Suitability of aquatic biomass from Lake Toba (North Sumatra, Indonesia) for energy generation by combustion process

Abstract

Several aquatic plant species were identified as aquatic pollution of Lake Toba, North Sumatra (Indonesia); specifically, water hyacinth Eichhornia crassipes and aquatic weeds Hydrilla verticillata and Myriophyllum spicatum due to their high biomass yield which causes impenetrable mats at the bottom and surface of the lake. That complicates other vegetation growth and utilization of water areas for fishing or recreation. In attempt to clean the lake and prevent plants expansion, great amount of plants populations are removed from water but subsequent efficient utilization of such aquatic biomass is not ensured. Present research investigated energy potential of aquatic biomass originated from mentioned aquatic plants from Lake Toba and its possible utilization for energy production by direct combustion. Performed chemical analysis contained from determination of moisture, ash and volatile matter contents and calorific values. Evaluation of results proved highest suitability and energy potential of Eichhornia crassipes with gross calorific value (GCV) 16.31 MJ•kg-1, followed by Hydrilla verticillata with GCV 15.24 MJ•kg-1. Samples of Myriophyllum spicatum exhibited unsatisfactory results due to its low GCV (11.27 MJ•kg-1) in combination with high ash content (36.99%) which indicates complications during combustion, thus, low energy production efficiency and overall unsuitability for combustion purposes.