Recent Trends on Liquid Air Energy Storage: A Bibliometric Analysis

The increasing penetration of renewable energy has led electrical energy storage systems to have a key role in balancing and increasing the e ciency of the grid. Liquid air energy storage (LAES) is a promising technology, mainly proposed for large scale applications, which uses cryogen (liquid air) as energy vector. Compared to other similar large-scale technologies such as compressed air energy storage or pumped hydroelectric energy storage, the use of liquid air as a storage medium allows a high energy density to be reached and overcomes the problem related to geological constraints. Furthermore, when integrated with high-grade waste cold/waste heat resources such as the liquefied natural gas regasification process and hot combustion gases discharged to the atmosphere, LAES has the capacity to significantly increase the round-trip efficiency. Although the first document in the literature on the topic of LAES appeared in 1974, this technology has gained the attention of many researchers around the world only in recent years, leading to a rapid increase in a scientific production and the realization of two system prototype located in the United Kingdom (UK). This study aims to report the current status of the scientific progress through a bibliometric analysis, defining the hotspots and research trends of LAES technology. The results can be used by researchers and manufacturers involved in this entering technology to understand the state of art, the trend of scientific production, the current networks of worldwide institutions, and the authors connected through the LAES. Our conclusions report useful advice for the future research, highlighting the research trend and the current gaps.This work was partially funded by the Ministerio de Ciencia, Innovación y Universidades de España (RTI2018-093849-B-C31—MCIU/AEI/FEDER, UE). This work was partially funded by the Ministerio de Ciencia, Innovación y Universidades - Agencia Estatal de Investigación (AEI) (RED2018-102431-T). The authors at the University of Lleida would like to thank the Catalan Government for the quality accreditation given to their research group GREiA (2017 SGR 1537). GREiA is a certified agent TECNIO in the category of technology developers from the Government of Catalonia. This work was partially supported by ICREA under the ICREA Academia program

Co-digestion of macroalgae for biogas production: an LCA-based environmental evaluation

Algae represent a favourable and potentially sustainable source of biomass for bioenergy-based industrial pathways in the future. The study, performed on a real pilot plant implemented in Augusta (Italy) within the frame of the BioWALK4Biofuels project, aims to figure out whether seaweed (macroalgae) cultivated in near-shore open ponds could be considered a beneficial aspect as a source of biomass for biogas production within the co-digestion with local agricultural biological waste. The LCA results confirm that the analysed A and B scenarios (namely the algae-based co-digestion scenario and agricultural mix feedstock scenario) present an environmental performance more favourable than that achieved with conventional non-renewable-based technologies (specifically natural gas - Scenario C). Results show that the use of seaweed (Scenario A) represent a feasible solution in order to replace classical biomass used for biofuel production from a land-based feedstock. The improvement of the environmental performances is quantifiable on 10% respect to Scenario B, and 38 times higher than Scenario

A new perspective on Workload Control by measuring operating performances through an economic valorization

Workload Control (WLC) is a production planning and control system conceived to reduce queuing times of job-shop systems, and to offer a solution to the lead time syndrome; a critical issue that often bewilders make-to-order manufacturers. Nowadays, advantages of WLC are unanimously acknowledged, but real successful stories are still limited. This paper starts from the lack of a consistent way to assess performance of WLC, an important burden for its acceptance in the industry. As researchers often put more focus on the performance measures that better confirm their hypotheses, many measures, related to different WLC features, have emerged over years. However, this excess of measures may even mislead practitioners, in the evaluation of alternative production planning and control systems. To close this gap, we propose quantifying the main benefit of WLC in economic terms, as this is the easiest, and probably only way, to compare different and even conflicting performance measures. Costs and incomes are identified and used to develop an overall economic measure that can be used to evaluate, or even to fine tune, the operating features of WLC. The quality of our approach is finally demonstrated via simulation, considering the 6-machines job-shop scenario typically adopted as benchmark in technical literature

Defining accurate delivery dates in make to order job-shops managed by workload control

