Techno-Economic Study of the Use of Refuse-Derived Fuel (RDF) Biomass Waste Conversion into Electricity Using the Three-Stage Gasification Method and Dual Fuel Diesel Engine on Batam Island

Abstract The increasing need for energy has also reduced the availability of fossil fuels so renewable alternative energy is needed. One of the uses of alternative energy that is currently being developed is biomass, one of the developments of biomass into renewable energy can be done through the gasification process. Gasification is the process of converting solid fuels, commonly called Municipal Solid Waste (MSW) which has a water content of 32.08%, volatile solids of 36.09%, ash content of 24.42%, the carbon content of 7.61%, a calorific value of 2,087% can be processed into Biomass Refuse Derived Fuel (RDF) pellets as raw materials for the three-stage gasification process to become syngas as fuel for diesel engines for electricity “Waste to Electric”. In this study, a diesel engine with a dual fuel diesel system was used. The purpose of the diesel engine running with a dual fuel system is to determine the effect of using syngas fuel from gasification with RDF biomass pellets on a diesel engine with a dual fuel system. The dual fuel diesel system is operated using two types of fuel, namely diesel fuel and gas fuel. The gas fuel used is syngas from the gasification of biomass pellets Refuse Derived Fuel (RDF). In the gasification process, the variation of the air ratio is adjusted in the pyrolysis, oxidation, and reduction zones to obtain the most optimal results with the best air ratio at 1:7:2. The comparison of the air ratio from this gasification process can produce the best performance for a diesel engine with a stable engine speed at 3000 rpm, an average voltage at each load change of 246.7 volts. Characterization of the performance of a dual fuel system diesel engine is carried out by testing the diesel engine with a loading variation of 500 watts to 4500 watts with an interval of increasing the loading every 500 watts and variations in the mass flow rate of syngas by adjusting the opening of the syngas valve to the diesel engine. The opening of the syngas valve from the gasifier used is 100%. Testing with a 100% syngas valve opening produces an average value of engine temperature, exhaust gas temperature, and oil temperature that is higher than other percentage variations. Meanwhile, when testing with single fuel mode, the lowest engine temperature, exhaust gas temperature and oil temperature values were produced at each load change. In addition, the results of the syngas test on a 4500 watt engine with dual fuel mode were scaled up if implemented on a Sekupang PLTD engine with a capacity of 4.48 MW. From the calculation results, the value of savings in the use of diesel fuel on the 4.48 MW PLTD engine was Rp. 875,169,082 per month. The initial investment cost is Rp. 11,460,452,687. While the annual income is Rp. 8,028,548,720.64. So that the Break Event Point (BEP) value is obtained for less than 2 years. In addition, a decrease in the decarbonization value was also produced by utilizing syngas from RDF biomass as fuel on a 4.48 MW dual fuel engine operating for 12 hours every day, 1,094.27 tons of CO2/year or Rp. 32,828,087.26.