Renewable Energy Inputs Research Articles

Incomplete information oriented optimal scheduling of multi-energy hub systems with thermal energy storage

The research on optimal scheduling of multi-energy hub(EH) systems based on EH is the direction of advance of optimizing energy structure. However, the restriction relationship and incomplete information among the multi-EHs have brought challenges to the optimal scheduling of the multi-EH system. Therefore, considering the uncertainty of renewable energy input, combined heat and power unit(CHP) thermoelectric coupling limit and electric-cooling-heat demand response(DR) in EH, this paper introduces thermal energy storage (TES) and power trading among multi-EHs, establishes economic optimization scheduling model of multi-EH system, and analyzes the constraints among multiple EHs under dynamic pricing mechanism, the incomplete information game decision method is used to optimize the scheduling of multi-EH systems. Based on considering the impact of user behavior characteristics on user participation in DR, interruptible load types are modelled as discrete random variables by introducing users’ load interruption willingness factor. On this basis, an optimal scheduling model of multi-EH systems is formulated, in which the information of DR between EHs is incomplete, and the Bayesian-Nash equilibrium solving algorithm description of this model is given, the optimal scheduling scheme of the model is obtained. Finally, case studies are conducted to verify the effectiveness of the proposed model and approach. The results show that the proposed multi-EH system optimization model can effectively decrease the system total cost and improve the dependability of system operation under the condition of incomplete information. Compared with the dispatching scheme without DR, TES and power trading, the cost of multi-EH systems is reduced by 1.6% on average.

Surface Basicity of Metal@TiO2 to Enhance Photocatalytic Efficiency for CO2 Reduction.

Photocatalytic reduction of CO2 to valuable chemical fuels is of broad interest, given its potential to activate stable greenhouse CO2 using renewable energy input. We report how to choose the right metal cocatalysts in combination with the surface basicity of TiO2 to enhance their photocatalytic efficiency for CO2 photoreduction. Uniform ligand-free metal nanoparticles (NPs) of Ag, Cu, Au, Pd, and Pt, supported on TiO2, are active for CO2 photoreduction using water as an electron donor. The group XI metals show a high selectivity to CO and Ag/TiO2 is most active to produce CO at a rate of 5.2 μmol g-1 h-1. The group X metals, e.g., Pd and Pt, mainly generate hydrocarbons including methane and ethane, and Pd/TiO2 is slightly more active in methane production at a rate of 2.4 μmol g-1 h-1. The activity of these photocatalysts can be enhanced by varying the surface basicity of TiO2 with primary amines. However, proton reduction selectivity is greatly enhanced in the presence of amine except amine-modified Ag/TiO2, which shows an activity enhancement by 2.4 times solely for CO2 photoreduction as compared to that without amines without switching its selectivity to proton reduction. Using in situ infrared spectroscopy and CO stripping voltammetry, we demonstrate that the improvement of electron density and the low proton affinity of metal cocatalysts are of key importance in CO2 photoreduction. As a systematic study, our results provide a guideline on the right choice of metals in combination of the surface functionality to tune the photocatalytic efficiency of supported metal NPs on TiO2 for selective CO2 photoreduction.

Does transitioning towards renewable energy accelerate economic growth? An analysis of sectoral growth for a dynamic panel of countries

This study examines the impact of non-renewable and renewable energy consumption on economic growth, differentiating between manufacturing and services growth. We derive our empirical model from an endogenous growth framework with expanding variety of intermediate capital goods embedding non-renewable and renewable energy inputs. Controlling for well-established growth determinants, we estimate the effects of non-renewable and renewable energy consumption, differentiated by type of use — industrial, residential, and total final energy consumption — on manufacturing and services growth. We find that renewable energy enhances growth in high-growth sectors, i.e. the services sector in high-income economies and the manufacturing sector in middle-income economies. In the case of high-income countries, renewable energy is a complement to non-renewables, whereas in the case of middle-income countries the two are substitutes. The growth effects are primarily due to industrial energy consumption. T Based on our findings, we propose that an effective renewable energy incentives policy for middle-income countries should be directed at manufacturing enterprises, and in high-income countries these incentives should be directed at the services sector.

