Kajian penggunaan gas hasil gasifikasi tongkol jagung sebagai bahan bakar motor diesel sistem bahan bakar ganda (dual fuel)

MADE SUMITA, Prof.Dr.Ir. Bambang Purwantana, M.Agr.; Prof.Dr.Ir. Lilik Sutiarso, M.Eng.

2015 | Tesis | S2 Teknik Pertanian

Kebutuhan terhadap energi terus meningkat untuk menopang kebutuhan hidup penduduk dunia yang jumlahnya terus meningkat secara eksponensial. Di antara produk olahan minyak bumi, solar merupakan jenis minyak bumi yang paling banyak digunakan. Menipisnya cadangan minyak bumi, menyebabkan semakin meningginya harga minyak. Beberapa upaya telah dilakukan untuk mengatasi kondisi ini diantaranya mencari sumber energi berbahan baku biomassa bersifat terbarukan. Gasifikasi merupakan suatu teknologi proses konversi bahan padat seperti biomassa, arang, batu bara menjadi gas yang mudah terbakar. Produk gas tersebut dapat digunakan sebagai bahan bakar motor penggerak generator untuk membangkitkan energi listrik. Tongkol jagung merupakan biomassa yang tersedia melimpah dan dianggap sebagai limbah dibeberapa sentra pertanian jagung. Penelitian ini bertujuan mengkaji penggunaan hasil gasifikasi tongkol jagung sebagai bahan bakar motor diesel dengan sistem bahan bakar ganda (dual fuel). Gas hasil gasifikasi tongkol jagung (kadar air 10,15%) dialirkan ke mesin melalui asupan udara dengan variasi 0, 25, 50, dan 75% dari asupan total udara ke mesin. Masing-masing variasi diberi perlakuan beban 0, 5, 10, 15, dan 20 buah lampu bohlam 100W dan dicatat perubahan putaran mesin, konsumsi bahan bakar, serta tegangan dan daya out generator yang digerakan oleh mesin. Semakin banyak gas hasil gasifikasi dialirkan semakin meningkat pula putaran mesin, penghematan konsumsi solar (hingga 56,61%), serta tegangan dan daya output generator. Pada uji statistik analisis varians dua arah tanpa interaksi (alfa: 0,01), variasi persentase gas hasil gasifikasi yang dialirkan berbeda nyata terhadap konsumsi solarnya. Uji DMRT untuk variabel persentase gas hasil gasifikasi menunjukan bahwa masing-masing variasi memberi pengaruh yang berbeda-beda terhadap konsumsi solar. Penggunaan gas hasil gasifikasi tongkol jagung untuk bahan bakar diesel dual fuel dapat memberikan keuntungan secara ekonomis hingga 4,67 kali lipat dari nilai tongkol jagung sebelumnya.

The need of energy is continuously increasing in line with the world population that also increases exponentially to support the human needs. Among the petroleum products, diesel fuel is used most frequently. The diminishing stock of the petroleum leads to the high cost. Several efforts have been done to conquer the issue, for instance finding renewable energy sources that use bio-mass raw material. Gasification refers to a term used for a technology to converse solid materials (bio-mass, charcoal, or coal) into flammable gas. The gas product can be used as diesel motor fuel to activate the generator in generating the electricity. Corncob is plenteous available bio-mass and considered as wasted materials in some corn agricultural centers. The objective of this research is to analyze the use of corncob gasification as diesel motor fuel in dual fuel system. The gas as the result of corncob gasification process (contains 10.15% water) was flowed into the machine through the air intake with 0, 25, 50, and 75% level of total air intake. Each variation was given the load of 0, 5, 10, 15, and 20 light bulbs, each with 100W capacity. The changes on rotary engine, fuel consumption, as well as the voltage and output generator power were recorded. The amount of resulted gas gasification was in line with the rotary engine, diesel consumption as well as the voltage and output power of the generator. It was resulted in the solar consumption which decreased 56.61%. In statistical testing using two-way anova (alfa: 0.01), variations of the flowed gas percentage showed the significant difference through the diesel fuel consumption. DMRT testing for the gas resulted in the fact that each variation contributed different effect in the diesel fuel consumption. The use of resulted gas of corncob gasification process as diesel motor fuel in dual fuel system led to economical profit 4.67 times the previous value of the corncob.

Kata Kunci : dual fuel, gasifikasi, mesin diesel, tongkol jagung, corncob, diesel engine, dual fuel, gasification.