03/21/2022
Wood Vinegar: History of Wood Vinegar and Tar
The use of wood vinegar in agriculture dates back at least two millennia in ancient China, Egypt, Greece, and India. Wood vinegar also has a long history, and it has been used daily, for example, in Japan as a result of numerous health claims related to the product. Since the 1930s, wood vinegar has also been used in agriculture as a fertilizer and growth promoting agent. Although the word ancient, related to the use of wood vinegar, has been mentioned in many documents and on web pages it was difficult to find good scientific evidence to attest the first records of wood vinegar used as pesticide. Probably only few documents are available or the information has been written in languages and in countries d to reach via modern information retrieval.
In conventional pyrolysis processes, wood is slowly heated up to the maximum temperature. Lower process temperatures (400 ºC) and longer vapour residence times favour the production of char. Besides slow pyrolysis, other terms such as carbonization, destructive distillation, and dry distillation are used for this kind of thermal process . The pyrolysis of wood was probably human’s first chemical process. It is known to have been practiced by the ancient Chinese. The Egyptians, Greeks, and Romans made charcoal by wood carbonization, and collected the condensable volatiles for embalming purposes and for filling joints in wooden ships.
The most important product of carbonization is charcoal. Industrial carbonization is carried out predominantly in large retorts with capacities up to 100 m3 of wood. The aver-age practical yields are about 35 wt.% of wood, and depend on the wood species and wood size, carbonization system, processing time and final temperature. Beech wood is the dominant raw material for the production of charcoal in Europe. In addition, oak, ash, alder and maple are used. In North America, the raw materials include also hickory, elm, sycamore and some softwood species. In the Nordic countries minor amounts of birch is used, and in South America and South Africa, charcoal is produced mainly from hardwood species of Eucalyptus
Until the late 1800’s, wood carbonization was the major pyrolysis process, and supplied the increasing amounts of charcoal that were required for iron ore smelting. The iron furnaces in the USA used charcoal exclusively until the 1840’s, and somewhat later the share of the iron market produced with charcoal was increasingly replaced by that of coal and coke iron. By the 1900’s, destructive distillation of wood was practiced widely on a commercial scale by heating wood in closed retorts. The vapors produced were condensed to give tar (wood tar or sedimentation tar) and an aqueous layer (pyroligneous acid). In the retorts about the same quantity of the major products charcoal and raw pyroligneous liquor (crude wood vinegar) are produced. This liquor is first settled and then decanted from the sedimentation tar. The tar can be fractionated into tar oils and tar pitch. Raw pyroligneous acid contains primarily methanol, acetic acid and soluble tar. By the turn of the century, wood was the only source for the latter chemicals.
Prakrit Khamduangdao was looking for an alternative to agricultural chemicals to control pests in his vegetable farm. However, he was not completely satisfied with various botanical pest control measures being promoted in northern Thailand. He reports that even though certain natural insect repellents were beneficial, their effects were too limited. Additionally, finding adequate amounts of necessary raw plant materials and processing them into sprays was laborious and time consuming. When Mr. Prakrit first heard about wood vinegar in 2000 he was intrigued. Compelled by the idea of a natural by-product of charcoal production that can control pests and diseases of crops, he bought his first bottle. Having used the product, Mr. Prakrit was pleased with the ease of mixing and application. Ultimately, after observing much fewer insect pests and fungal diseases on his crops, he became convinced of the effectiveness of wood vinegar. Not long afterwards, Mr. Prakrit became self-sufficient in producing both charcoal and wood vinegar with a 200-liter horizontal drum kiln. He has been an advocate of wood vinegar ever since. Wood vinegar (pyroligneous liquor) is rapidly gaining acceptance as an essential Asian natural farming input. Reported agricultural use as a fertilizer and growth-promoting agent goes back to the 1930s, making the product a relatively new innovation.
About Wood Vinegar
● Wood vinegar is often referred to as pyroligneous acid or wood acid. It is a liquid substance produced in precisely controlled pyrolysis of biomass. While a variety of biomass types can be used to produce wood vinegar, such as wood, crops, agricultural residues or different materials of biological origin, the most common types of biomass used are hardwood chips and sawdust.
The pyrolysis process is used to make wood vinegar, which is a sort of treatment that may be used on any organic (carbon-based) product. When biomass is subjected to high temperatures in the absence of oxygen, it splits into distinct molecules chemically and physically. Breakdown occurs due to the poor heat stability of chemical bonds in materials, which allows for decomposition. The composition of gases generated in biomass pyrolysis is influenced by the temperature and residence time employed in the pyrolysis process, thus attaining quality and consistency in wood vinegar production is directly linked to the controllability and accuracy of the thermal conversion unit. Wood vinegars of the highest quality and standardisation are made under precisely specified circumstances according to the producer's formula.
The global wood vinegar market was valued at $3.2 million in 2015, and it is expected to grow at a CAGR of 7.1% during 2016-2023. The factors driving the growth of the global market include improved crop yield, increasing base of end-use industries, increased government initiatives for bio-based products, and stringent environmental regulations. The key trend witnessed in the global market is poverty alleviation. Wood vinegar can be produced at either small scale or large scale in villages, utilizing local resources and feedstock. Wood vinegar production is helping to reduce poverty in several developing or underdeveloped countries. The global wood vinegar market is in its nascent form. Currently, very few players across the globe are involved in large scale production of wood vinegar. However, the distinct governments and organizations in several countries across the globe are framing regulations for bio-based economy and promoting bio-based products, which are supporting the growth of biochar production and biorefineries. As wood vinegar is a byproduct of char or biochar production, the government initiatives indirectly creates abundant opportunities for the growth of the wood vinegar market globally.
Based on application, the agriculture segment dominated the global wood vinegar market during 2013-2015 in terms of value and volume, and it is expected to retain its dominance throughout the forecast period. The growth of the agriculture application segment in the market is primarily driven by several advantages offered by wood vinegar in agricultural practices, such as root growth stimulation, improved seed germination, increased disease resistance in plants, and soil enrichment.
