The FIRST biochar production plant in Europe
The facility now operates 24 hours a day, producing around 1,500 kg of high-quality biochar daily. After extensive market research, we chose a Pyreg reactor because it was the most advanced and, importantly, offered the prospect of meeting the strict limits of the waste incineration regulations. As we now know, this was absolutely the right decision.
The biggest challenge was integrating the reactor into a comprehensive system—including full heat recovery. After several modifications, we succeeded perfectly. All the released energy (150 kW) is utilized through our heating network for heating and drying purposes.
The production of biochar involves a special pyrolysis process. The raw material is heated to 500-600°C in the absence of air.
The raw material is fed into the Pyreg reactor through a rotary valve. In this double-jacket reactor, the material is transported upwards by a double helix screw and heated to up to 600°C during the process. The gas produced is immediately extracted, cleaned via a cyclone, and burned in the combustion chamber at 1,200°C. The burnt exhaust gas is then passed through a cleaning stage over the reactor jacket, where it heats the freshly fed material.
No external energy is required for the entire process (except for the electric power needed to drive the screws and blowers). After leaving the reactors, the exhaust gas still has a temperature of about 600°C and is therefore passed through a heat exchanger. The energy recovered here (150 kW) is used in our drying chamber to pre-dry the cellulose fibers.
The finished charcoal falls from the reactor into the discharge screw, where it is cooled and moistened with water before passing through a rotary valve to the outside. The produced biochar has a fine, crumbly texture and can be used directly in fertilizer preparation or composting.
The following positive environmental effects are known and experimentally confirmed:
- Biochar is stable in the soil for hundreds to thousands of years (Glaser, 2011; Kuzyakov et al., 2009; Lehmann, 2007; Lehmann et al., 2009; Lehmann et al., 2008; Major et al., 2010); pyrolytic biochar always represents the oldest soil carbon pool where present.
- Adding biochar reduces emissions of climate-relevant gases such as methane and nitrous oxide from the soil (Kammann et al., 2012; Spokas and Reicosky, 2009; Taghizadeh-Toosi et al., 2011b; van Zwieten et al., 2009).
- Biochar binds nutrients and reduces leaching losses, especially nitrate contamination of groundwater (Ding et al., 2010; Singh et al., 2010; Steiner et al., 2010).
- Biochar increases the efficiency of mineral fertilizers applied—reducing fertilizer use and consequently lowering emissions from fertilizer production (www.terrapretawiki.org).
- Biochar enhances soil microbial activity, creating the foundation for soil-autonomous carbon sequestration, i.e., humus formation. At the same time, it reduces CO2 release from soils per gram of existing carbon content (the Terra Preta phenomenon). This effect has been repeatedly proven at original tropical sites as well as in Swiss-Gießen cooperative projects comparing compost versus biochar-compost.
- Biochar combined with organic fertilizers often increases soil fertility and improves plant growth, leading to enhanced CO2 incorporation into the ecosystem.
- Biochar improves the water retention capacity of sandy soils and increases the water use efficiency of plants (Kammann et al., 2011; Karhu et al., 2011; Oguntunde et al., 2008). This can reduce the impacts of floods and droughts, or ideally compensate them at a large scale when combined with increased humus accumulation.
8. During the production of biochar, energy is released. This represents the first technical possibility of CO2
negative energy provision, as carbon is simultaneously sequestered. (For example, our pilot plant has a
heat output of 100-150 kW when the fuel has a dry matter content of at least 70%; at the same time, one ton of carbon is “bound” daily, meaning it is converted from primary biomass into a stable form.) The released energy is used by us to dry the sludge, thereby saving primary energy. This technology enables the production of high-quality charcoal from wet sludge without the use of fossil fuels.
