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.

Further advan­tages:

  • 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.