanpää, Helsinki Urban Environment Division, Climate Unit, susanna.kankaanpaa[fi]
  • Prof. Mikko Jalas, Aalto University, mikko.jalas[at]

Contact persons:

  • Tuuli Markkanen, Project Coordinator (July 2022-December 2023), Aalto University + Helsinki city tuuli.markkanen[at]
  • Will van Twuijver, Project Coordinator in citizen engagement and visual communication, Aalto University. (December 2022- November 2023)
  • Miina Heikkinen, contact person for exhibitions and other outreach,  miina.heikkinen[at] 

Funding and support from abroad

Bloomberg Philanthropies announced that seven cities from Europe and the United States will receive support to adopt Stockholm’s 2014 Bloomberg Philanthropies’ Mayors Challenge Winning Biochar Project, which turns plant waste from parks and homes into a charcoal-like substance that residents can then use in their yards and gardens to help combat climate change. 

Darmstadt, Helsingborg, Sandnes, Helsinki, Cincinnati, Lincoln, and Minneapolis, will receive funding, along with implementation and technical support from Bloomberg Philanthropies to develop city-wide biochar projects and engage residents in the fight against climate change. Participating cities will also benefit from robust best practice sharing and peer-to-peer networking to share lessons learned in implementing their efforts

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