Charcoal Kilns Research Articles

The Soil Environment of Abandoned Charcoal Kiln Platforms in a Low-Altitude Central European Forest

This study examines the soil environment of eight charcoal kiln platforms and the neighboring soil in Czech and Bohemian low-altitude forest stands. Both mixed and undisturbed soil samples were used to assess the hydrophysical soil properties, nutrient content, cation exchange capacity, enzyme activity, and soil active carbon content, while soil color, stoniness, root density, and horizon thickness were estimated in the field. Charcoal-rich horizons had high total organic carbon concentrations and total nitrogen content (about 150% and 40% higher than in the organomineral horizons of the control plot, respectively), with total carbon stocks being higher than those in neighboring forest soils. Fine root density was highest in the charcoal-rich horizons, encouraged by high soil porosity, aeration, and favorable chemical properties. Enzyme group activity differed between individual soil horizons and kiln and control plots, with depolymerization enzyme activity highest in charcoal-rich horizons and humification enzyme activity highest in mineral horizons. Phosphatase, chitinase, and phenoloxidase activity were highest in charcoal-rich horizons, while β-glucosidase activity remained similar across horizons. After long-term abandonment, kiln sites shift from inhospitable sites to localized hotspots for plant and microbial growth, having more favorable physical, enzymatic, and chemical soil properties than the surrounding areas. This study confirmed that kiln production platforms act as microhabitat hotspots, also providing information on a wide spectrum of soil properties linked with soil microorganisms and root growth.

A Review on Conversion of Biomass to Liquid Fuels and Methanol through Indirect Liquefaction Route

AbstractGlobal urbanization and industrialization are energy‐intensive processes. Among different energy resources, fossil fuels meet more than 80 % of the energy demand. The factors such as the depletion of fossil fuel reserves, the unstable price of fossil fuels, and the emission of greenhouse gases (GHGs) due to the burning of fuels draw researchers’ attention towards the development of renewable and sustainable fuels. In this context, biomass may fill the gap between energy demand and petroleum availability in the foreseeable future. Moreover, half of this bioenergy comes from conventional uses of biomass, primarily in cooking and heating, as well as within small‐scale industries (such as charcoal kilns and brick kilns). The Biomass‐to‐Liquid (BTL) technology using Fischer‐Tropsch synthesis (FTS) and the Methanol process offers advantages over the traditional use of biomass. The FT/Methanol process is a propitious route to produce carbon‐neutral, ultra‐clean fuels that generate regulated emissions, including NOx, SOx, and PM. In this article, we have reviewed the processes of biomass gasification, syngas cleaning and conditioning, FTS and methanol synthesis.

Efficacy of Forest-Thermal Combined Therapy for Anxiety and Stress among Smoking-Cessation Attempters

Purpose: Smoking is a way of coping with anxiety and stress. This study aimed to identify the effects of forest-thermal combined therapy on anxiety and depression in smokers who desire to quit smoking. Methods: Thirty participants were included in the study, 15 in the experimental group and 15 in the control group. Those in the experimental group participated in a three-day forest-thermal combined therapy program. The program includes forest walks, meditation and thermal therapy in the charcoal kiln. Results: Before and after the program, physiological indicators such as cortisol, heart rate variability, and serotonin anxiety level using the state-trait anxiety inventory (STAI), and stress level using the psychosocial well-being index (PWI) were measured in both groups. The differences in STAI (p=.012) and PWI (p=.006) scores between the experimental and control groups were statistically significant. However, cortisol, heart rate variability, and serotonin were not significantly different between the two groups after the program. Conclusion: These results show that forest-thermal combination therapy effectively reduces anxiety and stress in smokers. It suggests that forest-thermal therapy can potentially increase smoking cessation rates. Key Words: Anxiety; Forest; Stress; Thermotherapy; Smoking

Effects of topography and historical human disturbance on the current-day distribution of Betula davurica in a secondary deciduous forest in central Japan

