Neutral Energy Research Articles

Land use of energy supply for carbon neutral mobility: a well-to-wheel analysis

BackgroundThe transition to carbon neutral mobility will require a lot of carbon neutral energy, but a lot of spaceas well. In many countries, it will be a challenge to find this space or to import enough energy. Land use indicators related to sustainable mobility usually focus on space for transport infrastructure and parking, i.e. direct land use, and do not include energy supply. Existing literature on the emerging research field of ‘energy landscapes’ has not covered the transport sector.ObjectiveThe aim of this paper is to estimate the order of magnitude of land or sea area required for carbon neutral mobility.MethodIn a well-to-wheel analysis, we investigate the land use for the production, transport, storage, distribution, and charging/refuelling of carbon neutral energy carriers for various modes of transport. The analysis focuses on the Netherlands, but part of the results are expected to be broadly applicable to other countries as well.FindingsThe results show that electricity from wind or solar energy supplied to electric vehicles is the most space efficient. Use of hydrogen and synthetic fuels in vehicles takes 2–5 times more land, while use of biofuels from energy crops takes 100 times more land compared to the electricity route. We also conclude that the indirect land use for energy supply for carbon neutral road transport in the Netherlands is in the same order of magnitude as the current direct land use of road mobility.

Experimental study on the regulation of NOX in co-pyrolysis of maize straw and woody biomass

The NOX emissions from biomass as a carbon–neutral energy source during thermal conversion are of great concern. The research on the transformation law of NOX precursors in the thermal conversion process of biomass is an effective measure to regulate the nitrogen migration path of raw biomass and reduce the emission of NOX pollutants. In this study, maize straw was mixed with Eucalyptus wood chips and apple wood chips, respectively, and the slow pyrolysis experiment was carried out at 700 °C to control the nitrogen-containing products, the properties of char-N, tar-N and NOX precursor were studied by TGA, XPS, GC-MS and spectrophotometry, respectively.The results showed that, compared with the theoretical value of pyrolysis nitrogen products of maize straw and woody biomass alone, the addition of Eucalyptus wood chips increased the char-N yield, and the synergistic effect was the strongest under the condition of 50 wt.% addition ratio of +0.2980, the yield of char-N was 32.06 wt.%, apple wood chips was only observed to promote char-N at the addition ratio of 25 wt.%, the synergy intensity was +0.2013, the yield of char-N was 30.27 wt.%, and other experimental groups showed inhibition effect. At the same time, the co-pyrolysis system has a significant inhibitory effect on the NOX precursor nitrogen (NH3-N + HCN-N), among which the Eucalyptus wood chips addition test group has a more obvious inhibitory effect on NH3-N, the synergistic intensity reached the strongest at −0.5926 when the addition ratio was 25 wt.%; while the apple wood chips addition test group had a more obvious inhibitory effect on HCN-N, and the synergistic strength reached the strongest at −0.5798 when the addition ratio was 50 wt.%. In summary, regulating the migration path of nitrogen in the process of thermal conversion of biomass is helpful for cleaner utilization of biomass resources.

Combining LCA-MFA models to identify China’s plastic value chain environmental impact mitigation pathways

Characterizing material flows and environmental impacts of plastic value chain is crucial for sustainable plastic management. Here, we combine material flow analysis and life cycle assessment methods to map the flows of eight major plastics and investigate the multiple environmental impacts of China's plastic value chain. We find that packaging and textile sectors dominate plastic consumption and are responsible for the value chain environmental burdens, but with low recycling rates. Major environmental impacts are generated in plastic production and product manufacturing stages because of the consumption of coal-based feedstocks and electricity. We therefore set up six scenarios by considering carbon neutrality energy pathway, plastic recycling improvement, and technology updating, finding that the value chain environmental impact can be reduced by 14%-57% in 2060 under combined scenario. Particularly, carbon neutrality renewable energy pathway plays an important role. These findings provide valuable insights to identify key mitigation pathways for plastic value chain.

