In recent years, the use of solid biofuels (SBF) in combustion systems to generate industrial heat has become more common as they are renewable, potentially carbon neutral, and able to support an energy transition away from fossil fuels. However, despite the ready availability of waste biomass in Mexico and its suitability for incineration, the development of SBFs as a fuel source had lagged behind other countries. Promoting the use of SBF requires technical, sustainability, and economic feasibility studies to identify optimization opportunities for known systems. This article presents two technical, economic, and environmental feasibility studies of the use of SBF for process heat. Carbon dioxide emissions and economic feasibility were compared to fossil fuels to ascertain whether SBFs could be useful as a transition fuel in the medium term. Finally, some circumstances where the implementation of SBF in an industrial process could be feasible were identified. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd

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A generalized model for the maximum work rate extractable from the Sun is developed considering a reversible and an endoreversible system to define a more practical upper-bound efficiency for the conversion of solar radiation into work and power. This model is based on a photo-thermal work extractor in communication with a high-temperature radiation reservoir and a low-temperature heat sink. Following the model, a parametric analysis of the concentration acceptance product (ξ) and thermal conductance is performed to identify the interdependence of variables for the solar exergy. The results are compared with existing models to provide a practical baseline of work and power extractable from concentrated solar power plants (CSP) technologies. Therefore, it is possible to quantify the irreversibilities of an idealized thermodynamic system operating between the Sun and the absorber (via radiative transfer) and the environment (via convective transfer).

The possible implementation of direct steam generation (DSG) in parabolic troughs in the Northweast region of Mexico is very limited, since there are no analyses of this type to try to define a first proposal for a solar plant. Recently, a methodology has been implemented to eliminate the convective coefficient h in order to model the DSG process in a simpler way. This methodology has been validated with experimental data from the DISS results from PSA. This methodology allows to evaluate the temperature evolution along the loop, the pressure drop and the flow pattern in a short time and with low computational resources. This allows generating the first evaluation of a solar field with parabolic troughs. Additionally, by applying a new practical efficiency limit for the conversion of solar radiation into work, the exergetic efficiency of the installation is evaluated. The results show that this first evaluation, seems to be adecuate acording to the results suggested in the open literature.

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