Abstract.To help reduce dependence on fossil fuels for mechanized farm operations, we developed and tested a distiller using fermented nipa sap with 7% alcohol content and diluted nipa sap fermentation liquor or crude bioethanol (15% concentration) to produce fuel-grade bioethanol for small spark-ignition engines. Keywords: Click here to enter keywords and key phrases, separated by commas, with a period at the end

While the Philippine Biofuels Act of 2006 mandates the use of anhydrous bioethanol as blend for gasoline, the potential of hydrous ethanol as an alternative fuel for spark-ignition engines has not been fully realized. This study explored the possibility of using hydrous ethanol as fuel for spark-ignition engines with minimal modifications and without the need for gasoline blend.A fuel feeding device was developed to feed hydrous ethanol fuel into the intake manifold of the engine, bypassing the carburetor. By replacing the components that are not compatible with hydrous ethanol and installing a fuel feeding device developed at PhilRice, two spark-ignition engines were able to run solely on 80-95% hydrous ethanol fuel. The fuel economy was found to be a significant issue in the utilization of hydrous ethanol fuel as there is a 75% increase in fuel consumption when using hydrous ethanol. There is potential for hydrous ethanol to be used as fuel if it can be produced locally and sold at half the pump price of gasoline.

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An appropriate rice-based (ARB) biomass gasifier was designed and developed for farmers' use. The gasification properties of rice-based biomass were determined before doing the design. The gasifier was built using salvage petrol drums, metal bars and concrete as primary construction materials. It has a 30 cm-diameter reactor insulated with refractory cement. A 10 cm-φ cross flow scrubber with 30 cm-thick packed-bed filter is used for conditioning the gas. The gas is converted to mechanical power with the use of a four-stroke-cycle, spark ignition engine commonly used by farmers. The gasifier was tested and underwent series of modifications and improvements. Performance test and evaluation showed that the gasifier performs satisfactorily as per design. Raw rice husk was found to have greater advantage as fuel for the gasifier than rice straw. It can drive stationary agricultural machines such as a 4-in. pump, a 30-cm biomass chipper, and a 20-cm rubber creeping mill. It can also power a 3-kWe AC generator for lighting and a 60-Amp DC alternator for charging batteries. The entire system can be built at a cost of P90,000.00 (USD1 = PHP50) using local materials and skills. Analysis showed that the operating cost of the gasifier is only P94.15 per day. A savings o P244.94 per day can be derived against the use of purely gasoline fuel for the engine. Payback period is 1.22 years.

A variable-feed hydrous-bioethanol fuel injector (VFHBFI) for retrofitted engine was designed and evaluated to provide a technology that would allow spark-ignition engines commonly used by farmers be fuelled with hydrous bioethanol from nipa. With this technology, farmers can make use of their farm resources to fuel their engines making them less dependent on imported fossil fuel. The VFHBFI consists of the following components: 1) Fuel tank; 2) DC pump; 3) Fuel line; 4) PWM switch; 5) Battery; and 6) Fuel injector. The tank is made of a stainless-steel cylinder with 2-liter capacity of hydrous bioethanol (95%). The DC pump that feeds alcohol fuel is a diaphragm-type operating on a 12-volt line. It is ran by a 16-AH gel-type battery and its pumpingrate is regulated by a 12-volt, 0.8-Amp PWM switch. The position of the switch and of the battery is dictated by the kind of machine to be powered. The fuel line that delivers the alcohol to the engine is made of an alcohol-resistant plastic hose. The VFHBFI was evaluated using a 6.5-hp spark-ignition Kenbo engine retrofitted to utilize hydrous bioethanol as fuel. The fuel feed rate was calibrated with the PWM switch setting. A micro-tiller and a power-tiller-operated hauler were used in the evaluation. The forward speed of the power-tiller-operated hauler was also evaluated at varying load. Results showed that the VFHBFI performs satisfactorily as per design. The fuel feeding rate of the injector behaves linearly with the PWM switch setting. It was observed that smooth engine speed is achieved at medium to high PWM switch setting. Using the VFHBFI, a retrofitted-engine-driven micro-tiller successfully tilled a 1500 m 2 farm making it ready for planting in 2 to 3 passes. The average amount of fuel consumed in tilling was 2.0 liters per hour, which is double than when using pure gasoline as fuel. Also using the VFHBFI, a retrofitted-engine-driven power-tiller hauler consumed an aver