Promoting Sustainability in the Energy Sector in Nepal-with a Focus on Biodiesel Fuel

Abstract

This study analyzes the sustainability of various energy sources including micro hydro power and biodiesel in the context of Nepal. The main focus is on the development of biodiesel fuels from non-edible oil resources including waste cooking oil, jatropha and soapnut oil feedstocks grown on the marginal lands of Nepal.

Biodiesel fuel samples were prepared by acid and/or base catalyst transesterification. Both single stage and dual stage transesterification processes were employed depending on the free fatty acid content of the oil feedstock. The oil to biodiesel conversion rate and total yield were monitored. The quality of the biodiesel fuels including viscosity etc was confirmed by an external laboratory and all fuels met the ASTM fuel quality requirements.

Canola, jatropha and soapnut biodiesel fuels were tested to determine some atomization properties - density, surface tension and viscosity - at elevated temperatures and pressures. The density of three biodiesel fuels and diesel were determined up to 523 K and 7 MPa using a capacitance type densitometer. The results showed a linear relationship with temperature and pressure over the measured range. The experimental data were well within the range of canola and other biodiesel fuels found in the literature. Kay’s mixing rule was used to predict the density of some biodiesel blends and the results were found to be in agreement with less than 5% error with the measured data.

The surface tension was measured using a pendant drop apparatus for all three biodiesel and diesel fuels for temperatures and pressures up to 473K and 7 MPa. Results showed a linear relationship with temperature as well as with pressure. Temperature has a higher effect on surface tension than pressure.

The viscosity of all three biodiesel and diesel fuels were measured using a torsional vibration viscometer up to 523 K and 7 MPa. Results showed that the viscosity-temperature relationship of all three biodiesel fuels tested followed a modified Andrade equation which was also applicable when temperature and pressure were both applied simultaneously. The measured and regressed kinematic and dynamic viscosities obtained were comparable with values in the literature.