Biochar

Biochar is environment-friendly material in a broad range of disciplines. It has already been established that biochar can be made from anything and everything containing biomass. Production techniques involve Pyrolysis or Gasification. It is potentially used in agriculture. However, many other areas can also benefit from using biochar.

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Table of Content

• What is Biochar?
• Biochar Production
• Uses of Biochar
• Biochar Applications
• Advantages of Biochar
• Disadvantages of Biochar
• Conclusion
• Frequently Asked Questions (FAQs)

What is Biochar?

• Meaning: Biochar is a solid product obtained in the pyrolysis of biomass.
• Biochar is a carbon-rich and porous material that can be used for a wide range of applications, among which soil improvement, soil remediation and pollution control take the most important roles.
• Biochar is mainly used in agriculture to enhance soil fertility, improve plant growth, and provide crop nutrition.
• As a result, it improves the overall farming productivity.
• It has also gained considerable attention in livestock farming as an animal feed.

Difference between Biochar and Charcoal

• Biochar differs from charcoal, which is produced at lower temperatures and considered a solid fuel, containing a high quantity of volatile matter.
• Because of higher process temperatures, the chemical structure of biomass changes and the content of hydrogen, nitrogen and oxygen in biochar is significantly decreased in relation to carbon.
• Contrary to charcoal, biochar is also not phytotoxic.

Biochar Production

• Biochar Production is majorly done by the Pyrolysis or Gasification technique.

Pyrolysis

• Pyrolysis is of two types: slow pyrolysis and fast pyrolysis.
• It is dependent on residence time and heating rate, with slow pyrolysis favouring syngas production and fast pyrolysis yielding more oils and liquids. Slow pyrolysis, also known as conventional carbonization, involves prolonged heating over days, resulting in higher biochar production, while fast pyrolysis quickly produces biochar at high temperatures in seconds.
• Fast pyrolysis produces more bio-oil, while slow pyrolysis yields higher biochar output.
• Process:  It begins with biomass drying, followed by heating to release volatile compounds (carbon dioxide, carbon monoxide, methane, hydrogen), or condensable organic compounds (acetic acids and methanol), with cracking and polymerization reactions affecting the overall product range.

Gasification

• Gasification enhances the porousness and surface area of biochar by converting biomass into gaseous form (such as syngas) through limited oxidation at high temperatures, where oxidizing agents like oxygen, water, or mixtures are involved.
• In biochar production, the focus lies on the carbonaceous solid product, with increased fixed carbon content resulting from water evaporation and the release of volatile components.
• Polymerization of organic materials in vapours and gases contributes to minor char formation and enhances solid yield, characterized by lower heating levels and longer residence times.
• The process conditions of temperature and residence time significantly impact the product outcome when biomass undergoes pyrolysis.

Uses of Biochar

Carbon Sink:

• When biomass undergoes combustion or natural decomposition, it releases significant amounts of carbon dioxide and methane into the atmosphere.
• In contrast, biochar also releases these elements, but its carbon content remains stable, making it an effective carbon storage option.
• Utilizing biochar can store carbon in the soil, potentially reducing greenhouse gas levels while simultaneously improving soil fertility and agricultural productivity.

Soil Amendment:

• Biochar’s porous nature makes it ideal for enriching soil, as it can retain water and water-soluble nutrients.
• It offers various benefits to soil health, including improving water quality, reducing nutrient depletion, mitigating soil acidity, and decreasing the need for irrigation and fertilizers.
• The application of biochar can enhance soil conditions, promoting healthier plants and reducing the reliance on external inputs.

Water Retention:

• Biochar exhibits hygroscopic properties, allowing it to absorb and hold water from the surrounding environment.
• This characteristic makes it particularly beneficial in areas prone to water shortages, as biochar can help retain moisture in the soil.
• Additionally, biochar retains essential plant nutrients such as phosphate and nitrogen, contributing to healthier plant growth and reducing the dependency on excessive fertilizer usage.

