Page 13 - InnoRenew CoE International Conference 2021, Healthy and Sustainable Renovation with Renewable Materials
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veloping electrically conductive materials through thermal conversions of
hemp stalk wastes
Laetitia Marrot 1,2, Kevin Candelier 3, Jérémy Valette 3, Charline Lanvin 3, Barbara Horvat 4, Lea
Legan 5, David B. DeVallance 1,2
1. InnoRenew CoE, Livade 6, 6310 Izola, Slovenia, laetitia.marrot@innorenew.eu, devallance@innorenew.eu
2. University of Primorska, Andrej Marušič Institute, Muzejski trg 2, 6000 Koper, Slovenia
3. UR BioWooEB, CIRAD, TA B-114/16, 73 Rue Jean-François Breton, F-34398 Montpellier Cedex 5, France, kevin.candelier@cirad.fr,
jeremy.valette@cirad.fr, charline.lanvin@cirad.fr
4. Slovenian National Building and Civil Engineering Institute, Dimičeva ulica 12, 1000 Ljubljana, Slovenia, barbara.horvat@zag.si
5. Institute for the Protection of Cultural Heritage of Slovenia, Poljanska 40, 1000 Ljubljana, Slovenia, lea.legan@zvkds.si
This study focuses on innovative ways for the valorisation of hemp by-products (i.e., hemp stalks)
from the cannabidiol industry through thermal conversion. Successive chemical extractions and
Scanning Electron Microscopy along with Energy-dispersive X-ray Spectroscopy Chemical were used
to characterize the elemental composition of hemp stalks. The chemical characterization of the hemp
biomass and its biochar was completed with proximate and elemental analyses. Kinetic of decomposition
during thermal conversion was investigated through thermogravimetric analysis of the hemp biomass.
Raman spectroscopy and CO2 gas adsorption were performed to assess the carbon structure and
porosity of the biochar. In this study, the energy production measured through calorific values, and the
electrical conductivity were the properties of interest. Two ways to value the hemp biomass were clearly
identified, depending mainly on the chosen carbonization temperature. Carbonization temperatures
between 400°C-600°C allowed to produce hemp biochar classified as lignocellulosic materials with a
good potential for solid biofuel applications. Specifically, the resulting carbonized biochar combined low
moisture content (higher fuel quality), low volatile matter (so likely to show lower particle matter emissions),
limited ash content (low risk of fouling issues during the combustion), high carbon content (suggesting
strong energy density) associated with fairly high higher heating values and optimized energy yield.
Carbonization temperatures between 800°C-1000°C led to carbon materials with interesting electrical
conductivity, opening opportunities for biochar use in electrical purposes. The electrical conductivity was
related to the higher order in carbon structure observed in biochar produced at high temperature, and
to the surface area associated with biochar microporosities, with higher surface area resulting in higher
conductivity.
Keywords: hemp, pyrolysis, carbonization, thermal conversion, biochar, electrical conductivity
Acknowledgement
Authors gratefully acknowledge the European Commission for funding the InnoRenew project (grant
agreement #739574 under the Horizon 2020 WIDESPREAD-2-Teaming program) and the Republic of
Slovenia (investment funding from the Republic of Slovenia and the European Regional Development
Fund), the European Union’s Horizon 2020 research and innovation programme under the Marie
Skłodowska-Curie Actions (grant number 898179), and COST Action CA17107.
HEALTHY AND SUSTAINABLE RENOVATION WITH RENEWABLE MATERIALS
13
hemp stalk wastes
Laetitia Marrot 1,2, Kevin Candelier 3, Jérémy Valette 3, Charline Lanvin 3, Barbara Horvat 4, Lea
Legan 5, David B. DeVallance 1,2
1. InnoRenew CoE, Livade 6, 6310 Izola, Slovenia, laetitia.marrot@innorenew.eu, devallance@innorenew.eu
2. University of Primorska, Andrej Marušič Institute, Muzejski trg 2, 6000 Koper, Slovenia
3. UR BioWooEB, CIRAD, TA B-114/16, 73 Rue Jean-François Breton, F-34398 Montpellier Cedex 5, France, kevin.candelier@cirad.fr,
jeremy.valette@cirad.fr, charline.lanvin@cirad.fr
4. Slovenian National Building and Civil Engineering Institute, Dimičeva ulica 12, 1000 Ljubljana, Slovenia, barbara.horvat@zag.si
5. Institute for the Protection of Cultural Heritage of Slovenia, Poljanska 40, 1000 Ljubljana, Slovenia, lea.legan@zvkds.si
This study focuses on innovative ways for the valorisation of hemp by-products (i.e., hemp stalks)
from the cannabidiol industry through thermal conversion. Successive chemical extractions and
Scanning Electron Microscopy along with Energy-dispersive X-ray Spectroscopy Chemical were used
to characterize the elemental composition of hemp stalks. The chemical characterization of the hemp
biomass and its biochar was completed with proximate and elemental analyses. Kinetic of decomposition
during thermal conversion was investigated through thermogravimetric analysis of the hemp biomass.
Raman spectroscopy and CO2 gas adsorption were performed to assess the carbon structure and
porosity of the biochar. In this study, the energy production measured through calorific values, and the
electrical conductivity were the properties of interest. Two ways to value the hemp biomass were clearly
identified, depending mainly on the chosen carbonization temperature. Carbonization temperatures
between 400°C-600°C allowed to produce hemp biochar classified as lignocellulosic materials with a
good potential for solid biofuel applications. Specifically, the resulting carbonized biochar combined low
moisture content (higher fuel quality), low volatile matter (so likely to show lower particle matter emissions),
limited ash content (low risk of fouling issues during the combustion), high carbon content (suggesting
strong energy density) associated with fairly high higher heating values and optimized energy yield.
Carbonization temperatures between 800°C-1000°C led to carbon materials with interesting electrical
conductivity, opening opportunities for biochar use in electrical purposes. The electrical conductivity was
related to the higher order in carbon structure observed in biochar produced at high temperature, and
to the surface area associated with biochar microporosities, with higher surface area resulting in higher
conductivity.
Keywords: hemp, pyrolysis, carbonization, thermal conversion, biochar, electrical conductivity
Acknowledgement
Authors gratefully acknowledge the European Commission for funding the InnoRenew project (grant
agreement #739574 under the Horizon 2020 WIDESPREAD-2-Teaming program) and the Republic of
Slovenia (investment funding from the Republic of Slovenia and the European Regional Development
Fund), the European Union’s Horizon 2020 research and innovation programme under the Marie
Skłodowska-Curie Actions (grant number 898179), and COST Action CA17107.
HEALTHY AND SUSTAINABLE RENOVATION WITH RENEWABLE MATERIALS
13
