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Topic Review
Enzymatic Hydrolysis and Fermentation of Woody Biomass
As greenhouse gas emissions are continuously increasing, research is now privileging greener and more sustainable human activities. An attractive strategy in the pursuit of sustainability is the valorization of lignocellulosic biomasses for the production of bioethanol. This approach relies on the bioconversion of wood and agricultural waste, which are abundant globally. They represent considerable sources of fermentable sugars that can be recovered through enzymatic hydrolysis. However, the presence of lignin in wood waste makes it more recalcitrant to enzymatic hydrolysis, and reduces the efficiency of the bioconversion process. Therefore, a pretreatment preceding hydrolysis is highly necessary in order to disrupt the resistant structure of woody biomass. The type and severity of the pretreatment affect the outcomes of the hydrolysis and fermentation steps, just as they strongly influence the overall process costs. Given this context, bioenergy production from this biomass is a promising alternative method of sustainably responding to energy demands while reducing the amounts of waste left in nature. 
  • 1.4K
  • 13 Jul 2023
Topic Review
Ionic Liquids and Lignin
This entry gives overview of the lignin separation methods from lignocellulosic biomass using various methods but the main attention has been paid on lignin separation using ionic liquids. Lignin is a natural polymer, one that has an abundant and renewable resource in biomass. Due to a tendency towards the use of biochemicals, the efficient utilization of lignin has gained wide attention. The delignification of lignocellulosic biomass makes its fractions (cellulose, hemicellulose, and lignin) susceptible to easier transformation to many different commodities like energy, chemicals, and materials that could be produced using the biorefinery concept. 
  • 1.4K
  • 10 Oct 2020
Topic Review
Production of BioH2 Using Microalgae
Demand for clean energy has increased due to the proliferation of climate change impact from excessive emission of greenhouse gases (GHG) from the combustion of fossil fuels. H2 is a clean energy source since water vapor is the only byproduct after its combustion. Growing microalgae offers a promising low-energy and low-cost approach for bioH2 production. Diverse microalgae can generate bioH2, including Chlorella sp., Scenedesmus sp., Monoraphidium sp., Platymonas sp., Tetraspora sp., Closterium sp., and Chlamydomonas sp. Even though green microalgae have high potential as a renewable energy source, only about 70 species from more than 30 genera have been researched so far.
  • 1.4K
  • 13 Jan 2023
Topic Review
Micro combined heat and power
       Micro Combined Heat and Power (µCHP) systems in a DG infrastructure can reduce a building’s primary energy consumption, reduce carbon footprint, and enhance resiliency. The simultaneous production of electrical and thermal energy from a single fuel source at a high overall energy efficiency can reduce primary energy consumption while lowering greenhouse gas (GHG) emissions. A comprehensive overview of various modeling approaches adopted by international researchers is presented. The key objective is to present the state-of-the-art models and approaches while identifying opportunities for further refinement to expand the capabilities of such models for versatile applications.  
  • 1.4K
  • 27 Aug 2020
Topic Review
Hybrid Renewable Energy Systems
According to literature, around 80% of the world’s total energy demand is supplied either through fuel-based sources such as oil, gas, and coal or through nuclear-based sources. Literature also shows that a shortage of fossil fuels is inevitable and the world will face this problem sooner or later. Moreover, the remote and rural areas that suffer from not being able to reach traditional grid power electricity need alternative sources of energy. A “hybrid-renewable-energy system” (HRES) involving different renewable resources can be used to supply sustainable power in these areas. The uncertain nature of renewable energy resources and the intelligent ability of the neural network approach to process complex time series inputs have inspired the use of ANN methods in renewable energy forecasting. 
  • 1.4K
  • 11 May 2021
Topic Review
NiFe Oxide Electrocatalyst
NiFe electrodes are developed for the oxygen evolution reaction (OER) in an alkaline electrolyser based on an anion exchange membrane (AEM) separator and fed with diluted KOH solution as supporting electrolyte. This study reports on the electrochemical behaviour of two different NiFe-oxide compositions (i.e., Ni1Fe1-oxide and Ni1Fe2-oxide) prepared by the oxalate method. These catalysts are assessed for single-cell operation in an MEA including a Sustainion™ anion-exchange membrane. The electrochemical polarization shows a current density of 650 mA cm−2 at 2 V and 50 °C for the Ni1Fe1 anode composition. A durability test of 500 h is carried out using potential cycling as an accelerated stress-test. This shows a decrease in current density of 150 mA cm−2 mainly during the first 400 h. The performance achieved for the anion-exchange membrane electrolyser single-cell based on the NiFeOx catalyst appears promising. However, further improvements are required to enhance the stability under these operating conditions.
  • 1.4K
  • 30 Dec 2020
Topic Review
Wind Energy Operation and Maintenance
 A new procedure to predict wind farm failures is developed based on statistical methods in real wind farms.
