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All Journal Jurnal Presipitasi : Media Komunikasi dan Pengembangan Teknik Lingkungan Jurnal IPTEK Bagi Masyarakat
Widayat Widayat
Universitas Diponegoro
Agriculture, Biological Sciences & Forestry Humanities Computer Science & IT Earth & Planetary Sciences Education Mechanical Engineering Physics Public Health Social Sciences

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Experimental Investigation of by-Product Hydrogen Gas in the Harvesting Process of Dunaliella salina using a Non-Sacrificial Cathode Purwono Purwono; Hadiyanto Hadiyanto; Marcelinus Christwardana; Widayat Widayat; Mochamad Arief Budihardjo
Jurnal Presipitasi : Media Komunikasi dan Pengembangan Teknik Lingkungan Vol 21, No 1 (2024): March 2024
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/presipitasi.v21i1.80-89

Abstract

Hydrogen gas is considered a pollution-free fuel in the future. However, the EC process using these non-sacrificial electrodes requires further research especially for the production of dissolved hydrogen gas and the efficiency of microalgae harvesting. The purpose of this study was to investigate the concentration of dissolved hydrogen gas produced from the harvesting process of Dunaliella salina microalgae species using EC and ORP concentrations including pH, harvesting efficiency due to voltage variations and harvesting time using EC with non-sacrificial electrodes. D salina harvesting using EC reactor made of cylindrical borosilicate glass. Spiral-shaped type 304 stainless steel (non-sacrificial) serves as the cathode and solid cylindrically-shaped Fe serves as the anode. The voltage set varies between 16, 18, and 20 Volts, while the electrolysis time is varied between 1.3.5 minutes. The results showed that the highest dissolved hydrogen concentration of 820 ppb (0.820 ppm) produced from the EC process used 18 V for 3 minutes. The volume of gas could not be measured because most of the hydrogen gas was dissolved in the D salina culture, so it was not enough to evaporate within 3 minutes. The maximum ORP concentration of -413 mV resulting from the EC process uses 18 V for 3 minutes. When hydrogen gas is present in a solution, it can decrease the ORP value of the solution. At EC time with non-sacrificial electrodes for 5 minutes managed to harvest D salina 50.79%; 61.90%; 74.60% at voltages of 16 V, 18V, and 20 V respectively. 
Integration of Energy Quality and Financial Feasibility in the Production of Oil Palm Frond Chips and Pellets Yogi Alamsah; Widayat Widayat; Sri Widodo Agung Suedy
Jurnal IPTEK Bagi Masyarakat Vol 5 No 3 (2026)
Publisher : Ali Institute of Research and Publication

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.55537/j-ibm.v5i3.1652

Abstract

Indonesia, as the world’s largest palm oil producer, generates significant quantities of oil palm frond (OPF) biomass that remain underutilized. This study evaluates the technical characteristics and economic feasibility of converting OPF into energy products in the form of chips and pellets. Laboratory analyses including proximate, ultimate, and calorific value tests were conducted to assess fuel quality, followed by a techno-economic evaluation using a 15-year investment horizon and an 11% discount rate. Results show that pelletization improves fuel properties, particularly by reducing moisture content and increasing calorific value under actual conditions. The higher heating value (HHV) of pellets reached 3,962 kcal/kg under air-dry conditions, compared to 1,746 kcal/kg for chips. On a dry ash-free basis, the calorific values of both products were comparable, indicating that moisture content significantly influences actual energy performance. Economic analysis indicates that pellet production under coal price equivalence schemes does not achieve attractive financial returns, with internal rates of return (IRR) below the discount rate and payback periods exceeding project lifetime. Sensitivity analysis suggests that a selling price of Rp1,000,000 per ton or a calorific value above 5,300 kcal/kg is required to reach financial feasibility. In contrast, chip production with low calorific value is economically unviable; however, improving chip quality to 4,060 kcal/kg results in a financially feasible scenario, achieving an IRR of 32.3% and payback within four years. The findings highlight that product form, energy quality, and market pricing mechanisms critically determine the viability of OPF-based bioenergy development.
Co-Authors H Hadiyanto Marcelinus Christwardana Mochamad Arief Budihardjo Purwono Purwono Sri Widodo Agung Suedy Yogi Alamsah