At Nulldissiplingsgården on Mære we are excited to get started with biochar production and we also get a lot of questions about biochar and the plant that is being built. We have collected questions we often get and hope you can find answers to what YOU are wondering.

What is biochar?

Biochar is defined as a 1) porous, 2) carbon-rich and 3) stable material, produced by pyrolyzing plant-based biomass and used so that the carbon content can be stored over long periods of time (e.g. in soil), or used as a replacement for fossil carbon in industry.»

                – European Biochar Certificate (2020)

Learn more about biocoal at the Norwegian Biocoal Network: www.biokull.info

What is pyrolysis?

Pyrolysis is the name of the process by which biochar is made. Pyrolysis is a process in which organic materials are broken down at high temperatures in the absence of oxygen. This usually occurs at temperatures between 400 and 800 degrees Celsius. The process is often used to convert biomass into biochar, bio-oil and gas.

Is the biochar process energy-intensive?

No. In the biochar plant, there is a large heat surplus. We use energy to start the process, but later it creates its own energy and gives off heat.

When we make biochar (pyrolysis), heat is produced, just like in a wood-burning stove. We can compare the pyrolysis stove to the wood-burning stove in our living room. When we burn wood in the stove at home with good draft, there is a lot of heat and little ash. When we burn wood with the draft closed, less heat is produced and more ash/charcoal pieces (pyrolysis).

What is biochar made of?

Biochar is made from biomass, and the most common are wood chips from twigs, recycled wood and garden waste. Agricultural resources such as straw, plant residues and dry manure, garden waste such as grass clippings and leaves, seaweed and kelp and food waste can also be pyrolyzed. Drying of the biomass is necessary before it can be pyrolyzed.

What can we use biochar for in agriculture?

Biochar can be used as a feed additive, bedding in barns, added to livestock manure, in compost or directly on the soil. Biochar can also be used in growing medium in nurseries and when planting fruit and berries.

We can give biochar as an additive to the feed: Experiments have shown that biochar can have an effect on the health of animals. An example with OBIO biochar can be found here: Robust calves with biochar?

We can add biochar to the manure both to reduce greenhouse gas emissions from the manure cellar and to make it easy to spread biochar on the field. You can read about an experiment with biochar in manure here: Can biochar reduce greenhouse gases from animal manure? | Zero Emission Farm

Incorporating biochar into compost binds ammonia and contributes to a better composting process with more even moisture levels, more stable pH and better preservation of nutrients.

Why is biochar good for the soil?

Biochar contains a lot of carbon, has a large surface area and is very porous. It contributes to increased aggregate stability, increased pore volume and reduced soil density. It will affect the water management in the soil so that there is more water available when it is dry and more air when it is wet.

Biochar increases soil pH and improves the soil's ability to retain nutrients. Biochar can reduce nitrous oxide emissions from soil and binds heavy metals in the soil.

Biochar has shown increased diversity of bacteria in the soil and increased growth of fungal roots (Mycorrhiza) which is important for good plant growth.

Biochar has shown good effects on plant growth where the soil is poor/has little organic matter. In Norwegian soil, there is in most places a good content of carbon and growth experiments show small effects on plant growth.

What is the climate impact of biochar?

Biochar binds carbon in a stable form that can be stored in the soil for hundreds to thousands of years. This helps reduce the amount of CO2 in the atmosphere. NIBIO has calculated that 1 ton of biochar binds 3 tons of CO2e.

In addition, the heat energy produced will also replace fossil energy, which also has a climate effect. Using biochar in soil can reduce emissions of other greenhouse gases from the soil (nitrous oxide) and improve soil health, which can increase plant production.

Is biochar dangerous to use? 

Inhaling dust is not good for our health. It is therefore important to use protective equipment such as a dust mask and gloves as biochar contains smaller particles.

Questions and answers about the biochar plant at Mære

What kind of biochar plant is being built at Mære?

We are investing in a German-made pyrolysis unit (160 F) from Biomacon. Bioland AS is a Norwegian dealer. The plant runs 24/7 and is only stopped for necessary maintenance.

How big is the facility?

The plant has a maximum capacity of 160 kW. At Mære we will not run the plant all year round, but will run it when we need heat at the school. We plan to produce 100 tons of biochar (500 m3) per year. In addition, there will be a surplus of heat of approximately 800,000 kWh which will be used for drying wood chips and for heating at the school.

What raw materials should we use at Mære?

The plant is built to pyrolyze wood chips and the best raw material is wood chips of 3-5 cm dried down to 20-23% moisture.

