This study provides a review of the emergence of hydrogen within low-carbon pathways from different integrated energy system models. The objective is to understand the drivers and policy scenarios ...that lead to the emergence of hydrogen over other low-carbon technologies. The review is divided into global, multi-regional and national integrated energy system models with drivers, marginal abatement costs and timing of hydrogen emergence assessed. Hydrogen's use in energy systems is complex as a result of its relationship with other energy sources. It was found that bioenergy can act as both a competitor and driver for hydrogen energy, along with increased electrification and high renewable electricity scenarios. However, electric vehicles are a main competitor in the passenger vehicle sector. In reviewed results, hydrogen mainly emerges after 2030; although, some technologies emerge as early as 2020 and as late as 2050. The uncertainty and complexity surrounding hydrogen may be as a result of the difficulty of representing hydrogen technologies and systems in energy system models. This study can allow policy makers to assess the various options to be considered regarding hydrogen and make informed decisions for moving towards a decarbonised energy system.
Studies focusing on 100% renewable energy systems have emerged in recent years; however, existing studies tend to focus only on the power sector using exploratory approaches. This paper therefore ...undertakes a whole-system approach and explores optimal pathways towards 100% renewable energy by 2050. The analysis is carried out for Ireland, which currently has the highest share of variable renewable electricity on a synchronous power system. Large numbers of scenarios are developed using the Irish TIMES model to address uncertainties. Results show that compared to decarbonization targets, focusing on renewable penetration without considering carbon capture options is significantly less cost effective in carbon mitigation. Alternative assumptions on bioenergy imports and maximum variability in power generation lead to very different energy mixes in bioenergy and electrification levels. All pathways suggest that indigenous bioenergy needs to be fully exploited and the current annual deployment rate of renewable electricity needs a boost. Pathways relying on international bioenergy imports are slightly cheaper and faces less economic and technical challenges. However, given the large future uncertainties, it is recommended that further policy considerations be given to pathways with high electrification levels as they are more robust towards uncertainties.
•100% renewable energy can be achieved by multiple pathways with similar cost levels.•Focusing only on renewables is not the most cost-effective path to decarbonization.•Pathways relying on bioenergy import are more susceptible to uncertainties.•Indigenous bioenergy needs to be exploited to its full potential.•Much greater efforts than current national action plans are required.
In this paper we present a soft-linking methodology that employs detailed simulation outputs from a dedicated power systems model to gain insights and understanding of the generation electricity ...plant portfolio results for the electricity sector from a separate energy systems model. We apply the methodology and present and discuss the results. The motivation for this soft-linking is to provide a transfer of information from the power systems model strong points to the energy systems model and use this information to improve and develop understanding of energy systems model results. Part of this motivation is derived from a view that one specific energy modeling tool cannot address all aspects of the full energy system in great detail and greater insights and progress can be gained by drawing on the strengths of multiple modeling tools rather than trying to incorporate them all into one comprehensive model. The methodology takes an optimized generation portfolio for a specific year from an energy systems model and undertakes a detailed high resolution chronological simulation of the same portfolio in the power systems model with added degrees of technical detail. Results presented here show that in the absence of key technical constraints, an energy systems model can potentially undervalue flexible resources, underestimate wind curtailment and overestimate the use of baseload plant.
► We present a soft-linking methodology for gaining insight into results from an energy system model. ► The methodology can be used to verify the technical appropriateness of the energy systems developed portfolio. ► Results show that an energy system model can produce a portfolio that is reliable. ► It can overvalue variable renewable resources, overestimate baseload operation and undervalue flexible resources.
