Simulation and Levelized Cost Analysis of Direct use Geothermal Energy for Enhanced Oil Recovery

To meet the demand for crude oil, which has a limited reserve; efforts are needed to maximize proven potentials. One of the solutions is the use of steam flooding as the most widely used Enhanced Oil Recovery (EOR) technology. However, the challenge that must be faced is the high production cost of steam which strongly depend on fuel cost. Meanwhile, the geothermal utilization in Indonesia is still low, only 9.3%. Seeing these problems and potential, it could be possible to utilize the geothermal heat for steam flooding. However, at present no research has been conducted related to geothermal utilization for steam flooding, only for water flooding. Therefore, this study is aimed to evaluate geothermal heat utilization for steam flooding by evaluating the maximum distance between geothermal and oil field, evaluating the technical aspect by using Honeywell UniSim Design and CMG Star and reviewing the levelized cost of steam. The results that geothermal heat can be used economically and technically possible as a pre-heating system before the boiler and it reduces the cost of steam production by 12% with a maximum distance between geothermal and oil field of 30.1 km

Implementasikan Single Service Set Identifier Menggunakan Dynamic VLAN Dan Active Directory Pada Perangkat Nirkabel

Semakin banyak perangkat akses dan mobilitas pegawai memerlukan pengelolaan agar bisa perangkat akses yang ada dapat dimanfaatkan  oleh banyak pengguna dari  unit kerja yang berlainan dengan tidak mengurangi  faktor keamanan.      Perancangan jaringan nirkabel dengan satu buah nama jaringan dengan autentikasi berbasis  data  Active Directory  diimplementasikan untuk mengatasi permasalahan yang ada. Penelitian ini merancang  dan mengimplementasikan single service set identifier  pada perangkat akses, keamanan  akses berbasis  layanan autentikasi Network Policy Server dengan data  pengguna tersimpan pada  layanan Active Directory Domain Services pada server Windows 2008R2.Hasil  pengujian pada perangkat laptop dengan sistem operasi Windows 10,  user dapat melakukan autentikasi dan mendapatkan ip address sesuai  profile grup user.The more access and employee mobility devices require management so that existing access devices can be used by many users from different work units without reducing security factors. Designing a wireless network with one network name with Active Directory data-based authentication is implemented to overcome existing problems. This research designs and implements single service set identifier on access devices, access security based authentication service Network Policy Server with user data stored on Active Directory Domain Services on Windows 2008R2 servers. The results of testing on laptop devices with Windows 10 operating system, users can authenticate and get ip address according to user group profile

Production Optimization for Plan of Gas Field Development Using Marginal Cost Analysis

Gas production rate is one of the most important variables affecting the feasibility plan of gas field development. It take into account reservoir characteristics, gas reserves, number of wells, production facilities, government take and market conditions. In this research, a mathematical  model of gas production optimization  has been developed using  marginal cost  analysis  in  determining  the  optimum  gas  production  rate  for  economic  profit,  by employing  the  case  study  of Matindok  Field.  The  results  show  that  the  optimum  gas  production  rate  is  mainly  affected  by  gas  price  duration  and time of gas delivery. When the price of gas  increases, the optimum  gas production rate  will increase, and then it  will become closer to the maximum production rate of the reservoir. Increasing the duration time of gas delivery will reduce the optimum gas production rate and increase maximum profit non-linearly.Keywords: marginal cost, natural gas fields, production optimizatio

NATURAL GAS AS PETROLEUM FUEL SUBSTITUTION: ANALYSIS OF SUPPLY-DEMAND PROJECTIONS, INFRASTRUCTURES, INVESTMENTS AND END-USER PRICES

The petroleum fuels (PF) subsidy has long burdens the government spending, and discourages less expensive energy usage such as natural gas (NG). Exporting NG and importing the more expensive PF products cause financial losses to Indonesia. The lack of NG infrastructure is the main hurdle in maximizing domestic NG usage and so does the perception of its high investment costs burdening government spending and pushing the NG transportation cost up. This study calculates the required NG infrastructure and its investments for several levels of PF substitutions up to 2030. To balance the NG demands, the supply from each field and its corresponding infrastructures needed was calculated and optimized using non-linear programming with generalized reduced gradient  method to calculate the lowest transportation cost for the consumers. The study shows with a favorable return on investments attractive to private investors, the NG prices can still be put much lower than PF prices, allowing subsidy, import and production cost savings in many sectors. Furthermore, the highest level of substitution scenario needs only US$2.07 billion a year investment, very low compare to the current US$ 14.17 billion a year PF and electricity subsidy.  Keywords: alternative energy, gas supply-demand, infrastructure cost, oil substitution, optimizatio

Synthesis of TiO2 nanotubes by using combination of sonication and hydrothermal treatment and their photocatalytic activity for hydrogen evolution

