The 55 uses of biochar

by Hans-Peter Schmidt & Kelpie Wilson

Biochar – that black charcoal like substance discussed so often in recent days for its miraculous effects on soil and compost - is good for more than just your garden. One of the key materials for a sustainable future of the planet, biochar has many other uses that can be integrated into new organic systems for farming, building, clothing, electronics and a whole range of consumer products. Biochar can initiate multiple cascades to optimize and recycle current material, nutrient and energy flows.

It turns out that the stable carbon matrix that biochar is made of has all kinds of interesting properties. This carbon matrix can hold on to things – water, air, metals and organic chemicals. And it also has unique thermal and electrical properties that are still being explored. Finally, the highly porous physical structure of biochar provides habitat for microorganisms. With so many different properties, biochar is bound to have a lot of different uses, but one function that all biochar applications (other than burning it for fuel) share is carbon sequestration. By fixing easily degradable plant carbon into long-lasting charcoal, carbon dioxide is slowly but surely removed from the atmosphere.

The biggest drawback to the application of biochar in soil is the cost. Making biochar is either a technical highly elaborate and capital-intensive process or a low-tech, slow and labor-intensive process; both paths are rather expensive. At current prices of $1000 a ton, the $5,000 to amend an acre of cropland with 5 tons of biochar would in most cases exceed the return from that acre.

Does it really make sense to work biochar into fields?

These economic considerations are not so different from what the natives in the Amazon had to face when they used biochar to improve their soils, and where you will still find plenty of places with over 40 tons of biochar buried into just one acre of soil. Even if no money existed back in those days, it would have made no economic sense to cut down some 80 huge rainforest trees and then use ancient charcoal kilns to make some 40 tons of biochar – just to bury the biochar into one acre of soil. And don’t forget: all this would have been done without any chainsaws or axes and no animals to pull the logs close to the field
The idea of applying dozens of tons of biochar to fields can only come from scholars who, on the basis of the Terra Preta example, have arrived at a false conclusion completely without any practical relevance – i.e. the massive one-time application of biochar.

Example of Terra Preta Cultures

The char used back then was probably created in the typical hearths of the natives, in which not just ash but also relatively large amounts of charcoal were produced at relatively low heat. This char, basically a waste product, was then apparently used as a way of preventing infectious diseases. This was done by regularly adding char to feces and kitchen waste in the large jungle settlements, thus sterilizing them. It helps to understand that the indigenous settlements were concentrated along the river branches on high bluffs safe from flooding. That is where the people lived, in densely populated villages, and where most of the Terra Preta is found.

Once the organic waste had been stabilized through composting or fermenting it with added char, people discovered that it was an excellent substrate for growing food plants. These methods led to the char being loaded with nutrients and its surfaces achieving greater binding capability through oxidization, with the consequence that, once worked into the soil, the char was able to fully unfold its function as a nutrient store and humus stabilizer (through the creation of char-clay-humus complexes).

According to investigations carried out by Bruno Glaser and colleagues the amount of phosphorus in Terra Preta soils compared to natural soils in the immediate vicinity can be up to 500 times higher. Unlike carbon and nitrogen, phosphorus cannot accumulate in the soil through plant growth, but must be added through amendments of excrement, bones and ash. A rough estimate shows that the char-stabilized organic waste of some 500 people must have been worked into every hectare of soil over a period of 1000 years to gain such nutrient content. Accumulating 100 tons of biochar not only took centuries; it also required a “stacking functions” approach.

The many uses of biochar

Biochar is much too valuable for it to be just added to soil without using it at least once for other beneficial purposes. Basic uses include: drinking water filtration,  sanitation of human and kitchen wastes, and as a composting agent. All of these uses have been documented in many different pre-industrial cultures. In the modern world, the uses multiply: adsorber in functional clothing, insulation in the building industry, as carbon electrodes in super-capacitors for energy storage, food packaging, waste water treatment, air cleaning, silage agent or feed supplement. All those uses could be part of more complex cascades when, after extended up- and down cycling, biochar can be used in a farmer’s manure slurry pit or in a sewage treatment plant, before being composted and thus finally becoming a soil amendment. Biochar should only be worked into the soil at the end of such “cascades,” keeping in mind that some biochar uses – for cleaning up metal or chemical contamination – would render the biochar unsuitable for agricultural soils and need different recycling pathways.

