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Concentrating solar power (CSP) with thermal energy storage has the potential for grid-scale dispatchable power generation. Thermochemical energy storage (TCES), that is, the reversible conversion of solar-thermal energy to chemical energy, has high energy density and low heat loss over long periods. To systematically analyze and compare candidate reactions for TCES, we design an integrated process and develop a general process model for CSP plants with TCES systems. We illustrate our model applicability by using ammonia and methane systems with two gas storage options. The analysis allows us to identify critical issues as well as key targets for fluid phase TCES systems. Gas storage is identified as the main cost driver and compressor electricity consumption as the main energy driver. The impacts of reaction temperature, operating pressure and plant characteristics are also studied. [ABSTRACT FROM AUTHOR]

[Display omitted] • Studied thermochemical energy storage systems in concentrated solar power plants. • Proposed nine strategies for the integrated plant. • Developed process models to optimize the design and operation of these strategies. • Showed that six strategies have better performance over commercial two-tank storage. • Provided general insights into the selection of reactions and process configurations. A system-level analysis is presented for concentrating solar power systems employing various solid-gas thermochemical energy storage strategies, that is, different combinations of chemical reactions and process configurations. Specifically, three representative types (carbonate, hydroxide, redox) of reactions are studied and six different process configurations are proposed. An optimization model is then developed for the design and operation of the plants considering seasonal solar variability. The proposed model is used to obtain the optimal design and system performance of nine thermochemical energy storage strategies. Results show that six out of the nine strategies have the potential to improve both energy efficiency and economic performance over two-tank molten salt storage. In particular, the strategy based on manganese (III) oxide/trimanganese tetraoxide reaction and a configuration with indirect heat transfer in fluidized-bed reactor and open-loop structure achieves about 10% reduction in levelized cost of electricity over the commercially developed concentrated solar power plants. Finally, the impacts of key reaction and process parameters are analyzed and general guidelines for reaction and configuration selections are developed. [ABSTRACT FROM AUTHOR]

• Studied TCES fixed-bed reactors under various operating conditions. • Optimized design & operation of CSP-TCES plants under solar variability. • Compared three types (redox, hydroxide, carbonate) of solid-gas TCES systems. • Identified key factors and areas of improvement for solid-gas CSP-TCES systems. • Showed that TCES has potential to improve performance over alternative systems. Concentrating solar power (CSP) integrated with thermochemical energy storage (TCES) has the potential to deliver cost-effective and dispatchable renewable power. In this work, a system-level analysis of CSP with fixed-bed reactors for TCES is provided. First, we simulate fixed-bed reactors at various operating conditions and build effective surrogate models. Second, we develop an optimization model for the design and operation of CSP plants under seasonal solar variability. Using the proposed model, we compare the performance of three types (redox, hydroxide, and carbonate) of solid-gas TCES systems. Results show that, with careful design, TCES can potentially improve the plant performance over two-tank molten salt storage. Finally, the impacts of key process parameters and reaction properties are analyzed to provide guidance for future TCES development. [ABSTRACT FROM AUTHOR]

We propose an optimization‐based framework for process synthesis under variability in two frequencies. Low‐frequency variability is represented through scenarios and high‐frequency variability is modeled using modes. The proposed framework allows for the selection of different process configurations during different modes, a feature necessary to model systems under wide high frequency variability (e.g., solar‐based technologies). The optimization problem is formulated as a two‐stage stochastic programming model with mode subproblems nested inside each scenario. The proposed framework is applied to the design of concentrating solar power plants with thermochemical energy storage, leading to the formulation of a computationally efficient model, as well as the identification of a superior design. © 2018 American Institute of Chemical Engineers AIChE J, 65: e16458 2019 [ABSTRACT FROM AUTHOR]

This work aims to provide an overview of producing value‐added products affordably and sustainably from greenhouse gases (GHGs). Methanol (MeOH) is one such product, and is one of the most widely used chemicals, employed as a feedstock for ≈30% of industrial chemicals. The starting materials are analogous to those feeding natural processes: water, CO2, and light. Innovative technologies from this effort have global significance, as they allow GHG recycling, while providing society with a renewable carbon feedstock. Light, in the form of solar energy, assists the production process in some capacity. Various solar strategies of continually increasing technology readiness levels are compared to the commercial MeOH process, which uses a syngas feed derived from natural gas. These strategies include several key technologies, including solar‐thermochemical, photochemical, and photovoltaic–electrochemical. Other solar‐assisted technologies that are not yet commercial‐ready are also discussed. The commercial‐ready technologies are compared using a technoeconomic analysis, and the scalability of solar reactors is also discussed in the context of light‐incorporating catalyst architectures and designs. Finally, how MeOH compares against other prospective products is briefly discussed, as well as the viability of the most promising solar MeOH strategy in an international context. [ABSTRACT FROM AUTHOR]