ABSTRACT Betula davurica is a relict species in Japan of which distribution is influenced by topography at local scale. This species may also be dependent on disturbance for regeneration. However, no studies found that estimate and compare the effects of topography and human disturbance on abundance of this species. Focusing on abandoned charcoal kilns and charcoals in the surface soil as proxies for historical disturbance, we assessed the status of B. davurica in a secondary deciduous broad-leaved stand in central Japan. Although B. davurica was once a dominant species in the study area, its regeneration has stagnated after decline of charcoal production. The oldest individual was 90 years of age, suggesting that the current-day population established following a period of grassland dominance 100 years ago. We found multiple abandoned kilns, as well as widespread charcoal fragments in the surface soils of the study area. Both individuals, that had established prior to and following the decline of charcoal production, tended to be distributed at sites with other tree species with smaller DBH and at gentle slope. Location of charcoal kilns did not significantly affect the distribution of this species. It is possible that B. davurica prefers to gentle slope at the sites where historical logging for charcoal production and fire disturbance had influenced at the whole. Cessation of logging and fire disturbance have likely inhibited the regeneration of B. davurica. Logging of other tree species around at gentle slope may be necessary for the survival of this species.

Soil fertility in slash and burn agricultural systems in central Mozambique

Slash and burn is a land use practice widespread all over the world, and nowadays it is formally recognized as the principal livelihood system in rural areas of South America, Asia, and Africa. The practice consists of a land rotation where users cut native or secondary forest to establish a new crop field and, in some cases, build charcoal kilns with the cut wood to produce charcoal. Due to several socio-economic changes in developing countries, some scientists and international organizations have questioned the sustainability of slash and burn since in some cases, crop yield does not justify the soil degradation caused. To estimate the soil quality in agricultural and forest soils at different ages of the forest-fallow period (25, 35, and 50 years), this survey investigated rural areas in three locations in Manica province, central Mozambique: Vanduzi, Sussundenga, and Macate. Soil profiles were trenched and sampled with a pedological approach under crop fields and forest-fallow. The chronosequence was selected to test the hypothesis that the increase in forest-fallow age causes an improvement of soil fertility. Results highlighted discrete variations among locations in mineralogy, Al- and Fe-oxyhydroxides, sand, silt, pH, total organic carbon, humic carbon, total nitrogen, available phosphorous, chloride, nitrate, fluoride, and ammonium. Few differences in mineralogy, Fe-oxyhydroxides, available P, chloride, and nitrate were detected between crop fields and forest-fallow within the same location. Such differences were mostly ascribed to intrinsic fertility inherited from the parent material rather than a longer forest-fallow period. However, physicochemical soil property improvement did not occur under a forest age of 50 years (the longest forest-fallow considered), indicating that harmonization of intrinsic fertility and agronomic practices may increase soil organic matter and nutrient contents more than a long forest-fallow period.

Thermal Performance Analysis of Materials and Configurations for Cylindrical Sidewalls of Charcoal Kilns

Most of the charcoal in the world comes from small and medium-sized producers, using rudimentary carbonization kilns that require significant time or energy during the heating and cooling stages of the process. Despite advances in improving the performance, the influence of materials used in the sidewalls of these kilns has been scarcely studied. Therefore, based on numerical simulations, the present study analyses the thermal performance of cylindrical sidewalls composed of combinations of metallic materials, ceramic materials, and insulating blankets grouped in three configurations: configuration I (sidewall with just one material), configuration II (sidewall with two materials assembled in series), and configuration III (pivoting sidewall). Results were encouraging, especially when comparing kiln configuration I with the novel configuration III. Simulations suggested that the proposed configuration III could reduce the heating time by 62%, the cooling time by 91%, the heat supplied to sidewalls by 80%, and the heat loss to the external environment by 99.7%. The save of wood charged into the charcoal kiln grew up to 7.3 times, varying the thickness of the inner layer of the sidewall.

A combined OSL and 14C dating study of charcoal production in the sandy environment of Zoersel forest (N Belgium)

We investigate the potential of quartz-based OSL-dating for application to heated sandy sediments that are closely associated with the remains of charcoal production (charcoal kilns). This is particularly relevant for post-1650 CE features, where 14C-dating lacks resolution. We first document the general OSL characteristics using large aliquots of sand-sized quartz. Results from procedural tests indicate that the laboratory measurement procedure should allow reliable equivalent dose estimation. The scale of analysis is then reduced to smaller aliquots for all samples, each composed of 100–200 grains, as well as to single grains for eight heated samples. For one sample, both the small and single-grain ages are consistent with the 14C-ages obtained for charcoal fragments in the same sedimentary unit. Also for three other samples, single-grains yield ages consistent with 14C-dating; all other OSL-ages are older although, for three of these samples, single grains and small aliquots yield results that are not significantly different. We discuss potential sources of inaccuracy for the OSL-dates, such as dose rate determination and homogeneous incomplete resetting. The latter is the most difficult to assess and requires additional empirical data.

