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.
Waste materials collected from Helsinki to be used as feedstock for biochar
Three different feedstocks were collected specifically for the project's purposes in 2022 and pyrolysed in the HSY (Helsinki region environmental services authority) pilot plant in 2022-23. The HSY plant has been previously developed and tested for making sludge char and now HSY is open for testing other materials. The resulting biochar will be used in urban green structures around Helsinki in 2023. Other materials were also evaluated for processing, but not realized due to low availability, high gravel content and logistical and storage issues. These materials included e.g. autumnal street sweeping waste, dog droppings, human waste from public outhouses and meadow clippings with invasive spanish slugs.
Intended experimental sites in Helsinki
Currently, a number of sites that are currently being designed for construction have been selected to be amended with biochar. The list is evolving, and the plans are subject to change. The information in the list is constantly being updated.
In an undergoing renovation, the Siltamäki sports park will have five new sports turfs with a high-class growing medium. The soils consist of 90vol-% sand and 10% peat. In a single pitch with a 810 m2 surface area, the peat in the topmost 15 cm layer is partly but at minimum with 5%, replaced with biochar. This will result to the site containing an estimated 20m3 of biochar. The turf will be made from ready lawn, and the construction is scheduled to be completed in spring 2023.
A new kind of dynamic perennial planting is being constructed in Kalasatama. The site is located in Työpajanpiha, in front of the house of the Helsinki Urban Environmental Division (KYMP). There are two plant community types that each will be receive biochar in their soils. Each experiment is also matched with a comparable replicate area with no biochar but same plants. The plant communities are composed using principles inspired by a naturalistic planting design. The biochar will be enriched in advance with nutrients by mixing it with compost in 1:1 ratio. The final volume of biochar in the substrate is 20%. The construction is expected in July 2023.
A new tram route is being built in Kruunuvuori and in order to increase water infiltration, many stretches are covered with hollow bricks. The brick intervals are filled with soil and sown with a grass mixture. As the depth of the soil is only 12 cm with gravel underneath, the growth environment is very dry. To improve the drought resilience and water availability, the soil is amended with 10% biochar. The biochar part of the project is expected to happen in July-August 2023
Located between the city library Oodi and the Musiikkitalo concert house, Tapahtumapuisto park includes vast lawns that are highly exposed and in intensive use. The same is valid for park lawns in Kaivopuisto park. The aim is to incorporate 3% biochar into the lawn soil and obtain better drought resilience and nutrient retention.
The application will be conducted together with the annual aeration procedure and the work is realized using the Turf Gamechanger machinery. The lawn is perforated and biochar is inserted into the holes together with fertiliser and a microbial inoculant. UPDATE: The application was realized during the 3rd of May, in the Tapahtumapuisto- and Makasiinipuisto parks. Changes were made to the original plan and they will be reported later. The application is planned to be repeated in the summer.
As the Vaasanpuistikko square, located above the Sörnäinen metro station, is undergoing massive renovation, five oak trees planted in the 1980's will remain in place. In order to improve their growth, three trees will have their growing medium changed to structural soil instead of the current, compacted soil. The structural soil matrix is designed to carry the heavy load of the square, and hence it consists mainly of 50-150mm stones. To improve the moisture and nutrient conditions, it will be amended with nutrient-enriched biochar which is flushed down in the cavities using water. The construction is scheduled to start in June 2023.
In line with the carbon neutrality targets, Helsinki is piloting sites where construction of infrastructure is aimed to be realized with net zero emissions. The second pilot is situated in Herttoniemi where the "itäbaana" bike street is being expanded. The park design includes planting approximately 70 new tree individuals. Further, the current plan is to select 46 trees that will receive 10% of biochar in their growing medium. The biochar for this site will be manufactured and donated by GRK, an infrastructure constructor company with its own ambitious climate targets. The biochar plantings will begin in early May 2023.
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.
Events related to the Helsinki Biochar Project
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.
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
Hiilipuisto - Carbon Park
Hiilipuisto project launches scientific monitoring of biochar-based planting soils and develops sustainable practices in the green building sector.
- Susanna Kankaanpää, Helsinki Urban Environment Division, Climate Unit
- Prof. Mikko Jalas, Aalto University
- Tuuli Markkanen, Project Coordinator, Aalto University tuuli.markkanen[at]aalto.fi
- Will van Twuijver, Coordinator in citizen engagement, Aalto University, will.vantwuijver[at]aalto.fi
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
Useful sites to read and follow regarding biochar use in urban green structures
Urban Biochar work in other cities
Several cities across the globe have started initiatives to promote biochar use to fight climate change.