Making seismology accessible to the public in Nepal: an earthquake location tutorial for education purposes

Earthquakes become a hot topic for discussion in Nepali communities when a big local event happens. Beyond the seismic monitoring and research, efforts to improve the population’s preparedness or to reduce earthquake related risks are limited, and there is a gap between scientific community and society. To establish the missing link between seismology and citizens we have initiated an educational approach called Seismology at School in Nepal and a total of 30 low-cost seismometers have been installed in schools. The program is engaging the public on earthquake related activities and found to be effective in raising the awareness levels of children, promoting broader earthquake learning in the community, thus improving the adaptive capacities and preparedness for future earthquakes. The aim of this work is to present a simple tutorial of earthquake location mainly for Nepali citizens and school teachers. We describe procedures for computing an earthquake epicenter using an open and user-friendly software, Seisgram2K. This tutorial helps the public to have first-order information on earthquakes, by allowing to locate epicenters, which will increase the frequency of earthquake discussion in the community. Open seismic data and the earthquake location tutorial helps to inspire the next generation to study Earth sciences, which is very important and required for earthquake prone countries, like Nepal

A modelling study of post-combustion capture plant process conditions to facilitate 95–99% CO2 capture levels from gas turbine flue gases

The principal purpose of this study is to examine the changes in process conditions that might be needed to achieve up to 99% capture levels in amine post-combustion capture (PCC) plants for combined cycle gas turbine (CCGT) flue gases. This information is of interest since, while 95% capture is adequate for current market and regulatory conditions, net zero fossil emissions (99% capture for a CCGT plant) will be required to deliver global climate mitigation targets and is increasingly a target for national climate policies. The conventionally-configured plant in the study is based on FEED studies carried out by Bechtel Corporation and uses MEA at 35% w/w. Performance modelling is undertaken using the Aspen Plus CCSI MEA Steady State Model. The results show that efficient operation at higher capture levels appears to be feasible with minimal adjustments to the plant configuration, provided that the absorber has a sufficient packing height and the stripper is capable of operation at pressures above 2 bar. The study primarily focuses on operation at low lean loadings (0.09–0.15 molCO2/molMEA) and correspondingly low L/G ratios (<1 by mass), the combination of which, in principle, can give a higher rich loading for a given capture level and packing height and consequently reduce energy consumption. However, for a given capture level, there is a minimum absorber packing height below which a near-optimal rich loading cannot be achieved for any lean loading and L/G ratio. For example, at a lean loading of 0.12 molCO2/molMEA, an absorber packing height of approximately 24 m is required for 99% capture with a minimal increase in specific energy requirements (3.77 GJ/tCO2 at 99% capture vs. 3.50 GJ/tCO2 at 95% capture). A stripper pressure of 2.4 bar is also found to be necessary to achieve this lean loading level without excessive energy requirements. The effect of varying lean loading at three constant rich loading levels is reported in detail, as are the effect of rich loading at constant lean loading and the effect of pressure on stripper performance and energy requirements. The study also examines the effects of cooling and intercooling at elevated capture levels. A simple analysis of break-even operating costs suggests that capture levels higher than the 95% envisaged in current United Kingdom guidance, to further reduce CO2 emissions costs for CCGT + PCC, might be attractive if carbon dioxide removal from air is the alternative

Techno‐economic assessment on the fuel flexibility of a commercial scale combined cycle gas turbine integrated with a CO2 capture plant

Post‐combustion carbon capture is a valuable technology, capable of being deployed to meet global CO2 emissions targets. The technology is mature and can be retrofitted easily with existing carbon emitting energy generation sources, such as natural gas combined cycles. This study investigates the effect of operating a natural gas combined cycle plant coupled with carbon capture and storage while using varying fuel compositions, with a strong focus on the influence of the CO2 concentration in the fuel. The novelty of this study lies in exploring the technical and economic performance of the integrated system, whilst operating with different fuel compositions. The study reports the design of a natural gas combined cycle gas turbine and CO2 capture plant (with 30 wt% monoethanolamine), which were modelled using the gCCS process modelling application. The fuel compositions analysed were varied, with focus on the CO2 content increasing from 1% to 5%, 7.5% and 10%. The operation of the CO2 capture plant is also investigated with focus on the CO2 capture efficiency, specific reboiler duty and the flooding point. The economic analysis highlights the effect of the varying fuel compositions on the cost of electricity as well as the cost of CO2 avoided. The study revealed that increased CO2 concentrations in the fuel cause a decrease in the efficiency of the natural gas combined cycle gas turbine; however, rising the CO2 concentration and flowrate of the flue gas improves the operation of the capture plant at the risk of an increase in the flooding velocity in the column. The economic analysis shows a slight increase in cost of electricity for fuels with higher CO2 contents; however, the results also show a reduction in the cost of CO2 avoided by larger margins