A Comparative Assessment Framework for Sustainable Production of Fuels and Chemicals Explicitly Accounting for Intermittency

The ubiquity of fossil fuels in the provision of mobility services and in the production of platform chemicals constitutes a substantial fraction of total anthropogenic CO2 emissions and resulting climate change. There is therefore substantial interest in the production of sustainable alternatives. Whilst much attention is directed to the individual elements in the value chain, there is a paucity of work focusing on the performance of the integrated system. To address this gap, we present a novel modelling framework for the design and scheduling of the production of platform chemicals and fuels from just air, water, and renewable energy throughout the year. Optimal routes are determined for solar ammonia and methanol. A combination of hydrogen storage for balancing seasonal intermittency and battery storage for balancing daily intermittency is determined as optimal. It is found that nitrogen-based fuels may offer advantages over carbon-based fuels. The cost of intermittency of renewable energy inputs is found to be as much as two thirds of total cost, again varying by location. This reinforces that future design of chemical plants needs to include a treatment of intermittency and opens questions on how to operate sustainable plants - for instance, operating seasonally, or more flexibly.

Solar Desalination Using Thermally Responsive Ionic Liquids Regenerated with a Photonic Heater.

Growing global water demand has brought desalination technologies to the forefront for freshwater production from nontraditional water sources. Among these, forward osmosis (FO) is a promising two-step desalination process (draw dilution and regeneration), but it is often overlooked due to the energy requirements associated with draw regeneration. To address this limiting factor, we demonstrate FO desalination using thermally responsive ionic liquids (ILs) that are regenerated using a renewable energy input, that is, solar heat. To efficiently harness sunlight, a simple photonic heater converts incoming irradiation into infrared wavelengths that are directly absorbed by IL-water mixtures, thereby inducing phase separation to yield clean water. This approach is markedly different as it uses radiative heating, a noncontact mode of heat transfer that couples to chemical functional groups within the IL for rapid energy transfer without a heat exchanger or secondary fluid. Overall, a solar-thermal separation efficiency of 50% is achieved under unconcentrated sunlight, which can be increased to 69% with the thermal design. Successful desalination of produced water from oil wells in Southern California highlights the potential of solar-powered IL-FO for energy-efficient and low-cost desalination of complex brines for beneficial water reuse.

Could energy equilibrium and greenhouse gas emissions in agroecosystems play a key role in crop replacement? A case study in orange and kiwi orchards.

The development of agriculture is linked to energy resources. Consequently, energy analysis in agroecosystems could be a useful tool for monitoring some measures in the agricultural sector to mitigate greenhouse gas emissions. The objectives of this study were to (a) evaluate differences of energy indices in orange and kiwi orchards, and (b) point out whether inputs, outputs, efficiency, productivity, and carbon footprint can play a key role in crop replacement. Proportional stratified random sampling was used to select 26 orchards (10 oranges, 16 kiwis) from the Prefecture of Arta, western Greece, during 2015 and 2016. Univariate statistical methods were combined with multivariate ones. Nitrogen, Mg, Zn, herbicides, insecticides, fungicides, renewable energy inputs, fruit production, total outputs, and energy efficiency and productivity were statistically significantly high in the orange orchards. Phosphorus, Ca, irrigation, machinery, total inputs, intensity, non-renewable energy consumption, and carbon footprint were statistically significantly high in the kiwi orchards. The most important energy inputs for both fruit crops were fertilizers, fuels, irrigation, machinery, and herbicides. The orange orchards seem to be more friendly to the environment than the kiwi orchards by having low total energy inputs 32,210.3 MJ ha-1, intensity 1.4, consumption of non-renewable energy 0.7 MJ kg-1 and CO2 equivalent/fruit production 0.08 kg kg-1, and high energy outputs 105,120.0 MJ ha-1 and fruit production 53,648.0 kg ha-1. The findings of the present study show a relation between climate change and the production of farming systems, which can be a tool for decision makers. The correlation of the abovementioned parameters ensure higher profits and could help in achieving the best possible sustainable management of the agricultural ecosystems.

