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Archeological studies have found that pyrolysis liquids were already used in the time of the Neanderthal. Wood vinegar and other slow pyrolysis liquids are produced as a by-product of charcoal production. However, future business ideas may be the other way round as pyrolysis liquids may replace synthetic chemicals in the form of pesticides and biocides.Directives and regulations related to the sustainable use of pesticides govern and direct plant protection strategies towards a lower use of synthetic chemicals. It is hoped that many mega trends of global policies will boost the use of plant based products given that a reduced reliance on fossil fuel is a general target in the global food and feed production economy. Pyrolysis technology has been actively studied and developed around the world and is linked to the development of the knowledge based bio-economy. The importance and social impact of pyrolysis technologies will also be enhanced because it is a practicable technique in the sustainable use of wastes and biomasses. However, very little scientific evidence is available to support efficacy claims of wood vinegar and toxicology assessments of the products used. Wood tar has been investigated a bit more thoroughly. The aim of this review was to clarify the potential of slow pyrolysis liquids in agricultural use, in particular, in pesticide applications. In addition, some of the main challenges in developing novel bio control technologies are discussed and the barriers in the commercialization of biological control agents are revealed.

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Birch distillate, a byproduct in charcoal production, has found to be a promising source for biological pesticides. The aim of this paper was to determine the yields and chemical compositions of liquid and gaseous products from the slow pyrolysis of birch hardwood, which is needed in the commercialization process of the byproduct. Test runs were performed using three different retorts. Distillates, aqueous phases, settled tars, wood vinegars, and gases were analyzed with an analytical scheme developed. About 95 wt % of the aqueous phases was analyzed. The main compounds were water, acetic acid, methanol, hydroxypropanone, furfurals, acetone, and syringol, catechol, and phenol derivatives, and sugarlike compounds. The tar and polycyclic aromatic hydrocarbons contents of aqueous phases were low, or they could be lowered by simple water addition when needed. On the basis of compositions, birch wood vinegars have potential to be used for example as biodegradable pesticides, to replace synthetic pesticides. At low temperatures, formed tar-free distillates (predistillates) can be separated from the main distillate and utilized. Because of their low pH and high organic load, they cannot be disposed to the environment without treatment. The amount of polycyclic aromatic hydrocarbons in the tars has to be considered, and therefore, the tars were suggested to be utilized mainly as energy. The gases are promising to be utilized, in addition to the process itself, for other energy needs. The differences obtained for the products of different processes were mainly between batch and continuous processes. The detailed compositions of the products may be exploited by enterprises and authorities for registration purposes in the commercialization process.

The products from slow pyrolysis of birch hardwood are promising to be used for various purposes, in addition to conventional charcoal. To evaluate their utilization, knowledge about their polycyclic aromatic hydrocarbons (PAHs) is needed. The content and distribution of the PAHs in the different products were determined in a test run with a typical slow pyrolysis carbonization retort. The PAH compositions of gases, and distillates including aqueous phases and tars, were followed in terms of time and retort temperature. Also, other compounds in gases and aqueous phases through the test run were analyzed. PAHs were found in all the products, but were mostly concentrated in the tars. Because of the results, the PAH contents in the tars has to be considered. In contrast, very low PAH concentrations were found for the tar-free aqueous phases. Because of low PAH and also low benzene contents, the aqueous phases are promising to be utilized in various applications, for example as biodegradable pesticides. Due to high proportions of combustible gases, such as carbon monoxide, methane, and hydrogen, the gases could be utilized as a fuel gas for energy. In addition to barbecue charcoal, the charcoal might have potential to be used as biochar as a soil amendment. The PAH results can be exploited when planning the utilization of the products and for registration purposes needed in the commercialization.