Evaluation of the performance and economic viability of a novel low temperature carbon capture process

A novel Advanced Cryogenic Carbon Capture (A3C) process is being developed using low cost but high intensity heat transfer to achieve high CO2 capture efficiencies with a much reduced energy consumption and process equipment size. These characteristics, along with the purity of CO2 product and absence of process chemicals, offer the potential for application across a range of sectors. This work presents a techno-economic evaluation for applications ranging from 3% to 35%vol. CO2 content. The A3C process is evaluated against an amine-based CO2 capture process for three applications; an oil-fired boiler, a combined cycle gas turbine (CCGT) and a biogas upgrading plant. The A3C process has shown a modest life cost advantage over the mature MEA technology for the larger selected applications, and substantially lower costs in the smaller biogas application. Enhanced energy recovery and optimization offer significant opportunities for further reductions in cost

Techno-economic assessment guidelines for CO2 utilization

Carbon Capture and Utilization (CCU) is an emerging technology field that can replace fossil carbon value chains, and that has a significant potential to achieve emissions mitigation or even “negative emissions”—however in many cases with challenging technology feasibility and economic viability. Further challenges arise in the decision making for CCU technology research, development, and deployment, in particular when allocating funding or time resources. No generally accepted techno-economic assessment (TEA) standard has evolved, and assessment studies often result in “apples vs. oranges” comparisons, a lack of transparency and a lack of comparability to other studies. A detailed guideline for systematic techno-economic (TEA) and life cycle assessment (LCA) for CCU technologies was developed; this paper shows a summarized version of the TEA guideline, which includes distinct and prioritized (shall and should) rules and which allows conducting TEA in parallel to LCA. The TEA guideline was developed in a co-operative and creative approach with roughly 50 international experts and is based on a systematic literature review as well as on existing best practices from TEA and LCA from the areas of industry, academia, and policy. To the best of our knowledge, this guideline is the first TEA framework with a focus on CCU technologies and the first that is designed to be conducted in parallel to LCA due to aligned vocabulary and assessment steps, systematically including technology maturity. Therefore, this work extends current literature, improving the design, implementation, and reporting approaches of TEA studies for CCU technologies. Overall, the application of this TEA guideline aims at improved comparability of TEA studies, leading to improved decision making and more efficient allocation of funds and time resources for the research, development, and deployment of CCU technologies

Sorption direct air capture with CO2 utilization

Direct air capture (DAC) is gathering momentum since it has vast potential and high flexibility to collect CO2 from discrete sources as “synthetic tree” when compared with current CO2 capture technologies, e.g., amine based post-combustion capture. It is considered as one of the emerging carbon capture technologies in recent decades and remains in a prototype investigation stage with many technical challenges to be overcome. The objective of this paper is to comprehensively discuss the state-of-the-art of DAC and CO2 utilization, note unresolved technology bottlenecks, and give investigation perspectives for commercial large-scale applications. Firstly, characteristics of physical and chemical sorbents are evaluated. Then, the representative capture processes, e.g., pressure swing adsorption, temperature swing adsorption and other ongoing absorption chemical loops, are described and compared. Methods of CO2 conversion including synthesis of fuels and chemicals as well as biological utilization are reviewed. Finally, techno-economic analysis and life cycle assessment for DAC application are summarized. Based on research achievements, future challenges of DAC and CO2 conversion are presented, which include providing synthesis guidelines for obtaining sorbents with the desired characteristics, uncovering the mechanisms for different working processes and establishing evaluation criteria in terms of technical and economic aspects

A new non-ideal second order thermal model with additional loss effects for simulating beta Stirling engines

