Characteristics of Biogas-Hydrogen Engines in a Hybrid Renewable Energy System

Van Ga Bui, Trung Hung Vo, Thi Minh Tu Bui, Le Bich Tram Truong, Thanh Xuan Nguyen Thi


Solar-biogas hybrid renewable energy system (HRES) is an effective way for electrification of rural area in the developing countries. When the power of the PV panels of the HRES is higher than that of the load, the excess energy is used to produce hydrogen through the water electrolyser. Hydrogen is then blended with biogas to fuel the internal combustion engine of the generator. A microcontroller connects the PV panels, the water electrolyser, and the consumed network to automatically start the generator when an additional power is needed. The addition of 20% hydrogen into biogas M7C3 leads to an increase in engine cycle work by 13%, 4% and 2% at 100%, 65% and 50% load operating mode, respectively. As compared to full load mode, CO and HC emissions of the engine are doubled, but the NOx emission drops down 50% in the half load operating mode. Independently loading regime, the addition of hydrogen to biogas results in a decrease in CO and HC emissions, but an increase in NOx emissions. At a given speed and engine loading mode, the optimal equivalence ratio and advance ignition angle decrease as increasing CH4 composition in biogas or/and H2 content in fuel blend.


Biogas; Hybrid renewable energy system; Hydrogen storage system; Renewable energy; Solar energy

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