9. By improving soil fertility, production effort and especially machinery effort for soil cultivation decrease. With a simultaneously promoted shift to conservation tillage (direct seeding systems), diesel consumption is reduced by 50 liters per hectare. (Wenz, 2010 – lecture at the Humus Symposium in the Ökoregion Kaindorf)
10. The utilization of biochar technology is a huge opportunity for the future use of sewage sludge. Sewage sludge is the most important phosphorus reserve of the future, as known deposits are expected to be depleted within a few decades (“peak phosphorus”). The main problems with direct use are hygiene (keywords: EHEC, botulism) and organic pollutants. These two main problems are clearly solved by carbonizing the sludge (400-700°C), and the nutrients contained in the sewage sludge can be made usable and kept in the cycle.
Leading internationally recognized climate researchers and soil scientists see biochar technology as a great, perhaps essential opportunity (Hansen et al., 2008; Lal, 2009).
Below is an attempt to express the climate effect of a Pyreg plant in tons of CO₂. Regardless of the assumptions that can be discussed, the enormous potential of using biochar and developing highly fertile Terra Preta soils is clearly evident. The major effect arises from the long-term stability of biochar in the soil and thus sustainable soil improvement, with the benefits known to last for centuries according to current knowledge. In the following balance, this effect is conservatively calculated over only 30 years.
1. Biochar production: The plant produces 350 tons of biochar annually from cellulose fibers and cereal husks with a carbon content of about 70%. This corresponds to approximately 900 tons of CO₂ sequestration per year.
2. Gas production: The gases produced are immediately fed back into the reactor after combustion to keep the process running. Upon leaving the reactor, they still have a temperature of around 600°C and are cooled down to about 200°C in the exhaust heat exchanger. This energy (about 100 kW) from the heat exchanger is then used for heating offices and drying sludge, thereby saving fossil energy (see below). No external energy is required for ongoing operation (except for the electricity to run the screw conveyors and fans, as well as liquefied gas to start the plant). The produced surplus heat can substitute approximately 500 tons of CO₂. (100 kW * 24 hours * 300 days = 720 MWh * 0.7 = 504 t CO₂)
3. Reduction of methane and nitrous oxide: An assessment is currently difficult, especially for CH₄, due to insufficient scientific studies. The first field study with continuous measurements (Karhu et al., 2011) showed a significant increase in methane sink (CH₄ oxidation in aerobic soils by methanotrophic bacteria). The addition of biochar almost always caused a significant reduction in N₂O emissions in all available studies (various authors), even with earthworm presence or in rice cultivation (anaerobic conditions).
4. Reduction of mineral fertilizers: Many studies confirm that the use of biochar can significantly reduce mineral fertilizer use. This is due to a reduction in losses through temporary surface binding on the biochar (Chen et al., 2010; Spokas et al., 2011; Steiner et al., 2010; Taghizadeh-Toosi et al., 2011a). Currently, around 50% of the applied mineral nitrogen fertilizer is lost (as nitrate, nitrous oxide, ammonia). The calculation assumes that the annual production of the Pyreg plant can remediate about 20 hectares of farmland. The required 15 tons of biochar per hectare only need to be applied once, as biochar is biologically stable. The resulting soil improvement is therefore permanent. However, only 30 years were used in the CO₂ balance. The estimated saving of 50 kg N/ha annually on 20 hectares corresponds to one ton of nitrogen. Production requires 2 tons of fossil oil and causes 6.22 tons of CO₂ – which corresponds to 187 tons of CO₂ over 30 years.
5. Increase in humus through the Terra Preta effect: As repeatedly reported by many independent experts, Terra Preta is capable of autonomously increasing the humus content. The suspected mechanisms involve a specially composed microbiology that, despite higher activity, produces and releases less CO₂. It appears possible here to convert a larger portion of organic residues in the soil (especially root exudates) into stable humus. The exact mechanisms are not yet known and are the subject of much scientific investigation, but the fact that autonomous carbon accumulation in these Terra Preta soils is possible is undisputed. The existence of humus-rich, coal-containing soils indicates a long-term buildup of stable, permanent humus in the presence of biochar (Glaser and Birk, 2011; Glaser et al., 2001), as found in soils from charcoal production sites in temperate regions. For the calculation of this effect, an autonomous humus accumulation or increase of humus content through reduction of carbon losses by 0.05% per year was assumed. This corresponds to a CO₂ sequestration of 3 tons per hectare per year at a soil depth of 30 cm. This effect was again calculated over 30 years, resulting in a CO₂ sequestration of 1,800 tons.
