Interconnection Capacity Research Articles

Optimising Portugal’s 2050 energy system: Electric vehicles and hydrogen integration using Grey Wolf Optimiser and EnergyPLAN

The global shift to sustainable energy, driven by climate concerns and energy security, is backed by worldwide governmental commitments to reduce greenhouse gas emissions and enhance renewable energy sources in the energy systems. In 2016, the Portuguese Government pledged to carbon neutrality by 2050 as part of this global effort. This article proposes technical solutions for reducing carbon dioxide emissions and increasing renewable energy in the Portuguese mainland energy system by 2050, considering the targets set by the government. An energy system modelling approach based on the Grey Wolf Optimiser and the EnergyPLAN software was introduced. Seven scenarios for 2050 assess the impacts of transport electrification and hydrogen grid integration while minimising costs and/or carbon dioxide emissions. The results show that achieving a nearly 100% renewable electricity system and carbon neutrality is possible, considering a carbon capture ranging from 2.65Mt to 5.87Mt. The 2050 energy system requires a minimum battery storage of 5.1GWh and a minimum natural gas storage of 2,063GWh. Transport electrification requires an increase in the total installed capacity by at least 1.83GW, while hydrogen integration increases it by a minimum of 8.25GW. Developing interconnection capacity beyond 15% of the total installed capacity is crucial for grid stability and reducing fossil fuel dependence.

Competitive effects of implicit auction on interconnectors: evidence from Japan

Interconnectors play a crucial role in electric power systems. They contribute to balancing demand and supply in real-time, guaranteeing efficient dispatch in wide geographic regions, and increasing competition by creating large markets. However, interconnector capacity is a scarce resource because vertically integrated utilities were required to have generating capacity enough to supply most customers within their operating region under a regulated monopoly. Hence, identifying the efficient allocation method is essential, particularly after recent electricity market restructuring. This study evaluates the competitive effect of the implicit auction on the interconnector transmission capacity. The implicit auction allocates all the interconnector capacity simultaneously with electric energy in the day-ahead market. This method prevents market participants from strategically withholding the physical interconnector capacity ex ante to exercise market power, as allowed under the first come, first served rule. This study empirically shows how the capacity was withheld from the day-ahead market under the first come, first served rule using detailed reservation data. Next, I show that the implicit auction increases interconnector capacity available at the day-ahead market and trade volume. I use machine-learning methods, such as random forest and deep neural networks, to predict the counterfactual market outcomes without implicit auction. I find that the gain from trade under the implicit auction is more than US$55 million per year in Japan, which is more than 100 times the implementation cost of the implicit auction.

Climate policy with electricity trade

Trade reduces the effectiveness of climate policies such as carbon pricing when domestic products are replaced by more carbon-intensive imports. We investigate the impact of unilateral carbon pricing on electricity generation in a country open to trade through interconnection lines. We characterize the energy mix with intermittent renewable sources of energy (wind or solar power). Electricity trade limits the penetration of renewables due to trade-induced competition. A carbon border adjustment mechanism (CBAM) removes this limit by increasing the cost of imported power, or by deterring imports. The CBAM must be complemented by a subsidy on renewables to increase renewable generation above domestic consumption. The interconnection line is then used to export power rather than importing it when renewables are producing. We also examine network pricing and investment into interconnection capacity. A higher carbon price increases interconnection investment which further reduces the effectiveness of carbon pricing. In contrast, when renewable electricity is exported, a higher subsidy on renewables reduces further carbon emissions by expanding interconnection capacity.

RES growth linked to grid development. Case Study: Romania

The paper presents Romania to illustrate how more production capacities from renewable energy sources can be integrated as part of the environmental protection and geostrategic policies, in an accelerated energy transition process. Increasing electricity production, especially for the widespread development of wind turbines and rooftop solar PV systems, requires the development of the electrical grid and increased interconnection capacity. The authors of this report also take into account the behavior in different seasons, cold and warm, in terms of the amount of renewable energy injected into the network. The data used in the study is based on the interpreting and associations of various information at the national and European levels, highlighting that the benefits of renewable energy are not only seen in terms of significant reductions in environmental impact but also in terms of cheaper energy! In summary, it is assumed that in 2023-2026, the electricity demand at the level of quality indicators will be covered by investments in new generation facilities related to grid reinforcement measures.