Renewable Energy Applications for Sustainable Agricultural Systems

Sustainable agriculture means meeting current food needs without compromising the ability of current or future generations to meet their own needs. Energy is the most important tool for sustainable agricultural development and growth. The agri-food chain accounts for around 30 % of the global energy demand. The agricultural sector is currently heavily dependent on the use of fossil fuels. The use of fossil fuels in agriculture leads to an increase in greenhouse gas (GHG) emissions in the sector. The total GHG emissions from the agri-food chain account for more than 30 % of global GHG emissions per year. Emissions from energy used in agricultural activities consist primarily of CO2, CH4, and N2O. Current fossil fuel-based energy generation needs to be shifted to renewable energy such as solar, biomass, wind, and geothermal to mitigate climate change and reduce GHG emissions. There are a variety of energy-related mitigation and adaptation opportunities in agriculture. Improvements will be made by enhancing access to electricity, making more efficient use of resources, and increasing the use of renewable energy sources in agriculture. This would have the dual advantage of providing renewable energy inputs to agriculture, thereby increasing productivity, economic and social sustainability, and reducing climate change commitments. This paper details the role of renewable energy in agriculture by linking sustainability aspects.

The Lithium Industry and Analysis of the Beta Term Structure of Oil Companies

According to a statement made in the BP Energy Outlook report in 2017, most of the world’s liquid fuel (petroleum) is being consumed by the transportation industry. The mechanisms used to stimulate changes in the energy markets are affected by government policies that act in more ambitious ways than purely market-driven forces; different governments have promoted incentives involving electric mobility, especially in urban areas. The substitution for crude oil by renewable energy inputs in the transport sector is a major concern for oil producers. Among the different types of clean energies, lithium (Li) is currently assuming an increasingly strategic role. The goals of this paper are two-fold: First, we study the dynamics of the lithium industry and then the beta risk behavior of the 10 largest oil companies in the world for the time period between 11 February 2008 and 10 January 2019. We use an approach based on the continuous wavelet transform (CWT) method. The results indicate that there is a period of dependence between late 2013 and 2016 that occurs in the long-run frequencies of between 32 and 198 days for all cases, except for in the case of PetroChina, thereby demonstrating that the beta term is time-varying. We also find evidence that the beta term reflects and advances oil companies’ responsiveness to movements in the lithium market. In the second part of the paper, we study the dynamics of the beta series by using long-run dependence approaches. The results indicate that the betas are highly persistent, with the order of integration found to be significantly above 1 in all cases.

Designing an ecofriendly and carbon-cum-energy efficient production system for the diverse agroecosystem of South Asia

There is an urgent need for identification of the eco-friendly/cleaner production system that is more productive and profitable; efficient user of energy, water, and carbon-based inputs, and also environmentally safer. The four years study was conducted from 2016 to 2019, where the dominant rice-wheat cropping system is practiced extensively after ‘Green Revolution’. The objectives of the experiment were to evaluate: (1) energy budgeting, (2) carbon auditing, (3) production and economic efficiency of diverse cropping systems for upland rainfed as well as irrigated ecosystems of eastern India. Tillage and cropping system treatments were laid out according to a completely randomized block design and replicated thrice. Ten cropping sequences were comprised of: T1) a farmers’ practice of transplanted rice-wheat-mungbean, T2) conventional till-direct seeded rice (CTDSR)-wheat-mungbean, T3) soybean-maize, T4) CTDSR-mustard-urdbean, T5) foxtail millet-lentil-fallow, T6) pearl millet-chickpea-fallow, T7) finger millet-toria-fallow, T8) sorghum (grain)-chickpea-fallow, T9) maize cob–pigeon pea, and T10) sorghum (fodder)-mustard-urdbean. Energy contributions of different inputs were 42–55, 12–21, 8–18, and 4–12% for fertilizers, diesel, labour, and electricity, respectively. The amount of indirect (fertilizer, chemicals, and machinery) and direct (diesel and electricity) non-renewable energy inputs were 40–60 and 18–26%, respectively. Indirect renewable energy input (seed and crop residues) was 1–7% as compared to 15–24% of direct-renewable energy (human labour and irrigation water). The maximum energy input was recorded for T1 (53511 MJ ha−1). The maximum biomass production (40.2 Mg ha−1) was recorded with T9, while the maximum benefit: cost ratio (3.64) was noted for T10 and T8. The highest specific energy (33.5 MJ kg−1) and energy productivity (0.92 kg MJ−1) were recorded in T8 treatment. Irrespective of cropping systems, retention of crop residues accounted for 28.6–58.5% of total carbon input. The carbon sustainability index was 5–7 times higher for the millet-based production system [T6 (9.32) and T8 (10.27)] compared to cereal-based systems [T1 (1.66) and T2 (1.21)]. Diversification of the rice-wheat system through climate-resilient millets-based production system reduced 84% energy consumption and 87% carbon footprint. The millet-based production system also helps in reducing the carbon input by 172% and improves the energy use efficiency by 61% compared to the cereal-based cropping system. Therefore, the study has an innovative idea to support the crop modelling, policymakers, government planners, researchers, and producers to achieve the sustainable development goals in Indo-Gangetic Plains and similar agro-climatic conditions of South Asia.