6. Increased plant growth: The increase in humus clearly and demonstrably improves soil fertility, a fact known since ancient times. Especially the water absorption and water retention capacity of soils are greatly enhanced (Glaser et al., 2002). Due to climate change, rainfall distribution is becoming more unfavorable, making soil water management increasingly important. One percent additional humus in soil can store up to 400 m³ of water. Especially during prolonged drought periods, significantly higher yields can be expected on humus-rich soils. An average yield increase of 10% is calculated (e.g., every fifth year a summer drought causes a 50% yield loss on conventional fields). For the cultivation of Miscanthus x giganteus (giant reed), this corresponds to an average yield increase of about 1.8 tons/ha; this can replace 0.8 tons of heating oil, which in turn corresponds to about 2.5 tons CO₂ per hectare per year. Since a Pyreg plant can remediate 20 hectares of farmland annually and this remediation effect is permanent (calculated over 30 years), a total of 1,500 tons of CO₂ can be credited from this effect. (Calculation basis: 2.23 kg Miscanthus at 14% moisture corresponds to the heating value of 1 liter of heating oil – see www.energiepflanzen.at; 1 liter of heating oil corresponds to 3.11 kg CO₂)
7. Reduced tillage: Improved soil fertility lowers production effort and especially machinery use for soil cultivation. With a simultaneously promoted shift to conservation tillage (direct seeding systems), diesel consumption is reduced by 50 liters/ha. One liter of diesel corresponds to 3.06 kg CO₂ – 50 liters correspond to 153 kg – over 20 hectares this is 3.06 tons – calculated over 30 years this is about 90 tons CO₂.
| Summary | Environmental impact of biochar | tons CO₂/year |
|---|---|---|
| 1) Production | 350 tons × 70% C × 3.67 = tons of CO₂ | 900 |
| 2) Substitution of natural gas | 100 kW heat year-round | 500 |
| 3) Reduction of nitrous oxide | Effectively relatively certain, magnitude not estimable | |
| 4) Reduction of mineral fertilizers | 20 ha / 50 kg N/ha = 1 ton N = 2 tons oil for 30 years = 60 tons oil | 187 |
| 5) Humus increase Terra Preta | 20 ha, 3 tons/ha per year, 30 years | 1800 |
| 6) Increased plant growth | 20 ha, +10% yield = 2.5 tons CO₂/ha, 30 years | 1500 |
| 7) Reduced soil cultivation | 20 ha, 50 liters of diesel = 153 kg CO₂, 30 years | 90 |
| Total | 4977 |
The proposed biochar production facility has the potential to offset approximately 5,000 tons of CO₂ annually, of which 1,400 tons are scientifically verified.
Hans-Peter Schmidt
Operator of the Delinat Institute in Switzerland, where the term “Climate Farming” was developed. Collaboration with numerous institutes such as Agroscope ART and the universities of Zurich, Tübingen, Halle, and Giessen. Conducting experiments to find a new, holistic approach so that more CO₂ is sequestered than emitted through agricultural production.
Prof. Dr. Bruno Glaser
Professor of Soil Biogeochemistry at Martin Luther University Halle-Wittenberg, teaching courses in soil science and sustainable use of natural resources. Numerous research projects (EU, BMBF, DFG) and publications on the indigenous dark earths of the Amazon (Terra Preta) and a pioneer in Terra Preta and biochar research.
Dr. Claudia Kammann
Justus Liebig University Giessen, interdisciplinary research center. Works on greenhouse gas-producing or -consuming processes in soils and the interaction of biochar in modifying these processes. Convinced of biochar technology and aims to contribute to making biochar a tool in the fight against climate change.
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