Hybrid renewable energy systems: the value of storage as a function of PV-wind variability

As shares of variable renewable energy (VRE) on the electric grid increase, sources of grid flexibility will become increasingly important for maintaining the reliability and affordability of electricity supply. Lithium-ion battery energy storage has been identified as an important and cost-effective source of flexibility, both by itself and when coupled with VRE technologies like solar photovoltaics (PV) and wind. In this study, we explored the current and future value of utility-scale hybrid energy systems comprising PV, wind, and lithium-ion battery technologies (PV-wind-battery systems). Using a price-taker model with simulated hourly energy and capacity prices, we simulated the revenue-maximizing dispatch of a range of PV-wind-battery configurations across Texas, from the present through 2050. Holding PV capacity and point-of-interconnection capacity constant, we modeled configurations with varying wind-to-PV capacity ratios and battery-to-PV capacity ratios. We found that coupling PV, wind, and battery technologies allows for more effective utilization of interconnection capacity by increasing capacity factors to 60%–80%+ and capacity credits to close to 100%, depending on battery capacity. We also compared the energy and capacity values of PV-wind and PV-wind-battery systems to the corresponding stability coefficient metric, which describes the location-and configuration-specific complementarity of PV and wind resources. Our results show that the stability coefficient effectively predicts the configuration-location combinations in which a smaller battery component can provide comparable economic performance in a PV-wind-battery system (compared to a PV-battery system). These PV-wind-battery hybrids can help integrate more VRE by providing smoother, more predictable generation and greater flexibility.

Exploring sustainable electricity system development pathways in South America’s MERCOSUR sub-region

We explore sustainable electricity system development pathways in South America’s MERCOSUR sub-region under a range of techno-economic, infrastructural, and policy forces. The MERCOSUR sub-region includes Argentina, Brazil, Chile, Uruguay, and Paraguay, which represent key electricity generation, consumption, and trade dynamics on the continent. We use a power system planning model to co-optimize investment and operations of generation, storage, and transmission facilities out to 2050. Our results show that, under business-as-usual conditions, wind and solar contribute more than half of new generation capacity by 2050, though this requires substantial expansion of natural gas-based capacity. While new hydropower appears to be less cost-competitive, the existing high capacity of hydropower provides critically important flexibility to integrate the wind and solar and to avoid further reliance on more expensive or polluting resources (e.g., natural gas). Over 90% emission cut by 2050 could be facilitated mostly by enhanced integration (predominantly after 2040) of wind, solar, and battery storage with 11%–28% additional cost, whereas enhanced expansion of hydropower reduces the cost of low-carbon transition, suggesting trade-off opportunities between saving costs and environment in selecting the clean energy resources. Achieving high emission reduction goals will also require enhanced sub-regional electricity trade, which could be mostly facilitated by existing interconnection capacities.

Risk aversion and flexibility options in electricity markets

Flexibility options, such as demand response, energy storage and interconnection, have the potential to reduce variation in electricity prices between different future scenarios, thereby reducing investment risk. Investing in flexibility options can also lower the need for generation capacity. However, there are complex interactions between different flexibility options. In this paper, we investigate the interactions between flexibility and investment risk in electricity markets. In particular, we focus on the investment strategies of risk-averse decision-makers. We employ a large-scale stochastic transmission and generation expansion model of the European electricity system, providing it with uncertain future scenarios based on ENTSOs’ Ten-Year Network Development Plan. Using this model, we first investigate the effect of risk aversion on investment decisions. We find that the interplay of parameters leads to (i) more investment in a less emission-intensive energy system if planners are risk averse (hedging against CO2 price uncertainty), (ii) constant total installed capacity, regardless of the level of risk aversion (i.e. planners do not hedge against demand and uncertainties when deploying renewable energy sources) and (iii) an allocation of investments that disregards cost differences for load shedding across Europe. Second, we examine the individual effects of three flexibility elements on optimal investment levels at different levels of risk aversion: demand response, investment in additional interconnection capacity and investment in additional energy storage. We show that flexible technologies have a higher value for risk-averse decision-makers, although the effects are nonlinear. Finally, we investigate the interactions between the flexibility elements. We find that risk-averse decision-makers show a strong preference for transmission-grid expansion once flexibility is available at a low cost.

