The hydrogen sulfide emissions abatement program at the Geysers Geothermal Power Plant

The scope of the hydrogen sulfide (H2S) abatement program at The Geysers Geothermal Power Plant and the measures currently under way to reduce these emissions are discussed. The Geysers steam averages 223 ppm H2S by weight and after passing through the turbines leaves the plant both through the gas ejector system and by air-stripping in the cooling towers. The sulfide dissolved in the cooling water is controlled by the use of an oxidation catalyst such as an iron salt. The H2S in the low Btu ejector off gases may be burned to sulfur dioxide and scrubbed directly into the circulating water and reinjected into the steam field with the excess condensate. Details are included concerning the disposal of the impure sulfur, design requirements for retrofitting existing plants and modified plant operating procedures. Discussion of future research aimed at improving the H2S abatement system is also included

Natural gas sweetening using tailored ionic liquid-methanol mixed solvent with selective removal of H₂S and CO₂

Natural gas is often preferred in various energy applications due to its many advantages over conventional fossil fuels such as oil and coal. However, the removal of pollutants from natural gas, particularly hydrogen sulfide (H2S) and carbon dioxide (CO2), requires complex treatment strategies, significantly impacting the cost of natural gas production. In this work, we propose a mixed solvent combining ionic liquid (IL) and methanol, which can selectively and simultaneously remove H2S and CO2 by customizing the IL structure and its ratio in the solvent. This purification process offers improved efficiency and energy savings compared to traditional methods. To determine the optimal IL structure in the mixed solvent, a computer-aided design method was employed. Through solving the formulated MINLP problem, the IL 1-methyl pyridinium trifluoroacetate ([C1OHPy][TFA]) was identified as having the highest affinity for H2S, making it suitable for use in the IL-methanol mixed solvent. Furthermore, the upgrading process of high-sulfur natural gas using the IL-methanol mixed solvent was simulated and evaluated, comparing it to the benchmark natural gas upgrading (Rectisol) process. The results demonstrate that the IL-methanol mixed solvent natural gas upgrading process achieved a 55.57 % power savings and reduced the annual total cost (TAC) by 23.90 % compared to the Rectisol process. These findings highlight the significant potential of our tailored IL-methanol mixed solvent in natural gas production.</p

Mitigating Carbon Dioxide Impact of Industrial Steam Methane Reformers by Acid Gas to Syngas Technology: Technical and Environmental Feasibility

The aim of this work is to evaluate the potential application of a new sustainable technology, called Acid Gas to Syngas, on steam reforming process in order to reduce the carbon dioxide emissions. Indeed, steam reforming has high emissions of carbon dioxide, at almost 7 kg of carbon dioxide per 1 kg of hydrogen produced. The key idea of the new technology is to convert carbon dioxide and hydrogen sulfide coming from natural gas desulfurization into additional hydrogen. Coupling different software, i.e. Aspen HYSYS and MATLAB, a complete plant model, able to manage the recycle of unconverted acid gases, has been developed. The importance of introduced innovations is highlighted and a comparison between the old process and the new one with Acid Gas to Syngas technology is built up. With Acid Gas to Syngas technology the natural gas consumption and carbon dioxide emissions can be reduced up to 3%

Pra-Desain Pabrik Amonia dari Gas Alam

Sebagai salah satu bahan baku utama dari industri pupuk, konsumsi amonia dunia sejak tahun 2010 hingga tahun 2020 terus mengalami peningkatan, yaitu sekitar 1,81% tiap tahunnya. Adapun konsumsi amonia dalam negeri juga mengalami peningkatan. Selain konsumsi amonia dalam negeri yang terus meningkat, pemerintah juga sedang menawarkan proyek pembangunan pabrik pupuk dan petrokimia di Papua Barat. Pabrik ini direncanakan beroperasi pada tahun 2025 dengan kapasitas produksi 2500 ton amonia/hari dan berlokasi di Kabupaten Teluk Bintuni, Papua Barat, seperti program yang telah didukung oleh Pemerintah Indonesia. Adapun proses produksi amonia terbagi menjadi empat tahapan utama, yaitu Feed Gas Pre-Treatment, Syngas Generation, Syngas Purification, dan Ammonia Synthesis. Bahan baku yang diperlukan dari proses produksi amonia ini, antara lain gas alam, steam, dan udara. Untuk memenuhi kapasitas produksi tahunannya, diperlukan nilai OPEX (operating expenditures) sebesar $513.097.665,87 dan nilai CAPEX (capital expenditures) sebesar$ 740.000.997,05. Selain itu, didapatkan nilai Internal Rate of Return (IRR) sebesar 19,04% dengan bunga deposito bank sebesar 2%. Waktu pengembalian modal atau Pay Out Time (POT) yang dibutuhkan dalam pendirian pabrik ini adalah selama 8 tahun 7 bulan dan nilai BEP sebesar 33,44%, serta nilai NPV sebesar $ 817.824.352,8

Soluble polysulphide sorption using carbon nanotube forest for enhancing cycle performance in a lithium-sulphur battery

