Biochar: Environmentally friendly and versatile
Biochar is produced by the carbonisation of biomass. The biomass – for example, green waste, nutshells or woodchips – is carbonised either in traditional coal kilns or in modern pyrolysis plants like PYREG systems under low-oxygen conditions, meaning it is thermally treated at lower temperatures but not burned. Modern industrial processes like PYREG technology produce pollutant-free, highly porous biochar. Depending on the processing stage, biochar can be used in a wide range of applications. It finds its way on the market as:
- natural soil conditioner (promotes nutrient & water content as well as humus build-up)
- natural feed additive (in the form of feed carbon; improves animal health)
- additive in the biogas process (improves the gas yield)
- natural stable bedding (improves the stable climate & reduces material costs)
- natural additive for composting (binds nutrients & reduces greenhouse gases)
- filter media (in the form of activated carbon or biochar)
- cosmetics & pharmaceutical additive (in the form of activated carbon or biochar)
Absolutely climate-friendly: Biochar improves CO2-footprint
In addition to the many possible uses of biochar, “green charcoal” has another decisive advantage: It is obtained through a cutting-edge pyrolysis process like PYREG process that is extremely environmentally friendly (use of residual biomass, energy-efficient, targeted control of process parameters, hygienisation & elimination of pollutants…) and additionally binds most of the carbon contained. This means that carbon is not released into the air as CO2 during the carbonisation process, but is stably bound in the biochar and thus removed from the atmosphere.
A positive influence: Biochar in the soil
Biochar has been rediscovered in recent years as a natural soil improver. Already thousands of years ago, South American Indians knew about the highly fertile effect of “terra preta” (black earth). Terra preta refers to fertile, dark soils in the Amazon region, which were created by pre-Columbian Indians thousands of years ago. Nutrient-poor soil was enriched with a composted or fermented mixture consisting of plant residues, manure and human faeces as well as charcoal from the hearths.
However, biochar is not a fertiliser if used alone. It is highly porous and has a surface area of up to 300m² per gram. Biochar acts as a sponge that can absorb up to five times its own weight. It stores water and nutrients and allows microorganisms to settle in its pores. This property is also described by the adsorption capacity (AC). It depends both on the pyrolysed biomass and on the pyrolysis conditions of the carbonisation process.
To achieve the same effect as in the Amazon region, however, the biochar first needs to be ‘activated’, meaning it must be enriched with nutrients and soil organisms, for example, during composting. If pure biochar is introduced into the soil, it withdraws the water and the substances dissolved in it from its surroundings and thus has exactly the opposite effect.
Biochar is available in different quality grades: Here you can see (from left to right) activated carbon, feed carbon and biochar.
BIOCHAR IN USE
Biochar doesn’t have to make a big splash to make an impact. It also has an effect in small areas, such as your own garden or balcony box. Everyone can do something good for their soil and at the same time help the climate.
Biochar alone does not make a good garden soil. A handful of healthy earth contains more living organisms than people on the planet: bacteria, flagellants and ciliates, fungi, algae, worms, beetles, larvae, snails, spiders, woodlice… (from: Ute Scheub, Haiko Piplow, Hans-Peter Schmidt: Terra Preta, Oekom Verlag 2015 [German]). Biochar gives these small organisms a habitat. It loosens up the garden soil, makes it permeable to water and oxygen and releases the stored nutrients in a slow, gradual process.
For biochar to work in the soil, it is best to mix it with traditional compost from garden and kitchen waste in an approximate ratio of 5 (compost) to 1 (biochar). Afterwards you should wait a few more weeks until the mixture has become soil. Ready. Incidentally, composting also works very well in stacked small lattice boxes on the balcony.
“A healthy soil contains up to ten percent humus. Today it is usually only two to three percent” (Fredy Abächerli, Managing Director of Verora GmbH and instructor for soil structure, humus management and composting).
An intact humus layer stores nutrients and water as well as large amounts of the greenhouse gas CO2. Biochar facilitates this process. With a surface of 200-500 m² per gram and a high porosity, biochar can absorb up to five times its own weight in water and the nutrients contained in it. The “green carbon” remains stable during decomposition and does not rot.
As a result, farmers can improve the quality of soil with biochar, save money for fertilisers and obtain additional credits from emission certificates.
- Less stench
- Nitrate loads in soil and groundwater are considerably reduced
- The formation of climate-damaging gases is considerably reduced
- Soil acidification is reduced
- Humus build-up is increased
- Plant nutrients remain available much longer
- The need for additional fertiliser is significantly reduced
The use of biochar has multiple advantages in the vineyard: It loosens the garden soil and makes it permeable to water and oxygen. Important microorganisms can settle in the soil, demonstrably improving soil fertility. Thanks to its huge surface area and high porosity, biochar also has an excellent capacity to store nutrients and water. Therefore, the ability of the grapevines to withstand extreme weather conditions such as weeks of drought stress and subsequent flood-like rainfall is significantly improved.
Biochar has also proven to be an environmentally friendly and effective carrier of manure. Biochar reduces nutrient leaching and environmentally harmful emissions. Last but not least, the use of biochar in the vineyard is an important contribution to climate protection: carbon is returned to the soil from the CO2-contaminated atmosphere.
