Design of a compressed air system is a complex issue, involving the design of structures formed by the air sources, air receptors and
installations connecting all structure components. Another major task is to ensure the required quality of compressed air. The paper briefly
outlines the methodology of integrated and network structure design, using an objective function to find the optimal solution. In terms of
quality assurance, the technological aspects of compressed air generation, treatment and distribution are defined.
The article deals with the subject of an important component of energy management, which is the performance of energy efficiency audits in companies. Using the case study analysis, the role of the energy audit was analyzed in the context of improvement of energy efficiency in selected production companies. The essence of legal requirements following from the implementation of the amended Energy Efficiency Act was presented. Specifically, problems and challenges, which refer to the method of implementation of the audit obligation in economic practice, were discussed. Furthermore, the issue of quality and usefulness (in the decision-making process) of prepared reports was raised. It was found that there were indications to claim that the obligatory energy audit of companies is not an instrument for the improvement of energy efficiency, which is always used optimally. The fault in this situation is partly attributable to the state, audit bodies and the company management. In this case, not only is the ineffective communication an issue here, but also the insufficient level of knowledge regarding energy management, as well as haste. The amendment of the Energy Efficiency Act (within just one year) imposed the necessity to conduct an energy audit on a specific group of companies. In principle, because all the entities, to which the obligation referred, had to take actions almost at the same time, numerous issues appeared. Some managers learned about the obligation to conduct the audit from companies who themselves had come out with a proposal to carry it out. This proves the lack of the proper information flow between the government administration authorities and the companies. Again, it turned out that practitioners did not keep pace with the implementation of actions, which were a consequence of numerous (and not always well thought-out) changes in the law. Haste in the fulfillment of the statutory obligation affected a high price spread of the bids sent during tenders, related to the performance of an energy audit. Bureaucratic regulations regarding tenders became another obstacle in the correct performance of the tasks. The entrepreneurs themselves, without clear guidelines on what to expect after the performed energy audit and what a report should look like, on many occasions, selected the “cheapest” bid – not always thinking too much about the qualitative consequences of such a decision. Some certifying bodies – taking advantage of an opportunity and the satisfactory combination of circumstances – offered unprofessional audit services of questionable quality. In the presented conditions, it is difficult to expect real, systemic and desirable results (economically, ecologically and socially) with regards to the energy efficiency both in the micro-, meso- and macr-economic scale. It is worth considering changes in the Energy Efficiency Act and spread the obligation to perform audits over different years according to clearly defined (in cooperation with business) criteria. If relevant actions are not taken, the situation of a temporary Eldorado on the market of energy audits will repeat in 4 years. Again, the consequence may be the poor quality and questionable usefulness of reports from energy audits of companies both at the business level and the ecological-political level. It is necessary to counteract all forms of unfair competition to interdisciplinary and specialist bodies which take actions to improve the energy efficiency of organisations. The creation of appropriate business conditions will have a positive impact on the improvement of energy efficiency. In this context, it is necessary to take actions, which enable the optimization of both the process of the implementation of obligatory legal regulations and voluntary (industry) norms and standards.
The paper presents a circuit structure that can be used for powering an IoT (Internet of Things) sensor node and that can use energy just from its surroundings. The main advantage of the presented solution is its very low cost that allows mass applicability e.g. in the IoT smart grids and ubiquitous sensors. It is intended for energy sources that can provide enough voltage but that can provide only low currents such as piezoelectric transducers or small photovoltaic panels (PV) under indoor light conditions. The circuit is able to accumulate energy in a capacitor until a certain level and then to pass it to the load. The presented circuit exhibits similar functionality to a commercially available EH300 energy harvester (EH). The paper compares electrical properties of the presented circuit and the EH300 device, their form factors and costs. The EH circuit’s performance is tested together with an LTC3531 buck-boost DC/DC converter which can provide constant voltage for the following electronics. The paper provides guidelines for selecting an optimal capacity of the storage capacitor. The functionality of the solution presented is demonstrated in a sensor node that periodically transmits measured data to the base station using just the power from the PV panel or the piezoelectric generator. The presented harvester and powering circuit are compact part of the sensor node’s electronics but they can be also realized as an external powering module to be added to existing solutions.
The optimal energy management (OEM) in a stand-alone microgrid (SMG) is a challenging job because of uncertain and intermittent behavior of clean energy sources (CESs) such as a photovoltaic (PV), wind turbine (WT). This paper presents the effective role of battery energy storage (BES) in optimal scheduling of generation sources to fulfill the load demand in an SMG under the intermittency of theWT and PV power. The OEM is performed by minimizing the operational cost of the SMG for the chosen moderate weather profile using an artificial bee colony algorithm (ABC) in four different cases, i.e. without the BES and with the BES having a various level of initial capacity. The results show the efficient role of the BES in keeping the reliability of the SMG with the reduction in carbon-emissions and uncertainty of the CES power. Also, prove that the ABC provides better cost values compared to particle swarm optimization (PSO) and a genetic algorithm (GA). Further, the robustness of system reliability using the BES is tested for the mean data of the considered weather profile.
In this paper, an energy coordination control method based on intelligent multi-agent systems (MAS) is proposed for energy management and voltage control of a DC microgrid. The structure of the DC microgrid is designed to realize the mathematical modeling of photovoltaic cells, fuel cells and batteries. A two-layer intelligent MAS is designed for energy coordination control: grid-connection and islanding of a DC microgrid is combined with energy management of PV cells, fuel cells, loads and batteries. In the hidden layer and the output layer of the proposed neural network there are 17 and 8 neurons, respectively, and the “logsig” activation function is used for the neurons in the network. Eight kinds of feature quantities and 13 different actions are taken as the input and output parameters of the neural network from the micro-source and the load, and the as the control center agent’s decision-makers. The feasibility of the proposed intelligent multi-agent energy coordination control strategy is verified by MATLAB/Simulink simulation, and three types of examples are analyzed after increasing the load. The simulation results show that the proposed scheme exhibits better performance than the traditional approaches.