Research on the Impact of Energy Saving and Emission Reduction Policies on Carbon Emission Efficiency of the Yellow River Basin: A Perspective of Policy Collaboration Effect

With China’s proposed carbon peak and carbon neutrality goals, energy conservation and emission reduction are becoming increasingly urgent for the ecological protection and high-quality development of the Yellow River Basin. Based on a systematic combing through of the energy saving and emission reduction (ESER) policies in the Yellow River Basin, this paper empirically analyzed the impacts of objectives collaboration and measures collaboration of ESER policies on the carbon emission efficiency of prefecture-level cities in the Yellow River Basin, by comprehensively adopting the super-slack-based measure (Super-SBM) model and the two-way fixed-effect model. The results of the study found that: (1) with the continuous improvement in policies, the collaboration level of ESER policies in the Yellow River Basin has been significantly improved; (2) the dual-objective collaboration of ESER policies has a significant promotional effect on the carbon emission efficiency of the Yellow River Basin with a lag effect, while the impact of multi-objective collaboration is not significant; (3) the dual-measure collaboration and multi-measure collaboration of ESER policies can effectively promote the improvement in carbon emission efficiency in the Yellow River Basin. This indicates that, in terms of carbon emission reduction in the Yellow River Basin, the objective setting of ESER policies can not be too much, and should pay attention to the mutual coordination of different policy measures to strengthen the carbon reduction effect of ESER policies collaboration.

The role of power – to – hydrogen in carbon neutral energy and industrial systems: Case Finland

To combat climate change, decarbonization measures are undertaken across the whole energy sector. Industry and transportation sectors are seen as difficult sectors to decarbonize, with green hydrogen being proposed as a solution to achieve decarbonization in these sectors. While many methods of introducing hydrogen to these sectors are present in literature, few system-level works study the specific impacts of large-scale introduction has on power and heat sectors in an energy system. This contribution examines the effects of introducing hydrogen into a Finnish energy system in 2040 by conducting scenario simulations in EnergyPLAN – software. Primary energy consumption and CO2 emissions of the base scenario and hydrogen scenarios are compared. Additionally, the differences between a constant and flexible hydrogen production profile are studied. Introducing hydrogen increases electricity consumption by 31.9%, but reduces CO2 emissions by 71.5% and fossil energy consumption by 72.6%. The flexible hydrogen profile lowers renewable curtailment and improves energy efficiency but requires economically unfeasible hydrogen storage. Biomass consumption remains high and is not impacted significantly by the introduction of hydrogen. Additional measures in other sectors are needed to ensure carbon neutrality.

On the numerical treatment of interlaced target values: modeling, optimization and simulation of regulating valves in gas networks

Due to the current and foreseeable shifts towards carbon dioxide neutral energy production, which will likely result in balancing fluctuating renewable energy generation by transforming power-to-gas-to-power as well as building a large-scale hydrogen transport infrastructure, the trading and transport operations of gas will become more dynamic, volatile, and hence also less predictable. Therefore, computer-aided support in terms of rapid simulation and control optimization will further broaden its importance for gas network dispatching. In this paper, we aim to contribute and openly publish two new mathematical models for regulators, also referred to as control valves, which together with compressors make up the most complex and involved types of active elements in gas network infrastructures. They provide direct control over gas networks but are in turn controlled via target values, also known as set-point values, themselves. Our models incorporate up to six dynamical target values to define desired transient states for the elements’ local vicinity within the network. That is, each pair of every two target values defines a bounding box for the inlet pressure, outlet pressure as well as the passing mass flow of gas. In the proposed models, those target values are prioritized differently and are constantly in competition with each other, which can only be resolved dynamically at run-time of either a simulation or optimization process. Besides careful derivation, we compare simulation and optimization results with predictions of the widely adopted commercial simulation tool SIMONE, serving as our substitute for actual real-world transport operations.