The following list of 55 possible uses of biochar is by no means complete. In fact it has only just been started. We will initially just comment shortly on a few applications in this list. The Biochar Journal (formerly known as Ithaka Journal) is publishing a series of in-depth articles on many of these uses, highlighting in particular the cascading benefits of biochar in agriculture and livestock farming. Biochar is without doubt one of this century’s most exciting new fields of research, with findings and their practical implementation increasing exponentially from year to year. Nevertheless, however much we enthuse over our field of research and the importance of our findings, it’s the real world that decides about its success.

The cascaded use of biochar in animal farming

1. Silage agent, 2. Feed additive / supplement, 3. Litter additive, 4. Slurry treatment, 5. Manure composting, 6. Water treatment in fish farming

At present some 90% of the biochar used in Europe goes into animal farming. Different to its application to fields, a farmer will notice its effects within a few days. Whether used in feeding, litter or in slurry treatment, a farmer will quickly notice less smell. Used as a feed supplement, the incidence of diarrhea rapidly decreases, feed intake is improved, allergies disappear, and the animals become calmer.  In Germany, researchers conducted a controlled experiment in a dairy that was experiencing a number of common health problems: reduced performance, movement disorder, fertility disorders, inflammation of the urinary bladder, viscous salivas, and diarrhea. Animals were fed different combinations of charcoal, sauerkraut juice or humic acids over periods of 4 to 6 weeks.  Experimenters found that oral application of charcoal (from 200 to 400 g/day), sauerkraut juice and humic acids influenced the antibody levels to C. botulinum, indicating reduced gastrointestinal neurotoxin burden. They found that when the feed supplements were ended, antibody levels increased, indicating that regular feeding of charcoal and other supplements had a tonic effect on cow health. Visit the Ithaka Journal online (http://www.ithaka-journal.net) for in-depth articles on the use of biochar in cattle and poultry farming, as well as many of the other uses described below.

Use as a soil conditioner

7. Carbon fertilizer, 8. Compost additive, 9. Substitute for peat in potting soil, 10. Plant protection, 11. Compensatory fertilizer for trace elements

In certain poor soils (mainly in the tropics), positive effects on soil fertility were seen when applying untreated biochar. These include the higher capacity of the soil to store water, aeration of the soil and the release of nutrients through raising the soil’s pH-value. In temperate climates, soils tend to have humus content of over 1.5%, meaning that such effects only play a secondary role. Indeed, fresh biochar may adsorb nutrients in the soil, causing  – at least in the short and medium term – a negative effect on plant growth. These are the reasons why in temperate climates biochar should only be used when first loaded with nutrients and when the char surfaces have been activated through microbial oxidation. The best method of loading nutrients is to co-compost the char. This involves adding 10–30% biochar (by volume) to the biomass to be composted. Co-composting improves both the biochar and the compost. The resulting compost can be used as a highly efficient substitute for peat in potting soil, greenhouses, nurseries and other special cultures.

Because biochar serves as a carrier for plant nutrients, you can produce organic carbon-based fertilizers by mixing biochar with such organic waste as wool, molasses, ash, slurry and pomace. These are at least as efficient as conventional fertilizers, and have the advantage of not having the well-known adverse effects on the ecosystem. Such fertilizers prevent the leaching of nutrients, a negative aspect of conventional fertilizers. The nutrients are available as and when the plants need them. Through the stimulation of microbial symbiosis, the plant takes up the nutrients stored in the porous carbon structure and on it’s surfaces.

The thermal process that produces biochar is called pyrolysis (from the Greek, “pyro,” meaning fire and lysis,” meaning separation). During pyrolysis, the crucial trace elements found in plants (over 50 metals) become part of the carbon structure, thereby preventing them from being leached out while making them available to plants via root exudates and microbial symbiosis. This feature can be used specifically when certain trace elements are missing in a certain regional soil or in soil-free intensive cultures such as “Dutch tomatoes”.