Multi-Area Frequency Restoration Reserve Sizing

Frequency Restoration Reserves are traditionally sized using deterministic methods. The constant growth in non-dispatchable renewable energy, however, is increasing the importance of probabilistic methods for reserve sizing. In addition, as the geographical scope of reserve sizing expands, overall power imbalance stochasticity is reduced. In this paper, we propose a probabilistic method for shared cross-border frequency restoration reserve commitment and sizing, based on the concept of system generation margin and employing mathematical optimization. The aim is to reduce overall reserve volumes and costs. The cross-border interconnection capacities among countries are taken into account, and the shared uncertainty across interconnections is addressed via a novel robust approach. The method is tested on the cross-border system of south-east Europe that includes 9 countries. 5 different operational scenarios are used and a detailed calculation of the uncertainty distributions in each country is employed. Results show that cross-border shared sizing can significantly reduce overall reserve volumes and costs in a secure way.

Economic incentives for capacity reductions on interconnectors in the day-ahead market

We consider a zonal international power market and investigate potential economic incentives for short-term reductions of transmission capacities on existing interconnectors by the responsible transmission system operators (TSOs). We show that if a TSO aims to maximize domestic total welfare, it often has an incentive to reduce the capacity on the interconnectors to neighboring countries. In contrast with the (limited) literature on this subject, which focuses on incentives through the avoidance of future balancing costs, we show that incentives can exist even if one ignores balancing and focuses solely on welfare gains in the day-ahead market itself. Our analysis consists of two parts. In the first part, we develop an analytical framework that explains why these incentives exist. In particular, we distinguish two mechanisms: one based on price differences with neighboring countries and one based on the domestic electricity price. In the second part, we perform numerical experiments using a model of the Northern-European power system, focusing on the Danish TSO. In 97% of the historical hours tested, we indeed observe economic incentives for capacity reductions, leading to significant welfare gains for Denmark and welfare losses for the system as a whole. We show that the potential for welfare gains greatly depends on the ability of the TSO to adapt interconnector capacities to short-term market conditions. Finally, we explore the extent to which the recently introduced European “70%-rule” can mitigate the incentives for capacity reductions and their welfare effects.

A distributed robust control strategy for electric vehicles to enhance resilience in urban energy systems

Resilient operation of multi-energy microgrid is a critical concept for decarbonization in modern power system. Its goal is to mitigate the low probability and high damaging impacts of electricity interruptions. Electrical vehicles, as a key flexibility provider, can react to unserved demand and autonomously schedule their operation in order to provide resilience. This paper presents a distributed control strategy for a population of electrical vehicles to enhance resilience of an urban energy system experiencing extreme contingency. Specifically, an iterative algorithm is developed to coordinate the charging/discharging schedules of heterogeneous electrical vehicles aiming at reducing the essential load shedding while considering the local constraints and multi-energy microgrid interconnection capacities. Additionally, the gap between electrical vehicle energy and the required energy level at the departure time is also minimised. The effectiveness of the introduced distributed coordinated approach on energy arbitrage and congestion management is tested and demonstrated by a series of case studies.

