Judul: Spatial Analysis of Rice Husk Availability as Biomass Cofiring Material at Power Plant in Indramayu
Abstrak: Indonesia berencana mengurangi emisi gas rumah kaca (GRK) sebesar 29% pada tahun 2030 untuk mengatasi tingginya penggunaan energi fosil. PLN berencana mengimplementasikan teknologi cofiring biomassa di 52 pembangkit listrik pada tahun 2025. Teknologi ini menghadapi tantangan keberlanjutan pasokan karena penelitian yang kurang memadai dan pencatatan pada penggilingan padi yang hanya sebesar 33,52%. Penelitian ini mengevaluasi ketersediaan sekam padi sebagai sumber biomassa di Indramayu, daerah penghasil padi terbesar di Indonesia. Pengumpulan data dilakukan melalui survei dan wawancara, dengan analisis spasial menggunakan Quantum GIS (QGIS) 3.22.12. Studi ini menghasilkan peta ketersediaan sekam padi di Indramayu. Sebanyak 95 penggilingan padi disampel: kecil (79), menengah (12), dan besar (4), masing-masing beroperasi 4, 5, dan 6 hari. Potensi produksi sekam harian adalah 0,87 ton/hari (kecil), 4,83 ton/hari (menengah), dan 10,74 ton/hari (besar). Ketersediaan teoritis sekam padi tahunan di Indramayu adalah 272.106 ton, dengan data spasial menunjukkan 601.669 ton/tahun dan distribusi skala menunjukkan 588.861 ton/tahun. Penggunaan sekam padi bersaing dalam delapan distribusi, terutama sebagai bahan bakar di industri genteng, bata, dan semen. Fraksi pemulihan sekam pada musim panen adalah 13,23% (kecil), 17,50% (menengah), dan 23,33% (besar), dan pada musim tidak panen adalah 3,90%, 10%, dan 15%. Ketersediaan sekam padi yang dapat dimobilisasi di Indramayu adalah 77.102,17 ton/tahun, cocok untuk cofiring biomassa di PLTU Indramayu, meskipun masih kurang untuk kebutuhan biomassa secara keseluruhan. Kebijakan terkait penggunaan dan pengelolaan sekam padi diperlukan untuk implementasi yang lebih luas di daerah penghasil padi., Indonesia aims to reduce greenhouse gas emissions by 29% by 2030, addressing high fossil energy use. PLN plans to implement biomass cofiring technology at 52 power plants by 2025. This technology faces supply sustainability challenges due to inadequate research and low milling documentation (33.52%). This study evaluates the availability of rice husks as a biomass source in Indramayu, Indonesia's largest rice-producing area. Data collection involved surveys and interviews, and spatial analysis used Quantum GIS (QGIS) 3.22.12. The study produced a map of rice husk availability in Indramayu. Ninety-five rice mills were sampled: small (79), medium (12), and large (4), operating 4, 5, and 6 days respectively. Daily rice husk production potential is 0.87 tons/day (small), 4.83 tons/day (medium), and 10.74 tons/day (large). Theoretical annual rice husk availability in Indramayu is 272,106 tons, with spatial data showing 601,669 tons/year and scale distribution showing 588,861 tons/year. Rice husk usage competes across eight distributions, mainly as fuel in tile, brick, and cement industries. Recovery fractions during harvest are 13.23% (small), 17.50% (medium), and 23.33% (large), and during non-harvest are 3.90%, 10%, and 15%. Mobilizable rice husk availability in Indramayu is 77,102.17 tons/year, suitable for biomass cofiring at Indramayu power plant, though insufficient for overall biomass needs. Policies on rice husk use and management are needed for broader implementation in rice-producing regions.
Keyword: cofiring biomassa, Indramayu, penggilingan padi, QGIS, sekam

Judul: Transportation Cost Planning of Rice Straw as Raw Material for Bio-LNG Manufacturing in Indramayu Regency
Abstrak: Industri bioenergi di Indonesia memiliki persentase terkecil sebesar 4% dari total penghasil emisi gas metana di sektor energi. Hal ini membuka peluang untuk mengembangkan Bio-LNG sebagai salah satu bentuk bioenergi dan sesuai dengan Rencana Umum Energi Nasional dan mendukung SDG 7 Energi Bersih dan Terjangkau. Jerami padi merupakan salah satu bahan baku Bio-LNG. PT XY yang merupakan perusaahaan pengembangan energi, berencana membangun pabrik pengolahan Bio-LNG di Kabupaten Indramayu dengan bahan baku dari jerami padi. Penelitian dilaksanakan di Kabupaten Indramayu pada bulan Desember 2022 sampai dengan Maret 2023 dengan tujuan menganalisis perencanaan biaya transportasi dan total biaya pengadaan jerami padi sebagai bahan baku Bio-LNG di Kabupaten Indramayu. Solusi optimum awal diperoleh menggunakan Vogel’s Approximation Method dan uji optimalitas menggunakan Modified Distribution. Hasil penelitian menunjukkan bahwa biaya transportasi jerami padi di Kabupaten Indramayu dipengaruhi oleh jarak dari pemasok ke pabrik dan jumlah jerami padi yang dapat diangkut dalam satu kali perjalanan. Semakin jauh jarak dari pemasok ke gudang mengakibatkan biaya transportasi semakin besar., The bioenergy industry in Indonesia has the smallest percentage of 4% of the total methane gas emitters in the energy sector. This opens up opportunities to develop Bio-LNG as a form of bioenergy and is in line with the National Energy General Plan and supports SDG 7 Clean and Affordable Energy. Rice straw is one of the raw materials for Bio-LNG. PT XY, an energy development company, plans to build a Bio-LNG processing plant in Indramayu Regency with raw materials from rice straw. The research was conducted in Indramayu Regency from December 2022 to March 2023 with the aim of analyzing transportation cost planning and the total cost of procuring rice straw as raw material for Bio-LNG in Indramayu Regency. The initial optimum solution was obtained using Vogel's Approximation Method and optimality test using Modified Distribution. The results showed that the transportation cost of rice straw in Indramayu Regency is influenced by the distance from the supplier to the factory and the amount of rice straw that can be transported in one trip. The longer the distance from the supplier to the warehouse results in greater transportation costs.
Keyword: bio-lng, rice straw, transportation, Sdgs

Judul: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
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