In this paper, comprehensive governing differential equations of Stirling engines have been developed by coupling the effect of gas leakage through the displacer gap, gas leakage into the crank case and the shuttle heat loss into the traditional model. Instantaneous pressures and temperatures of the working fluid in the engine were evaluated at same time step. The present model was deployed for the thermal simulation of the GPU-3 Stirling engine and the obtained results were robustly compared to experimental data as well as results from previous numerical models. Then, parametric studies were conducted to assess the impact of geometrical and operating parameters on the performance of Stirling engines working with helium or hydrogen. Results suggest that the modifications made in this model led to better accuracy and consistency in predicting the experimental data of the prototype engine at all speeds, compared with most previous models. It was found that there exists a minimum dimensionless gap number, for every engine pressure below which mass leakage into the compression volume may not impact the brake power and energetic efficiency of the engine. In addition, an optimum mean effective pressure was found for maximum energetic efficiency of the engine. This optimum value is higher for helium gas than for hydrogen gas. Further results indicated that the brake power and energetic efficiency of the prototype Stirling engine can be significantly improved by 30% and 18%, respectively, provided that the heater temperature is raised to 850 °C while the cooler temperature is reduced to 0 °C

Moho depths beneath the European Alps: a homogeneously processed map and receiver functions database

We use seismic waveform data from the AlpArray Seismic Network and three other temporary seismic networks, to perform receiver function (RF) calculations and time-to-depth migration to update the knowledge of the Moho discontinuity beneath the broader European Alps. In particular, we set up a homogeneous processing scheme to compute RFs using the time-domain iterative deconvolution method and apply consistent quality control to yield 112 205 high-quality RFs. We then perform time-to-depth migration in a newly implemented 3D spherical coordinate system using a European-scale reference P and S wave velocity model. This approach, together with the dense data coverage, provide us with a 3D migrated volume, from which we present migrated profiles that reflect the first-order crustal thickness structure. We create a detailed Moho map by manually picking the discontinuity in a set of orthogonal profiles covering the entire area. We make the RF dataset, the software for the entire processing workflow, as well as the Moho map, openly available; these open-access datasets and results will allow other researchers to build on the current study.</p

Energetic assessment of a combined heat and power integrated biomass gasification-internal combustion engine system by using Aspen Plus®

This study aims at the assessment of a combined heat and power (CHP) biomass bubbling fluidized bed gasification unit coupled with an internal combustion engine (ICE) by using a comprehensive mathematical model based on the Aspen Plus® process simulator. The model is based on a combination of modules that Aspen Plus simulator provides representing the 3 steps of gasification process (drying, pyrolysis, and oxidation), gas cleaning and ICE. The model is based on mass and energy balances and reaction kinetics. The model was validated by using data obtained by operating a pilot atmospheric bubbling fluidized bed gasifier at Aristotle University of Thessaloniki, fed with olive kernel with a capacity of 1 kg/h and an energy output of 5 kW th, and has showed very good agreement. A sensitivity analysis was further conducted for the investigation of the system's behavior under different temperatures and air equivalence ratios. The proposed model is capable of dealing with a wide variety of biomasses (olive kernel, corn cob/stalks, rapeseed and sunflower stalks) using air as the fluidization agent and to predict the system's performance in terms of cold gas and thermal efficiency. © 2011 Elsevier B.V. All rights reserved

An open-access, detailed description of post-combustion CO2 capture plant

Bechtel National (Reston, VA) have undertaken a FEED study for retrofitting a 2x2x1 natural gas-fired gas turbine combined cycle power plant with post-combustion carbon capture (PCC) for CO2 storage/utilization. The comprehensive programme of work covers the integration of the retrofitted carbon capture and compression plant to the combined cycle power plant, together with the detailed design of an amine-based conventional absorber-stripper scrubbing system with a non-proprietary solvent, 35% w/w MEA. Supporting studies have analysed options for single- and two-stage thermal reclaiming and also examined discrepancies between process modelling packages and the possible scope for alternative trade-offs between capital and operating costs. Given that modelling alone cannot predict commercially-important factors such as solvent management costs a long-term pilot test programme is strongly recommended, with outline details supplied for pilot size and the testing period