Planetary boundaries assessment of deep decarbonisation options for building heating in the European Union

Building heating is one of the sectors for which multiple decarbonisation options exist and current geopolitical tensions provide urgency to design adequate regional policies. Heat pumps and hydrogen boilers, alongside alternative district heating systems, are the most promising alternatives. Although a host of city or country-level studies exist, it remains controversial what role hydrogen should play for building heating in the European Union compared with electrification and how blue and green hydrogen differ in terms of costs and environmental impacts. This work assesses the optimal technology mix for staying within planetary boundaries, and the influence of international cooperation and political restrictions. To perform the analysis, a bottom-up optimisation model was developed incorporating life cycle assessment constraints and covering production, storage, transport of energy and carbon dioxide, as well as grid and non-grid connected end-users of heat. It was found that a building heating system within planetary boundaries is feasible through large-scale electrification via heat pumps, although at a higher cost than the current system with abatement costs of around 200 €/ton CO2. Increasing interconnector capacity or onshore wind energy is found to be vital to staying within boundaries. A strong trade-off for hydrogen was identified, with blue hydrogen being cost-competitive but vastly unsustainable (when applied to heating) and green hydrogen being 2–3 times more expensive than electrification while still transgressing several planetary boundaries. The insights from this work indicate that heat pumps and renewable electricity should be prioritised over hydrogen-based heating in most cases and grid-stability and storage aspects explored further, while revealing a need for policy instruments to mitigate increased costs for consumers.

Welfare Effects of Implicit Auction on Interconnector Capacity: Evidence from Japan

Welfare Effects of Implicit Auction on Interconnector Capacity: Evidence from Japan

Numerical Evaluation of Melting and Breaking Characteristics of Return Conductor Strands of 200kV HVDC Overhead Transmission Line Struck by Lightning

In March 2021, the Shin-Shinano Substation of TEPCO Power Grid, Inc. was connected to the Hida Convertor Station of Chubu Electric Power Grid Co., Inc. by HVDC transmission system with an interconnection capacity of 900MW in order to increase the interconnection capacity between the eastern and the western areas in Japan. The 200kV HVDC overhead transmission lines have a pair of energized conductors and a return conductor. It has been investigated that TACSR (410mm2 [AC410], 610mm2 [AC610], 810mm2 [AC810]) would be used as the return conductor. However, as the return conductor plays the role of a ground wire, the melting and breaking of TACSR strands due to lightning strike was concerned. Therefore, in this paper, numerical evaluations of melting and breaking characteristics of the return conductor strands were carried out supposing the return conductor was struck by DC arc discharge simulating lightning whose maximum current was 400kA. As a result, the number of breaking strands of AC610 was more than that of AC410 and AC810 because the diameter of strands of AC610 was smaller than that of AC410 and AC810. The remaining rate of cross-section area of strands of AC410 decreased more than AC610 and AC810 as DC arc current increased.

Wind, water and wires: Evaluating joint wind and interconnector capacity expansions in hydro-rich regions

Countries or regions with a high share of storage hydro and good renewables resources may be able to interconnect to less well-endowed neighbours. To maximise joint benefits, coordinating interconnector and renewables investment is desirable. Suitable long-term contracts ensure that beneficiaries pay and jointly cover the highly dispersed costs and benefits. The article develops a simple model calibrated for Tasmania that demonstrates how this can be quantified and various counterfactuals tested. The key to the simplification is that the value of water is both stable over time and the key driver of outcomes. The economic attraction of proposed wind and interconnector investment depends sensitively on the value placed on CO2 reductions.

Cross-regional electricity and hydrogen deployment research based on coordinated optimization: Towards carbon neutrality in China

In order to achieve carbon neutrality in a few decades, the clean energy proportion in power mix of China will significantly rise to over 90%. A consensus has been reached recently that it will be of great significance to promote hydrogen energy, that is produced by variable renewable energy power generation, as a mainstay energy form in view of its potential value on achieving carbon neutrality. This is because hydrogen energy is capable of complementing the power system and realizing further electrification, especially in the section that cannot be easily replaced by electric energy. Power system related planning model is commonly used for mid-term and long-term planning implemented through power installation and interconnection capacity expansion optimization. In consideration of the high importance of hydrogen and its close relationship with electricity, an inclusive perspective which contains both kinds of the foresaid energy is required to deal with planning problems. In this study, a joint model is established by coupling hydrogen energy model in the chronological operation power planning model to realize coordinated optimization on energy production, transportation and storage. By taking the carbon neutrality scenario of China as an example, the author applies this joint model to deploy a scheme research on power generation and hydrogen production, inter-regional energy transportation capacity, and hydrogen storage among various regions. Next, by taking the technology progress and cost decrease prediction uncertainty into account, the main technical–economic parameters are employed as variables to carry out sensitivity analysis research, with a hope that the quantitative calculation and results discussion could provide suggestion and reference to energy-related companies, policy-makers and institute researchers in formulating strategies on related energy development.