A range of organic chemicals are produced during pyrolysis. Some of these remain stuck to the pores and surfaces of the biochar and may have a role in stimulating a plant’s internal immune system, thereby increasing its resistance to pathogens. The effect on plant defense mechanisms was mainly observed when using low temperature biochars (pyrolysed at 350° to 450°C). This potential use is, however, only just now being developed and still requires a lot of research effort.

Use in the building sector

12. Insulation, 13. Air decontamination, 14. Decontamination of earth foundations, 15. Humidity regulation, 16. Protection against electromagnetic radiation (“electrosmog”)

Two of biochar’s properties are its extremely low thermal conductivity and its ability to absorb water up to 6 times its weight. These properties mean that biochar is just the right material for insulating buildings and regulating humidity. In combination with clay, but also with lime and cement mortar, biochar can be added to clay at a ratio of up to 50% and replace sand in lime and cement mortars. This creates indoor plasters with excellent insulation and breathing properties, able to maintain humidity levels in a room at 45–70% in both summer and winter. This in turn prevents not just dry air, which can lead to respiratory disorders and allergies, but also dampness and air condensing on the walls, which can lead to mold developing. You can read about the Ithaka Institute’s biochar-plaster wine cellar and seminar rooms in the Ithaka Journal. Such biochar-mud plaster adsorbs smells and toxins, a property not just benefiting smokers. Biochar-mud plasters can improve working conditions in libraries, schools, warehouses, factories and agricultural buildings.

Biochar is an efficient adsorber of electromagnetic radiation, meaning that biochar-mud plaster can prevent “electrosmog”.

Biochar can also be applied to the outside walls of a building by jet-spray technique mixing it with lime. Applied at thicknesses of up to 20 cm, it is a substitute for Styrofoam insulation. Houses insulated this way become carbon sinks, while at the same time having a more healthy indoor climate. Should such a house be demolished at a later date, the biochar-mud or biochar-lime plaster can be recycled as a valuable compost additive.

Decontamination

17. Soil additive for soil remediation – for use in particular on former mine-works, military bases and landfill sites).

18. Soil substrates – Highly adsorbing, plantable soil substrates for use in cleaning wastewater; in particular urban wastewater contaminated by heavy metals.

19. A barrier preventing pesticides getting into surface water – berms around fields and ponds can be equipped with 30-50 cm deep barriers made of biochar for filtering out pesticides.

20. Treating pond and lake water – biochar is good for adsorbing pesticides and fertilizers, as well as for improving water aeration.

Biogas production

21. Biomass additive, 22. Biogas slurry treatment

Initial tests show that, through adding biochar to a fermenter’s biomass (especially heterogeneous biomasses), the methane and hydrogen yield is increased, while at the same time decreasing CO2 and ammonia emissions. Through treating biogas slurry with lacto-ferments and biochar, nutrients are better stored and emissions prevented.

The treatment of wastewater

23. Active carbon filter, 24. Pre-rinsing additive, 25. Soil substrate for organic plant beds, 26. Composting toilets

The treatment of drinking water

27. Micro-filters, 28. Macro-filters in developing countries

 

Other industrial uses

Exhaust filters (29. Controlling emissions, 30. Room air filters)

Industrial materials (31. carbon fibers, 32. plastics)

Electronics (33. semiconductors, 34. batteries)

Metallurgy (35. metal reduction)

Cosmetics (36. soaps, 37. skin-cream, 38. therapeutic bath additives)

Paints and coloring (39. food colorants, 40. industrial paints)

Energy production (41. pellets, 42. substitute for lignite)

Medicines

(43. detoxification, 44. carrier for active pharmaceutical ingredients, 45. Cataplasm for insect bites, abscesses, eczema…)

There are several hundred other medical uses proven in its efficiency for many centuries. Somewhat forgotten during the last 40 years, more and more people and doctors rediscover it’s efficiency to treat a whole range of symptoms. Have a look to: www.CharcoalRemedies.com)

Textiles

46. Fabric additive for functional underwear, 47. Thermal insulation for functional clothing, 48. Deodorant for shoe soles

In Japan and China bamboo-based biochars are already being woven into textiles to gain better thermal and breathing properties and to reduce the development of odors through sweat. The same aim is pursued through the inclusion of biochar in shoe soles and socks.

