Future Energy Supply Research Articles

Improvement of a semipermeable shell for encapsulation of calcium hydroxide for thermochemical heat storage solutions: Material design and evaluation in laboratory and reactor scale

Thermochemical heat storage concepts offer a promising contribution to an economic, efficient and sustainable future energy supply. The reaction system CaO/Ca(OH)2 is amongst the most considered systems for Concentrated Solar Power (CSP) applications, but as the cost efficiency and good availability of the material are accompanied by poor powder properties, complex and costly reactor solutions are required. Hence, modifications of the storage material promise a option for a reliable long-term operation. The present work discusses considerations on inter- and intraparticular changes of the storage material and options for particle size stabilization. With the background of a previous work, the experimental section presents a successful approach for the enhancement of the mechanical stability of a ceramic shell material by admixing selected additives to the powdery precursor. To assign for possible complex, mutual interactions of the additives, the approach is based on a full factorial design of experiments. Investigations of the microstructure of the material are performed by gas-adsorption and mercury intrusion measurements and enriched by combining light- and scanning electron microscopy on respective samples. The obtained mechanical stability of the selected material is accompanied by a significantly enhanced thermal conductivity. Cycling stability is proven over ten reaction cycles in laboratory and reactor scale. Due to a minimization of the contact area between the storage material core and its stabilizing shell by utilizing spherical particles, it is demonstrated that only a minor formation of thermochemically inert side product is detectable.

THERMOCHEMICAL PRETREATMENT METHOD FOLLOWED BY ENZYME HYDROLYSIS OF TOBACCO STALKS FOR BIOETHANOL PRODUCTION

Energy use from fossil fuels increases, causing an energy crisis, increasing greenhouse gases, and other environmental issues. In this study, obtaining renewable energy sources from biomass to replace fossil fuels is vital for future energy supply. Ethanol production from lignocellulosic materials was gain more attention recently. It is an interesting process and an alternative way countries with agricultural waste can be recycled as energy. To convert such waste biomass source into energy in ethanol needed to adjust cellulose conversion to different suitability. Therefore, to obtain the fermentable sugars for bioethanol production, the pretreatment process involved a vital role. In this experimental study, 4% of calcium oxide (CaO) was applied. Moreover, a scanning electron microscope (SEM) distinguished the characteristics of untreated and pretreated samples. In this study, the separated hydrolysis and fermentation (SHF) method was used for bioethanol production. Total and reducing sugars yield confirmed that tobacco stalks are suitable feedstock for bioethanol production.

Research on a Comprehensive Maintenance Optimization Strategy for an Offshore Wind Farm

Offshore wind is considered a crucial part in the future energy supply. However, influenced by weather conditions, the maintenance of offshore wind turbine system (OWTs) equipment is challenged by poor accessibility and serious failure consequences. It is necessary to study the optimized strategy of comprehensive maintenance for offshore wind farms, with consideration of the influences of incomplete equipment maintenance, weather accessibility and economic relevance. In this paper, a Monte Carlo algorithm-improved factor is presented to simulate the imperfect preventive maintenance activity, and waiting windows were created to study the accessibility of weather conditions. Based on a rolling horizon approach, an opportunity group maintenance model of an offshore wind farm was proposed. The maintenance correlations between systems and between equipment as well as breakdown losses, maintenance uncertainty, and weather conditions were taken into account in the model, thus realizing coordination of maintenance activities of different systems and different equipment. The proposed model was applied to calculate the maintenance cost of the Dafengtian Offshore Wind Farm in China. Results proved that the proposed model could realize long-term dynamic optimization of offshore wind farm maintenance activities, increase the total availability of the wind power system and reduce total maintenance costs.