Soil bacterial communities under slash and burn in Mozambique as revealed by a metataxonomic approach

The slash-and-burn system is a subsistence agronomical practice widespread in tropical areas worldwide. This system has been extensively studied, especially for its impacts on agronomical aspects and soil physicochemical properties; however, knowledge of soil microbial diversity under slash and bum is scarce. In this study, for the first time, soil bacterial diversity of three locations from Central Mozambique, where slash and burn has been practiced for different durations of the forest fallow period (ca. 25, 35, and 50 years), was elucidated through a metataxonomic approach. Bacterial communities were evaluated in the genetic horizons of soils under charcoal kilns, crop fields, and forests. The aim of this study was to examine the influence of spatial (location and land use), temporal (forest fallow period), and vertical (horizon) variations on bacterial community structure in relation to soil physicochemical properties. Metataxonomic analysis detected 25 different phyla whose distribution varied horizontally and vertically in relation to soil properties (i.e., pH, easily oxidizable organic carbon, total nitrogen, and available phosphorus), as well as particle size distribution and mineralogical composition. Such properties were strongly affected and altered by land-use management; in particular, charcoal kilns exhibited better soil properties and greater differences in bacterial community than crop fields and forests, which were quite similar. This might suggest the inability of a forest fallow period shorter than 50 years to improve soil fertility and induce changes in bacterial community. The uncommon application of the pedological approach for microbial evaluation facilitated the detection of a clear separation in bacterial composition along the soil profile, with eutrophic bacteria mainly located in the A horizon whereas oligotrophic bacteria were found in the Bo horizon. These horizontal and vertical heterogeneities in the same study represent a novelty for bacterial metataxonomic analysis.

Did the charcoal-based iron industry really drive the forest cover decline in the Northern Pyrenees?

Through a reconstruction of the chronology and intensity of charcoal-making activities, this paper re-opens the debate about the supposed impact of the charcoal iron industry on forest cover in the French Pyrenees. This reappraisal focuses on the former territory of the communities of Haut-Vicdessos valley. This more refined chronology, based on the analyses of historical documents (n = 617) and charcoal kiln remains (n = 42), has highlighted the non-linear industrial development. The emergence of water-powered bloomeries during the early 14th c. led to a brief expansion of the iron industry, but was followed by a slowdown in the 15th c. The combined effect of regulation and the outsourcing of a part of the charcoal supply on other territories, mitigated the impact of the iron industry on local forest, avoiding a forest crisis. The most significant industrial growth occurred from the mid-17th c. with development of the Catalan bloomery. Forests underwent major changes in structure and composition but cover was maintained to satisfy the local economy and people's needs. Charcoal production always occurred in well-stocked forests dominated by beech and fir. The increase of charcoal supply combined to the agro-pastoral growth led to the prohibition of charcoal-making in the mid-18th c. and to the exclusive recourse to an external fuel supply. Minimum forest cover was only reached in the mid-19th c. due to the demographic explosion resulting in the increase of daily needs and in the refocus on agro-pastoral economy. Conversely to the common premise, the iron charcoal industry in European mountains did not necessarily induce forest depletion but rather its maintenance through sustainable management and policies. • We revisited the chronology and intensity of the charcoal iron industry in Vicdessos. • The spread of water-powered bloomeries did not lead to a 14th c. forest crisis. • The iron industry’s real impulse occurred in the 17th c. with the Catalan bloomery. • Local communities preserved woodland cover through efficient management. • The iron industry was not a major driver of the mid-19th c. forest-cover minimum.

