REPLACEMENT OF DIESEL BY BIOGAS GENERATED FROM WASTEWATER TREATMENT IN A SMALL DIESEL GENERATOR BY DUAL FUEL TECHNOLOGY

Canada's remote communities experience harsh weather much of the year and run diesel generators 24 hours a day to provide heat and power. These generators utilize diesel fuel that is transported at great expense and generate greenhouse gas (GHG) and pollutant emissions. Meanwhile, remote communities produce organic wastes, such as wastewater and food wastes. Appropriate treatment of these wastes not only improves the community health and environment, but also generates certain amount of renewable fuels, such as biogas and/or syngas. Replacing diesel fuel by the renewable fuels generated from the waste treatment in the diesel generators can offset the use of diesel and also reduce GHG and pollutant emissions in remote communities. This paper reports an application of biogas generated from wastewater treatment to replace diesel in a small diesel generator by dual fuel engine technology. With simple modification, the biogas containing 50-95% of methane was introduced into the engine intake manifold. Tests were conducted to evaluate the effects of biogas flow rate and composition on average diesel fuel consumption and emissions of carbon dioxide (CO2), carbon monoxide (CO), nitrogen oxides (NOx) and unburned hydrocarbons (HC). The results reveal that the introduction of biogas into the engine reduced the average diesel consumption. However, the reduction of average diesel consumption with increasing biogas flow rate was not linear, possibly due to the increase in HC emissions. The introduction of biogas reduced NOx emissions but increased CO emissions. A change in the composition of biogas (methane to CO2 ratio) did not significantly affect the average diesel consumption and emissions.