Straw pyrolysis for use in electricity storage installations

Abstract

A concept has been proposed for an installation designed to store excess electricity periodically occurring on the grid. Excess electricity will be used for straw pyrolysis. The main pyrolysis product, gas, will be used to generate electricity using a combustion generator to feed back power into the grid during periods of shortage. The resulting biochar from the pyrolysis can be introduced into the soil to improve soil quality and play a significant role in carbon sequestration. The system uses an electrically heated reactor with a screw conveyor. To preliminarily assess the feasibility of this system, experiments were carried out using wheat straw at temperatures of 300, 400, 500, 600, and 700 degrees C for the pyrolysis reactor. The resulting gas -to -feedstock mass ratio ranged from 29.04 % at 300 degrees C to 52.7 % at 700 degrees C reactor temperature, the biochar mass yield ratio to feedstock varied from 39.41 % to 27.36 % (at 700 degrees C), and the pyrolysis liquid ranged from 31.55 % to 27.36 % (at 700 degrees C). The pyrolytic liquid contained a high water content relative to its mass, reaching up to 95.2 % at 700 degrees C, rendering it less suitable as an energy feedstock. At a reactor temperature of 700 degrees C, the energy value of the gas produced from the feedstock was twice that of the electricity used for the pyrolysis process. These results suggest the feasibility and operation of the proposed installation.