Energy Nexus (Dec 2022)
Application of organic additives as voltage enhancers for vermicompost-derived bio-battery
Abstract
Vermicomposting enhances the breakdown of the organic wastes into vermicompost by adding earthworms. Recent studies revealed the potential of vermicompost to be used as electrolyte of bio-battery however, the voltage is lower and less stable than conventional batteries. The main goal of this research is to evaluate the quality of vermicompost generated and improve the voltage generation of vermicompost-derived battery. The vermicompost was first produced from green wastes collected in the vicinity of Universiti Teknologi PETRONAS (UTP) campus at optimum carbon-to-nitrogen (C:N) ratio of 30:1. Next, humic and fulvic acid were extracted from vermicompost and used as electrolytes for bio-batteries with different organic additives namely, deionized water, spent tea waste, spent coffee waste, fruit enzyme and lemon juice which served as voltage enhancers. Vermicompost quality was established by final C:N ratio with respect to the total organic carbon and total Kjeldahl nitrogen as well as humic and fulvic acid yields and moisture content analysis in comparison to commercial vermicompost while voltage enhancement was assessed via voltage profiling using digital multimeter over a period of time. Key highlights include the generated vermicompost reaching maturation on day 40 with mass reduction of 18% and humic and fulvic acid yields at 3.41% and 0.38%, significantly higher than that of commercial vermicompost. The highest voltage recorded was 0.62 V for humic acid electrolyte with fruit enzyme additive followed by humic acid electrolyte with lemon juice additive which exhibited 0.61 V voltage generation. Should UTP make the move to harness electricity from vermibatteries, a comprehensive economic feasibility study with sound assumptions deduced that the payback period of the project is approximately 2.8 years which is very promising. Vermicomposting green wastes has multiple benefits from cutting down labour requirement to promoting eco-friendly waste management and generating high-quality compost and bio-battery electrolytes.