Woodland Management as Major Energy Supply during the Early Industrialization: A Multiproxy Analysis in the Northwest European Lowlands

Wood and charcoal were key sources of energy during early industrialization in Europe (18th century), preceding the large-scale exploitation of fossil coal. Past timber harvesting implied land transformation and woodland resources management. Therefore, relict charcoal kilns and historical documents of forest management are important sources of information about past woodland composition and structure. However, ancient charcoal kilns are poorly documented in temperate woodlands in the lowlands of western Europe, especially combined with historical written sources. In this study, charcoal production was investigated in an area in NE France, by combining charcoal and historical sources analysis, along with innovative dating methodologies. Thus, by using both radiocarbon and optically-stimulated luminescence dating, we showed that the activity lasted until recent times (19th–early 20th centuries) and Carpinus was the dominant taxon in charcoal assemblage. Moreover, kiln attributes seemed to be independent of topographical variables. Woodlands in this area were subject to a coppice-with-standards management, where small diameter wood was preferred to produce charcoal and large diameter stems, mainly Quercus and Fagus, were traded as timber. The dominance of Carpinus is rather uncommon in charcoal studies but supports the importance of Carpinus as fuelwood since the Middle Ages, as confirmed by many written sources.

The Mining Legacy of William S. Godbe

The Mining Legacy of William S. Godbe

English

Most drying equipment required constant electricity, which is rarely available in Sub-Saharan African countries for local farmers. In order to reduce postharvest loss, it is important to develop and use alternative equipment that is cheap and does not require electricity. The aim of this study was to compare the charcoal kiln oven and microwave oven on the drying characteristics of tomato and yam slices, as well as the effects of these different drying techniques on the chemical parameters of tomato and yam slices. The experiment was laid out based on a completely randomized design. In the charcoal kiln, the final moisture content of dried tomato and yam slices was 16.20 and 5.70%, while in the microwave it was 12.25 and 6.60%. These differences were significant (p<0.05). The ash content was higher in microwave-dried tomatoes (1.35%) and kiln-dried yams (3.15%) slices. The protein and carbohydrate contents of kiln-dried tomato slices were significantly (p<0.05) higher than microwave-dried ones, but microwave-dried yam slices were significantly (p<0.05) higher than kiln-dried yam slices. The potassium and iron contents of kiln-dried yam slices were significantly (p<0.05) higher than microwave-dried samples. The heat transfer in microwave-dried tomato and yam slices was significantly (p<0.05) higher than in kiln-dried ones. The charcoal kiln oven was better at drying yam than tomato. Local farmers could benefit from charcoal kiln dryers for the drying process since they do not require power supply.   Key words: Drying, microwave, kiln, tomato, yam.

Effects of Charcoal Production on Soil Physicochemical Properties in Moro Local Government Area of Kwara State, Nigeria

Charcoal production is a major economic activity in rural Kwara State, North-Central Nigeria. Given that it generally involves the use of traditional earth kilns, this study was designed to investigate the effects of charcoal production on the physical and chemical properties of soil. Replicate soil core samples were collected within a depth of 0 - 20 cm from 19 charcoal kiln sites (CKS) and 19 adjacent control sites (ACS) across five administrative districts in the study area. These samples were subjected to laboratory analysis to determine their physical and chemical qualities and then t-test was used to statistically compare the CKS and ACS soils. There was no significant difference in soil texture between both sites. However, CKS soil pH and electrical conductivity significantly increased (p 0.05) due to charred biomass introduced to soils by the process of charcoal production. The CKS cation exchange capacity, Ca and Mg increased significantly (p < 0.0001) by 40.11%, 57.15% and 89.16%, respectively. Charcoal production significantly reduced Fe by 28.54%, while the concentration of other heavy metals remained similar between both sites. The findings showed that charcoal production using traditional earth kilns improves soil physical and chemical properties for agriculture purposes. However, further studies are suggested to understand its effects on vegetation cover and soil biota.

