In June 2023, the City of Helsingborg on Sweden’s southwest coast played host to a four-day International Biochar Summit that attracted over 400 experts from around the world. The event, which included site visits to a newly opened Biochar Competence Centre and a first-of-its-kind biochar plant, has firmly placed Helsingborg on the international biochar map.
One of the oldest cities in the Nordics on account of its strategic location overlooking the narrowest part of the Öresund strait, Helsingborg is already “historic” when it comes to biomass – the world’s first-ever transatlantic shipment of wood pellets arrived in April 1998 to Öresundskraft’s combined heat and power (CHP) plant in Helsingborg having been shipped from Prince Rupert, British Columbia (BC), Canada thus paving the way for the global pellet industry of today.
Sweden’s Biochar Capital
Twenty-five years on, the city can add the “Biochar Capital of Sweden” to its biomass merit listing. And for good reason as Bioenergy International finds out.
2014 with the Stockholm Biochar Project was the starting point for what we see here today. People like Björn Embrén, Tree Officer for the City of Stockholm park’s department and one of the originators of the Stockholm Biochar Project, and Jonas Dahllöf from Stockholm Water and Waste were a great source of knowledge and inspiration, recounted Ludvig Landen, CEO and Business Partner at BiocharTech but who at the time worked for Helsingborg city council in the urban planning department.
In Swedish municipalities and biochar circles, both names are legendary with Björn Embrén carrying out the first trials with biochar and skeletal soil beds for urban trees in 2009 – with the biochar reputedly imported from Germany.
The Stockholm Biochar Project gained much wider attention in 2014, not least internationally, as it won the Bloomberg Philanthropies’ Mayors Challenge.
In March 2017, the project commissioned one of the first facilities in Sweden to process urban green waste into biochar for use in the Capital’s parks and green spaces.
Developing Filborna
Fasttrack to January 2020, when Nordvästra Skånes Renhållningsbolag AB (NSR), the regional waste management company owned by the municipalities of Bjuv, Båstad, Helsingborg, Höganäs, Åstorp, and Ängelholm announced plans to invest in a biochar production facility at the Filborna site located on the outskirts of Helsingborg.
At that point, Ludvig Landén was Head of Environmental Development at NSR. At Filborna, NSR operates a materials recycling centre, and a technical landfill along with a landfill gas-to-power unit.
The integrated site also houses a state-of-the-art 72 MWth/18 MWe waste-to-energy combined heat and power (CHP) plant.
Operated by municipal energy company Öresundskraft, the WtE plant processes around 220,000 tonnes of non-recyclable household- and industrial solid waste annually providing heat to the city’s expansive district heating network, and power to the grid.
There is also a biogas plant on site that processes around 150,000 tonnes of food- and municipal organic waste (MOW) to produce biogas, operated by Biond.
The raw biogas is supplied to an upgrading facility operated by Gasum (previously Liquidgas Biofuel Genesis) that injects the biomethane (aka renewable natural gas – RNG) into a low-pressure gas grid, around 80 GWh per annum.
Ideal site
With a SEK 12.4 million grant from the Swedish Environmental Protection Agency’s “Climate Step” (Klimatklivet) program, the SEK 50 million NSR biochar project entailed building a state-of-the-art biochar plant to process residual urban green waste into biochar while providing heat to the district heating network.
The facility, currently the largest of its kind in Sweden, was officially inaugurated in June 2022.
Apart from the educational aspect of a recycling centre, placing the biochar project at Filborna made so much practical sense. There is ample brownfield space available for the plant, biomass- and biochar storage, the biomass feedstock was already available on site, service- and energy utilities were already in place, and there were staff-sharing possibilities. It also made permitting easier as no new access roads were needed, and no additional truck movements as the material was already being brought and handled on-site, commented Ludvig Landen.
Novel integration of Nordic technologies
The NSR biochar plant essentially consists of two novel technology lots that loosely can be described as outdoors and indoors.
The former includes everything from the biomass feedstock receiving bin to the reactor infeed storage bin, while the latter is the pyrolysis reactor and allied processes.
The former was supplied by the Danish company EUROmilling, which designed, produced, and delivered a complete solution including the control system for receiving, grinding, screening, drying, and intermediate storage of the biomass for the reactor.
Integrated pre-heating and grinding
A key feature of the EUROmilling delivery is the unique grinding- and drying process, whereby a pre-drying process starts already with the grinder and continues with a heated screw auger into the dryer itself.
Hot water (up to 95o C) is used for air-heating of internal space of the grinder and the drum dryer, while the screw auger from the grinder discharge to the dryer has a water jacket.