Workload control (WLC) is a lean oriented system that reduces queues and waiting times, by imposing a cap to the workload released to the shop floor. Unfortunately, WLC performance does not systematically outperform that of push operating systems, with undersaturated utilizations levels and optimized dispatching rules. To address this issue, many scientific works made use of complex job-release mechanisms and sophisticated dispatching rules, but this makes WLC too complicated for industrial applications. So, in this study, we propose a complementary approach. At first, to reduce queuing time variability, we introduce a simple WLC system; next we integrate it with a predictive tool that, based on the system state, can accurately forecast the total time needed to manufacture and deliver a job. Due to the non-linearity among dependent and independent variables, forecasts are made using a multi-layer-perceptron; yet, to have a comparison, the effectiveness of both linear and non-linear multi regression model has been tested too. Anyhow, if due dates are endogenous (i.e. set by the manufacturer), they can be directly bound to this internal estimate. Conversely, if they are exogenous (i.e. set by the customer), this approach may not be enough to minimize the percentage of tardy jobs. So, we also propose a negotiation scheme, which can be used to extend exogenous due dates considered too tight, with respect to the internal estimate. This is the main contribution of the paper, as it makes the forecasting approach truly useful in many industrial applications. To test our approach, we simulated a 6-machines job-shop controlled with WLC and equipped with the proposed forecasting system. Obtained performances, namely WIP levels, percentage of tardy jobs and negotiated due dates, were compared with those of a set classical benchmark, and demonstrated the robustness and the quality of our approach, which ensures minimal delays

Preliminary study on mini-modus device designed to oxygenate bottom anoxic waters without perturbing polluted sediments

The Tangential Guanabara Bay Aeration and Recovery (TAGUBAR) project derives its origins from a Brazilian government decision to tackle the planning and management challenges related to the restoration of some degraded aquatic ecosystems such as Guanabara Bay (state of Rio de Janeiro), Vitória Bay, and Espírito Santo Bay (state of Espírito Santo). This was performed by using the successful outcomes of a previous Ministry of Foreign Affairs and Directorate General for Cooperation and Development (i.e., Direttore Generale alla Cooperazione allo Sviluppo, MFA– DGCS) cooperation program. The general objective of the program was to contribute to the economic and social development of the population living around Guanabara, Vitória, and Espírito Santo Bays, while promoting the conservation of their natural resources. This objective was supposed to be achieved by investing money to consolidate the local authorities’ ability to plan and implement a reconditioning program within a systemic management framework in severely polluted ecosystems such as Guanabara Bay, where sediments are highly contaminated. Sediments normally represent the final fate for most contaminants. Therefore, it would be highly undesirable to perturb them, if one wishes to avoid contaminant recycling. In this context, we explored a bench-scale novel technology, called the module for the decontamination of units of sediment (MODUS), which produces an oxygenated water flow directed parallel to the sediment floor that is aimed to create “tangential aeration” of the bottom water column. The purpose of this is to avoid perturbing the top sediment layer, as a flow directed toward the bottom sediment would most probably resuspend this layer. Three kinds of tests were performed to characterize a bench-scale version of MODUS (referred to as “mini-MODUS”) behavior: turbulence–sediment resuspension tests, hydrodynamic tests, and oxygenation–aeration tests. In order to understand the functioning of the mini-MODUS, we needed to eliminate as many variables as possible. Therefore, we chose a static version of the module (i.e., no speed for the mini-MODUS as well as no water current with respect to the bottom sediment and no flume setting), leaving dynamic studies for a future paper. The turbulence tests showed that the water enters and exits the mini-MODUS mouths without resuspending the sediment surface at all, even if the sediment is very soft. Water flow was only localized very close to both mouth openings. Hydrodynamic tests showed an interesting behavior. An increase of low air flows produced a sharp linear increase of the water flow. However, a plateau was quickly reached and then no further increase of water flow was observed, implying that for a certain specific geometry of the equipment and for the given experimental conditions, an increase in the air flow does not produce any reduction of the residence time within the aeration reactor. Oxygenation–aeration tests explored three parameters that were deemed to be most important for our study: the oxygen global transfer coefficient, KLa; the oxygenation capacity, OC; and the oxygenation efficiency, OE%. An air flow increase causes an increase of both KLa and OC, while OE% decreases (no plateau was observed for KLa and OC). The better air flow would be a compromise between high KLa and OC, with no disadvantageous OE%, a compromise that will be the topic of the next paper