There has been a renewed commercial and technical interest in pumped hydro energy storage (PHES) recently with the advent of increased variable renewable energy generation and the development of ...liberalized electricity markets. During the next 8 years over 7
GW of PHES capacity will be added to the European network while projects are also planned in the USA and Japan. This paper provides a review of existing and proposed PHES plant and discusses the technical and economic drivers for these developments. Current trends for new PHES development generally show that developers operating in liberalized markets are tending to repower, enhance projects or build ‘pump-back’ PHES rather than traditional ‘pure pumped storage’. Capital costs per kW for proposed PHES in the review region range between €470/kW and €2170/kW, however these costs are highly site and project specific. An emergence has also been observed in recent PHES developments of the use of variable speed technology. This technology, while incurring slightly higher capital costs, offers a greater range of operational flexibility and efficiency over conventional PHES. This paper has primarily been prompted by a lack of detailed information on PHES facilities worldwide and reviews current developments in the context of market and generation mix changes. The most recent large scale review of PHES faculties was undertaken by the American Society of Civil Engineers Hydro Power Task Committee on Pumped Storage in 1996. In the absence of data in the literature on new PHES plant development, this review draws primarily on publicly available information from utilities, government bodies and electricity regulators. In the same context this study is limited to a review region of the European Union, Japan and the United States as information on developments outside these areas is difficult to procure. This paper also gives a review of locations and proposed timelines for new PHES development and provides a thorough up-to-date overview of the development trends of this technology.
•This work investigates the impact of temporal resolution on power systems modelling.•Increased temporal resolution captures more variability and costs.•Increased resolution betters captures the ...inflexibilities of thermal units.•Significant cycling and ramping of units is also captured.
The objective of this work is to determine the impact of sub-hourly modelling of a power system with significant amounts of wind generation. This paper presents the modelling of the Irish power system for a one year period at 5min, 15min, 30min and 60min resolution simulations using a unit commitment and economic dispatch model assuming perfect foresight. The work examines how much operational costs increase with more accurate resolution. Results show that increased temporal resolution captures more variability in system load and renewable generation, and is necessary to capture the inflexibilities of thermal units that lead to more realistic estimations in total generation costs. Significant cycling and ramping of units is also captured in higher resolution modelling that hourly resolution modelling is unable to capture.
The European Council has agreed ambitious EU climate and energy targets for 2030, including a 40% reduction in greenhouse gas emissions compared to 1990 levels and a minimum share of 27% renewable ...energy consumption. This paper investigates the challenges faced by the European power systems as the EU transitions towards a low carbon energy system with increased amounts of variable renewable electricity generation. The research here adds value to, and complements the power systems results of the PRIMES energy systems model that is used to inform EU energy and climate policy. The methodology uses a soft-linking approach that scrutinizes the power system in high temporal and technical detail for a target year. This enables generation of additional results that provide new insights not possible using a single model approach. These results point to: 1) overestimation of variable renewable generation by 2.4% 2) curtailment in excess of 11% in isolated member states 3) EU interconnector congestion average of 24% 4) reduced wholesale electricity pricing and few run hours raising concerns for the financial remuneration of conventional generation 5) maintenance of sufficient levels of system inertia in member states becomes challenging with significant penetrations of variable renewable generation.
•Develops a multi-model framework to quantify impacts of increased RES-E in the EU.•Builds an EU-28 PLEXOS power systems model with high technical & temporal resolution.•Quantifies interconnector congestion, electricity curtailment and wholesale electricity prices.•Identifies concerns for conventional generation in an energy only market.
Whereas amyloid-β (Aβ) accumulates in the brain of normal animals dosed with low levels of copper (Cu), the mechanism is not completely known. Cu could contribute to Aβ accumulation by altering its ...clearance and/or its production. Because Cu homeostasis is altered in transgenic mice overexpressing Aβ precursor protein (APP), the objective of this study was to elucidate the mechanism of Cu-induced Aβ accumulation in brains of normal mice and then to explore Cu’s effects in a mouse model of Alzheimer’s disease. In aging mice, accumulation of Cu in brain capillaries was associated with its reduction in low-density lipoprotein receptor-related protein 1 (LRP1), an Aβ transporter, and higher brain Aβ levels. These effects were reproduced by chronic dosing with low levels of Cu via drinking water without changes in Aβ synthesis or degradation. In human brain endothelial cells, Cu, at its normal labile levels, caused LRP1-specific down-regulation by inducing its nitrotyrosination and subsequent proteosomal-dependent degradation due in part to Cu/cellular prion protein/LRP1 interaction. In APP ˢʷ/⁰ mice, Cu not only down-regulated LRP1 in brain capillaries but also increased Aβ production and neuroinflammation because Cu accumulated in brain capillaries and, unlike in control mice, in the parenchyma. Thus, we have demonstrated that Cu’s effect on brain Aβ homeostasis depends on whether it is accumulated in the capillaries or in the parenchyma. These findings should provide unique insights into preventative and/or therapeutic approaches to control neurotoxic Aβ levels in the aging brain.