INVESTIGATING COST-EFFECTIVE POLICY INCENTIVES FOR RENEWABLE ENERGY IN JAPAN: A RECURSIVE CGE APPROACH FOR AN OPTIMAL ENERGY MIX

The Great East Japan Earthquake (GEJE) and Fukushima nuclear disaster that occurred in 2011 gave a sharp reminder to Japan’s energy security to reconsider the reduction of nuclear power dependence with a better energy mix. We use a recursive CGE model based on Japan’s renewable energy input–output model to analyze the energy composite of power generation and consumption to investigate cost-effective policy incentives to achieve an optimal energy mix to reduce the nuclear power dependence to less than 5% within 10 years. Moreover, we create scenarios of: (1) nuclear power decommission, (2) renewable energy promotion and (3) virtual power plant (VPP) implementation with public R&D expenditure and power infrastructure investment. The simulation results show that renewable energy could gradually replace nuclear power with capital-use subsidies. Under the direction of nuclear power decommission, the VPP installation could reduce the fiscal cost of wind power by 13%, solar energy by 8% and the social cost by 36%. We provide empirical evidence that the implementation of VPP should be promoted in addition to the renewable policy promotion policy to facilitate power allocation and overcapacity problems better.

Renewable and non-renewable energy consumption and economic growth in the US: A Markov-Switching VAR analysis

We examine the relationship between renewable and non-renewable energy consumption and economic growth in the United States. While the regime-dependent Granger causality test results for the non-renewable energy consumption and economic growth suggest bi-directional causality in both regimes, we cannot validate any causality between renewable energy consumption and economic growth. The US meets its energy demand from non-renewable sources; as such, renewable energy consumption does not seem to affect economic growth. Given the efficiency and productivity of renewable energy investments, we conclude that it is worthwhile to consider renewable energy inputs to replace fossil fuels given potential benefits in terms of global warming and climate change concerns. In this regard, increasing the R&D investments in the renewable energy sectors, increases in productivity and profitability of renewable energy investments are likely to accrue benefits in the long run.

Buy Coal or Kick-Start Green Innovation? Energy Policies in an Open Economy

This paper analyses two unilateral policies available to countries that want to rapidly curb carbon emissions in the global economy, but do not own any fossil fuel resources. If fossil fuel owners do not cooperate in hbox {CO}_2 emission reduction efforts, the only strategy to reduce their fossil fuels’ use is to exploit the interconnectedness of production given by international trade. We compare a Pigouvian approach, namely a subsidy for renewable energy prices, and a Coasian supply-side strategy, buying extractive rights over fossil fuel deposits abroad. Using a dynamic North–South trade model with endogenous innovation, we show how these policies, designed to prevent an environmental disaster, have different cost and welfare profiles. If fossil fuel deposits can be purchased at their market price, the supply-side policy achieves the highest welfare. If instead the fossil fuel owners require a full compensation for their income loss, subsidies for renewable energy inputs can result in higher welfare, but only if the resource-rich region has less advanced technologies for green energy production than the countries implementing the policy.

Interfacing metals and compounds for enhanced hydrogen evolution from water splitting

Abstract

Two dimensional electrocatalyst engineering via heteroatom doping for electrocatalytic nitrogen reduction.