We will use:

• Own raw materials: Twigs from the park at Mære, edge wood from the school's areas and possibly gravel from the school's forest
• Sorted garden waste from Tranamarka, Steinkjer municipality
• Purchased wood chips from local suppliers

How much wood chips should go into the plant?

It is planned that we will use 600 tons of wood chips each year (35% moisture). In volume, this amounts to approximately 1700 m3 of wood chips, meaning that we must bring in approximately 50 m3 of wood chips per week during the operating period. The plant does not run all year round; there is a production stoppage from approximately May to September.

What should we use the biochar for?

We will be using a lot of the biochar in the composting plant at school. When we mix biochar into the compost we improve the composting process and we can spread compost and biochar in one operation on our fields.

In addition, we will sell biochar to other farmers, as well as share biochar and knowledge about the biochar process and use of biochar with the other nature farming schools in Trøndelag.

How much does the facility cost and how is it financed?

The plant is estimated to cost 12 million kroner excluding VAT. This includes both the foundation work, the pyrolysis unit and buildings. The plant is financed by Trøndelag County Council, Bionova and Klimasats.

How will the facility be operated?

We will run the plant from September to May. The plant runs continuously and is only stopped for necessary maintenance throughout the season, as well as production shutdowns in the summer. We have planned to have 20-30 % position resources for the operation, but are unsure where we will end up once we have gained experience and moved into regular operation.

The operational tasks at the plant are logistics of raw materials and finished products, delivery of wood chips for drying, delivery of finished biochar, operational management/monitoring, follow-up of operational shutdowns, service and maintenance.

How should we use the surplus heat?

There will be a surplus of heat in the pyrolysis process. This heat will be used for drying wood chips that will enter the plant and for heating buildings at the school. How this is distributed depends on how dry the wood chips/raw material we take in, the drier the wood chips we take in, the more surplus heat we get.

Outlet pipes are also installed on the system so that we can connect it for drying other materials, e.g. grain.

Are there any safety challenges with operating the facility?

Routine maintenance of pyrolysis furnaces is carried out by a qualified operator and is carried out based on detailed routine descriptions. This work involves a risk of dust exposure for the operator.

The biochar process generates heat and in the pyrolysis furnace it is between 600 and 800 degrees. The hot biochar that comes out of the furnace is added with water to cool it down. Fire risk has been taken into account with sufficient distance to other buildings. Biochar production is carried out by qualified operators who are familiar with the risks to health and the environment.

Does biochar production produce smoke or dust?

Smoke from the pyrolysis oven is completely minimal. The gases formed in the heat are burned up and the smoke development is therefore very small. We can easily explain this by when we make a fire: Make a tower of sticks/wood and light it at the top, not at the bottom. When the fire burns from the top down, we burn up the gases formed in the heat and the smoke development is minimal.

The biochar is in its own chamber (the pyrolysis oven) and does not come out in the smoke.

There will be some ash in the boiler room from the pyrolysis process, so regular cleaning is important to avoid as much dust as possible in the air in the plant. There will be some biochar dust locally from the big bag system. Finished biochar is transported out of the pyrolysis, cooled with water and stored in big bags.

The biochar plant has a wood chip dryer where fine dust will be generated and collected in a dust trap. There may be some local dispersion of dust from here.

Is the use of biochar profitable on Mære?

Biochar production will contribute to a significant reduction in greenhouse gas emissions at the school. Calculations show that we can reduce emissions by up to 25 % of the school's total emissions each year.

Our facility is also being built because we want to demonstrate biochar production and use to our students and farmers, as well as conduct experiments with biochar and develop the agricultural benefits of biochar in the future.

Economic profitability from the use of biochar can be obtained through better animal health, better soil health or through support for carbon storage or the sale of carbon credits.

Experiments show that biochar improves plant growth on humus-poor, sharp soil. The soil at Mære contains a lot of humus/carbon. We therefore do not expect a short-term increase in yield when using biochar. We also do not expect major effects on animal health if we use it as a feed additive (certification required).

The economic effect of using biochar is therefore primarily through support for carbon storage (RMP funds), improved composting processes and possible sale of carbon credits.

What happens if metal, plastic or other fragments enter the system?

It is important that the raw materials are free of metal, plastic or anything else that could contaminate the finished biochar. We want a biochar without contamination. It will also be a challenge in the production itself if metal pieces or other fragments get stuck and lead to a production stoppage.

We depend on the residents of Steinkjer being good at delivering garden waste without metals and plastic mixed in.