Effect of sonication and hydrothermal treatments on the synthesized of Titania nanotubes (TiO2 NT)has been investigated. Sonication of TiO2 P25 sol was performed using ultrasonic probe for certain time followed by hydrothermal treatment in a teflon lined stainless steel autoclave. The samples were characterized by means of X-ray powder diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), UV-vis diffuse reflectance spectroscopy (UV-vis DRS) and Brunauer-Emmett-Teller (BET).The photocatalytic activity of prepared samples was evaluated with photocatalytic H2 evolution from aqueous methanol solution. The result showed that TiO2 NT was formed rapidly along with the duration of sonication treatment but the longer processing time of it would destroy the morphology of TiO2 NT. The optimal sonication time for the TiO2 NT formation was 10 min. It was obtained TiO2 NT with high crystallinity, high surface area and a perfect nanotubes structure.  Hydrogen production by using this sample was about two times higher than TiO2 P25 nanoparticle.   Keywords : TiO2 nanotubes, sonication, hydrothermal, hydrogen   Abstrak   Efek kombinasi proses sonikasi dan hidrotermal pada pembentukan TiO2 nanotubes telah dilakukan. TiO2 P25 disonikasi menggunakan ultrasonik probe dengan waktu tertentu kemudian dilanjutkan dengan proses hidrotermal di autoklaf berbahan teflon dan stainless steel. Sampel yang diperoleh di karakteriksasi menggunakan X-ray powder diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), UV-vis diffuse reflectance spectroscopy (UV-vis DRS) and Brunauer-Emmett-Teller (BET). Aktifitas fotokatalis dari sampel diuji untuk produksi hidrogen dari larutan metanol. Dari hasil yang diperoleh TiO2 nanotubes lebih cepat terbentuk dengan adanya proses sonikasi, akan tetapi semakin lama waktu sonikasi bentuk nanotubes yang diperoleh menjadi rusak. Waktu optimal untuk proses sonikasi adalah 10 menit. Pada kondisi ini TiO2 yang terbentuk memiliki kristalinitas dan luas permukaan tinggi serta bentuk nanotubes yang sempurna. Produksi hidrogen pada kondisi inipun dua kali lebih besar dibandingkan dengan TiO2 P25 nano partikel.   Kata Kunci : TiO2 nanotubes, sonikasi, hidrotermal, hidroge

Decomposition of Carbon Dioxide in the Three-Pass Flow Dielectric Barrier Discharge Plasma Reactor

Carbon dioxide (CO2) as one of the green house gas emissions can be decomposed in the three-pass flow configuration of Dielectric Barrier Discharge plasma reactor. The main products were Carbon Monoxide (CO) and Oxygen (O2). This article is a result of the preliminary research which aims to observe the performance of three-pass flow Dielectric Barrier Discharge plasma reactor in utilizing CO2, mixed with CH4, to produce synthesis gas CO and H2, also known as synthesis gas. This research was conducted using three types of reactors lengths, which are 36, 24 and 12 cm (Re1, Re2 and Re3), to observe the possibility of CO2 decomposition performance inside the reactors in several reactor lengths. Other parameters involved in this research were feed flow rates and the reactor voltage. The CO2 flow rates were 500, 1000 and 1500 SCCM/minutes and the voltage of the reactor were 5.4; to 9.5 kV. The conversion of CO2 was increased with the increasing of reactor voltage and the longer of the reactors. The subsequent research would be conducted using CO2 and CH4 mixed feed to observe the plasma reactor performance in producing synthesis gas CO and H2 with the longer reaction time and more product composition data analysis. The best feed flow rate was 500 SCCM/minutes. The CO2 conversion reached the maximum value at the reaction time of 2.1 minute, and dropped off after that time. It is possibly caused by occurring of the reversed reaction due to the high temperature of plasma reaction. The Specific Energy (SE) was 270 kJ/mol. This value is lower compared to the previous researches, as well as to its energy bonding

Techno-economic analysis of a combined cooling, heating and power system based on hot sedimentary aquifer for hotel building in tropical countries

Low enthalpy geothermal based Combined Cooling, Heating and Power (CCHP) system for building is expected can increase energy efficiency and reduce carbon dioxide emission. The aim of this study is to assess techno-economic performances of a CCHP for hotel building in tropical countries with total energy demand of 7.64 MW. The fresh geothermal fluid was divided by 15% to power generation system of Organic Rankine Cycle (ORC) and the waste heat merged with the rest fresh geothermal to absorption refrigeration system and heating systems. Cycle Tempo and COMSOL are used to simulate CCHP system and a borehole of hot sedimentary aquifer (HSA), respectively. The simulation results indicate that total CCHP system efficiency is 36.61% consist of ORC efficiency and absorption cycle efficiency are 12.77% and 57.88%, respectively with emission reduction of 1.4 ton CO2 eq. per year compare to conventional grid electricity. The best business scheme was BOO with financial incentives, which were tax allowance, soft loan, and grant. Therefore, the production prices were 0.08 USD/kWth, 0.10 USD/kWeh, and 12.03 USD/MMBtu for cooling, electricity, and heating respectively

Effect of Biomass Types on Bio-oil Characteristics in a Catalytic Fast Pyrolysis Process with a Ni/ZSM-5 Catalyst