The rapid capacity decay of lithium–sulphur batteries has been a significant obstacle for practical application, which is generally considered to arise from dissolution of lithium polysulphide in the electrolyte and diffusion away from the cathode. As the lithium content in the polysuphide increases with further discharge, capacity decay occurs also from the passivating effects by the formation of insoluble sulphides, further amplified by volume increase. More recently, weakening of sulphur adhesion to carbon with progress in discharge is also an important factor in the sulphur cathode degradation. In order to overcome capacity decay caused by all the above mechanisms, we have prepared a composite cathode made of sulphur and high density carbon nanotube (HD-CNT) forest scaffold that is able to interfacially adsorb and volumetrically confine the polysulphide species and accommodate the expansion of sulphur discharge products effectively. This cathode demonstrates very high electrochemical stability and high discharge capacity up to 200 full discharge/charge cycles even with the use of the basic organic ether electrolyte where polysulphide shows high solubility, thus providing evidence for confinement and interfacial contact. Retention and surface adsorption favoured by minimizing the wall-to-wall distance between the aligned CNTs arise from a decrease in the reaction energy of the adsorption. Computational simulation of the interface between polysulphide species and carbon nanotube surface provides first-principle confirmation of improved binding between C and S in the polysulphides as wall-to-wall distance is decreased. The HD-CNT scaffold is self-binding and highly-conducting thus the conventional additives of binder and carbon black are also fully eliminated. A high discharge capacity of 812 mA h g⁻¹ of sulphur (corresponding to 503 mA h g⁻¹ of the whole cathode material mass) is stably retained after 200 cycles at 400 mA g⁻¹ with a small average capacity decay of only 0.054% per cycle on average These encouraging results provide novel approaches to designing and fabricating long cycle life cathode in a lithium–sulphur battery.Financial support from EC project Technotubes is greatly appreciated. Kai Xi wishes to thank the Cambridge Overseas Trust.This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.nanoen.2014.12.02

Amine modified silicates applied to direct air capture of CO2 with room temperature regeneration

There is an urgent need to directly remove CO2 from the atmosphere. Solid adsorbent based chemisorption is a promising solution. In this work, two types of amines, Jeffamine T403 and TEPA, were combined with two types of mesoporous silica, pore-expanded MCM-41 and SBA-15, as well as fumed silica. The adsorbents were then characterized in a TGA to determine their CO2 capacity at ambient conditions. Our best example was SBA-15 loaded in a 1 to 2 mass ratio with Jeffamine T403. The capacity was 9.806 mg CO2 / g of adsorbent with good cycling stability. The main benefit of these specific solid chemisorption systems is their ability to regenerate at ambient conditions. This has the potential to drastically decrease the energy requirements for scaled-up direct air capture systems.Includes bibliographical references

Implementation of molecular modeling to investigate ion transportation in proton exchange membranes comprising graphene oxide and polyacrylate nanocomposites

Proton exchange membranes (PEMs) play a critical role in various energy conversion devices, such as fuel cells. Developing advanced PEMs with improved hydronium ion transportation and chemical stability is essential for enhancing the performance and durability of these devices. In this research project, we focus on the development and molecular modeling study of a novel composite material based on poly(acrylic acid) and graphene oxide for application as a high-performance proton exchange membrane. The need for better PEMs has led us to explore the potential of combining poly(acrylic acid) and graphene oxide, as both materials offer unique advantages in terms of proton conductivity and mechanical strength. Our goal is to investigate how these two components interact and synergize to enhance the overall performance of the PEM, particularly in challenging operating conditions. To achieve this, classical all-atom Molecular Dynamics (MD) simulations using Gromacs software were employed. The simulations allowed us to study the formation mechanism of the poly(acrylic acid) and graphene oxide composite material and its application in facilitating hydronium ion transportation within the PEM. Our simulation results revealed fascinating insights into the composite material's behavior. Notably, we observed the emergence of new interactions between poly(acrylate) oligomers and graphene oxide layers, evident from the analysis of interaction energy values. These interactions contribute to the material's enhanced transport properties, making it promising for PEM applications. Moreover, we assessed the mobility of hydronium ions in the graphene oxide and polyacrylate nanocomposite-based PEM and found it comparable to the mobility in traditional poly(acrylate)-based PEMs. This indicates that the introduction of graphene oxide provide compatible proton transport efficiency and renders the composite suitable for practical application in PEM devices. In conclusion, our study demonstrates the potential of the poly(acrylic acid) and graphene oxide composite as a high-performance proton exchange membrane

Reducing the Manufacturing Cost of Tubular SOFC Technology

In recent years, Westinghouse Electric Corporation has made great strides in advancing tubular solid oxide fuel cell (SOFC) technology towards commercialization by the year 2001. In 1993, Westinghouse initiated a program to develop a `MWe Class` (1-3 MWe) pressurized SOFC (PSOFC) gas turbine (GT) combined cycle power system for distributed power applications because of its: (1) ultra high efficiency (approx. 63% net AC/LHV CH{sub 4}), (2) its compatibility with a factory packaged, minimum site work philosophy, and (3) its cost effectiveness. Since then two cost studies on this market entry product performed by consultants to the U.S. Department of Energy have confirmed Westinghouse cost studies that fully installed costs of under $1300/kWe can be achieved in the early commercialization years for such small PSOFC/GT power systems. The paper will present the results of these cost studies in the areas of cell manufacturing cost, PSOFC generator manufacturing cost, balance-of-plant (BOP) cost, and system installation cost. In addition, cost of electricity calculations will be presented