Minimum marginal abatement cost curves (Mini-MAC) for CO2 emissions reduction planning

The economic impact of CO2 emissions reduction requirements demands strategic planning to identify low-cost CO2 mitigation pathways from combinations of the many available CO2 emissions reduction options. Different tools have been developed to plan minimal cost CO2 reduction pathways taking into consideration various options such as CO2 capture, utilization, and sequestration (CCUS), shifting from fossil to renewable energy sources, as well as adopting sector-specific low emissions technologies. Current methods used to support strategic planning include high-level tools that cannot account for many possible options or fail to incorporate cost objective, and complex optimization approaches that are capable of identifying detailed low-cost solutions yet are demanding to use and often yield complex solutions in terms of processing schemes that are not easily understood by strategic planners. To address these limitations, a simple and clear methodology is proposed that allows to determine minimum cost CO2 reduction pathways from the rich set of available options. The novel methodology employs an algebraic targeting technique that yields minimum marginal abatement cost (Mini-MAC) curves to clearly represent the low-cost CO2 emissions reduction pathway available. The application of the methodology is illustrated with an example to develop minimum cost emissions reduction pathways considering CCUS, power shifting options, and negative emissions technologies. The benefits of the proposed Mini-MAC curves over alternative methods stem from their richness in terms of assessing CCUS, energy management options, and various integration options. Further, the clarity of the proposed Mini-MAC curves enables planners to easily understand available minimum cost pathways when developing strategies aimed at achieving low-cost CO2 emissions reduction. Graphical abstractOther Information Published in: Clean Technologies and Environmental Policy License: https://creativecommons.org/licenses/by/4.0See article on publisher's website: http://dx.doi.org/10.1007/s10098-021-02095-y</p

Optimization across the Water–Energy Nexus for Integrating Heat, Power, and Water for Industrial Processes, Coupled with Hybrid Thermal-Membrane Desalination

The water–energy nexus continues to gain traction around the world, because of the inherent merits in simultaneously considering both resources. In this paper, a systematic procedure is developed for maximizing the benefits of this interdependent relationship, when coupled with industrial processes exhibiting a net surplus of heat energy. The presented methodology utilizes a total site analysis to first screen the process for power and water generation potential. In addition to process water streams, seawater desalination is considered as an additional resource. Based on this analysis, heat integration is carried out to capture the options for steam production for process requirements, thermal desalination of seawater, and power production. For the power generation system, a turbine network is developed, whereas, for the water desalination system, a hybrid multieffect distillation–reverse osmosis (MED-RO) system is utilized. A superstructure is constructed to embed the various configurations, and the associated optimization formulation is solved to obtain an optimal process that economically balances the need for water and power. A case study is solved to evaluate several scenarios for developing water and energy strategies for a gas-to-liquids (GTL) process in a region with various demands, as well as power and water exportation restrictions

Development of a Kinetic Model for Catalytic Reforming of Naphtha and Parameter Estimation Using Industrial Plant Data

In the present paper, a semi-empirical kinetic model for catalytic reforming has been developed. In the developed model, the component “lumping” strategy is based on a paraffins, olefins, naphthalenes, and aromatics (PONA) analysis. “Activation energy lumps” are introduced to take into account different values of activation energies within specific reaction classes. The parameters of the model have been estimated by bench marking with industrial data. Simulation results have been found to be in very close agreement with plant data. One of the advantages of the present kinetic model is that it predicts the concentration of hydrogen and light gases very well. Because it is formulated from basic principles, this kinetic model with some modification can be applied to any catalytic reformer

Toward Optimum Working Fluid Mixtures for Organic Rankine Cycles using Molecular Design and Sensitivity Analysis

This work presents a Computer-Aided Molecular Design (CAMD) method for the synthesis and selection of binary working fluid mixtures used in Organic Rankine Cycles (ORC). The method consists of two stages, initially seeking optimum mixture performance targets by designing molecules acting as the first component of the binaries. The identified targets are subsequently approached by designing the required matching molecules and selecting the optimum mixture concentration. A multiobjective formulation of the CAMD-optimization problem enables the identification of numerous mixture candidates, evaluated using an ORC process model in the course of molecular mixture design. A nonlinear sensitivity analysis method is employed to address model-related uncertainties in the mixture selection procedure. The proposed approach remains generic and independent of the considered mixture design application. Mixtures of high performance are identified simultaneously with their sensitivity characteristics regardless of the employed property prediction method

Water and Energy Issues in Gas-to-Liquid Processes: Assessment and Integration of Different Gas-Reforming Alternatives

The substantial discoveries of shale gas are leading to increasing attention of gas-to-liquid processes using Fischer–Tropsch chemistry. Traditionally, focus has been given to the reaction schemes, while major issues such as energy and water matters have been handled subsequently. There is a need to examine the impact of selecting the reforming technology on issues pertaining to sustainability such as energy and water usage. This paper analyzes energy and water generation and management options for three primary alternatives for the production of syngas: steam reforming, partial oxidation, and autothermal reforming. A combination of thermodynamic models and computer-aided simulation is used to quantify those aspects. Trade-offs are established for the use of a desired H₂:CO ratio on water and energy usage. Also, systematic process integration techniques are used to identify the impact of energy and mass integration on the usage of energy and water in the process and to benchmark the process performance