Predictive maintenance has revealed as one of the paradigms of Industry 4.0. This paper addresses a complete system for the acquisition, computing, monitoring and communication of ventilation equipment in underground tunnels based on TCP/IP protocol and accessible via WEB services. Not only does the proposed system collect different sensor data (temperatures, vibrations, pressures, tilt angles or rotational speed), it performs local data processing as well. This feature is the newest and most important of all those provided by the system design, and there is no equipment that offers a similar performance in current ventilation systems. This paper shows the design and implementation of the equipment (system architecture and processing), as well as the experimental results obtained.

The growing demand for clean, decentralized energy has increased interest in blue energy, which generates power from water with different salt concentrations. Despite its potential as a renewable, low-cost energy source, optimizing electrode materials remains a challenge. This work presents a nanomaterial developed via microwave-assisted sol-gel methodology for blue energy applications, where ion diffusion and charge storage are critical. AX-7 carbon, designed for this study, features wide pores, enhancing ion diffusion. Compared to commercial NORIT carbon, AX-7 has a higher mesopore volume and external surface area, improving its overall performance. The synthesis process has been optimized and scaled up for evaluation in CAPMIX electrochemical cell stacks. Moreover, the lower series resistance (Rs) significantly boosts energy recovery, with AX-7 demonstrating superior performance. This advantage is especially evident during fresh-water cycles, where this material achieves significantly lower Rs compared to the commercial one.

Capacitive deionization cells, already present in different industrial applications, can also be used to generate electrical energy by alternating salt and fresh water flows (CapMix cells). Unfortunately, the performance inherent to these cells gives rise to large losses when extracting the energy harvested. This article provides contributions to the appropriate characterization of CapMix cells and to the optimization of the energy-extraction process. The optimization analysis carried out concludes that the best strategy consists of extracting the energy by discharging the cell with a constant current to minimize cycle times. This determines the operation conditions of the power converter that will be eventually used for that task. A test bench has been developed that allows the theoretical analysis presented to be experimentally validated.

Circulation of salty and fresh water through the electrodes of a deionization cell produces a voltage between the electrodes caused by the Capacitive Donnan Potential (CDP). The voltage so generated is very low (100 mV), but this work demonstrates that it is possible to develop a power converter suitable to inject this energy into the grid or into energy storage systems; this is a relevant aspect of this paper, for most works in the literature simply dissipate this energy over a resistor. To increase the input voltage, a stack of electrodes is connected in series. A bridgeless rectifier that uses a dual buck–boost converter to operate with both the positive and negative cycles is used to extract the energy from the cell. The topology chosen, which is operated as a current source, can work at extremely low voltage levels and provide power factor correction. After this stage, an H-bridge inverter can be included to inject the energy into the AC grid. The whole system implements a hysteresis control system using the current through the inductor of the power converter as control variable. This paper investigates the influence of such current on the efficiency of the total system.

Blue energy has revealed as an alternative to other widely used sources of renewable energy. This power source derived from the process of mixing sea and river water still remains to be fully developed. Research on the materials used to produce the cells that capture this energy is one of the topics that will definitely contribute to the development of this technology. And just as important, if not more, is the research related to the systems that must be used to extract the stored energy. This paper shows the influence of the porous carbon used to manufacture the cells and provides insight into the selection of the optimum current that must be used to extract the energy from the cell. These contributions are supported by both simulations and experimental results.