Application of a cost-benefit model to evaluate the investment viability of the small-scale cogeneration systems in the Portuguese context

Increasingly, modern society is dependent on energy to thrive. Remarkable attention is being drawn to high energy-efficient conversion systems such as cogeneration. World energy sustainability depends on the rational use of energy, fulfilling the demands without compromising the future of energy supply. The market trends foresee the use of decentralized production and the increasing replacement of conventional systems by small-scale cogeneration units as solutions to meet the energy needs of the building sector. Analysing the influence of the variables that determine the economic viability of decentralized energy production systems has become more important given the scenario of energy dependence and high energy costs for the final consumer. A cost-benefit model was developed and presented to identify the potential of small commercial scale cogeneration systems in the Portuguese building sector, based on cost-benefit analysis methodology. Five case-scenarios were analysed based on commercial models, using different technologies such as internal combustion engines, gas turbines and Stirling engines. A positive value of CBA analysis was obtained for all the tested cases, however, the use of classic economic evaluation criteria such as the net present value, internal rate of return and payback period results led to different investment decisions. The model also highlights the influence of energy prices in the economic viability of these energy power plants. The inclusion of subsidized tariffs for efficient energy production is the most contributing aspect in the analysis of the economic viability of small-scale cogeneration systems in the Portuguese building sector. Only in that case, it would be possible for an investor to recover the capital costs of such technology, even if the technical and societal benefits are accounted for.

To Prevent or Promote Grid Expansion? Analyzing the Future Role of Power Transmission in the European Energy System

Future energy supply systems must become more flexible than they are today to accommodate the significant contributions expected from intermittent renewable power sources. Although numerous studies on planning flexibility options have emerged over the last few years, the uncertainties related to model-based studies have left the literature lacking a proper understanding of the investment strategy needed to ensure robust power grid expansion. To address this issue, we focus herein on two important aspects of these uncertainties: the first is the relevance of various social preferences for the use of certain technologies, and the second is how the available approaches affect the flexibility options for power transmission in energy system models. To address these uncertainties, we analyze a host of scenarios. We use an energy system optimization model to plan the transition of Europe’s energy system. In addition to interacting with the heating and transport sectors, the model integrates power flows in three different ways: as a transport model, as a direct current power flow model, and as a linearized alternating current power flow model based on profiles of power transfer distribution factors. The results show that deploying transmission systems contribute significantly to system adequacy. If investments in new power transmission infrastructure are restricted—for example, because of social opposition—additional power generation and storage technologies are an alternative option to reach the necessary level of adequacy at 2% greater system costs. The share of power transmission in total system costs remains widely stable around 1.5%, even if cost assumptions or the approaches for modeling power flows are varied. Thus, the results indicate the importance of promoting investments in infrastructure projects that support pan-European power transmission. However, a wide range of possibilities exists to put this strategy into practice.

Robust design of a future 100% renewable european energy supply system with hydrogen infrastructure

Variable renewable energy sources (VRES) will be the cornerstones of future energy supply systems. Nevertheless, their inherent intermittency remains an obstacle to their widespread deployment. Renewably-produced or ‘green’ hydrogen has been suggested as an energy carrier that could account for this in a sustainable manner. In this study, a fully VRES-based European energy system in the year 2050 is designed using an iterative minimal cost-optimization approach that ensures robust supply security across 38 weather-year scenarios (1980–2017). The impact of different power generation locations is factored in by defining exclusive VRES groups within each optimization region. From this, it can be seen that higher numbers of groups in each region offer cheaper electricity generation locations to the optimizer and thus decrease the system's total annual costs. Furthermore, the robust system design and impact of inter-annual variability is identified by iteratively combining the installed capacities of different system designs derived through the application of the 38 historical weather years. The system design outlined here has significantly lower capacities in comparison to the maximum regional capacities obtained in the first round of optimization.

Natural gas hydrate resources and hydrate technologies: a review and analysis of the associated energy and global warming challenges

The roles of natural gas hydrates and their related technologies in the future energy supply, carbon cycle and climate change mitigation.

