Judul: Economic Benefits Analysis of Fly Ash and  Bottom Ash Waste Utilization Business in West Sumbawa Steam-Electric Power Plant
Abstrak: Peningkatan permintaan energi dan penggunaan listrik menyebabkan konsumsi batubara di Pembangkit Listrik Tenaga Uap (PLTU) meningkat. Pembakaran batubara menghasilkan limbah fly ash dan bottom ash (FABA) dengan dampak negatif terhadap lingkungan. Salah satu PLTU yang berhasil mengelola limbah FABA adalah PLTU Sumbawa Barat. Penelitian ini bertujuan mengidentifikasi proses pemanfaatan limbah FABA, menganalisis karakteristik usaha, serta mengestimasi nilai tambah dan pendapatan. Metode yang digunakan meliputi analisis deskriptif, nilai tambah dengan metode Hayami, dan analisis pendapatan. Hasil penelitian menunjukkan bahwa pengelolaan limbah FABA telah dilakukan sesuai dengan prosedur yang berlaku. Pemanfaatan limbah FABA dilakukan secara luas, baik dalam penggunaan internal maupun eksternal. Limbah FABA dimanfaatkan sebagai bahan baku dalam produksi batako dan paving block, serta digunakan oleh kelompok usaha mikro dan usaha kecil. Rata-rata nilai tambah yang dihasilkan dari pemanfaatan limbah FABA mencapai Rp1.548,30 per kg limbah FABA. Pendapatan rata-rata untuk jenis usaha mikro mencapai Rp61.699.525,58 per bulan dengan nilai R/C sebesar 2,64. Sementara itu, pendapatan rata-rata untuk jenis usaha kecil mencapai Rp142.229.626,67 per bulan dengan nilai R/C sebesar 1,73., Increased energy demand and electricity usage have led to an increase in coal consumption in Steam Power Plants (PLTU). The combustion of coal produces fly ash and bottom ash (FABA) waste with negative environmental impacts. One successful PLTU in managing FABA waste is the West Sumbawa Regency steamelectric power plant. This research aims to identify the FABA waste utilization process, analyse the process of FABA, and estimate the value added and income. The methods used include descriptive analysis, value added using the Hayami method, and income analysis. The research results show that the management of FABA waste has been carried out in accordance with applicable procedures. The utilization of FABA waste is extensive, both for internal and external use. FABA waste is used as raw material in the production of brick and paving blocks, and it is also used by micro and small business groups. The average value added generated from the utilization of FABA waste reaches Rp1.548,30 per kg of FABA waste. The average income for micro-scale businesses reaches Rp61.699.525,58 per month with an R/C value of 2,64. Meanwhile, the average income for small-scale businesses reaches Rp142.229.626,67 per month with an R/C value of 1,73.
Keyword: added value, coal, Hayami method, income analysis

Judul: Analisis Kelayakan Pemanfaatan Limbah Fly Ash-Bottom Ash (FABA) dan Dampak Ekonomi serta Lingkungan di UMKM Workshop FABA Desa Lontar
Abstrak: Pembangkit Listrik Tenaga Uap (PLTU) berbasis batu bara menghasilkan limbah berupa fly ash-bottom ash (FABA) yang jika dibiarkan dan tidak diutilisasi akan menjadi masalah bagi lingkungan. Mengacu pada kewajiban pengelolaan limbah FABA, PLTU Banten 3 Lontar melalui BUMDes Lontar berkomitmen melakukan pemanfaatan FABA menjadi paving block. Tujuan dari penelitian ini adalah memetakan dan menghitung timbulan FABA dan pemanfaatannya menjadi paving block, menganalisis dampak ekonomi dan lingkungan, serta menganalisis kelayakan finansial dari proyek ini. Metode yang digunakan meliputi analisis kelayakan finansial dengan Net Present Value (NPV), Net Benefit Cost Ratio (BCR), Internal Rate of Return (IRR), dan Payback Period (PP) sebagai indikator, serta analisis deskriptif. Hasil penelitian menunjukan jumlah timbulan limbah FABA dari PLTU Banten 3 Lontar pada tahun 2023 mencapai 167.675,9 ton fly ash dan 6.111,7 bottom ash yang dapat dimanfaatkan menjadi paving block. Pemanfaatan FABA berbasis masyarakat dilakukan di Workshop FABA BUMDES Lontar. Workshop FABA memberikan dampak positif secara ekonomi berupa penyerapan tenaga kerja dan secara lingkungan berupa termanfaatkannya limbah FABA. Dampak negatif yang timbul berupa polusi dan kebisingan. Hasil analisis kelayakan usaha pemanfaatan FABA menjadi paving block layak secara finansial apabila menggunakan premium price minimal harga Rp65.000,00 per m2 atau peningkatan kualitas mutu tekan menjadi kelas B., Coal-based Steam Power Plants (PLTU) produce waste in the form of fly ash-bottom ash (FABA) which if left untreated will become a problem for the environment. Regarding the obligation to manage FABA waste, PLTU Banten 3 Lontar through BUMDes Lontar is committed to utilizing FABA in paving blocks. This research aims to map and calculate the generation of FABA and its use as paving blocks, analyze the economic and environmental impacts, and analyze the financial feasibility of this project. The methods used include financial feasibility analysis with Net Present Value (NPV), Net Benefit Cost Ratio (BCR), Internal Rate of Return (IRR), and Payback Period (PP) as indicators, as well as descriptive analysis. The research results show that the amount of FABA waste generated from PLTU Banten 3 Lontar in 2023 will reach 167.675,9 tons of fly ash and 6.111,7 tons of bottom ash which can be used as paving blocks. Community-based FABA utilization was carried out at the Lontar BUMDES FABA Workshop. The FABA Workshop has a positive impact economically in the form of employment and environmentally in the form of utilizing FABA waste. The negative effects that arise include pollution and noise. The feasibility analysis results of using FABA to make paving blocks are financially feasible if you use a premium price of at least IDR 65.000 per m2 or increase the press quality to class B.
Keyword: Kelayakan finansial, Dampak Ekonomi dan Lingkungan, Ekonomi Hijau, Pemanfaatan Limbah FABA

Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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