Biochar

Coal plants (including biochar, Biochar from English ) pure vegetable starting materials is produced by pyrolytic carbonization. In conjunction with other admixtures, such as bones, fish bones, biomass waste, fecal matter and ash, it is part of Terra preta. Biochar in some countries (eg Austria, Switzerland ) approved in agriculture as a soil conditioner and as carrier for fertilizer and as an adjuvant for composting and nutrient fixation of manure. Biochar is also used as a feed additive and dietary supplements. In recent years, the production of biochar was intensified. She is said among other things a great potential as a means to compensate for the carbon dioxide emissions in the light of global warming.

• 5.1 biochar as a soil conditioner
• 5.2 C sink

Production

Biochar is produced under exclusion of air at temperatures between 350 ° and 1000 ° C ( pyrolysis). Under these process conditions is mainly split water, biochar, syngas and heat. The minerals in the original biomass, bound in the pores and on the surface of coal plants.

Traditional production

Biochar has been produced since the beginning of the Iron Age in so-called charcoal kilns. The starting material wood was also used straw for most. In this traditional method, the yield of coal is relatively low and the Pyrolysesegase escape unused into the atmosphere.

Technical pyrolysis

With modern technical methods that have been developed since the 1990s, now all plant raw materials can be pyrolyzed with a moisture content of up to 50 % on high quality biochar. That are produced during pyrolysis synthesis gases are burned very low emissions, among others, by flameless oxidation ( PYREG system). A part of the heat is used for heating the biomass nachgeförderten, so that it is altogether a self-sufficient process. By far the greater part of the waste heat can be used for heating purposes or to convert about combined heat and power into electricity and heat.

The pyrolysis is used in the gasification timber. The resulting gas is fed to an internal combustion engine. Means, steam levels high and low pressure of the efficiency of the system can be further improved. The wood gasification technology is also used to generate electricity. As a by-product is also produced coal in very fine-grained state.

Two-thirds of the accumulated through photosynthesis plants energy is stored in the resulting biochar.

Known manufacturers of pyrolysis are German companies like PYREG, Carbon Terra, BioMaCon, Regenis, as well as the Australian companies Eprida, Pacific Pyrolysis ( PacPyro ). Further industrial equipment manufacturers are in China and Japan. Until the beginning of 2014 10 industrial plants were built in composting plants, city nurseries, farms, municipalities, wastewater treatment plants and waste disposal companies.

In addition to the above-mentioned industrial plants numerous small and Kleinstpyrolyse systems are currently being developed that will benefit both in the home and garden use as well as in developing countries to use (Source :).

Hydrothermal carbonization

A further process for the production of carbon from biomass is the so-called hydrothermal carbonization (HTC) with the addition of water under a pressure of about 20 bar and temperatures of 180 ° C. The chemist Friedrich Bergius was awarded the Nobel Prize for this discovery in 1931.

In 2010, two industrial plants for the production of hydro- carbon ( HTC - coal) commissioned ( Terra Nova Energy in Dusseldorf and AVA-CO2 in Karlsruhe). In hydro carbon is compared to coal plants, although to a related, but chemically and physically different product, which nevertheless has interesting perspectives for the use in agriculture.

Vapothermale carbonization

A further development of the hydrothermal carbonization is the vapothermale carbonization (VTC ), is produced in plant coal in a steam atmosphere. This allows the reaction conditions are better controlled and the process can faster and more energy efficient, and are thus carried out more cost effective. When vapothermalen carbonization is an exothermic process, the bar takes place at temperatures between 180 to 250 ° C and pressures between 16 to 42.

Vapothermale the carbonization is particularly suitable to use organic waste with a moisture content of about 50%.

Charging and activation

Biochar is not a fertilizer, but also a carrier for nutrients and habitat for microorganisms. In order to bring their soil-enhancing properties quickly and efficiently to effect which biochar must first be physically loaded with nutrients and / or biologically active. In addition to the composting plant with coal, there are numerous other methods of activation and the production of relevant products such as biochar terra preta.

Vegetable carbon is extremely porous and has an enormous specific surface area of ​​about 300 sqm partially per gram. Due to the high porosity can biochar up to five times its weight of water and the dissolved nutrients record. This property is called adsorption capacity (AC ) of the biochar which depends on the one hand of the pyrolyzed biomass and on the other hand by the pyrolysis. In the range from 450 ° C to 700 ° C plants coals occur with the highest adsorption capacity.

Another important feature to explain the specific nutrient dynamics of biochar is the high cation exchange capacity (CEC ). The CEC depends on the surface of the vegetable carbon, but is a chemical quantity, which increases by oxygen, and contact with the ground and reaches its maximum value only after some time. A high CEC prevents the leaching of mineral nutrients such as organic system and adds a higher nutrient availability. A high CEC also favors the binding of heavy metal ions, whereby the soil microflora and fauna soil to be protected.

The high AK and CEC of biochar cause the plants coal ideally suited as a nutrient carrier. The nutrients absorbed by the plants coal cause micro-organisms find ideal habitats in and around the plants coal. This leads to microbial life to the soil, which may symbiosis of microorganisms and plant roots benefit.