Wellness

49. Filling for mattresses, 50. filling for pillows

Biochar adsorbs perspiration and odors, shields against electromagnetic radiation (electrosmog), and removes negative ions from the skin. Moreover, it acts as a thermal insulator reflecting heat, thereby enabling comfortable sleep without any heat build-up in summer. In Japan, pillows have been filled with biochar for a long time. This is supposed to prevent insomnia and neck tension.

51. Shield against electromagnetic radiation

Biochar can be used in microwave ovens, television sets, power supplies, computers, power sockets, etc. to shield against electromagnetic radiation. This property can also be used in functional clothing as protection for parts of the body particularly sensitive to radiation.

52. Food Conservation

Put a small bowl of biochar into the fridge (or small linen bags with biochar) and it will not only absorb bad odours but also Ethylen which will retard the post ripening of fruits and vegetables prolonging thus their conservation time. As the biochar takes-up humidity, the risk of mould is diminished. In food packaging the conservation time can be increased through the addition of  biochar either in the packaging material or as an additive in small tea bags. For the long-term storage of potatoes, carrots, cabbage, apples, and other winter vegetables and fruits, to dig them into biochar can increase storage time for several months.

All of the proposed biochar uses except nos. 35, 41, 42 are carbon sinks. After its initial or cascading use, the biochar can be recycled as a soil conditioner. Fully depreciated when finally returned to the soil, the black carbon will slowly build up in the soil – and over a few generations the soil’s biochar content could easily reach 50 to 100 tons per hectare, as it’s the case in the ancient Terra Preta soils.

We have listed 52 possible uses of biochar. But the title refers to 55 uses…. This is to be seen as an indication of our intention to keep on adding to the list over the coming years, as experience builds up. We can also be sure that the author has missed out a number of uses already available today (the first version of this article published in the Ithaka Journal only contained 44 possible uses). However, new uses of biochar will most certainly be published first in the form of an article in The Biochar Journal, just check it regularily. 

comments

  • Dolph Cooke, Australia
    13.03.2013 19:31

    Charcoal should not be referred as biochar

    Hello Folks This is a good run-down. My only issue is that charcoal used for any application outside of agriculture should not be referred to as biochar. The English language already had words for carbonised material, so using the word biochar for non-agricultural applications confuses the fact that biochar is a charcoal specifically intended for agriculture, not industry. The word biochar should not be used as a catch-all word for any carbonised biomass. Charcoal = The catch all word for carbonised biomass. Covers a very wide range of qualities. May used as a fuel, for making activated carbon, as biochar (when prepared properly), or any one of 8000 different uses. Biochar = A form of charcoal specially prepared to be “fed” to plants or animals. You should not feed just any grade of charcoal to plants and animals .. if you do not want to make them sick. My personal test of a fresh biochar (with the exception of those made from manures) is that I should be able to put it in my mouth and chew on it. If I can’t do that then it is probably not suitable for plants or animals without additional processing. Activated carbon = Carbonised material, which might be from biomass, coal or petrochemcials, which has been prepared with a high surface area (typically more than 400 m2/gram). Sometimes acgivated carbon is used in agriculture, but most of the time it is used in industrial and household applications as an adsorbent. Some biochars have properties similar to a low grade activated carbon, however they should not be called biochar when used for industrial applications. Keep up the Great work : )  Charmaster Dolph Cooke Channeling Biochar Experts since 2009

    [the above comment was initially posted in the Ithaka Journal where the article was first published]
  • Hans-Peter Schmidt, Switzerland
    13.03.2013 19:34

    Meaning of biochar

    Hi Dolph, You are quite right to insist on the meaning of biochar. The problem arises as the article is a translation from German where we use the term “Pflanzenkohle” which means vegetal carbon. In German this is clearly distinguished to Holzkohle (charcoal). For the most of the 55 uses the same quality exigencies that you described for agronomic uses apply (chewing on it with no harm or the EBC-certificat). The whole thing about the 55 uses is that ot the end of their cycle they eventually finish charged and enhanced in soil. The end of fate of all this uses is a soil amendment which is for free as it was paid by all the preceding uses in the biochar cascade. Thanks Dolph, as an admirer of your work, I am happy to have you commenting here.

