Sukir Maryanto

Membrane staging and SOFC operating pressure strongly influence the balance between carbon dioxide capture and net energy performance in integrated gasification fuel cell systems. This study investigates the effects of single stage and two stage membrane configurations and solid oxide fuel cell operating pressure on carbon dioxide removal and overall thermodynamic performance using process simulation. A reference configuration without membrane based carbon dioxide capture was compared with single stage and two stage configurations under consistent operating conditions. The analysis considered gross power, auxiliary power, carbon dioxide compression, net power, net lower heating value efficiency, and carbon dioxide removal. The single stage membrane increased gross power from 32,889.98 to 36,055.65 kW and net power from 26,561.20 to 27,639.12 kW, increasing net lower heating value efficiency from 61.11% to 63.59%. The two-stage configuration further increased gross and net power to 38,477.22 and 30,450.49 kW, respectively, with a net lower heating value efficiency of 70.04%. However, carbon dioxide removal decreased from 88.88% to 79.01%, indicating a trade-off between capture and energy performance. Increasing fuel cell operating pressure from 1 to 3 atm increased the average Nernst voltage from 0.886 to 0.922 V and fuel cell power from 11,576.04 to 12,820.26 kW. However, higher auxiliary power consumption reduced net power from 25,969.91 to 25,621.30 kW and net lower heating value efficiency from 59.74% to 58.94%, while carbon dioxide removal remained approximately 88.8%. These results demonstrate the importance of evaluating carbon dioxide capture and integrated net energy performance simultaneously.

The hot spring manifestations in the Karangrejo–Tinatar area indicate hydrothermal activity influenced by geological structures. In general, the research methods used are as follows:Data acquisition: Gathering gravity measurements from 53 points within the research area.Data processing: Transforming the field data acquisitions into a 2D model.Interpretation: Verifying the findings using established regional geological map.2D forward modeling was performed to represent rock density distribution and construct geological cross-sectional models. The results show that the Karangrejo–Tinatar geothermal area exhibits a residual anomaly range from -9.3 mGal to 9.7 mGal. SVD and FHD map analysis succeeded in mapping the Karangrejo, Tinatar, Sedayu, and 'X' Faults, with locations that match the local geological map. Modeling shows that the Karangrejo and Tinatar Faults control the manifestation of hot springs as geothermal fluid pathways, while the Sedayu and 'X' Faults act as water recharge pathways to the Karangrejo–Tinatar geothermal system. Sections A and B confirm the role of andesite lava as a heat conductor from geothermal sources and porous volcanic rock as a path for surface water flow to the reservoir.

The “Nyi Sindurejo” geothermal manifestation in Batu City, East Java, is an atypical geothermal feature. It is located in the central part of Batu City, relatively distant from the active volcanic center. Although it is close to the Kasinan and Songgoriti geothermal systems, no previous specific geoscientific study has evaluated its structural framework and geothermal potential. This study aims to analyze the structural controls of Nyi Sindurejo and assess its possible relationship with adjacent geothermal systems. We utilized Digital Elevation Model (DEM) data to extract geomorphological lineaments and GGMplus data to examine anomaly contrasts. Lineaments were identified and mapped based on topographic features. The gravity data were analyzed to delineate subsurface density differences. Geomorphological lineament analysis reveals a dominant N-S trend with a secondary NNW-SSE orientation. No structural trends appear to connect Nyi Sindurejo with the Kasinan-Songgoriti geothermal systems. The residual Bouguer anomaly indicates local variations in subsurface density without significant continuity toward adjacent geothermal areas It represents a local system rather than being connected to the nearby Songgoriti-Kasinan geothermal areas.

Geothermal energy is a key renewable resource in Indonesia, including non-volcanic regions where subsurface conditions remain poorly understood. The Karangrejo–Tinatar area in Pacitan, East Java, displays hot spring manifestations that suggest a structurally controlled geothermal system. This study characterises the system using integrated primary ground magnetic data and GGMPlus satellite gravity data over a 25 km² area. Magnetic data were processed using Reduction to the Pole and Tilt Derivative, while gravity data were analysed through Bouguer correction, upward continuation, and 3D inversion modelling with ZondGM3D and Grablox 1.6. Results show magnetic susceptibility values ranging from −0.01759 to 0.0402 SI and rock density values from 1.88 to 3.11 g/cm³. The inversion model identified five major fault structures—Kebonsari, X, Karangrejo, Sedayu, and Tinatar Faults—that control geothermal fluid circulation as recharge and discharge pathways. This study provides a new framework for understanding non-volcanic geothermal systems in Indonesia.