  • 1.3K
  • 20 Mar 2021
Topic Review
Heterogeneous Catalysts Used in Hydrothermal Gasification
Supercritical water gasification has emerged as a promising technology to sustainably convert waste residues into clean gaseous fuels rich in combustible gases such as hydrogen and methane. The composition and yield of gases from hydrothermal gasification depend on process conditions such as temperature, pressure, reaction time, feedstock concentration, and reactor geometry. However, catalysts also play a vital role in enhancing the gasification reactions and selectively altering the composition of gas products. Catalysts can also enhance hydrothermal reforming and cracking of biomass to achieve desired gas yields at moderate temperatures, thereby reducing the energy input of the hydrothermal gasification process. 
  • 1.3K
  • 04 Jul 2023
Topic Review
Optimization Control Strategies in Building Energy Management Systems
Due to rising energy demands, the industrial revolution has brought with it a slew of new issues. This phenomenon fosters the development of more resource-efficient control approaches. The building sector has a huge potential to mitigate energy demand using intelligent energy management systems (IEMS) and the concept of the internet of energy (IoE). The IoE combines features of a smart grid and the internet of things (IoT). The IoT refers to internet-based architecture in two ways: communication allows the system to be monitored and controlled in real-time via cloud computing or another internet service. It is proven that the potential of IoE-based building energy management systems (BEMS) will enhance the performance of future building energy utilization. The key idea of BEMS is monitoring and controlling the energy consumption in buildings with the aim of reducing emissions. The design of BEMS has taken into account factors such as efficiency, scalability, robustness, flexibility, and an ability to sense the environment and make decisions autonomously.
  • 1.3K
  • 27 Feb 2023
Topic Review
Features and Barriers of Hydrogen Combustion
After reviewing hydrogen and hydrogen blends combustion characteristics (laminar and turbulent flame speeds, adiabatic flame temperature, preferential diffusion), combustion applications in both thermo-electric power generation and hard-to-abate industry sectors are considered, highlighting the main issues due to hydrogen addition related to safety, pollutant emissions, and potentially negative effects on industrial products.
  • 1.3K
  • 25 Oct 2023
Topic Review
Energy Efficiency Improvement
The school buildings represent an energivorus sector of the real estate where different efficiency actions are necessary. Literature shows how the design of a multi-energy system offers numerous advantages, however, there are problems related to the integration of cogeneration units with renewable energy sources due to the low flexibility of the first one and the high degree of uncertainty of the latter. The authors provide an alternative solution through the analysis of a case study consisting of a Multiple Energy System on three Sicilian schools, focusing on the system's operational strategy, on design and sizing of components and trying to exploit the energy needs complementarity of buildings instead of integrating the conventional energy storage systems. Not considering school activities in summer, it was decided to install a cogeneration unit sized on winter thermal loads, whereas the electricity demand not covered was reduced with photovoltaic systems designed to maximizing production for seasonal use and with loads concentrated in the morning hours. The effectiveness of this idea, which can be replicated for similar users and areas, is proved by a payback-time less than 11 years and a reduction of 31.77%, of the CO2 emissions.
  • 1.3K
  • 10 Nov 2020
Topic Review
Physical and Market Structure of Peer-to-Peer Trading Networks
A peer-to-peer (P2P) network is a distributed self-organising network that does not need to have central nodes, and each node can act as either a server or a client at any given time. The evolution of DERs and the principles of peer-to-peer networks have given rise to interest in the concept of P2P energy trading networks. In a P2P energy trading network, there are no intermediate energy suppliers. People are encouraged to share their energy surplus directly with their local communities. The energy surplus will be sold at an export price, and the additional electricity demand can be encouraged by a cheaper-than-normal retail price.
  • 1.3K
  • 27 Feb 2024
Topic Review
Water–Energy Nexus
The sustainability or green building rating system used in the United Arab Emirates (UAE), Pearl Rating System (PRS) of Estidama, similar to other international rating systems such as LEED and BREEAM, considers several strategies, regulations, and policies to improve the energy and water performance in buildings. However, the applicability of considering water as part of energy or the fact that utilization of energy mandates the usage of water seems unexplored and not yet included in any of the existing building rating systems including LEED. A unified approach of the water and energy resources is hence vital for future considerations in energy policy, planning and the inclusion of the same in the sustainability rating systems as well. This paper investigates, as a case study, the prospects of water-energy nexus in the prevailing UAE green building rating system; Pearl Rating System(PRS) to bring out if any water conservation strategy has an adverse effect on energy and vice versa. The review revealed that the major shortcomings of PRS in terms of water-energy nexus strategy are the usage of reference codes not suitable to UAE’s climate and geographical conditions, inexistent synergy between some credit categories, oversight of rebound effects, and a need for credit reassessment. The paper also recommends that any proposed strategy to realign credit categories in terms of water-energy nexus with the potential risk to also have a hidden negative rebound effect which the researchers and practitioners should identify lest the water- energy tradeoff bring unprecedented repercussions. The theoretical analysis established that the bifurcating management of water and energy in the sustainability rating system and energy policy needs to be revisited in order to reap more sustainable and optimum results that is environmentally, ecologically and financially consistent. The theoretical analysis established that the bifurcating management of water and energy in the sustainability rating system and energy policy need to be reformed in order to reap more sustainable and optimum results that is environmentally, ecologically and financially consistent.  