Marine Predators Algorithm Optimized Reduced Sensor Fuzzy-Logic Based Maximum Power Point Tracking of Fuel Cell-Battery Standalone Applications

Fuel cell (FC) represents one of the promising efficient solutions for future energy supply. Improving performance and integration methods of FCs via maximum power point tracking (MPPT) and high boosting factor inverters are key requirements for research in renewable energy fields. Recently, hybrid FC-battery structures have shown wide applications in several areas. Accordingly, marine predators algorithm (MPA) is proposed in this article for optimizing the design of reduced sensor fuzzy-logic based MPPT scheme. The proposed scheme inherits the following benefits: reduced sensors and hence reduced costs, more flexibility and smooth performance due to fuzzy-logic based MPPT, and optimized design method of fuzzy-logic based MPPT through MPA method. Moreover, a high boosting ratio inverter is introduced in this article based on using the switched capacitor multilevel inverter (SCMLI). The proposed system achieves self capacitor voltage control without complex control or extra sensors. The proposed hybrid FC-battery system has been validated at various operating points. In addition, comprehensive comparisons with existing schemes in the literature are provided in the paper. The superiority of the proposed scheme has been verified with robust, fast and accurate tracking, reduced cost, flexible, simple, and smooth output waveforms. The proposed method achieves the lowest output power fluctuations with fast tracking speed compared to the studied classical methods.

THE IMPACTS OF CLIMATE CHANGE ON ENERGY-WATER SYSTEMS AND ECONOMIC ANALYSIS

In order to develop a valued decision-support system for climate alteration policy and planning, recognizing the regionally-specific features of the climate change, energy-water nexus, and the history of the current and possible future climate, water and energy supply systems is necessary. This paper presents an integrated climate change, water/energy modeling platform which allows tailored climate alteration and water-energy assessments. This modeling platform is established and described in details based on particular regional circumstances. The modeling platform involves linking three different models, including the climate change model from Coupled Model Intercomparison Project Phase 5 under the most severe scenario (Representative Concentration Pathways, Water Evaluation, and Planning system and the Long-range Energy Alternatives Planning system). This is to understand the impacts of climate variability (changes in temperature and precipitation) on water and electricity consumption in Zayandeh Rud River Basin (Central Iran) for the current (1971–2005) and future time period (2006–2040). Climate models have projected that the temperature will increase by 7 °C and precipitation will decrease by 44%, it is also proposed that electricity imports will rise during a severe dry scenario in the basin, while power generation will decrease around 8%.

Establishment and evaluation of mixed refueling scheme for M2LFR-1000 core

ABSTRACT Lead-cooled fast reactor (LFR) is one important candidate for the advanced reactors for future sustainable energy supply due to its excellent inherent safety and economic characteristics. The fuel management scheme of LFR affects application potentials and fuel cycle scheme of the entire nuclear system. In order to research the establishment and evaluation of the mixed refueling scheme for LFR, a mixed refueling scheme was adopted and established in this paper for the core of 1000MWth Medium-power Modular Lead-cooled Fast Reactor M2LFR-1000. The neutronic performance analysis was conducted from the first cycle to the equilibrium cycle by using the neutronics analysis code SRAC. The calculation results showed that an acceptable fuel management scheme for LFR was obtained. The cycle length of this scheme can reach 18 months and the radial assembly power peaking factors of the first six cycles are all below the design limits. Evaluations of other important neutronic parameters also proved that this mixed refueling scheme could be applied to the M2LFR-1000 core.

A facile strategy of in-situ anchoring of Co3O4 on N doped carbon cloth for an ultrahigh electrochemical performance

Enhancement of supercapacitors (SCs) with high-energy density and high-power density is still a great challenge. In this paper, a facile strategy for in situ anchoring of Co3O4 particles on N doped carbon cloth (pCoNCC) is reported. Due to the interaction of the doped N and Co3O4, the electrochemical performance improves significantly, reaching 1,940.13 mF·cm−2 at 1 mA·cm−2 and energy density of 172.46 µWh·cm−2 at the power density of 400 µW·cm−2, much larger than that without N doping electrode of 28.5 mF·cm−2. An aqueous symmetric supercapacitor (ASSC) assembled by two pCoNCC electrodes achieves a maximum energy density of 447.42 µWh·cm−2 and a highest power density of 8,000 µW·cm−2. Utilizing such a high-energy storage ASSC, a digital watch and a temperature-humidity detector are powered for nearly 1 and 2 h, respectively. Moreover, the ASSC displays a superb electrochemical stability of 87.7% retention after 10,000 cycles at 40 mA·cm−2. This work would provide a new sight to enhance active materials performance and be beneficial for the future energy storage and supply systems.