The use of the combined cycle for the generation of electric energy by the gases obtained from the carbonization of wood using

The effluents from carbonization or pyrolysis and wood charcoal have aggregated thermal energy and, in conventional charcoal kilns, part of the wood is burned to ignite the burning in the kilns and the effluents generated are dispensed in the atmosphere and in the soil, which causes energy losses and environmental pollution. In this study we seek a clean and sustainable alternative to produce energy, in addition to the search for a system with satisfactory performance in the generation of electric energy. The objective of this study was to evaluate how much electricity can be produced from wood carbonization effluents by ONDATEC technology, using the Brayton and Rankine cycle, also known as Combined Cycle. This method presents a high power generation efficiency, around 50%, compared to other generation systems. A field experiment was carried out from October 21st to 24th, 2010 to determine the calorific value of wood carbonization effluents, using a microwave oven, (condensable and non-condensable gas), in the city of Uberaba -Mg, Brazil. The data generated in this study reveals important information for companies looking for a way to produce clean and renewable electricity from reforestation wood, in addition to the effort to minimize environmental pollution, ensure sustainability in production systems and the growing search for new sources of energy. A complete description of the experiment, including details of the project, is presented in this work.

The use of remote sensing tools for accurate charcoal kilns’ inventory and distribution analysis: Comparative assessment and prospective

Historical charcoal production is one of the significant factors affecting today’s forest dynamics. A key challenge is to develop tools to investigate historical charcoal production over large areas, allowing a more comprehensive understanding of past impacts and history of charcoal production over a given landscape. In this study, high-resolution remote-sensing airborne LiDAR images over a large woodland area were used to compare manual on-screen versus algorithm-based automatic methods to inventory charcoal kilns with inputs of field-validated data. The results revealed that (1) the on-screen detection method provided less false-positives, (2) the automatic method detects a higher number of kilns and (3) kiln distribution seemed to be connected mostly to land ownership rather than to environmental variables. This study validates a new method of charcoal kilns’ inventory and spatial analysis that can be applied to other areas to better understand the effect of past biomass harvesting for charcoal production on forest dynamics.

The 2018–2019 excavation of the Xiwubi site in Jiangxian County, Shanxi

Abstract A series of excavations were conducted at the Xiwubi site during 2018–2019, yielding abundant copper metallurgy remains dating to the Erlitou and Erligang cultural periods. Archaeological features include remains of smelting furnaces, charcoal kilns, houses, and refuse pits. A variety of artifacts were retrieved, ranging from copper ores, fragments of smelting furnaces, crucibles, and slag to objects made of pottery, stone, and bone. It is the first copper metallurgy site found in the Zhongtiao Mountains in the vicinity of the heartland of the Xia and Shang dynasties. Characterized by early dates, large scale, and advanced specialization in copper metallurgy, the excavation of the Xiwubi site provides substantial materials for the study of mining and use of copper ore resources by the Xia and Shang dynasties, as well as interactions between copper metallurgy and the destiny of the royal courts.

Limited effects of century-old biochar on taxonomic and functional diversities of collembolan communities across land-uses

Biochar is often considered as a promising climate-smart agricultural tool capable of stabilizing carbon overtime in soils while improving crop productivity. However, long-term consequences for soil biodiversity have barely been addressed. The main aim of this study was to investigate the effects of centennial biochar on the total collembolan densities, the taxonomic and functional diversities of collembolan communities. We sampled preindustrial charcoal kiln sites across three land-uses (cropland, grassland and forest) in temperate soils as model for aged biochar. The complementarity use of total collembolan densities, a taxonomic approach (species richness, Pielou evenness) and a functional approach (functional richness, Rao quadratic entropy, community-weighted means of the functional traits) showed that charcoal enrichment had little effect on collembolan communities. Yet, there was a systematic shift in traits composition of collembolan communities towards traits adapted to life at depth in the presence of charcoal across land-uses. In cropland soils, charcoal induced minor species and abundance changes that significantly shifted the traits composition. In grassland soils, charcoal significantly decreased the taxonomic evenness of communities and host new species with more diverse functional profiles. In forest soils, charcoal was suggested to induce a species domination and a functional homogenization of collembolan communities. Our results suggest that the long-term effect of biochar on soil fauna are related to slight direct or indirect modifications of soil habitat, which hinges on land-use. Indeed, the land-use was a much stronger driver in shaping soil collembolan communities than centennial charcoal. We advocate furthering functional traits studies on the ecological and edaphic mechanisms driving Collembola long-term responses to biochar amendment.

