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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.

The use of solid biofuels in for industrial heat has gained interest in several countries of the world, due to the economic advantages offered by its use since it is considered a neutral renewable energy source of greenhouse gas emissions greenhouse. Even with the high availability of biomass in Mexico, with appropriate characteristics for incineration, its development has lagged behind other countries. It is important to carry out economic and environmental feasibility studies of the biomass systems already installed in order to identify opportunities for its optimization. This article presents 2 environmental and economic feasibility studies of the use of BCS for process heat; using agave bagasse and pine woodchip among other biofuels. An emission analysis, an ACV analysis as well as an economic feasibility analysis are carried out and the results are compared with the use of fossil fuels to determine their feasibility in the medium term

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