Photoelectrochemical CO2 Reduction Using CuInS2 Photocathode Modified with CdS and Noble Metal Catalysts

Photoelectrochemical CO2 reduction using sunlight is a promising approach to producing a clean energy carrier that could replace fossil fuels, providing a sustainable future energy supply. Copper chalcopyrite compounds, Cu(In,Ga)(S,Se)2, have recently received considerable attention as promising candidates for photocathodes owing to their high absorption coefficients and high carrier mobilities, and efficient photoelectrochemical H2 production using a series of Cu(In,Ga)(S,Se)2-based photocathodes has been demonstrated. Moreover, the photoelectrochemical performance of these photocathodes has been reported to improve when combined with n-type semiconductor buffer layers due to the formation of a p–n junction, which facilitates charge separation at the interface. Meanwhile, noble metal catalysts have been widely used to catalyze redox reactions efficiently because they can lower the overpotential for desirable reactions. Especially, some Au and Ag catalysts have been reported to proceed highly efficient and selective electrochemical CO2 reduction. Based on these backgrounds, in this study, we investigated photoelectrochemical CO2 reduction using CuInS2 electrode modified with CdS buffer layer and noble metal catalysts.CuInS2 thin film electrodes were synthesized on Mo foil using electrodeposition and subsequent sulfurization. The electrode surface was modified with CdS by chemical bath deposition method, followed by photoelectrochemical deposition of Pt, Au, and Ag. As shown in Figure, the prepared photoelectrodes showed distinct photocurrent generation under visible light irradiation. Modification with noble metal catalysts was effective to enhance the photoresponse and the photocurrent density increased in the order of Pt > Au > Ag. As a result of photoelectrolysis at -0.1 V vs RHE in CO2-saturated NaHCO3 solution, generation of CO was confirmed from all the electrodes although the Faradaic efficiency was different depending on the noble metal catalysts. Details will be discussed at the conference.

Fuzzy multi-objective decision making approach for nuclear power plant installation

Due to the increase in energy demand, many countries suffer from energy poverty because of insufficient and expensive energy supply. Plans to use alternative power like nuclear power for electricity generation are being revived among developing countries. Decisions for installation of power plants need to be based on careful assessment of future energy supply and demand, economic and financial implications and requirements for technology transfer. Since the problem involves many vague parameters, a fuzzy model should be an appropriate approach for dealing with this problem. This study develops a Fuzzy Multi-Objective Linear Programming (FMOLP) model for solving the nuclear power plant installation problem in fuzzy environment. FMOLP approach is recommended for cases where the objective functions are imprecise and can only be stated within a certain threshold level. The proposed model attempts to minimize total duration time, total cost and maximize the total crash time of the installation project. By using FMOLP, the weighted additive technique can also be applied in order to transform the model into Fuzzy Multiple Weighted-Objective Linear Programming (FMWOLP) to control the objective values such that all decision makers target on each criterion can be met. The optimum solution with the achievement level for both of the models (FMOLP and FMWOLP) are compared with each other. FMWOLP results in better performance as the overall degree of satisfaction depends on the weight given to the objective functions. A numerical example demonstrates the feasibility of applying the proposed models to nuclear power plant installation problem.