The electrocatalytic N2 reduction reaction (eNRR) - which can occur under ambient conditions with renewable energy input - became a promising synthetic pathway for ammonia (NH3) and has attracted growing attention in the past few years. Some achievements have been made in the eNRR; however, there remain significant challenges to realize satisfactory NH3 production. Therefore, the rational design of highly efficient and durable eNRR catalysts with N[triple bond, length as m-dash]N bond activating and breaking ability is highly desirable. Two-dimensional (2D) materials have shown great potential in electrocatalysis for energy conversion and storage. Although most 2D materials are inactive toward the eNRR, they can be activated by various modification methods. Heteroatom doping engineering can impact the charge distribution and spin states on catalytic sites, therefore accelerating the dinitrogen adsorption and protonation process. This review summarises the recent research progress of heteroatom-doped 2D materials, including carbon, molybdenum disulfide (MoS2) and metal carbides (MXenes), for the eNRR. In addition, some existing opportunities and future research directions in electrocatalytic nitrogen fixation for ammonia production are discussed.

Renewable and non-renewable energy-growth nexus: A panel data application for the selected Sub-Saharan African countries

In order to protect the environment the role of renewable energy is gratefully appreciated. This study investigates the effects of renewable energy and non-renewable energy on output for the selected six Sub-Saharan African countries during 1990–2015 period by employing a simple production function of capital, labor, renewable and non-renewable energy inputs. The impact of the variables on output are quantified by using panel estimation techniques. The Pedroni Panel cointegration test indicates long run relationship between the variables. The results show that the long-run estimated coefficients of the analyzed variables are positive and statistically significant. According to the findings the elasticity estimates of renewable energy and non-renewable energy are very close. The policy implications of the results are discussed as well.

Revisiting energy efficiency, renewability, and sustainability indicators in biofuels life cycle: Analysis and standardization proposal

Abstract Life Cycle Energy Analysis (LCEA) has been widely used for net energy balance and energy ratio calculation, expressing the overall efficiency, renewability, and sustainability of biofuels production. However, over 27 methodologies have been found in the literature, representing a barrier for the comparison between different studies. The aim of this research is to discuss the main LCEA indicators methodologies and to propose a more comprehensive and user-friendly system of standard equations for the calculation of energy efficiency indicators, considering allocation criteria and renewability of energetic inputs. The standardized equations were evaluated via their application in two case studies related to sugarcane ethanol and biodiesel production and the results were compared to evaluate the influence of allocation criteria and inputs characteristics (renewable and non-renewable) in both attributional and consequential LCEA. As a result, 10 methodologies were proposed in order to standardize those 27 energy indicators. It was observed a significant variation in energy values depending on the use of allocation criteria, which were 114–468% for attributional LCEA and 114–387% for consequential LCEA in ethanol production, and between a range of 106–147% for attributional LCEA and 159–212% for consequential LCEA, in biodiesel production. The consideration of renewable energy inputs resulted in energy variations between 99 and 428% (attributional LCEA) and 61–268% (consequential LCEA) in ethanol production and between 47 and 76% (attributional LCEA) and 78–114% (consequential LCEA) in biodiesel production. Also, results showed that allocation criteria, input characteristics, and LCEA approach have a significant influence on the energy balance. Standardized methodologies proposed for energy balance equations in a biofuel production system make easier the application, understanding, and comparison among results of an LCEA.

Energy Consumption, Carbon Emissions and Global Warming Potential of Wolfberry Production in Jingtai Oasis, Gansu Province, China

During the last decade, China's agro-food production has increased rapidly and been accompanied by the challenge of increasing greenhouse gas (GHG) emissions and other environmental pollutants from fertilizers, pesticides, and intensive energy use. Understanding the energy use and environmental impacts of crop production will help identify environmentally damaging hotspots of agro-production, allowing environmental impacts to be assessed and crop management strategies optimized. Conventional farming has been widely employed in wolfberry (Lycium barbarum) cultivation in China, which is an important cash tree crop not only for the rural economy but also from an ecological standpoint. Energy use and global warming potential (GWP) were investigated in a wolfberry production system in the Yellow River irrigated Jingtai region of Gansu. In total, 52 household farms were randomly selected to conduct the investigation using questionnaires. Total energy input and output were 321,800.73 and 166,888.80 MJ ha−1, respectively, in the production system. The highest share of energy inputs was found to be electricity consumption for lifting irrigation water, accounting for 68.52%, followed by chemical fertilizer application (11.37%). Energy use efficiency was 0.52 when considering both fruit and pruned wood. Nonrenewable energy use (88.52%) was far larger than the renewable energy input. The share of GWP of different inputs were 64.52% electricity, 27.72% nitrogen (N) fertilizer, 5.07% phosphate, 2.32% diesel, and 0.37% potassium, respectively. The highest share was related to electricity consumption for irrigation, followed by N fertilizer use. Total GWP in the wolfberry planting system was 26,018.64 kg CO2 eq ha−1 and the share of CO2, N2O, and CH4 were 99.47%, 0.48%, and negligible respectively with CO2 being dominant. Pathways for reducing energy use and GHG emission mitigation include: conversion to low carbon farming to establish a sustainable and cleaner production system with options of raising water use efficiency by adopting a seasonal gradient water pricing system and advanced irrigation techniques; reducing synthetic fertilizer use; and policy support: smallholder farmland transfer (concentration) for scale production, credit (small- and low-interest credit) and tax breaks.