The application of bio-oil for biofuel has been limited due to its low heating value, high acidity and high oxygenate content. Pursuant to the urgency of obtaining access to sustainable energy from renewable resources, the studies for bio-oil upgrading have been recently placed in high priority. This study is aimed at identifying the effect of biomass types on bio-oil product characteristics. The conversion of several types of biomass, i.e. rice straw, rubberwood (Hevea brasiliensis), and palm Empty Fruit Bunches (EFB) to bio-oil by-products was investigated in a Catalytic Fast Pyrolysis (CFP) reactor using a Ni/ZSM-5 nickel nitrate and zeolite catalyst at 550oC and at atmospheric pressure. The results show that Ni/ZSM-5 catalyst has actively enhanced the de-oxygenation reaction process and aromatic production. The composition of aromatic compounds in bio-oil from rubberwood, rice straw, and EFB are 10.25 wt%, 7.8 wt%, and 5.98 wt%, respectively. In the absence of a catalyst, bio-oil from rice straw contains no aromatics

PREPARASI MEMBRAN ELEKTROLIT BERBASIS POLIAROMATIK UNTUKAPLIKASI SEL BAHAN BAKAR METANOL LANGSUNG SUHU TINGGI

PREPARASI MEMBRAN ELEKTROLIT BERBASIS POLIAROMATIK UNTUKAPLIKASI SEL BAHAN BAKAR METANOL LANGSUNG SUHU TINGGI. Operasi sel bahan bakar metanol langsung (Direct Methanol Fuel Cell / DMFC) suhu tinggi (>120 oC) mempunyai keuntungan yaitu meningkatkan reaksi baik di anoda maupun di katoda. Saat ini membran yang banyak digunakan untuk aplikasi DMFC adalah Nafion. Kelebihan dari membran Nafion memiliki konduktivitas ionik yang tinggi tetapi kelemahannya adalah permeabilitas metanol yang tinggi, termasuk membran yang mahal dan kinerja membran menurun jika digunakan pada suhu >80 oC. Untuk hal tersebut perlu pengembangan polimer pengganti Nafion diantaranya adalah polimer aromatik yaitu polisulfon (PSf) dan polieter-eterketon (PEEK). PEEK dan PSf adalah polimer yang bersifat hidrofobik, untuk menjadi elektrolit perlu diberikan gugus sulfonat melalui proses sulfonasi. Sulfonasi PSf dilakukan setelah membuat membran terlebih dahulu, dengan memvariasikan konsentrasi asam sulfat (0,5 M dan 1 M) dan waktu sulfonasi (2 jam, 3 jam dan 4 jam) pada suhu tetap 80 oC. Sedangkan sulfonasi PEEK menggunakan asam sulfat pekat dengan variasi suhu (50 oC , 60 oC dan 70 oC) pada waktu tetap 3 jam, yang kemudian dibuat membran. Karakteristik membran elektrolit polisulfon yang tersulfonasi (sPSf) menghasilkan swelling air pada membran 10 % hingga 25 %, konduktivitas ionik sebesar 10-4 S/cm hingga 10-3 S/cm, permeabilitas metanol sebesar 10-7 cm2/detik hingga 10-6 cm2/detik dan suhu transisi glass membran PSf dan sPSf sebesar 220 oC dan 237 oC. Karakteristik membran elektrolit polieter eter keton yang tersulfonasi (sPEEK) menghasilkan swelling air pada membran 8 % hingga 28 %, konduktivitas ionik sebesar 10-2 S/cm, permeabilitas metanol sebesar 10-7 cm2/detik hingga 10-6 cm2/detik dan suhu transisi glass membran PEEK dan sPEEK sebesar 187 oC dan 266 oC. Kedua polimer tersebut berpeluang untuk aplikasi DMFC suhu tinggi, walaupun konduktivitas ionik dari sPSf perlu ditingkatkan

Computational Study of the Time-dependent Flow Field of a Water-Molasses Mixture Inside a Stirred Vessel

Detailed information on the flow field in the operation of a mixing unit is necessary for the optimal design of the reactor. The flow field characteristic is an essential factor in obtaining an optimal stirred vessel design. The efficiency of the stirred vessel system depends on, for example, the stirred vessel geometry, the flow induced by the impeller, the working fluid properties and the operating condition. The aim of this study is to exhibit the time-dependent flow field of the mixing process inside a stirred vessel for different propeller rotational speeds using computational fluid dynamics methods. The working fluid in question is molasses and water, which is a miscible liquid. The stirred vessel is a conical-bottomed cylindrical vessel (D = 0.28 m and H = 0.395 m) equipped with a three-blade propeller (d = 0.036 m). The transient calculation was conducted using ANSYS Fluent version 18.2. The Mixture multiphase flow model coupled with the Reynolds-averaged Navier-Stokes Standard k-? (SKE) turbulence model was applied to capture the information on the time-dependent flow fields at various propeller rotational speeds inside the stirred vessel. The flow generated by the propeller was compared at 1000 rpm, 1300 rpm and 1500 rpm. The Multiple Reference Frame method was used to solve the moving domain and stationary domain multiple frames case. The results revealed the local velocity, flow pattern, molasses volume fraction value, density gradient distribution, power number and flow number. The profile of all the variables determines the optimal operating conditions for the degree of mixing required