Government subsidies, market competition and the TFP of new energy enterprises

Exploring the relationship between government subsidies, market competition, and the total factor productivity (TFP) of new energy enterprises will help countries optimize renewable energy support policies in the context of carbon neutrality constraints and energy demand growth. Based on the panel data of 145 listed new energy enterprises from 2007 to 2020, this paper investigates how government subsidies affect the TFP of new energy enterprises and the moderating effects of market competition. Our main findings are as follows: (1) Government subsidies positively affect the TFP of new energy enterprises. Heterogeneity analysis suggests that government subsidies have a larger effect on the TFP of non-SOEs, midstream and upstream enterprises, and smaller enterprises. (2) Industry market competition negatively moderates the effect of government subsidies on TFP, while enterprise competition power has a positive moderating effect. The marginal effect of government subsidies is significantly positive only when the industry market competition is below a certain threshold or the enterprise competitive power exceeds a certain threshold. (3) Government subsidies enhance the TFP by promoting invention and utility model innovation of new energy enterprises. In addition, market competition significantly moderates the relationship between government subsidies and utility model innovation, thereby moderating the marginal effect of government subsidies on TFP. The findings contribute to a better understanding of the relationship between government support, market competition, and new energy development.

Grid investment and subsidy tradeoffs in renewable electricity auctions

Geographically neutral renewable energy auctions incentivize investors to locate their plants in optimal locations to minimize their bid prices, but this concentration might result in substantial grid investments. Ultimately, maximizing the social welfare for consumers requires minimizing the sum of renewable energy auction subsidies and grid investments. We quantify the trade-offs between grid investment costs and auction subsidies in geographically neutral and geographically diverse renewable energy auctions. We find that consumer costs are minimized in geographically diverse auctions, e.g., when renewables are not only located in the most optimal regions and, thus, when the auction subsidies are not minimized.

The future role of thermal energy storage in 100% renewable electricity systems

Modeling tools and technologies that will allow reaching decarbonization goals in the most cost-effective way are imperative for the transition to a climate-friendly energy system. This includes models which are able to optimize the design of energy systems with a large number of spatially distributed energy generation sources coupled with adequate short, medium, and long duration storage technologies. Solar photovoltaic and wind energy are likely to become the backbone in a future greenhouse gas neutral energy system and will require low-cost, geographically independent storage technologies in order to balance their intermittent availability. As an alternative to lithium-ion batteries and hydrogen systems, thermal energy storage coupled with a power block (e.g., Carnot batteries, pumped thermal storage, etc.) could be a promising option. Therefore, the current study aims to investigate the influence of renewable generation profiles coupled with alternate storage options (i.e., Li-ion and hydrogen cavern) on the installed capacity of electric-to-thermal-to-electric systems using a 100% renewable electricity system in Germany as a case study. The analyses reveal that Carnot batteries complement established and near-future storage technologies, as they could fill the gap between daily storage such as batteries and seasonal storage such as hydrogen salt caverns. Furthermore, Carnot Batteries could offer multiple options for heat integration further increasing their potential.

Impact of turbine technology on wind energy potential and CO2 emission reduction under different wind resource conditions in China

Comprehensive knowledge about wind energy potential is critical for decision-making to achieve carbon neutrality and shape future energy pathways. Wind turbine technology advances (e.g., higher hub-heights, larger rotor diameters and rated power) can better support wind energy harvesting and alter wind energy potential. This study established an integrated model to evaluate the impact of wind turbine technology advances on onshore wind energy potentials under different wind resource conditions by using China as a case study. We found that technological advances of wind turbine can significantly impact wind energy potential. Compared with land-based 1.5-MW turbines, the onshore wind energy potential using newer generation turbines (land-based 2.5-MW turbines) would increase by 43% to 14.8 PWh (i.e., 2.0 times the electricity consumption of China in 2020). Importantly, advances in wind turbine technology can significantly increase capacity factor in poor wind resource regions, and thus enable economically viable generation in more areas. This can significantly increase wind energy potential in poor wind resource regions with large electrical load (e.g., Central, South and East China). Moreover, in contrast to the wind production of 0.46 PWh in 2020, China's wind energy potential is projected to hit 20.1 PWh by 2030 under the assumption of developed turbine technology in line with the trends of the past decade. The corresponding potential CO2 emission reduction would range from 12.6 Gt in 2020 to 21.7 Gt in 2030. These values are 1.3 and 2.2 times higher than China's CO2 emissions in 2020, respectively. To enhance wind energy contribution toward China's carbon neutrality goal, we recommend that the conversion of wind turbines to be accelerated, especially in poor wind resource regions with large electrical load.