Significance of Engineering the Octahedral Units to Promote the Oxygen Evolution Reaction of Spinel Oxides.

The clean energy carrier, hydrogen, if efficiently produced by water electrolysis using renewable energy input, would revolutionize the energy landscape. It is the sluggish oxygen evolution reaction (OER) at the anode of water electrolyzer that limits the overall efficiency. The large spinel oxide family is widely studied due to their low cost and promising OER activity. As the distribution of transition metal (TM) cations in octahedral and tetrahedral site is an important variable controlling the electronic structure of spinel oxides, the TM geometric effect on OER is discussed. The dominant role of octahedral sites is found experimentally and explained by computational studies. The redox-active TM locating at octahedral site guarantees an effective interaction with the oxygen at OER conditions. In addition, the adjacent octahedral centers in spinel act cooperatively in promoting the fast OER kinetics. In remarkable contrast, the isolated tetrahedral TM centers in spinel prohibit the OER mediated by dual-metal sites. Furthermore, various spinel oxides preferentially expose octahedral-occupied cations on the surface, making the octahedral cations easily accessible to the reactants. The future perspectives and challenges in advancing fundamental understanding and developing robust spinel catalysts are discussed.

Estimation of realistic renewable and non-renewable energy use targets for livestock production systems utilising an artificial neural network method: A step towards livestock sustainability

This study estimated energy use flow of buffalo farms, energy use indices, production efficiency, energy use targets, impact of energy inputs on energy output, and sensitivity analysis of energy inputs. A well-structured questionnaire was used to collect data of 360 domestic buffalo farms from Punjab Pakistan during May–July 2017. Results revealed that milk production was mainly dependent on renewable energy inputs, particularly millet, minerals, concentrates, and sorghum. Energy use efficiency (0.08) and production efficiency (0.24) indicate that energy inputs were overused. An artificial neural network (ANN) method suggested that 30.5% of total energy input could be saved if farmers followed the targeted inputs recommended by ANN. The Cobb-Douglas production function found a negative significant impact of sorghum, millet, and wheat straw; and positive significant impact of labour, concentrates, and electricity on energy output. Among the non-renewable energy sources, electricity was found to be the most wasteful use of energy input, mainly due to the mismanagement of farmers. Sensitivity analysis estimated that a unit increase in renewable energy significantly decreased milk yield by 0.02 unit. While a unit increase in non-renewable energy significantly increased milk yield by 0.01 unit. This study stresses the importance of using energy inputs at the target quantities prognosticated by ANN method, and recommends the use of energy-efficient equipment.

Energy Planning and Urban Form: Solar Energy as a Design Parameter in Ouargla, a Southern City in Algeria

Energy planning plays a crucial role in the built environment, particularly when aiming at reaching sustainable cities. Today, most researchers are focusing on exploring the accurate potential of renewable energies. However, few studies have explored the correlation between urban forms and renewable energy inputs. The objective of this paper is to examine the relationship between the incident solar irradiation, urban form and the potential of photovoltaic energy at a local level. The study focuses on the case of the city of Ouargla, which is located in southern Algeria. In terms of methodology, it adopts three main steps. Firstly, three different types of urban form have been identified according to three main criteria (morphology of streets and lot, buildings use and environment). Secondly, numerical simulations were performed based on 3D models of these urban forms, with the purpose of evaluating the distributions of solar irradiations on the different building roofs, which helps to determine the most appropriate urban form for solar energy use. The study demonstrates that urban form has an impact on solar energy potential, which means that the latter provides a significant increase in the photovoltaic energy production.