Date of Award

Summer 8-2-2024

Degree Type

Thesis

Degree Name

Master of Science in Materials Science and Engineering (MSMSE)

Department

Materials Science

Committee Chair

Richard Ladouceur

First Advisor

Jack Skinner

Second Advisor

Grant Wallace

Abstract

Solar process heat pyrolysis mobilizes the production of biochar via selective solar absorbance. Mobilization allows for the production of pyrolysis products at the location of the biomass source while eliminating the need for infrastructural power to operate the reactor. Traditionally, the implementation of economies of scale has led to large, permanent biochar production facilities; however, biochar feedstock is often in remote locations or stockpiled temporarily in mill/forestry operation locations. Modular reactors are important to eliminate feedstock location, transportation, and variability limitations. Previous work at Montana Technological University’s CHAR Laboratory has developed two lab scale modular, both tethered to infrastructural power. The utilization of concentrated solar power frees the reactor operation location to any area with incident solar radiation. Pyrolysis conditions require elevated temperatures up to 600 °C combined with an inert atmosphere to decompose biomass into biochar, bio-oil, and syngas. Temperatures this high are difficult to achieve through solar absorption due to re-radiation from the absorbing surface. Selective solar absorbers (SSAs) are a class of optical surfaces that prevent re-radiation by selecting which bandwidths of the solar spectrum are reflected and absorbed. Tuning the solar concentration and cutoff wavelength between reflection and absorption determines the operating temperature of the surface. Reactor design accounts for convective and conductive heat losses, creating a one-way stream of energy directed at the biomass feedstock, facilitating pyrolysis once sufficient temperatures are achieved. Selective solar absorbers applications have been limited to water heating applications while pyrolysis is currently unobtainable without infrastructure-based power sources. The reactor and methods produced provide a basis for testing and validating the use of selective solar absorbance for process heat-based pyrolysis, allowing the mobilization of biochar production.

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