Pengeringan menggunakan energi gelombang mikro menjadi alternatif agar pengeringan berjalan lebih cepat tanpa terpengaruh kondisi cuaca. Namun performa dan efisiensi energi dalam mengeringkan rumput laut belum diketahui. Tujuan penelitian ini adalah untuk mengetahui performansi pengeringan rumput laut menggunakan energi gelombang mikro (microwave) dan analisa konsumsi energinya. Metode yang digunakan ialah mengeringkan rumput laut segar dalam oven gelombang mikro secara batch. Dalam proses pengeringan dilakukan variasi level daya (400, 500, 600 watt) ke dalam oven gelombang mikro dan variasi ketebalan rumput laut (3, 5, 7 cm). Parameter yang diamati meliputi rasio kadar air (moisture ratio/MR), laju pengeringan (g/menit), difusi efektif air/Deff (mm2/detik), specific energy consumption/SEC (J/g H2O) dan efisiensi energi (%). Hasil penelitian menunjukkan, level daya magnetron 600 watt menghasilkan MR terendah (0,19), laju pengeringan tertinggi (13,15 g/menit) dan Deff tertinggi (2,28 x 10-2 mm2/detik). Rumput laut ketebalan 3 cm memperoleh MR terendah (0,05), laju pengeringan tertinggi (6,42 g/menit) dan Deff tertinggi (9,42 x 10-2 mm2/detik). SEC pengeringan sebesar 4,38-4,51 J/g H2O dan efisiensi energi 22,56-23,42% untuk level daya 400-600 watt. Perbedaaan level daya tidak memberikan pengaruh signifikan terhadap SEC dan efisiensi. Sedangkan variasi ketebalan rumput laut antara 3 cm dan 7 cm memberi hasil yang berbeda. SEC terendah diperoleh pada perlakuan rumput laut tebal 3 cm yaitu 2,96 J/g H2O sementara efisiensi tertinggi pada rumput laut dengan tebal 5 cm yaitu 22,93%.Oleh karena itu pengeringan rumput laut menggunakan energi gelombang mikro dengan level daya 600 watt dan ketebalan 3 cm menghasilkan performasi dan konsumsi energi yang lebih baik. AbstractMicrowave drying becomes alternative method to get faster process without being influenced by weather. However performance and energy efficiency of microwave drying for seaweed are still unknown. This research aims to find out performance of seaweed drying in microwave oven as well as energy consumption analysis. The method used was drying seaweed in microwave oven. Seaweed drying was conducted at various power level (400, 500, 600 watt) and thickness of seaweed (3, 5, 7 cm). Observed parameters were moisture ratio/MR, drying rates (g/min), effective diffusion/Deff (mm2/s), specific energy consumption/SEC (J/g H2O) and energy efficiency (%). Result of research showed that power level, 600 watt of magnetron produced lowest MR (0,19), highest drying rate and Deff i.e 13.15 g/min and 2.28 x 10-2 mm2/s respectively. Seaweed 3 cm thickness achieved lowest MR (0.05), highest drying rates 6.42 g/min and Deff 9.42 x 10-2 mm2/s. SEC of drying were 4.38-4.51 J/g H2O while energy efficiency were 22.56-23.42 % for 400-600 watt. Differences of power level have not given significant effect to SEC and efficiency values. Whereas differences of seaweed thickness between 3 cm and 7 cm have given significant effect. Seaweed in 3 cm thickness resulted in the lowest SEC i.e 2.96 J/g H2O, however, the highest efficiency energy was 5 cm thickness i.e 22.93%. Therefore drying seaweed utilize microwave energy of 600 watt power level and 3 cm thickness generated better performance and energy consumption.

Process production of floating fish feed in a society constrained by processing technology. The objective of this study was to observe effect of  condition process of twin screw extruders to the physical and chemical properties of produced of floating fish feed. Ingredients used involve fish meal, soybean meal, corn meal, and tapioca flour. The ingredients are mixed with 15, 20 and 25% water added to the total weight. Extrusion process condition conducted by several treatments i.e screw speed (540, 540, 600, 660 rpm) and barrel temperatures (80, 90, 100, 110, 120℃). In order to study, expansion ratio, unit density, floatability and hardness of feed were observed as physical parameters while chemical properties include moisture and protein content. Experimental result showed that addition 25 % water to the formula gives a good performance of expansion ratio, unit density and floatability than 15% and 20% moisture content. Higher of screw speed produces feed with higher ratio expansion, lower unit density, and higher floatability. The optimum of screw speed is 600 rpm.  Meanwhile increasing of barrel temperature caused reduction of unit density, and escalation floatability of feed. Best barrel temperature to meet the physical properties is 120℃. The produced feed contain protein 32.38-41.95% and moisture content 4.37-5.70%.

Energy and exergy analysis has been conducted on photovoltaic (PV) system in Bantul Regency, a special region of Yogyakarta, Indonesia. The PV exergy analysis was used to determine the performance of the PV system by considering environmental factors other than solar irradiance. This research aims to obtain values of exergy and energy efficiencies in the PV system. The experiment results show that the energy efficiency value produced by the PV system was 8.62–74.18%, meanwhile its exergy efficiency was 0.29%-9.40%, respectively. The value of exergy efficiency is lower than the value of energy efficiency. This result confirmed that the environmental factor greatly affects the output of the PV system. It can be concluded that high solar radiation does not always increase the production of exergy, since it is also influenced by the environmental temperature and the PV cells' temperature.

Direct sunlight is commonly used to dry fresh seaweed by artisanal farmers in Indonesia due to its low cost and ease of handling. Nevertheless, this method poses some drawbacks such as lengthy duration, weather dependency and quality degradation. The application of microwave technology in food processing has progressed dramatically, including in the drying process. The microwave drying method is more efficient and can shorten the processing time. This study aimed to describe a large-scale microwave dryer (MD) design and performance to assist the fresh seaweed drying process. The design concept applies microwave energy with a volumetric heating feature to accelerate the seaweed drying process without damaging its functional groups. The MD dimensions were 2410 (l) x 270 (w) x 210 (h) mm with a dryer capacity of up to six kilograms, an enlarged cavity and multiple magnetrons. The main components of the MD were cavity, air circulation system, drying system and control system. According to the performance testing, the MD’s optimum performance was at a power level setting of P7 and six kilograms load. At this setting, we obtained a dried seaweed with a moisture ratio of 0.68±0.05, drying rate of 30.29±1.32 g/min, specific energy consumption of 3.96±0.08 MJ/kg H2O and energy efficiency of 58.45±2.65%. The total power of the P7 setting operation required 2.00 kW. Fourier-Transform Infrared (FTIR) spectra showed that the functional groups of the dried seaweed were unaltered.