Membrane reactors for hydrogen generation: From single stage to integrated systems

The excessive production of carbon dioxide, the greenhouse effect, and the resulting global warming due to the use of fossil fuels have prompted governments, industry, and researchers toward renewable and clean energy sources. Hydrogen has emerged as a novel carbon neutral energy carrier with the highest specific energy content. Production, storage, distribution, and utilization of hydrogen are rapidly increasing. In this context, the use of hydrogen in power plants, fuel cells and internal combustion engines is constantly being developed. However, widespread use of hydrogen requires its sustainable production at low cost and under high purity conditions, which is the subject of further research. Hydrogen separation using membrane reactors is not a new concept; however, it has gained special attention in the last decades and represents a relevant and promising option to potentially overcome the above mentioned problems. This review examines advances in industry and research in hydrogen utilization, hydrogen production using membrane reactors, the nature and physicochemical properties of membranes, and the various configurations of membrane reactors. The effects of membrane reactors on the interplay of temperature, pressure, reactant conversion, hydrogen production, and thermodynamic equilibrium are explained, and the results are compared with those of conventional reactors. Finally, fuel cells, solar collectors, and their integrability into membrane reactors are discussed.

Time-dependent axial fluid model of the Hall thruster discharge and its plume

One-dimensional axial models of a Hall thruster give a good qualitative picture of the main physical phenomena in the discharge with small computational effort. Time-dependent models, in particular, are widely used for the analysis of low-frequency axial oscillations (i.e. the breathing mode). The standard time-dependent three-fluid model found in the literature is here enhanced by extending the physical domain beyond the cathodic surface into the far plume, and improving the modeling of some physical phenomena. A suite of five models is presented in this work with an increasing complexity of added physics; the most complete version accounting for ion and neutral energy evolution equations along with the partial inclusion of electron inertia. The added physics has a non negligible impact on both the dynamics of the breathing mode and the time-averaged response of the plasma. In particular, it is found that the onset of the instability is sensitive to both the level of modeled physics and the operational parameters. In some cases, the strong breathing mode oscillations can result in a weak plasma attachment to the anode, leading to the collapse of the normal anode sheath and to the subsequent failure of the model.

Fusion model with attention mechanism for carbon-neutral sports competitions

IntroductionIn sports competitions, using energy-saving and emission-reduction measures is an important means to achieve the carbon neutrality goal.MethodsIn this paper, we propose an attention mechanism-based convolutional neural network (CNN) combined with the gated recurrent unit (GRU) for carbon neutral energy saving and emission reduction prediction model in sports competitions, CNN is a feedforward neural network whose input is a two-dimensional matrix. The main feature of CNN is that it can handle multi-channel input data, and the use of GRU can make the model structure simple and largely reduce The use of GRU can make the model structure simple, which largely reduces the hardware computational power and time cost and also better solves the long dependency problem in RNN networks. CNN-GRU extracts the data for features and then optimized by the attention mechanism.ResultsThe model collects real-time carbon emissions data from sports events, including game times, lighting usage, air conditioning emissions and other carbon emissions data, and uses deep learning algorithms to predict and compare carbon emissions from sports competition.DiscussionIn identifying energy saving and emission reduction measures conducive to the realization of the goal of carbon neutral sports events, the model has a certain reference value for realizing energy saving and emission reduction in sports competitions under carbon neutrality goals.

