Inducing plasma in biomass could make biogas easier to produce

Date:
September 22, 2020
Source:
American Institute of Physics
Summary:
Producing biogas from the bacterial breakdown of biomass presents
options for a greener energy future, but the complex composition of
biomass comes with challenges. Cellulose and woody lignocellulose
are especially hard for bacteria to digest but pretreatment can
make it easier. Researchers are testing plasma formation in biomass
and finding a promising method: A plasma-liquid interaction forms
reactive species that help break down the biomass and decrease
the viscosity of the biomass material.



FULL STORY ========================================================================== Producing biogas from the bacterial breakdown of biomass presents
options for a greener energy future, but the complex composition of
biomass comes with a long list of challenges.


========================================================================== Cellulose and woody lignocellulose in biomass are especially hard for
bacteria to digest, making the process inefficient. Chemical, physical,
or mechanical processes, or several of them combined, can be used for pretreatment to make biomass easier to digest, but many of the current solutions are expensive or inefficient or rely on corrosive chemicals.

In research supported by the European Regional Development Fund, published
in AIP Advances, by AIP Publishing, researchers at the Leibniz Institute
of Plasma Science and Technology are testing plasma formation in biomass
and finding a promising method for pretreatment of biomass.

"The plasma can be seen as a reactive gas, which contains populations of particles that contain several electron volts of kinetic energy. This
energy can be used to break the bond of the chemicals and break the
bonds of molecules with which they interact," author Bruno Honnorat said.

"The most surprising thing was to be able to obtain plasma discharge
conditions in a moving liquid. The presence of a flow considerably
complicates the situation compared to all the other experimental setups
studied in the literature." The work involves creation of a reactor in
which 2-kilowatt microwave pulses injected into a moving liquid model
induce plasma formation within one millisecond. The totality of the
microwave power is concentrated to a small cavity, containing less than
1 milliliter of liquid, which is heated, vaporized, and finally ignited, forming an expanding plasma bubble.

The plasma-liquid interaction forms reactive species, including oxidizing agents, such as hydroxyl radicals and hydrogen peroxides, that help break
down the biomass and decrease the viscosity, or resistance to flow, of the biomass material. In partnership with an industrial agriculture partner,
the process will be further tested at full scale in a biogas plant.

The authors plan to continue their work by more closely examining whether
the plasma breaks the polymer chain and investigating plasma-bubble
dynamics to evaluate the size and shape evolution, lifetime, and
pressure of bubbles in the plasma to better understand the reactive
species created in the plasma.

Their work could be used for increasing biogas production, improving the efficiency of microwave-plasma-liquid interactions, and functionalizing
and modifying polymer length in polymer science.


========================================================================== Story Source: Materials provided by American_Institute_of_Physics. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. B. Honnorat, V. Bru"ser, J. F. Kolb. Microwave plasma discharges for
biomass pretreatment: Degradation of a sodium carboxymethyl
cellulose model. AIP Advances, 2020; 10 (9): 095025 DOI:
10.1063/5.0018626 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/09/200922112307.htm

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