Biochar can significantly improve the biogas yield. This is firstly due to the properties of biochar, which binds impurities thanks to its porous structure and large surface area and thus stabilises the biogas process. In addition, the substrates in the fermenter can be broken down more effectively because the microorganisms in the biochar matrix are better protected.
Biochar also has a number of advantages for the biogas process when it comes to climate protection. If biochar is added to the fermentation residue, nutrient losses and climate-damaging methane gas losses are reduced. If the fermentation residue is carbonised, high-quality biochar can be produced from it and the carbon contained in the fermentation residue is bound over the long term. This not only protects the environment, but also substantially improves the efficiency of the gas production process.
In Europe, 90% of biochar is first used in animal husbandry (see Joachim Gerlach, Ithaka Journal 1/2012). Biochar is used in silage, as animal feed, in litter, for manure treatment or as a compost additive. Biochar improves animal health, reduces unpleasant odours, optimises the quality of fertiliser and reduces losses of nutrients that are harmful to the climate and the environment.
Guaranteed quality: European Quality Label EBC
This is precisely why coal for animal feed is subject to strict quality control. It must be free of toxins, in particular all tar substances and their derivatives must be completely expelled. Last but not least, heavy metals are undesirable in animal feed, which is why the raw material must also be carefully selected. In order to define a quality standard, the European Biochar Certificate (EBC) was established, which sets the standards for high-quality biochar.
Highly sustainable: Cascading use of biochar
The cascading use of biochar in animal husbandry and fertiliser management, where the adsorption capacity of biochar plays an outstanding role, is also interesting from an economic point of view.
Stage 1: Silage
At the beginning, biochar is added to the silage, which prevents the formation of mycotoxins. At the same time, pesticides are fixed and the formation of butyric acid is prevented, resulting in cleaner fermentation and a noticeable improvement in feed quality.
Stage 2: Digestive process
The biochar then enters the feed via the silage, enhancing digestion of the animals. The feed intake is increased, which results in an increase in weight. This also reduces the formation of greenhouse gases.
Stage 3: Stable hygiene
Biochar is added to the litter, thus binding the liquid nutrients and reducing ammonia emissions. It helps prevent putrefaction, which in turn improves stable hygiene. After just a few days, unpleasant odours are noticeably reduced. What’s more, stables do not have to be mucked out so often, thus saving time and material.
Stage 4: Liquid manure
Biochar can also be mixed into the liquid manure, which binds volatile nutrients and improves the microbial environment. This reduces nutrient losses, which improves the fertilizing effect of the liquid manure. In addition, the liquid manure becomes almost odourless.
Stage 5: Farmland
After absorption of the manure (solid-liquid separation), the solids are composted together with the stable bedding, which produces valuable black earth thanks to the high proportion of biochar. The incorporation of this black soil and the stabilised liquid manure into the soil improves the water retention capacity, the filter performance and the aeration of the soil, which results in higher fertility. Soil acidification is prevented and the leaching of fertilisers and pesticides into groundwater is reduced.
The advantages at a glance:
- Improved health and increased vitality of the animals
- Increased feed efficiency
- Increase in feed intake
- Increase in weight
- Strengthening of the immune system
- Increase in milk quality in cows due to improved udder health
- Reduction of diarrhoea and diseases of the hooves and footpad
- Increase in egg production and egg quality in poultry
- Improvement of meat quality
- Decrease in mortality rate
- Significant increase in milk ingredients
- Improved stable hygiene and reduced odour pollution
- Enormous odour reduction of the liquid manure
- Reduction of costs for medicines and veterinarians
The possible uses of biochar (pyrolytically produced biomass carbon) are extremely varied. It also has numerous positive effects when used in industrial processes. Mainly in the form of activated carbon (adsorbent) in water, gas and air purification, but also as a reducing agent in metallurgical processes, activated biochar has great potential. In the cement industry, biochar can be used as an additive/replacer as well as in the production of building materials.
Last but not least, biochar is beneficial because it substitutes fossil fuels and thus improves the CO2 footprint (for more reading: Weber 2016, Biokohle. Herstellung, Eigenschaften und Verwendung von Biomassekarbonisaten, p. 279–282 [German]).
Improving the resistance of urban trees: Biochar as planting substrate
Millions of new trees are planted every year in Germany – to decorate spaces, as fruit trees or to improve air quality in urban areas. Their growth does not always progress smoothly; young trees increasingly suffer from stress, depending on the location. Too narrow planting pits restrict root growth and soil compaction prevents sufficient oxygen and water from reaching the tree. What’s more, many trees suffer from climatic changes such as rising temperatures, increasing drought stress in summer and more frequent extreme weather events.
Some large cities such as Melbourne or Toronto have therefore switched over to planting their trees in mixed substrates of gravel and biochar. Biochar is not only much more porous than sand or clay, it is also not biodegraded or compacted as quickly as peat, for example. The high porosity of biochar increases gas exchange and water storage capacity and ensures enhanced root penetration thanks to its high permeability.