The Copenhagen Accord established political consensus on the 2°C limit (in global temperature increase) and for deep cuts in greenhouse gas (GHG) emissions levels to achieve this goal. The European ...Union has set ambitious GHG targets for the year 2050 (80–95% below 1990 levels), with each Member State developing strategies to contribute to these targets. This paper focuses on mitigation targets for one Member State, Ireland, an interesting case study due to the growth in GHG emissions (24% increase between 1990 and 2005) and the high share of emissions from agriculture (30% of total GHG emissions). We use the Irish TIMES energy systems modelling tool to build a number of scenarios delivering an 80% emissions reduction target by 2050, including accounting for the limited options for agriculture GHG abatement by increasing the emissions reduction target for the energy system. We then compare the scenario results in terms of changes in energy technology, the role of energy efficiency and renewable energy. We also quantify the economic impacts of the mitigation scenarios in terms of marginal CO2 abatement costs and energy system costs. The paper also sheds light on the impacts of short term targets and policies on long term mitigation pathways.
► We developed a techno-economic energy model of Ireland to the year 2050. ► Reductions between 80% and 95% of GHG emissions can be technically achieved. ► A 50% emissions cut in agriculture requires a 95% reductions from the energy system. ► Extending current policies implies greater electrification and efficiency measures. ► The additional cost to achieve mitigation remain less than 2% of GDP levels in 2050.
This paper describes a model of the 2020 Irish electricity system which was developed and solved in a mixed integer programming, unit commitment and economic dispatch tool called PLEXOS®. The model ...includes all generators on the island of Ireland, a simplified representation of the neighbouring British system including proposed wind capacity and interconnectors between the two systems. The level of wind curtailment is determined under varying levels of three influencing factors. The first factor is the amount of offshore wind, the second is the allowed limit of system non-synchronous penetration (SNSP) and the third is inclusion or exclusion of transmission constraints. A binding constraint, resulting from the 2020 EU renewable energy targets, is that 37% of generation comes from wind. When the SNSP limit was increased from 60% to 75% there was a reduction in wind curtailment from 14% to 7%, with a further reduction when the proportion of wind capacity installed offshore was increased. Wind curtailment in the range of SNSP limit of 70–100% is influenced primarily by the inclusion of transmission constraints. Large changes in the dispatch of conventional generators were also evident due to the imposition of SNSP limits and transmission constraints.
► Wind capacity required to meet renewable targets has previously been underestimated. ► Between 5911 MW and 6890 MW of wind capacity will be required in 2020. ► 7–14% of wind production in 2020 will be lost due to curtailment or constraints. ► Shifting some wind capacity offshore reduces the proportion of wind curtailed.
A new model which comprehensively explains the working principles of contact-mode triboelectric nanogenerators (TENGs) based on Maxwell's equations is presented. Unlike previous models which are ...restricted to known simple geometries and derived using the parallel plate capacitor model, this model is generic and can be modified to a wide range of geometries and surface topographies. We introduce the concept of a distance-dependent electric field, a factor not taken into account in previous models, to calculate the current, voltage, charge, and power output under different experimental conditions. The versatility of the model is demonstrated for non-planar geometry consisting of a convex–concave surface. The theoretical results show excellent agreement with experimental TENGs. Our model provides a complete understanding of the working principles of TENGs, and accurately predicts the output trends, which enables the design of more efficient TENG structures.
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