Digital revolution for the agroecological transition of food systems: A responsible research and innovation perspective

CONTEXTSo far, digital technology development in agriculture has mainly dealt with precision agriculture, often associated with conventional large-scale systems. The emergence of digital agriculture - based on the triptych of “new data sources / new processing methods / new inter-connection capacities (internet)” - opens up prospects for mobilizing digital technologies to accelerate the deployment of other forms of agriculture, such as agroecology. A specific research agenda must therefore be built to redirect researchers specialized in digital technologies towards these new issues. This construction is significant because digital technology and agroecology are disruptive innovations that shake up the actors' practices, agricultural innovation ecosystems, and value chains. OBJECTIVEAn interdisciplinary group of INRAE researchers (covering 10 scientific departments) was mandated to carry out this reflection, with the objective of developing a research agenda to better couple digitalization and agroecology, in order to pave the way for responsible digital farming. The group used the framework of responsible research and innovation. METHODOver 18 months, the group met monthly by video-conference, to overcome the interdisciplinarity barrier, and at three face-to-face seminars, where creative design exercises were carried out (based on a world café format, and “remember the future” method). This work gave rise to three prospective lines of research aimed at putting digitalization at the service of agroecology and local food systems. These topics prioritize research that fosters innovations in digital technology, as well as organisations and policies that (1) accelerate the agroecological transition on the farm and in the territories, (2) manage the territories as commons, (3) empower farmers and consumers. Then, the group examined these three prospective lines of research from an RRI perspective as well as three current research topics on digital agriculture (digital soil mapping, precision agriculture, technologies for food wastage reduction). RESULTS AND CONCLUSIONSThis work allowed us to highlight the gaps between current research on digital agriculture and the RRI expectations, and the tensions (between rationalization and diversity of farming systems, between complexity of agroecological systems and the need for simplification of models, and finally between data speculation and frugality). We were also able to refine the specific scientific questions of each prospective line of research and finally to draw attention to the key levers that will have to be integrated if these research efforts are to be approached from an RRI perspective. SIGNIFICANCEThis contribution shows RRI can be used not only to reflect on research practices but also as a framework to build a research agenda paving the way for responsible digital agriculture.

The role of hydrogen in a greenhouse gas-neutral energy supply system in Germany

Hydrogen is widely considered to play a pivotal role in successfully transforming the German energy system, but the German government's current “National Hydrogen Strategy” does not specify how hydrogen utilization, production, storage or distribution will be implemented. Addressing key uncertainties for the German energy system's path to greenhouse gas-neutrality, this paper examines hydrogen in different scenarios. This analysis aims to support the concretization of the German hydrogen strategy. Applying a European energy supply model with strong interactions between the conversion sector and the hydrogen system, the analysis focuses on the requirements for geological hydrogen storages and their utilization over the course of a year, the positioning of electrolyzers within Germany, and the contributions of hydrogen transport networks to balancing supply and demand. Regarding seasonal hydrogen storages, the results show that hydrogen storage facilities in the range of 42 TWhH2 to 104 TWhH2 are beneficial to shift high electricity generation volumes from onshore wind in spring and fall to winter periods with lower renewable supply and increased electricity and heat demands. In 2050, the scenario results show electrolyzer capacities between 41 GWel and 75 GWel in Germany. Electrolyzer sites were found to follow the low-cost renewable energy potential and are concentrated on the North Sea and Baltic Sea coasts with their high wind yields. With respect to a hydrogen transport infrastructure, there were two robust findings: One, a domestic German hydrogen transport network connecting electrolytic hydrogen production sites in northern Germany with hydrogen demand hubs in western and southern Germany is economically efficient. Two, connecting Germany to a European hydrogen transport network with interconnection capacities between 18 GWH2 and 58 GWH2 is cost-efficient to meet Germany's substantial hydrogen demand.