Climatological analysis of solar and wind energy in Germany using the Grosswetterlagen classification

Solar and wind energy play an important role in current and future energy supply in Germany and Europe. The production of renewable energy highly depends on weather conditions resulting in an increasing impact of meteorological fluctuations on energy production. Here, climatological data of solar radiation and wind speed are used to simulate hourly capacity factors for solar and wind energy for Germany from 1995 to 2015. Using renewable energy production data for 2015 these data are converted into time series of generated electrical power. Events with very low energy production, i.e., shortfall events, have been identified and related to large-scale weather regimes over Europe.In Germany, on average about twice as much electrical energy is generated from wind compared to solar radiation; in addition there is a distinct annual cycle with an equal share of generated energy during summer and a 70/30% wind/solar share in winter. There is an unambiguous dependency of wind and solar energy production on weather regimes. Shortfall events in Germany only occur in winter, often associated with a high pressure system over Central Europe. During this weather regime, the renewable energy potential in Northern and Southeastern Europe is above average, possibly allowing to balance shortfall events in Germany.

Analysis of the influence of climate change on the fatigue lifetime of offshore wind turbines using imprecise probabilities

AbstractWhen discussing the connection of wind energy and climate change, normally, the potential of wind energy to reduce green house gas emissions is emphasised. Hence, effects of wind energy on climate change are analysed. However, what about the other direction? What is the impact of climate change on wind energy? Recently, the effect of a reversal in global terrestrial stilling,that is, an increase in global wind speeds in the last decade, on the wind energy production has been analysed. Certainly, knowledge about potential changes in energy production is essential to plan future energy supply. Nonetheless, at least similarly important is the effect on loads acting on wind turbines. Increasing loads due to higher wind speeds might reduce wind turbine lifetimes and yield higher costs. Moreover, especially for already existing turbines, it might even affect the structural reliability. Since the impact of climate change on wind turbine loads is largely unknown, it is studied in this work in more detail. For this purpose, different existing models for predicted changes in wind speed and air temperature and their uncertainties are used to forecast the environmental conditions an exemplary offshore wind turbine is exposed to. Subsequently, for this turbine, the lifetime fatigue damages are calculated for different prediction models. It is shown that the expected changes in lifetime fatigue damages are present but relatively small compared to other uncertainties in the fatigue damage calculation.

“What is in it for me?” A people-centered account of household energy transition co-benefits in Poland

Household energy services account for a large percentage of global final energy use and of carbon emission reduction potentials. Phasing out solid fuels is expected to contribute to the low-carbon energy transition while delivering health and environmental co-benefits. Poland, a coal-based country where nearly half of the population relies on solid fuels for domestic heating, has introduced fuel switching schemes for assisting households transition towards cleaner energy carriers. In this paper, we investigate the experiences and motivations of beneficiary households in a solid fuel stove replacement programmes operating in Northern Poland between 2015 and 2017 through the lens of co-benefits. Collected data include a 140-household survey and 15interviews with programme intermediaries at the municipal level. Theresults identify significant increases in thermal comfort, free time and cleanliness along with improved indoor air quality as key well-being effects of heating systems upgrade. These reported impacts contrast with the institutional clean air rationales underpinning the interventions. Our findings challenge the idea of a neat one-way transition, as participant households stated their reluctance to fully abandon solid fuel-based heating because of perceived uncertainties around future energy prices and supply. Thefindings warn too about the potentially regressive distributional effects when subsidy allocation mechanisms overlook the income and needs of beneficiaries. To conclude, we put forward the notion of household-level ‘everyday life’ co-benefits as a lever for improved citizen engagement and for advancing energy transitions in the residential sector.