Legacies of historic charcoal production affect the forest flora in a Swedish mining district

Iron production was historically associated with major impacts on forests worldwide, as vast amounts of wood were harvested to produce the charcoal needed for heating the furnaces and reducing iron oxides in the ore to iron. This impact has left abundant legacies which potentially may remain in the present‐day vegetation. We investigated how remains of historic charcoal production, mainly from the 18th to the early 20th century, at still remaining charcoal kiln platforms (CKPs), affect the current species richness, species occurrences and cover of vascular plants in the ground vegetation in a Swedish mining district located in the boreo‐nemoral forest zone. CKPs have a significantly higher species richness than the surrounding forest, and they also affect cover (negatively) for ericaceous species typically dominating the forest ground vegetation. Several forest species are more frequent at CKPs, and these also harbor significantly more uncommon species, of which many are typical for traditionally managed grasslands. These latter species are likely to represent remnants in present‐day forests reflecting former land‐use such as livestock grazing. The soil chemistry at CKPs is strongly deviating from the surrounding forest, and this, together with a lower cover of ericaceous shrubs, are the most likely mechanisms behind the higher species richness. CKPs represent conspicuous and abundant historic anthropogenic habitats in the forest vegetation. As far as we are aware, the flora at CKPs in boreal and boreo‐nemoral forests has not previously been investigated in detail, and they deserve more attention, both from a biological and a cultural–historical perspective.

The socio-ecological legacies of centuries-old charcoal making practices in a mountain forest of the northern Pyrenees

Centuries of charcoal making has profoundly shaped European mountain forest ecosystems. However, it remains difficult to assess this impact due to a lack of knowledge about the full operational sequence and related silvicultural systems. To accurately reconstruct such practices and shed light on the resulting legacies, we carried out an interdisciplinary study in the Bernadouze forest, a 46 ha mountain forest of European beech (Fagus sylvatica L.) in the French Pyrenees. We performed a multi-proxy analysis of 7990 charcoal fragments from 28 charcoal kilns to assess the long-term changes in forest composition and structure, but also in harvesting practices and related silvicultural systems. In addition, we assessed the legacy of such practices on the forest’s main features, by evaluating the biodiversity on 13 one-hectare plots using the Index of Potential Biodiversity (IBP). The 18 radiocarbon dates showed that charcoal making took place at least from the 9th-10th c. to the 19th-20th c. Beech and silver fir (Abies alba Mill.) were the main species used. We discerned sustainable silvicultural practices performed over the centuries without significant change. Charcoal burners harvested well calibrated wood pieces mostly from the end of the growing season until the early spring, and charred after a seasoning period. The forest was managed as a beech coppice with fir standard before being progressively transformed, between the mid 15th-mid 17th c. period, into a monospecific beech coppice, probably treated in a coppice selection system. While this management allowed forest cover to be continuously sustained, it also resulted in the homogeneity of the forest today, both in composition and structure, and led to low hosting capacity for biodiversity. Nevertheless, this ancient forest, which constitutes a high biocultural legacy due to immemorial use rights, needs dedicated management.

Pitch oil production – An intangible cultural heritage in Central Europe

Pitch oil production from Scots pine (Pinus sylvestris L.) resinous wood is an intangible cultural heritage in the Central European region including the Czech Republic, Northern Austria and South Eastern Germany, and is related to traditions in Finland and Southern France. The heating of wood in small kilns also fueled by wood produces liquid for collection. Our detailed investigations of three pitch oil kilns in Upper Austria led to the discovery of relationships to the production of pine and birch tar in Fennoscandia and black pine tar production in Western Anatolia. Our measurements of temperatures at the bases of the kilns revealed a slow temperature rise. We predicted maximum temperatures based on infrared spectra, and measured overall temperatures in the range of 250 °C–650 °C. With gas chromatographic analyses of pitch oil we detected a dominant proportion of resin components and only a minor proportion of compounds attributable to pyrolytic transformation of solid wood mass. In most pitch oil samples the extractives comprised 90 %. Most samples were similar and only the first samples at the starting outflow were systematically dominated by pyrolysis products. Tar runoff from a traditional circular charcoal kiln for charcoal production – used as a reference – had a strongly different composition, with a high proportion of pyrolysis compounds.