Low Carbon Emissions and Energy Consumption: A Targeted Approach Based on the Life Cycle Assessment of a District

Nowadays, the methodology aiming to achieve carbon neutrality and net zero energy on a large scale is known. Despite this, few specialists are mastering this technology globally. What new scenarios. applied at the neighbourhood scale. generate a significant reduction in the rate of CO2 emissions and energy demand? In addition, a lack of massive, regular, and consistent data on carbon emissions and energy consumption has made it significantly difficult to understand the origins of climate change at the building and neighbourhood scales. This work has, as its main goal, the assessment of different strategies that facilitate reduction in the concentration of CO2 and lower energy demands at the district level. The life cycle assessment of a new district has been carried out over 100 years during the four stages of the life cycle of the neighbourhood (construction, operation, demolition and end of life). The results showed that up to 93% of greenhouse gas (GHG) was produced during the operational stage. The energy demand due to transport and waste management represented 60% of the total energy demand of the district during the operational stage. There is still a possibility to maintain air temperature growth around 1.5 °C in the next decade by means of the following: Global warming + 100% of heavy renovation of all buildings + 100% of electric car − renewable energy. This strategy would facilitate a reduction of over 92% of the CO2 produced at the district level.

Macroscale altimetry-based estimation and analyses of wave power: A foundation of wave energy development over Canada

Wave power is essential to carbon neutrality and other energy strategies. Its estimation and analyses at macroscales are enabled by extensive satellite altimetric data, but several challenges or questions exist. Thus, this study develops an advanced macroscale altimetry-based wave-power estimation and analysis (WPEA) method through integrating regionalized ensemble estimates of wave heights, wind speeds and wave periods, models of wave energy flux, indices of flux variabilities and wave power potentials, and statistical analyses of associations between wave power and selected externalities (e.g., offshore distances, water depths, ice-free days, and wind speeds). The method is applied to all Canadian waters, which reveals a series of findings. For instance, Pacific Ocean, Atlantic Ocean, St. Lawrence, and Davis Strait in Canada are suitable for harvesting wave energy, because of considerable fluxes and low variabilities of wave energy at various timescales. Annual total wave power (approximately 2.04 PWh) largely exceeds national electricity consumption (249 TWh in 2021). The regionalized ensemble estimation helps WPEA enhance wave-power estimation accuracy under significant effects of data uncertainty. At the national scale, high wave power tends to be produced over remote, deep, windy, eastern waters and, without the consideration of technological applicability, over ice-free, southern waters. Potential associations of wave power with the externalities present seasonalities and heterogeneities under intensification effects of power-externality covariations and tech-applicability restrictions. Besides advancing wave-power estimation, analyses and modeling at macroscales (including the globe), this study provides data and scientific supports for studies and practices of local, regional and national wave energy development over Canada.

Systematic effects of flexible power-to-X operation in a renewable energy system - A case study from Japan

For achieving a carbon–neutral energy system, economical flexibility mechanisms are crucial to accommodate intermittent and decentralized renewable energy sources. Power-to-X (P2X) is a promising technology for this purpose. This study aims to elucidate the systematic effects and competition of dynamically operated power-to-X (P2X) technologies as a flexibility option in comprehensive renewable energy systems. We developed a linear programming model to optimize energy systems incorporating P2X technologies, including water electrolysis, methanation, Fischer–Tropsch synthesis, and Haber–Bosch synthesis, and investigated the impact of P2X flexibility on the system structure and energy costs, focusing on Japan as a case study. The results demonstrate that each P2X technology effectively shifts electricity loads and reduces curtailment by more than 80%. The contribution of each P2X technology varies, with water electrolysis playing a dominant role due to its relatively low fixed costs and large scale. Furthermore, the mechanism significantly reduces system costs by 35% and supply costs of electricity and hydrogen by 41% and 30%, respectively, by reducing the required capacities of electricity generators, stationary batteries, and transmission grids. Therefore, P2X has a cost advantage over these flexibility options. The results also highlight that the maximum effect is achieved when the capacity factor of P2X is 30%. However, synthetic hydrocarbons would require a carbon price of over 356 EUR/tCO2 to compete with fossil fuels. Domestic electrofuels would face tough competition with global fuel costs. Nevertheless, the reduction in electricity costs through P2X, along with its contribution to energy security, may incentivize its adoption.