  • 1.3K
  • 12 Apr 2021
Topic Review
Oxygenated Biofuel
The need for lowering the environmental impacts has incentivized the investigation of biomass and biofuels as possible alternative sources for energy supply. Among the others, oxygenated bio-derived molecules such as alcohols, esters, acids, aldehydes, and furans are attractive substances as chemical feedstock and for sustainable energy production. Indeed, the presence of oxygen atoms limits the production of aromatic compounds, improves combustion efficiency (thus heat production) and alleviates the formation of carbon soot. On the other hand, the variability of their composition has represented one of the major challenges for the complete characterization of combustion behaviour. This work gives an overview of the current understanding of the detailed chemical mechanisms, as well as experimental investigations characterizing the combustion process of these species, with an emphasis on the laminar burning velocity and the ignition delay time.
  • 1.3K
  • 30 Jun 2021
Topic Review
Energy storage technologies application Potentials
Renewable energy sources (RESs) such as wind and solar are frequently hit by fluctuations due to, for example, insufficient wind or sunshine. Energy storage technologies (ESTs) mitigate the problem by storing excess energy generated and then making it accessible on demand. While there are various EST studies, the literature remains isolated and dated. The comparison of the characteristics of ESTs and their potential applications is also short. This paper fills this gap. Using selected criteria, it identifies key ESTs and provides an updated review of the literature on ESTs and their application potential to the renewable energy sector.
  • 1.3K
  • 04 Jan 2021
Topic Review
100% Renewable Energy: Concepts and Progresses
Some advanced countries’ rapid population, economic growth, and energy consumption expansion contribute significantly to global CO2 emissions. And while developed countries have achieved 100% universal access to electricity, mainly from non-renewable sources, many developing countries still lack it. This presents challenges and opportunities for achieving the United Nations’ Sustainable Development Goals (SDGs) 7 and 13 of generating all energy from cleaner or low-carbon sources to reduce CO2 emissions in all countries and combating climate change consequences. Renewable energies have been widely acknowledged to greatly advance this endeavour, resulting in many studies and about 30 countries already with over 70% of their national electricity mix from RE. It has birthed a new paradigm and an emerging field of 100% RE for all purposes, receiving much attention from academia and in public discourse. 
  • 1.3K
  • 20 Sep 2023
Topic Review
Solid-State Anaerobic Digestion
Anaerobic digestion (AD) is a promising way to produce renewable energy. The solid-state anaerobic digestion (SSAD) with a dry matter content more than 15% in the reactors is seeing its increasing potential in biogas plant deployment. The relevant processes involve multiple of evolving chemical and physical phenomena that are not crucial to conventional liquid-state anaerobic digestion processes (LSAD). A good simulation of SSAD is of great importance to better control and operate the reactors. The modeling of SSAD reactors could be realized either by theoretical or statistical approaches.
  • 1.3K
  • 07 Feb 2023
Topic Review
Grouting in Coal Mass
Pre-grouting as an effective means for improving the stability of roadways can reduce maintenance costs and maintain safety in complex mining conditions. In the Guobei coal mine in China, a cement pre-grouting technique was adopted to enhance the overall strength of soft coal mass and provide sufficient support for the roadway. However, there are very limited studies about the effect of grouting on the overall strength of coal in the laboratory.
  • 1.3K
  • 31 Aug 2021
Topic Review Peer Reviewed
Reactive Transport Processes in Proton Exchange Membrane Fuel Cells
Proton exchange membrane fuel cells are devices that directly convert chemical energy to electricity. A hydrogen oxidation reaction takes place on the anode side, generating protons and electrons. In the cathode, oxygen reduction reaction involving oxygen, proton and electron occurs, producing water and heat. The water content in PEMFCs should be maintained at a reasonable amount to avoid water flooding or membrane dehydration. The thermal management and water management of PEMFCs are important for an efficient and stable operation of PEMFCs. Inside the multiscale spaces of PEMFCs, multiphase flow with a phase change, heat and mass transfer, proton and electron conduction, and electrochemical reaction simultaneously take place, which play important roles in the performance, lifetime and cost of PEMFCs. These processes should be well understood for better designing PEMFCs and improving the thermal management and water management.
  • 1.3K
  • 13 May 2025
Topic Review
Direct Methods for Solar Energy Harnessing
The escalating concerns regarding greenhouse gas (GHG) emissions and finite fossil fuel resources have propelled scientists and engineers to explore alternative and renewable energy sources (RES). Among these, solar energy stands out as a remarkable prospect because it is abundant, renewable, and emits no direct pollutants during operation. The fundamental principles of solar energy conversion through photovoltaic technology is introduction, shedding light on the progress and potential of harnessing the sun’s energy for a cleaner, sustainable energy future.
  • 1.3K
  • 27 Sep 2023
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