Future of Renewable Energy Use in Pakistan in the Context of Agrifood-Energy Nexus

Pakistan is facing a serious energy supply problem due to lack of energy that results in a shortfall of power supply from 6–10 hours/day, especially outside the big cities. The energy demand is expected to increase in every sector such as industrial, agricultural, household and transport in the years ahead due to population growth, economic development and modern lifestyle. Agricultural sector plays a vital role in the country’s economy contributing around 20% share in GDP. At present the direct energy consumption in the agricultural sector is 2%. To avoid a worse situation in the future years renewable energy resource potential exploitation is needed. This requires also proper planning and implementation of energy policies. In this work present and future electrical energy consumption, demand and supply gap of the country is presented. A sustainable agricultural productive system has become a major priority to maintain food security for the increasing population. Both direct and indirect electrical and energy consumption has emerged in agrifood sector with farm machinery, production, packing and transport of fertilizers, food processing and transport, crop production, animal product production, poultry production, etc. In addition to this excel based model is developed to integrate the renewable energy into the agrifood – energy nexus supply chain and to fulfil the current and future energy demand of the sector.

Iron and Manganese Containing Multi‐Walled Carbon Nanotubes as Electrocatalysts for the Oxygen Evolution Reaction ‐ Unravelling Influences on Activity and Stability

AbstractHydrogen economy is a central aspect of future energy supply, as hydrogen can be used as energy storage and fuel. In order to make water electrolysis efficient, the limiting oxygen evolution reaction (OER) needs to be optimized. Therefore, C‐based composite materials containing earth‐abundant Fe and Mn were synthesized, characterized and tested in the OER. For pyrolysis temperatures above 700 °C N‐rich multi‐walled carbon nanotubes (MWCNT) are obtained. Inside the tubes Fe3C particles are formed, Fe and Mn oxides are incorporated in the carbon matrix and metal spinel nanoparticles cover the outer surface. The best catalyst prepared at 800 °C achieves a low overpotential of 389 mV (at 10 mA/cm2) and high stability (22.6 h). From electrochemical measurements and characterization it can be concluded that the high activity is mainly provided by MWCNT, Fe3C and the metal oxides in the conductive carbon matrix. The metal spinel nanoparticles in contrast protect the MWCNT from oxidation and thereby contribute to the high stability.

Underwater superaerophobic Ni nanoparticle-decorated nickel–molybdenum nitride nanowire arrays for hydrogen evolution in neutral media

Abstract Electrochemical water splitting into hydrogen and oxygen in neutral electrolytes has great significance for future energy supply security, potentially offering a pathway for H2 generation from seawater. However, the electrocatalytic hydrogen evolution reaction (HER) generally occurs at low rates in neutral solutions due to the low proton concentration in such media. Herein, we fabricated a novel HER catalyst capable of efficient H2 evolution in water at neutral pH, comprising a nickel-molybdenum nitride nanowire array modified with metallic Ni nanoparticles (Ni/NiMoN). The entire Ni/NiMoN array was supported on a Cu foam. The Ni nanoparticles promoted the dissociation of adsorbed water to enhance the supply of protons in the neutral electrolyte, whilst the nanowire array imparted the electrode surface with underwater superaerophobic properties, thus allowing H2 gas bubbles to detach from the electrode in a facile manner. On the basis of the synergies realized between the different electrode components, the Ni/NiMoN nanowire array electrode offered exceptional HER performance, with an overpotential of only 37 mV at a current density of 10 mA cm−2 in a neutral electrolyte. Results guide the development of next-generation earth-abundant element electrocatalysts for HER in neutral media.

Promoting Electrocatalytic Hydrogen Evolution Reaction and Oxygen Evolution Reaction by Fields: Effects of Electric Field, Magnetic Field, Strain, and Light

AbstractHydrogen fuel is considered as one of the most clean renewable resources, warranting it a primary alternative to fossil fuels for future energy supplies. Electrocatalytic water splitting is an eco‐friendly technique for high‐purity hydrogen production. However, the sluggish dynamics of its two half‐reactions, hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), are tough challenges impeding the practical application of this technology. In these years, external field‐assisted HER and OER have attracted extensive research interests. Herein, the effects of various fields, including electric field, magnetic field, strain, and light, on electrocatalytic HER and OER are systematically discussed. The focus is how to integrate the external fields with the electrocatalytic systems and the fundamentals of field promoted HER/OER activities. In the end, the key challenges facing this rapidly progressing research field are highlighted and possible strategies addressing them are indicated.