A comprehensive evaluation integrating thermodynamics and mechanism kinetics for the Bunsen reaction in a sustainable iodine–sulfur cycle

Carbon neutrality makes hydrogen a promising alternative source of energy. Iodine-sulfur cycle shows the greatest potential among hydrogen production methods. Bunsen reaction holds significant research value as the core reaction of the iodine-sulfur cycle. This paper presents an innovative method for evaluating Bunsen reactions, integrating equilibrium thermodynamics and kinetics to explore the influence of temperature, pressure, and reactant concentration on the Bunsen reaction. The thermodynamic results show that the influence of pressure on reaction balance is weak; with the gradual excess of I2, the amount of H2O required for Bunsen reaction decreases; the optimal operation ratio of H2O:I2:SO2 is 16:4:1 at 360K; the Bunsen reaction system should be carried out in an acidic system, while H2O promotes the spontaneous exothermic reaction of Bunsen. Additionally, we propose 8 reactions as Bunsen reaction mechanisms, and derive the rate equation. Bunsen reaction rates are promoted by [I2], [I3−], and [SO2] concentrations, inhibited by [I−] and [H+] concentrations, and the reaction rate of the whole solution system is sensitive to pH, [I−] and [H+] concentration changes. Added H2O improves pH, whereas acidic systems benefit from higher pH. Lastly, the interconnection of thermodynamic and kinetic results is discussed and compared with other literature. The method proposed in this study has universal application value for Bunsen reaction. It contributes to system process optimization and Bunsen reactor amplification, and facilitating carbon neutralization and hydrogen energy.

Does Mobility Experience Matter? Insights from a Model-Oriented Practice in Zaragoza, Spain

ABSTRACT This study evaluates the role of model-oriented decision support systems in the understanding of complex variables related to urban mobility challenges. To this end, the MobilityExperience platform has been developed as a planning support system (PSSs) to contribute to better informed decision-making in citizens’ commitment to climate neutrality and self-sufficient energy city policies. The results show that the three proposed visualization modes lead to an increase in understanding urban mobility; emphasize the importance of an interactive approach to reinforce the role of an increasing number of agents; and enable a deeper level of collaboration in a data ecosystem framework.

The role of liquid hydrogen in integrated energy systems–A case study for Germany

Hydrogen (H2) is expected to be a key building block in future greenhouse gas neutral energy systems. This study investigates the role of liquid hydrogen (LH2) in a national, greenhouse gas-neutral energy supply system for Germany in 2045. The integrated energy system model suite ETHOS is extended by LH2 demand profiles in the sectors aviation, mobility, and chemical industry and means of LH2 transportation via inland vessel, rail, and truck.This case study demonstrates that the type of hydrogen demand (liquid or gaseous) can strongly affect the cost-optimal design of the future energy system. When LH2 demand is introduced to the energy system, LH2 import, transportation, and production grow in importance. This decreases the need for gaseous hydrogen (GH2) pipelines and affects the location of H2 production plants. When identifying no-regret measures, it must be considered, that the largest H2 consumers are the ones with the highest readiness to use LH2.

Techno-Economic assessment of synthetic E-Fuels derived from atmospheric CO2 and green hydrogen

E-fuels have long been thought of as one way to realise a carbon–neutral energy economy but many concerns over their economic feasibility have arisen over the years, shifting the dialogue away from their utilization, even though they provide a way to carbon-neutrally power the existing fossil fuel intensive infrastructures. In this article, we assess the potential of e-fuels as a net-zero carbon pathway and the economic implications of shifting the entire fuel demand in Saudi Arabia for powering its transportation needs to e-fuels through MTO-MOGD (Methanol-to-Olefin, Mobil’s Olefin to Gasoline and Distillate Fuels) process. This demand is currently ∼ 1 million barrel oil equivalent per day, and the study conducts a techno-economic analysis on a process simulation plant modelled to meet this demand. A minimum fuel selling price of 3.24 USD/litre for e-gasoline and 2.89 USD/litre for e-diesel were estimated, when the plant was powered by solar power. Levelized cost of e-fuel was estimated to be the lowest (∼379 USD/MWh) when the process was entirely powered by an in-situ solar photovoltaic plant and lithium ion battery banks and highest (∼564 USD/MWh) when the process was modified to produce additional methanol (while still being powered entirely by solar energy), across four different scenarios that were considered. These results show the economic implications of e-fuels aimed at decarbonizing the road transport (legacy fleet) and consequently the need for continuous and significant policy support.