Effect of Harvesting Age and Size Reduction in the Performance of Anaerobic Digestion of Pennisetum Grass

Abstract

In the rural zones of Latin American and Caribbean developing countries, the poorest households rely on traditional fuels such as firewood to meet their daily cooking needs. Many of those countries are located near the equator, where they have a tropical climate and grass is one of the most common biomass crops. The aim of this study was to evaluate the effect of harvesting age (30, 44, and 57 days) in the performance of anaerobic digestion of King Grass (Pennisetum purpureum cv. King Grass) grown under tropical climate conditions. Three reduction methods of crop size were also compared. Results showed that 44-day harvesting age presented the greater specific methane yield (347.8 mLCH4 g−1VS) and area-specific methane yield (9773 m3CH4 ha−1 y−1). The machine chopped method (1–3 cm for stems and 1–10 cm for leaves) was the reduction method that maximized the methane production. From those results, the calculated area required for grass cultivation to provide the cooking energy to a typical family in the Colombian rural zones is 154 m2.

Avances en investigación sobre el mejoramiento del compostaje de residuos verdes en países en desarrollo: experiencias desde Colombia

“…Table 1 identifies the physicochemical characteristics of GW, showing the high variability of this type of waste in eight Colombian cities, in parameters such as moisture (ranging from 20% to 78%), TOC (ranging from 26% to 43%) and TN (ranging from 0.65 to 2.75%). Cali (33) Cali-Rural (34) Palmira (35) Moisture…”

Environmental, social and health benefits of alternative renewable energy sources. Case study for household biogas digesters in rural areas

“…Later, during a similar period, the crop was fertilized with digestate of the biogas household unit and complemented with mineral fertilizers. The agronomic and methane yields were determined in Pizarro-Loaiza et al (2020).…”

“…Previous studies evidenced that anaerobic digestion of King Grass (Pennisetum purpureum cv. king grass) in domestic digesters could generate a specific methane yield of 347 mLCH4 g -1 VS, and area-specific methane yield of 9,773 Nm 3 CH4 ha -1 y -1 with optimal harvest age of 44 days (Pizarro-Loaiza et al, 2020).…”

“…Previous studies, also shown that cooking energy for a typical family in Colombian rural zones, with biogas produced by anaerobic digestion of grass, would require 154 m 2 of King Grass crop, that can be easily assumed by this type of housing (Pizarro-Loaiza et al, 2020).…”

Estimating the Methane Potential of Energy Crops: An Overview on Types of Data Sources and Their Limitations

“…This requires a detailed knowledge of the biomass composition and thus involves some laboratory analyses. This method is also applied to complement experimental AD testing and allow evaluation of the efficacity of the AD process [140].…”