Acute Kidney Injury in Coronavirus Disease 2019 Infected Patients: A Meta-Analytic Study

Introduction: In clinical reports on coronavirus disease 2019 (COVID-19), the incidence of acute kidney injury (AKI) is extremely variable, although AKI is described as an independent risk factor for mortality. A meta-analysis was performed to clarify the incidence and the impact of COVID-19-related AKI on mortality. Methods: All trials reporting the incidence of AKI in COVID-19 patients were searched using MEDLINE, the Cochrane Library, and EMBASE databases (last update April 26, 2020). Results: Ten trials with a sample of 5,166 patients were included. AKI occurred in 947 out of 5,166 (18.3%) patients. AKI incidence was higher in severe cases: 62/305 severe patients developed AKI (20%) versus 27/1,268 nonsevere patients (2%) (p = 0.00001). AKI occurred in 475 out of 915 (52%) deceased patients versus 183 out of 2,678 (7%) survivors (p = 0.00001). Continuous renal replacement therapy was significantly more frequent in severe cases and in dead patients. Conclusion: A significant increase in mortality rate was observed in COVID patients who developed AKI, and AKI incidence was also higher in severe cases. Any supportive strategies to protect kidney could represent valuable intervention to reduce mortality in severe COVID-19 patients

Algae-based biorefinery concept. An LCI analysis for a theoretical plant

Both micro and macro algae have a potential to be a valuable feedstock for biorefineries. The theoretical impact assessment of this kind of plant can be carried out through an LCA, which is a key tool in order to evaluate the potential environmental impact of a process throughout its entire life cycle. Hence, it is a priority to perform an LCI with the aim of gathering all the data and simulating all the unit process of a theoretical biorefinery. The Inventory ensures to obtain a simple and immediate way to represent several aspects of a biorefinery, e.g. productivity, environmental pressures, required resources in terms of raw materials and energy. One of the main aspects clearly shown in this study is the significant environmental pressures due to the cultivation and harvesting steps, for which it is desirable to consider a biomass collection from the environment, especially from areas where eutrophication phenomena are particularly recurrent. Another conclusion drawn from the study is that the total plant production per year appears very limited, if compared to any conventional refinery. The following approach can also provide a starting data set to perform a first approximate economic analysis of the costs/gains of the outlined project, and it could be used as a first concept design for the project development of a real plant

Low temperature BMP tests using fish waste from invasive Round goby of the Baltic Sea

ArticleRound goby (Neogobius melanostomus ) is an invasive fish species in the Baltic Sea. While meat can be used for human consumption, fish processing residues are considered as a waste. Within circular economy and bio - economy perspectives fish waste could be used as a valuable feedstock for biogas prod uction. However, the research is mostly focused on evaluating biogas yield at mesophilic conditions (i.e. 37 °C ). In this study the impact of low temperature on Biochemical Methane Potential (BMP) tests has been investigated. Round goby’s processing leftov ers - heads, intestines and skin/bone mixture were tested in codigestion with sewage sludge. Anaerobic digestion (AD) was carried out in 100 mL batch tests at low temperature 23 °C and 37 °C conditions, over an incubation period of 31 days. The results sho w that AD at low temperature occurs twice as slowly as under 37 °C conditions. However, after 31 days the BMP values for 23 °C samples were only 2% lower than for high temperature samples. Heads and skins showed similar BMP values reaching on average 502 L CH 4 kg VS - 1 and 556 L CH 4 kg VS - 1 respectively. BMP for fish intestines was higher, reaching on average 870 L CH 4 kg VS - 1 . Average BMP for mixes of fish heads, skins, intestines and bones was 660 L CH 4 kg VS - 1 . Acquired BMPs were further compared with the theoretical BMPs from Buswell's formula. Research results suggests that anaerobic digestion of fish waste under low temperature conditions could be feasible as the process still efficiently occurs, in fact ope ning a new opportunity to explore the overall sustainability of technologies based on these conversion processes