Value of Interconnectors Operating in Simultaneous Energy-Frequency Response Markets

This paper investigates the potential contribution that interconnectors can provide to efficiently support the security of interconnected power systems. The proposed modelling setup introduces a radical paradigm shift in the operation of the interconnectors and in their interactions with multiple markets. To the best of our knowledge, this is the first paper that models a simultaneous allocation of the interconnector capacity for the exchange of energy and of inertia-dependent primary frequency response. The benefits and impact of this new methodology are evaluated with typical market indicators (e.g., social welfare and interconnector revenues) under two different paradigms: a centralized approach where the interconnectors are operated to minimize the system operational cost and a market-based framework where the interconnectors are privately-owned assets with self-interested objectives. By modelling the interconnectors as “price-maker”, the proposed work quantifies the potential inefficiencies of market solutions while considering key elements such as capacity withdrawing. A case study of the GB-France systems assesses the value of interconnectors on system efficiency and security under the considered paradigms.

Electricity market relationship between Great Britain and its neighbors: distributional effects of Brexit

BackgroundBeyond Great Britain, Brexit could also have ripple effects on the electricity systems of certain other EU member states. This paper investigates the possible effects of reduced growth in interconnectivity between Great Britain and mainland Europe by 2030 on the electricity system in GB and across other EU member states in addition to the effects of Pound depreciation. Effects are analyzed across a “Green Scenario” and “Blue Scenario” in 2030, based on the ENTSO-E (European Network of Transmission System Operators-Electricity) 10-year development plans. There is a greater expansion of nuclear and renewables in Green than in Blue and, in Blue, the British CO2 price is higher than in the EU. Within each scenario, there are four variants: full vs. reduced expansion of interconnection capacity, in combination with no devaluation and 10% depreciation of the British Pound. The EMME (Electricity Market Model for Europe) is used to model these impacts across the different scenario variants.ResultsInterconnector utilization is more volatile in the Green Scenario variants, leading to concerns about investor incentives, especially given the increased uncertainty under Brexit. In terms of electricity prices, GB consumers lose out across both Blue and Green scenario variants, whereas EU and GB producers both gain and lose in different variants. Across the Green Scenario variants, EU neighbors’ trade balances with GB deteriorate slightly, but the impact is far stronger in Blue due to a loss of opportunities to export power. GB sees significant increases in electricity costs across scenario variants. Green scenario variants offer potential for modest emission reductions in certain EU nations, whereas Blue Scenario variants lead to greater emission reductions in the EU neighbors which contrasts with a sharp rise in GB emissions.ConclusionsThere is a significant link between NTC expansion and wholesale prices. Delayed or cancelled NTC expansion could negatively affect the GB power system’s low-carbon transition. Pound depreciation and reduced expansion of NTCs lead to shifts in generation-related CO2 emissions. A higher cost burden for electricity is a risk for GB, whereas, for EU neighbors, their trade position with the UK risks deteriorating.

Design and operation of Hybrid Multi-Terminal Soft Open Points using Feeder Selector Switches for flexible distribution system interconnection

Distribution systems will require new cost-effective solutions to provide network capacity and increased flexibility to accommodate Low Carbon Technologies. To address this need, we propose the Hybrid Multi-Terminal Soft Open Point (Hybrid MT-SOP) to efficiently provide distribution system interconnection capacity. Each leg of the Hybrid MT-SOP has an AC/DC converter connected in series with a bank of AC switches (Feeder Selector Switches) to allow the converter to connect to any of the feeders at a node. Asymmetric converter sizing is shown to increase feasible power transfers by up to 50% in the three-terminal case, whilst a conic mixed-integer program is formulated to optimally select the device configuration and power transfers. A case study shows the Hybrid MT-SOP increasing utilization of the converters by more than one third, with a 13% increase in system loss reduction as compared to an equally-sized MT-SOP.