Yani Permanawati
Marine Geological Institute

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Late Holocene Heavy Metals Record of Jakarta Bay Sediments Rina Zuraida; Riza Rahardiawan; Yani Permanawati; Indra Adhirana; Andrian Ibrahim; Nazar Nurdin; Haryadi Permana
BULLETIN OF THE MARINE GEOLOGY Vol 33, No 2 (2018)
Publisher : Marine Geological Institute of Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1209.764 KB) | DOI: 10.32693/bomg.33.2.2018.569

Abstract

This paper reports copper, zinc, lead, cadmium, and chromium records of Jakarta Bay sediment since 600 AD and reonstruct environmental changes since that time. Jakarta Bay This study uses samples from a 150 cm long gravity core (TJ-17, 106.902488°E, 5.99381°S) that was acquired from the eastern part of Jakarta Bay in 2010 onboard RV Geomarin I by the Marine Geological Institute. Heavy metal content in Jakarta Bay sediments is used to track environmental changes onland from this site. Heavy metal concentration was analyzed using atomic absorption spectrometry on bulk samples that were taken in 5 cm interval. The results yield background level of Cu at 16 ppm, Zn at 75 ppm, Pb at 20 ppm, Cd at 0.01 – 0.15 ppm, and at Cr 80 ppm. Vertical record of heavy metals show two stages of environmental changes in the region: from 600 AD to 1600 AD and 1800 AD onward. These changes are interpeted as related to land use changes caused by human activity in the West Java region.
Site Determination for OTEC Turbine Installation of 100 MW Capacity in North Bali Waters Delyuzar Ilahude; Ai Yuningsih; Yani Permanawati; Mira Yosi; Rina Zuraida; N. Annisa
BULLETIN OF THE MARINE GEOLOGY Vol 35, No 1 (2020)
Publisher : Marine Geological Institute of Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32693/bomg.35.1.2020.594

Abstract

This research was conducted to investigate a suitable location for the OTEC (Ocean Thermal Energy Conversion) pilot plant in North Bali. The investigation was done by calculating the theoretical potential of electric power output using the method of Uehara and Ikegami (1990) for closed cycle OTEC. OTEC power plants require a temperature difference between surface and bottom water layers at least 20°C. Temperature data were obtained from the HYCOM temperature model for a period of 9 years (2008 - 2017) at 4 points which were verified with field data taken in 2017 using KR Geomarin III. The results of field measurements show that the sea surface temperature (SST) in the study area ranges from 28 to 31°C while at depth of 800 m 5.75°C. ∆T values range from 22 to 25°C. Verification of modelling temperature and measurement temperature shows that the modeling results resemble the temperature of North Bali Waters. Analyses results for the four points showed that B-11, located in the Tedjakula area, has the largest electrical power output (71,109 MW). Thus, point B-11 is the best location for development of OTEC pilot plant in North Bali Waters.Keywords: sea water temperature, net power, OTEC closed cycle, North BaliPenelitian ini dilakukan untuk menentukan lokasi yang layak untuk pilot plant OTEC (Ocean Thermal Energy Conversion) di perairan Bali Utara. Penentuan dilakukan dengan menghitungpotensi teoritis output daya listrik menggunakan metoda Uehara dan Ikegami (1990) untuk OTEC siklus tertutup. Pembangkit listrik OTEC membutuhkan perbedaan suhu antara lapisan permukaan dan lapisan dalam sebesar 20°C atau lebih. Data suhu didapatkan dari model suhu HYCOM untuk jangka waktu 9 tahun (2008 – 2017) pada 4 titik yang diverifikasi dengan data lapangan yang diambil pada tahun 2017 dengan menggunakan KR Geomarin III. Hasil pengukuran lapangan menunjukaan bahwa suhu permukaan laut (SPL) daerah penelitian berkisar 28-31°C dan suhu air pada kedalaman 800 m adalah 5,75°C. Nilai ∆T berkisar 22-25°C. Verifikasi suhu hasil pemodelan dengan suhu hasil pengukuran menunjukkan bahwa suhu hasil pemodelan dapat mewakili suhu perairan Bali Utara. Hasil analisis yang dilakukan pada 4 titik menunjukkan bahwa titik B-11 yang terletak di daerah Tedjakula memberikan output daya listrik terbesar (71,109 MW). Titik B-11 merupakan lokasi terbaik untuk pengembangan pilot plant OTEC di perairan Bali Utara.Kata kunci: suhu air laut, daya listrik, OTEC siklus tertutup, Bali Utara
STUDY OF POTENTIAL INSTALLATION OF OCEAN THERMAL ENERGY CONVERSION (OTEC) IN THE NORTH WATERS OF LEMBATA, NTT Gisela Malya Asoka; Denny Nugroho Sugianto; Yani Permanawati
BULLETIN OF THE MARINE GEOLOGY Vol 38, No 1 (2023)
Publisher : Marine Geological Institute of Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32693/bomg.38.1.2023.789

Abstract

Ocean thermal energy conversion is an attempt to convert potential energy in the variances heat content of seawater into other energy by utilizing the temperature change between the sea surface and deep sea at least 20°C. The Lembata waters is near to the equator, sea surface temperature tends to be warm and stable. This research was conducted to estimate the potential energy generated from a closed cycle OTEC system in North Lembata Waters. This study used temperature data from Global Ocean Physics Reanalysis from Copernicus Marine Environment Monitoring Service (CMEMS) for 9 years (2012-2020) in 6 stations. Validation was performed using the primary CTD Lembata OTEC Team of the Marine Geological Institute (MGI). Temperature data validation results on the MSE (Mean Square Error), RMSE (Root Mean Square Error), and MAPE (Mean Absolute Percentage Error) methods are considered to represent field temperature conditions. The variability value shows the station point in the North Lembata Waters has a temperature with slight differences. The vertical temperature change (ΔT) shows between 20.98°C to 23.44°C. Potential electric power resulting from the OTEC system using the technical estimation formula. The average net power generated from those temperature gradients ranges from 5.65 MW-7.56 MW, respectively. The Lembata waters have temperature conditions suitable for OTEC installations. Station C-4 has a power potential of 6.84 MW with a depth of 763 m and the distance of 1.86 km from the coastline. Station C-4 in the Omesuri sub-district is the best point for OTEC installation in North Lembata Waters.