    [the above comment was initially posted in the Ithaka Journal where the article was first published]
  • Dolph Cooke, Australia
    14.03.2013 19:41

    Awesome Hans, thank you for that it makes it crystal clear now : ) I did not even think about translation problems. Your entire site is really well done. Charmaster Dolph Cooke

    [the above comment was initially posted in the Ithaka Journal where the article was first published]
  • Richard S. Levine , USA
    02.05.2013 20:43

    Biochar in the sustainable city

    The ultimate value of biochar is in the realization of a complex network of causes and effects in the development and management of sustainable city-regions. This has been the subject of our research for more than thirty years. (For more on this see: “The City as Fulcrum of Global Sustainability,” Ernest J. Yanarella & Richard S. Levine, Anthem Press (UK),2011.) The sustainable city will be powered by renewables – principally solar energy and wind, however these are intermittent sources and it is difficult to store the energy they produce.

    Pyrolysis of biological materials has two fractions: the gases driven off in the heating process – principally carbon monoxide and hydrogen, and the char, which is left behind. the process may be driven in two different ways: the gases – also called producer gas, which can be stored and which can be substituted for natural gas, may be burned to produce the bio-char, or the biochar can be used as the fuel to pyrolyze the producer gas, or the same process can be used to produce a combination of producer gas and char. At the moment the emphasis is mostly on the production of bio-char using the producer gas fraction to do so. In the current economic situation this doesn’t appear to be very attractive although when long term considerations are taken into account, particulerly the alieviation of global warming through carbon sequestration, the economics couldn’t be better.

    To see how attractive a pyrolysis based local economy will be try this thought experiment: Imagine a small town-region where both agriculture and forestry and value-added industries derived from them are being practiced all centered around a small, but dense urban core. The buildings in this community are all built to the Passivhaus standard greatly reducing their use energy. Production from the land produces a good deal of cellulostic residue and along with human and animal wastes becomes fuel for a pyrolysis process. Wind and photovoltaic collectors provide the great majority of the electricity needed in the town, but as these renewable sources of energy are intermittent (no sun at night and on cloudy days) another source of renewable, but storable energy is required. The pyrolysis process is used to build up a store of producer gas which is used to power a standing engine coupled to a generator to produce all the required electricity when wind energy or solar energy (nights and cloudy days) is not available. When a sufficient store of producer gas has been produced, the pyrolysis process reverses its output to produce bio-char for all its many uses. The waste heat from the pyrolysis process is used to power any industries that are able to use it as well as a district heating system to provide most of the heat necessary to heat the (now reduced energy requirements through the use of the passivhaus standard) homes, factories and other buildings in the town. The town-region is a zero energy, zero unemployment economic ecology as the energy-employment couple becomes self adjusting to accommodate ongoing conditions. The town-region system satisfies the requirements of sustainability as it has the capacity of being the sort of no-growth, balance-seeking, self-provisioning (on a net basis) system that both Ecological Economists and Sustainable City theorists advocate. It also describes a system which is designed for continuous improvement (increasing the bio-char quotient of the soil for one thing), and toward the enrichment of an empowering participatory negotiation process as surpluses continue to accumulate. This is a short sketch of the ultimate value and use of bio-char/pyrolysis processes (for more detail, including the Sustainable Area Budget, see the book or www.centerforsustinablecities.com).

    [the above comment was initially posted in the Ithaka Journal where the article was first published]
  • Elise Hancock , Great Britain
    27.06.2013 02:23

    Chlorine in irrigation water

    This compendium is really excellent. Thanks for all the thought and work. I will refer people to it. I have a question that may be important, based on a report I can no longer find on your site about the results—bad—when you gave urban “hobby gardeners” some char to use. As I remember it, you were puzzled, because the avid urban gardeners who had sought you out in previous years, agitating for char, had in general had EXCELLENT results. You were expecting the same from the hobby gardeners, but even after you supplied them with good live compost (in case that was the problem), their results were ragged. A few had a good increase in yield, but most? many? actually got worse. So I wonder… could the hobby gardeners have been using city water, full of chlorine? Most people do, after all, and think nothing of it. It’s what everyone does—water with the water you have. Of course. And if you’re using NPK fertilizers, all might seem to be well. Avid long-time gardeners, on the other hand, would probably have rain barrels, having had an experience like mine described on my website, when I finally figured out that city water kills microbes, all right, not only the ones that might make me sick, but the ones that my plants might need. This idea makes sense to me because it also makes sense of the works-in-the-tropics factor: those tropical fields are not urban, and the water isn’t treated. If this is true, harvesting enough rainwater to fill cities with backyard forest gardens won’t be easy, but at least we’ll know our struggle is not the fault of the char.