There is no magic recipe for nutrient charge, but only the following recommendations:

Properties

Use

Ecological potential

Biochar as a soil conditioner

Biochar for over 2500 years already contributes in many regions of the world to contribute to soil improvement. Most biochar was thereby introduced in combination with other organic wastes such as livestock manure, compost or Bokashi into the ground. The biochar was used primarily as a carrier for nutrients as well as micro- habitat for soil microorganisms such as bacteria and fungi. The best-known example of the use of biochar for the sustainable improvement of weathered soils is terra preta.

Due to the entry of activated biochar to agricultural soils is extremely positive effects on soil type, soil health and yield capacity can be achieved. In scientific studies, among others, the following advantages for soil cultures could be detected:

• Significant improvement of the water storage capacity of soils
• Growth of soil bacteria, which are a protected habitat in the niches of highly porous carbon, whereby the nutrient recycling is promoted for the plants.
• Increase of mycorrhizas, resulting in improved water and mineral uptake and effective protection is provided against plant pests.
• Adsorption of toxic soil constituents such as organic pollutants and heavy metals, making the food quality and groundwater protection be improved.
• Higher soil aeration and improved activity of N - bacteria and thus significant reduction of greenhouse methane and nitrous oxide emissions.
• More efficient nutrient dynamics, which ensures both increased plant growth, as well as reduced nutrient leaching
• Improve plant health through induced resistance

C sink

Biochar consists predominantly of pure carbon, which can be degraded very slowly by microorganisms. If this biochar incorporated into agricultural soils, accounting for over 80 % of the carbon for more than 1000 years remains stable and thus represents a possibility in the long term to deprive the original CO2 assimilated by plants to the atmosphere and thus slow down the climate change.

Since biochar remains relatively stable for thousands of years in the ground, thus forming carbon sinks, it has become increasingly addition to its role as a soil as a means of climate protection into view.

Organic waste such as green waste, residue or manure are fed either currently composting, fermentation or rotting. In composting and rotting escape about 60 % of the carbon contained in the biomass as CO2 and methane. In the locally applicable pyrolysis resulting from the original biomass about 30 % vegetable charcoal. If biochar incorporated into the soil, the atmosphere is removed from carbon in the long term, which consequently can no longer contribute to global warming. Moreover, since the energy of the synthesis gas can be used to generate electricity, replacing fossil fuels, the carbon footprint in the pyrolysis of organic waste materials is carbon- positive compared to their mere rotting. Pyrolysis can also be used in the most efficient waste recycling. Thus, residual wastes from biogas plants that use Press radicals from the sunflower, canola or olive oil production and digestate from bio-ethanol production.

By means of a PYREG pyrolysis plant can be, for example, each 2 tons of green waste around 1 tonne of CO2 from the atmosphere over the long term. All expenses such as energy for the transport of the green good, comminution, the operation of the plant and the introduction of biochar in the soil are already taken into account. The used pyrolysis plant is energy self-sufficient and is operated in a continuous process. The energy required to over 400 degrees Celsius for heating the biomass is derived from the biomass itself, and is generated by the combustion of the pyrolysis gas produced in the. BioMaCon plants use for carbonization of biomass, the heat generated by other systems. Such systems are e.g. Biogas plants. For carbonization of biomass here the hot exhaust gases of internal combustion engines are used. The whole formed by the pyrolysis gas to internal combustion engines for power generation air supplied to the positive, since it is no longer needed to carbonize the biomass. The pyrolysis gas is used as very effective. The pyrolysis plant can be operated either continuously or intermittently, as the plant is always kept at operating temperature by the use of waste heat and so accounts for heating phases.

In addition to carbon dioxide, nitrous oxide is a major greenhouse gas. Agriculture is responsible for about 60% of anthropogenic nitrous oxide emissions. In addition to a soil improvement and earnings growth in agriculture also reduced the incorporation of biochar into the soil nitrous oxide emissions caused by nitrogen fertilization.

Biochar incorporated into the soil there can survive for thousands of years.

It is assumed that sustainable biochar production (CO2) - Methane ( CH4) - and nitrous oxide (N2O ) emissions at a height of 1.8 Pg CO2 - equivalent ( = CO2e), ie 12 % of the annual anthropogenic greenhouse gas emissions can be compensated. In the course of a century, a lot of biochar are produced, the total emissions of 130 Pg correspond CO2e, without jeopardizing food security and conservation.

CO2 certificates

If biochar obtained by pyrolysis introduced into agricultural soils, it is stored there, like crude or lignite stable over several millennia. The carbon of the plant is thus removed from the carbon cycle, since it is converted to CO2 or methane neither combustion nor decomposition. Through the bottom entry of biochar agricultural soils can become carbon sinks that could be made ​​, in contrast to unstable humus claimed as CO2 certificates. At the last world climate conferences but there was no decision to include such Sequestrierungen in a global carbon trading. This is due to the unsolved question of whether the method is feasible at scales that contain a sufficient reduction potential and thus justify the administrative effort for inclusion in the carbon market. In contrast to voluntary CO2 certificates, ( Austria ) are traded successfully as for example in the ecoregion Kaindorf.