The update of anaerobic digestion and the environment impact assessments research

An increasing number of studies on biogas as a renewable energy including the industrial implementation have been published. The important issues dealing with anaerobic digestion (AD) includes integration of the evidence into patterns, capable of illustrating the current research trend and gaps. Although AD is widely perceived as a clean technology, the assessing and reporting of its environmental impacts remain an important research scope. This work attempts to highlight the recent AD development through a systematic reviewing approach. The criteria for searching are year, type of search engine, keywords and for the selection according to the relevance of the available sources. The presented review covers a case study, mixed mode, by experiment and review. The environmental impact analysis in AD life cycle assessment is also discussed. This facilitates the future studies in improving the environmental impact of AD system. The digestate management and application were suggested as the hotspot of AD system that needs to be improved as the first priority. The AD overview that has been presented statistically proposes the other potential research direction through the interpretation of the type, amount and characteristics of available research. The key future research area is a feasibility study of AD with the consideration to optimise the energy efficiency, economic and environmental aspects which would attract the investors as well as convince the policy makers

Heat integration of ammonia refrigeration cycle into buildings heating systems in buildings

The possibility of utilizing the low potential heat of the ammonia refrigeration cycle has been shown. The design of an energy saving heat exchangers network to heat water and air in municipal buildings has been proposed. The possibility of increasing the pressure of ammonia with the purpose of improving the heat recovery in the system and reducing the load of the heating and cooling systems was considered. The minimum temperature difference in the heat exchangers network was selected. The economic efficiency of the retrofit project was estimated

The Development of Heat Substation for Drying Waste Heat Utilisation

The problem solution of waste heat utilization at the tobacco factory is considered in this work. The analysis of the possibility of waste heat utilization and appropriate calculations of plate heat exchangers were carried out. The method for multi component mixture condensation calculation is used. This allows obtaining optimal parameters for the working conditions of the heat exchangers according to the energy efficiency retrofit of industrial enterprises. The design of heat substation for waste heat utilisation was developed

Sustaining the low-carbon emission development in Asia and beyond: Sustainable energy, water, transportation and low-carbon emission technology

Climate change is global issues with significant economic, social and environmental implications. Climate change mitigation in Asia has large impacts on global CO2 emission reduction. CO2 emission is the largest source of greenhouse gas emission constitutes about 65% of the total emission. Low-carbon Society initiative is one of the various mechanisms that have been deployed to achieve green economic growth, societal well-being and development, environmental preservation and management in a holistic manner. Energy efficiency improvement in Asia will be a key factor to tackle the climate change issues. Water and energy conservation, green transportation and low emission technology are the key aspects to catalyse the shift towards climate-resilient economic growth. The latest developments in these aspects are reviewed in this special volume to sustain the development of low-carbon emission in Asian countries. The use of holistic management system to integrate these key areas for long-term sustainability goal is also highlighted

Mini-review on substrate & inoculum loadings for anaerobic co-digestion of food waste

Increasing production of food waste can lead to major environmental pollution if it is disposed without proper control in many countries. Food waste can be regarded as a resource rather than unwanted discard due to its high potential for resource recovery. Anaerobic digestion of food waste has shown promising potential for food waste treatment and valorisation by producing biogas as a renewable energy and digestate as fertiliser. Food waste has high biogas potential due to the presence of highly labile organic matter but this can lead to process instability. The process instability is often linked to the imbalance of process intermediates that affects the microbial community. Common parameters that are crucial for ensuring optimal metabolic activity of anaerobes includes temperature, pH, carbon-nitrogen ratio, organic loading rate, retention time and nutrient concentration. Co-digestion of food waste with other feedstocks are increasingly being practiced for better nutrient balance and reducing chances for rapid acidfication. The optimum conditions for the process has been shown to vary following different microbial inoculants and loadings of the respective substrates. This study aims to review only the effect of substrate and inoculum used during the AD of food waste, including the type of co-digested substrate, the mixing ratio, the microbial inoculant used and the substrate to inoculum ratio

Ensemble evaluation of hydrological model hypotheses

It is demonstrated for the first time how model parameter, structural and data uncertainties can be accounted for explicitly and simultaneously within the Generalized Likelihood Uncertainty Estimation (GLUE) methodology. As an example application, 72 variants of a single soil moisture accounting store are tested as simplified hypotheses of runoff generation at six experimental grassland field-scale lysimeters through model rejection and a novel diagnostic scheme. The fields, designed as replicates, exhibit different hydrological behaviors which yield different model performances. For fields with low initial discharge levels at the beginning of events, the conceptual stores considered reach their limit of applicability. Conversely, one of the fields yielding more discharge than the others, but having larger data gaps, allows for greater flexibility in the choice of model structures. As a model learning exercise, the study points to a “leaking” of the fields not evident from previous field experiments. It is discussed how understanding observational uncertainties and incorporating these into model diagnostics can help appreciate the scale of model structural error

NeuralHydrology -- Interpreting LSTMs in Hydrology

Despite the huge success of Long Short-Term Memory networks, their applications in environmental sciences are scarce. We argue that one reason is the difficulty to interpret the internals of trained networks. In this study, we look at the application of LSTMs for rainfall-runoff forecasting, one of the central tasks in the field of hydrology, in which the river discharge has to be predicted from meteorological observations. LSTMs are particularly well-suited for this problem since memory cells can represent dynamic reservoirs and storages, which are essential components in state-space modelling approaches of the hydrological system. On basis of two different catchments, one with snow influence and one without, we demonstrate how the trained model can be analyzed and interpreted. In the process, we show that the network internally learns to represent patterns that are consistent with our qualitative understanding of the hydrological system.Comment: Pre-print of published book chapter. See journal reference and DOI for more inf