According to EUROmilling, this thermal cascading setup for the grinding- and drying process is very energy efficient compared to a conventionally designed setup.
Using a wheeled loader, the coarsely pre-shredded material is put into a Saxwerk Doser Bin from which the material is fed into the air-heated hammermill and screened before the accepted particle size (up to 30 mm) enters a low-temperature hot-air rotating drum-dryer via the heated screw auger.
From the dryer, the sized material, which has a moisture content of 10 percent is augured into an enclosed intermediate storage container equipped with a walking floor from which the material is fed to the reactor inside the building.
A Vow BioGreen reactor
The heart of the plant is a BioGreen pyrolysis reactor module developed and supplied by Norwegian company Vow. Unlike most pyrolysis technologies, the patented BioGreen process uses electricity as the energy source.
Specifically, it uses a proprietary “Spirajoule” technology, which is an electronically controlled, hollow shaft worm screw conveyor that transports the biomass through the process while heating it using a low voltage current. The technology is designed for advanced thermal treatment of materials in temperatures of up to 800o C.
The temperature of the screw is maintained thanks to the joule effect – aka resistive or ohmic heating whereby the energy of an electric current is converted to heat through resistive losses in material with finite conductivity, in this case, the biomass particles.
The biomass temperature is precisely controlled using temperature settings while the residence time inside the BioGreen reactor is regulated by the screw rotation speed.
The thermal conversion is performed in an oxygen-free atmosphere, which the company says guarantees a consistent quality of the biochar product obtained from the pyrolysis process.
The syngas is extracted and combusted in a new gas-fired hot-water boiler and fed into the district heating network as well as to a separate dryer heating loop.
The boiler has also fuel feeds from the low-pressure gas grid as well as from the two NSR-operated landfill gas genset units adjacent to the facility. The gensets also power the biochar plant.
Cooled and bagged
The biochar discharge from the BioGreen unit also features another patented technology, the UPK cooling screw conveyor. This ensures continuous, safe, and efficient evacuation of the biochar using chilled water in the screw and double jacket.
The cooled biochar is then conveyed to the outside bagging unit, and watered before being bagged into big bags for intermediate storage or delivery transport.
The NSR pyrolysis carbon capture and sequestration (PyCCS) installation, is a standard BioGreen module. It can produce around 1,500 tonnes per annum of biochar from around 7,000 tonnes of biomass material thereby binding up 3,000 tonnes of carbon dioxide (CO2) while supplying around 11 GWh of district heat. This is roughly the annual heat demand for 700 households in Helsingborg, remarked Ludvig Landen.
Leveraging the momentum
That’s not all. As mentioned in the introduction, there is also a state-of-the-art Biochar Competence Centre, along with a biochar application “vegetable patch” research station both located on the Filborna site a short walk from the plant.
The Biochar Competence Centre came about in June 2022 when the City of Helsingborg via NSR was awarded a US$400,000 grant from Bloomberg Philanthropies.
Helsingborg was one of ten cities worldwide that received technical expert and implementation support for the biochar plant from Bloomberg Philanthropies in 2021. Of these ten, Helsingborg was reselected as one of seven cities to receive continued technical support, and financial support during 2022-2023 toward the Biochar Competence Centre and the Biochar Summit that NSR hosted last summer, said Ludvig Landen.
The other six cities selected by Bloomberg Philanthropies were Darmstadt (Germany), Helsinki (Finland), Sandnes (Norway) along with Cincinnati, Minneapolis, and Lincoln in the United States.
The Biochar Competence Centre comprises a laboratory equipped to meet the needs of applied research and includes a small-scale biochar reactor, also supplied by Vow, for testing various feedstocks.
There is also a permanent exhibit area about biochar – history, production, and uses – along with meeting rooms and an office in which NSR staff coupled to centre work including Eva Stål, Business Developer at NSR.
The outdoor research patch includes test beds for biochar applications. This includes ongoing research into bio-remediation of contaminated soils in collaboration with, among others, the Swedish University of Agricultural Sciences (SLU) and the Swedish Geotechnical Institute (SGI).
Everything is in place, now it is about getting the word out to more potential research partners, and projects along with more off-takers for the biochar, ended Ludvig Landen.
With its new biochar facility and Biochar Competence Centre, NSR comes ever closer to its mission of a sustainable society where waste is minimized, and the region’s residual materials are refined into valuable resources.
In doing so it has firmly positioned NSR, Helsingborg, and the surrounding region on the international biochar map.