The tectonic complexity in Indonesia has made it one of the most interesting targets for studies on seismic tomography. The Indian oceanic plate sunk beneath the Eurasian continental plate, forming the subduction zone in Southern Indonesia. This activity led to the formation of volcanoes along the Sunda Arc, including East Java, the research area covered in this study. This research is mainly aimed at identifying the influence of the volcanic activities by tomography analysis. The data of the earthquakes was recorded by 22 seismic stations of the Indonesia Tsunami Early Warning System (InaTEWS) seismic network in the period of 2009–2017. The tomographic image was analysed by exploring the anomalies of primary (P)‐ and secondary (S)‐wave velocities and Vp/Vs ratio. The result shows the presence of a low‐velocity zone with a high Vp/Vs ratio found around the volcanic area, which is correlated with the partial melting zone or magma chamber. The low‐velocity zone was observed at the depth range of 27–155 km, which was also correlated with the subducted slab beneath Java Island. This leads to an assumption that there is an interlinked volcanic system which extends from west to east of Java.

The East Java M = 6.1 Earthquake struck on April 10, 2021, at the bottom of the Indian Ocean, about 96 km south of Kepanjen District, Malang Regency, Indonesia. The neighbouring Pronojiwo District in Lumajang Regency suffered significant damages and loss of lives. The earthquake aftermath underscored the necessity of examining susceptibility factors in the Pronojiwo area for future mitigation efforts. This research focuses on assessing earthquake vulnerability in Pronojiwo District using two methodologies: microtremor analysis and PS-InSAR. Microtremor data were directly collected, while PS-InSAR data were acquired from the Sentinel-1 satellite and processed using the ranging from 0.579 × 10 to 24.840 × 10 s /cm, in Pronojiwo District, with notably higher values found in areas with Semeru deposits, characterized by soft sediments. PS-InSAR analysis indicates concentrated negative shifts in residential zones, signaling structural damage. Regions with elevated vulnerability index values and negative PS points are considered more prone to earthquakes and subsequent building damages.

As per the Geothermal Potential Book published by the Ministry of Energy and Mineral Resources (MEMR) in 2017, Pacitan Regency in East Java Province, Indonesia, has the potential for geothermal energy. Two hot spring manifestations, namely, Karangrejo and Tinatar, located in the Arjosari and Punung districts of Pacitan Regency, respectively, have a combined resource of 25 MWe. We acquired ground-gravity data and evaluated gravity anomalies to explore the underlying geological structure in order to understand the geothermal system behind these manifestations. The results of the study show that the gravitational anomaly in the Karangrejo-Tinatar region ranges from 163 to 176 mGal. Additional analysis of the complete Bouguer anomaly (CBA) map, first horizontal derivative (FHD) map, and field observations points to the existence of three NW-SE trending faults. Two of the faults, which are the Karangrejo fault and the Tinatar fault, may be the flow paths for the manifestation of Karangrejo and Tinatar hot springs.

Mount Semeru erupted on December 4, 2021, followed by hot clouds falling. The eruption caused significant destruction to one school, moderate damage to five schools, and impacted 19 schools with volcanic ash, resulting in the tragic loss of six students' lives. Subsequently, a disaster mitigation program named "School Watching" was implemented. It involved observing school environments and identifying hazardous elements to prepare for future disasters. Therefore, using the Design Thinking method, the researchers designed the user experience (UX) for the Semeru School Watch application to assist with the school environment's preparedness. This application implements geotagging and context-aware to accommodate information about school location and the impact of the disaster. The final design of the application was evaluated with a usability test on 20 respondents to assess their effectiveness, efficiency, and satisfaction. The results for effectiveness scored 98.89%, the efficiency aspect achieved an overall relative efficiency calculation of 98.5%, and the satisfaction aspect received an SUS calculation of 83 with a grade A (excellent). Additionally, the user experience aspect was tested using the UEQ calculation, yielding a score of 1.99 (very good) for attractiveness, 1.68 (above average) for insight, 1.99 (very good) for efficiency, 2.00 (very good) for dependency, 1.88 (very good) for stimulation, and 1.71 (very good) for novelty. So, the School Watching application design with geotagging and context-aware will provide a model for mitigation reporting with mobile apps.

This research was conducted with the aim of explaining the physical processes that occur at the source. The duration-amplitude distribution is an amplitude scaling method that can describe the process of sustained earthquake sources such as volcanic tremors. The data used in this study are seismic data from Mount Ijen for the period from January to March 2012 and January to March 2014. Scaling the duration amplitude distribution is done by converting the amplitude to reduced displacement (D_R). The cumulative duration is calculated with a range of 3-12 cm² which is the lowest and highest reduced displacement values. The cumulative duration plot results are then adjusted to the power law model and the exponential model. a correlation coefficient (R₂) was calculated to evaluate the fit for each of these models. The results showed that the R₂ exponential model was higher than the R₂ power law model for all events in both 2012 and 2014 and there was no transition between the two models. This indicates that the source process of the Ijen volcano volcanic tremor is related to the scale-bound source process and there was no source change in either 2012 or 2014. However, differences in amplitude characteristics were found in 2012 and 2014. The volcanic tremors in 2012 were stronger than those in 2014, according with the reality of changing the condition of the crater lake which is stronger in 2012. Volcanic tremors and changes in the Ijen crater lake are important for forecasting the eruption of the Ijen volcano.