Promoting Soil and Substrate Properties:

• Biochar holds promise as a soil conditioner and substrate amendment in agricultural and horticultural practices.
• Its application has the potential to enhance various physical, chemical, and biological properties of soil and substrates.
• Incorporating biochar can improve soil structure, nutrient availability, and microbial activity, fostering a more favourable environment for plant growth.

Biochar Applications

Climate change mitigation

• Biochar production is proposed as one of the best ways to mitigate climate change.
• It is done so by sequestering carbon in the soil.
• It shows long-term soil stability, and it acts as a key factor in decreasing carbon dioxide emissions into the atmosphere.
• Biochar can reduce nitrous oxide and methane emissions from the soil by biotic and abiotic mechanisms.
• Biochar has been estimated to be capable of tackling 12% of current anthropogenic carbon emissions.

Soil improvement

• Biochar is potentially a soil conditioner because it has high organic carbon content.
• It does so by improving the physicochemical and biological properties of soils.
• Biochar enhances plant productivity because it has a neutral to alkaline pH which induces a liming effect on acidic soils.
• Remarkable increases in seed germination, plant growth, and crop yields have also been reported in soils amended with biochars.
• Biochar application with organic or inorganic fertilizers can even multiply crop yields.

Waste management

• Waste biomass is used for the production of biochar, which is economically beneficial.
• Biomass includes crop residues, forestry waste, animal manure, food processing waste, paper mill waste, municipal solid waste, and sewage sludge.
• Biochar has great potential for waste management originating from animals or plants as it decreases the pollution associated with it.
• Biochar production gives us an alternative to overcome pollution. 

Energy production

• Another potential use of biochar is in the production of bioenergy, which could be associated with the conversion of waste biomass to biochar.
• This energy will serve as an alternative to fossil fuels and will lower carbon emissions.
• However, bioenergy production is dependent on the conditions involved in the process of pyrolysis.

Capturing the contaminants

• Environmental remediation has recently been recognized as a promising area where biochar can be successfully applied.
• Organic contaminants of the greatest concern have been pesticides, herbicides, polycyclic aromatic hydrocarbons, dyes, and antibiotics.
  • Simultaneously, inorganic contaminants are of a wide variety too.
• Biochar has emerged as an excellent option to reduce the bioavailability of contaminants in the environment.
• Biochar is a very effective environmental sorbent for organic and inorganic contaminants both in soil and water.

Advantages of Biochar

• Biochar is less expensive than activated carbon.
• The cost of biochar production is approximately one-sixth of commercially available activated carbon.
• Biochar shows significant adsorption for both organic as well as inorganic contaminants.
• It contains a non-carbonized fraction (such as oxygen-containing carboxyl, hydroxyl, and phenolic surface functional groups) that interacts with soil contaminants.
• Biochar has greater water-holding capacity compared with activated carbons.
• Biochar has low density therefore it provides additional voids and aeration in the soil.
• Biochar reduces the loss of nutrients in the soil through leaching.
• Biochar is prepared from sewage sludge and manure, which has a high nutrient content that enriches soil quality.

Disadvantages of Biochar

• Environmental pollution from dust, erosion and leaching of biochar particles could be a possibility.
• Biochar poses a risk for respiratory diseases because of the fine ash associated with it.
• Sometimes yields may decline because of the sorption of water and nutrients by biochar, which reduces their availability for the crops.
• Long-term removal of crop residues, like stems, leaves and seed pods, can reduce overall soil health by diminishing the number of soil microorganisms and disrupting internal nutrient cycling.
• Biochar can cause short-term negative impacts on earthworm population density.

Conclusion

Biochar plays an important role in soil improvement, soil remediation and pollution control. It has a wide range of advantages including reducing loss of nutrients, enriching soil quality increasing water holding capacity etc. It seems that biochar can just be the solution for the various issues threatening our planet. Adequate research on biochar can turn out to be the most beneficial step humankind can take.

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FAQs (frequently asked question)