    [the above comment was initially posted in the Ithaka Journal where the article was first published]
  • Hans-Peter Schmidt, Switzerland
    28.06.2013 02:28

    Biochar for Hobby Gardeners

    The article you were looking for is here: Biochar in Hobby Gardening. Results of biochar have been not been bad with an average increase of more than 10%. However, you are right that chlorine treated water is not beneficial for soil microbes.

    [the above comment was initially posted in the Ithaka Journal where the article was first published]
  • Edward Someus, Sweden
    18.10.2014 04:23

    Meaning of biochar - Charcoal should not be referred as biochar

    There are many different types of carbon products made from different types of feed material with different methods for different specific applications - resulting different product character - required for different quality/safety/user product criteria. The different carbon product systems for different applications having different legal structure and producer's product responsibility as well. Charcoal is made for energetic application so it is not biochar from technical and legal point of view. Even if it happens in some cases that the charcoal product quality may meet biochar to be used in open ecological soil environment, the legal structure behind it is very different. The new EU regulation law harmonization will soon (hopefully) mandatory determine what biochar is for soil application, which minimum and mandatory quality requirements must be determined and how it should be labelled. The MS may even specify improved biochar quality beyond the EU regulation mandatory minimum level for justified reason/case, such as environmental, for which there is already case ongoing as well. The new EU regulation law harmonization will make clear basic line what is expected as minimum quality, safety, official Government permit for the production, trading, import and use of labelled biochar products in the EU28 above 1 t/y capacity.

  • Gregory Stangl, United States
    01.11.2014 17:34

    Would love to see more on biochar as a sorbent

    Filter carbon is a $2BN market in the US today. Biochar for Ag seems a tiny fraction of the size to me, yet the focus of the overwhelming majority of the text. Despite it's many proven lab qualities as a sorbent I see little here in detail that might help us break in to this market. Rather than ship coal based carbon from Asia and West Virginia so the good folks of Los Angeles don't have to smell waste water, wouldn't locally produced biochar make more sense! I'd love some help in telling this story.

  • Gregory Stangl, United States
    01.11.2014 17:44

    And one more thing!

    Recognizing, I am very late to this conversation I'd just like to add that calling biochar charcoal for non-Ag uses seems like a bad idea. As I see it in the marketplace carbon or charcoal can be made from anything. Including tires and coal. We believe the biogenic sources (Ag byproducts, forest residue, etc.) we use to make our biochar are in a different environmental universe from those made from things like tires, anthracite coal and all the other carbons i've found in use today. I recognize that the Ag folks have been the major driver of biochar but let's keep our industry in a big tent!

  • Daniel Young, United States
    11.11.2014 22:09

    Chlorine in irrigation water

    I enjoyed Elise Hancock's comment about Chlorine in irrigation water, and it brings back memories of when I was in the water treatment business, and I think we used to use activated carbon to de-chlorinate water for specialized industrial processes that could not tolerate Chlorine in their water. So, I guess this makes 53, or is it 56, uses for biochar, - taking chlorine out of water supplies. I'm not sure if it works as well as activated carbon, but I'm sure this would be a residual effect, at least.

  • Jim Brown,
    15.07.2015 19:46

    Storing Pyrolisis Gas

    In one of the articles it says the gas can be stored; can anyone show me how this works; everything I have read says it can not be stored.

  • Sandeep Kumar,
    20.07.2015 12:29

    @Jim Brown

    Dear Jim Brown, could you please send or reference the article where you read and got this question about pyrolysis gas storage. It might be that the author proposes pyrolysis gas condensation and storage in liquide state. By the way your question also increases my curiosity to get the answer of this question, so please send me a copy of that article. Kind regards, Sandeep

  • Bill Gunn,
    06.08.2015 18:32

    Transportation regulations

    What, if any, are the transportation regulations associated with shipping biochar?

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