Transmission Grid Extensions Research Articles

Quantifying the impacts of biomass driven combined heat and power grids in northern rural and remote communities

Northern rural and remote communities face several energy system related concerns such as high heating and electricity rates, dependence on imported energy, and low levels of energy security and autonomy. Many of these issues can be addressed via the implementation of local community-based sustainable energy generation technologies such as biomass driven combined heat and power (CHP) plants. The current research investigates the technical, economic, socio-economic, and environmental impacts of implementing biomass driven CHP plants as the primary energy source in both remote (off-grid) and rural (grid-connected) community energy systems that comprise a district heating grid. The MoCreebec Eeyoud community located in Northern Ontario, Canada, is used as the case study in the analysis. Results show that biomass driven CHP grids are an economically attractive alternative for both remote and rural energy systems. Biomass driven CHP grids are shown to be up to 42% less costly than conventional diesel power generation systems in remote community settings. Similarly, remote biomass driven CHP grids are shown to be up to 66% less costly than rural energy systems when electrical transmission grid extension lengths exceed 100 km. Biomass driven CHP grids can also drastically reduce greenhouse gas emissions, lower carbon tax payments, generate local economic employment, and increase energy autonomy. Although the findings of this study are specific to the community under investigation, the research methodology and insights gained are generalizable to remote and rural communities located across Canada and abroad.

An innovative business model for rural sub-Saharan Africa electrification

Despite a significant progress in electrification over the last decade, more than 1 billion people have no access to electricity, and about 3 billion use solid fuel or kerosene for cooking and heating purposes. More than 95 % of them live in sub-Saharan Africa or developing Asia, and around 80 % are situated in rural areas. Conventional approach to power supply such as transmission grid extension is not economical due to high investment and connection costs. Technological progress has shifted down capital costs of renewable off-grid solutions. However, in the most cases, it is not enough to reach feasibility of these solutions due to weak investment conditions and weak purchasing power of the local population in these areas. The choice of business model can have a vital role in bringing electrification and connectivity to rural areas, providing flexibility and adaptability of the technology to the market conditions. Analysis of existing literature on business models for off-grid solutions concludes that the model for rural areas in developing countries should be more service oriented, be scalable to various use case scenarios, should provide good risk balance between customer and provider, and should enable transparency and quality of service. This paper analyses recent developments in off-grid system solutions for sub-Saharan Africa and provides classification of business model innovations. Based on the analysis, the paper proposes an innovative business model for Fusion Grid project, scalable mini-grid integrated with connectivity solution. Feasibility of the project is tested for three different cases, depending on the type of the rural community. Results suggests that combining micro-grid based power supply and internet connection as one service can contribute to a viability of the project, and, furthermore, can contribute to achieving global electrification goal.

Optimal Sizing and Spatial Allocation of Storage Units in a High-Resolution Power System Model

The paradigm shift of large power systems to renewable and decentralized generation raises the question of future transmission and flexibility requirements. In this work, the German power system is brought to focus through a power transmission grid model in a high spatial resolution considering the high voltage (110 kV) level. The fundamental questions of location, type, and size of future storage units are addressed through a linear optimal power flow using today’s power grid capacities and a generation portfolio allowing a 66% generation share of renewable energy. The results of the optimization indicate that for reaching a renewable energy generation share of 53% with this set-up, a few central storage units with a relatively low overall additional storage capacity of around 1.6 GW are required. By adding a constraint of achieving a renewable generation share of at least 66%, storage capacities increase to almost eight times the original capacity. A comparison with the German grid development plan, which provided the basis for the power generation data, showed that despite the non-consideration of transmission grid extension, moderate additional storage capacities lead to a feasible power system. However, the achievement of a comparable renewable generation share provokes a significant investment in additional storage capacities.

Can Lignite Take a Back Seat?

Transmission grid extension is a central aspect of the future energy system transition in Germany. This stems from the diverging occurrence of renewable energy feed-in and consumption as well as the targeted nuclear and currently discussed carbon phase-outs. After realizing the retirement of the domestic nuclear energy fleet by 2022, a next policy objective could be the phase-out of domestic lignite generation. The German electricity grid was not designed to accommodate these emerging challenges. Hence, the following paper addresses the impact of decommissioning lignite power plants on the most cost-effective grid extensions by 2030. To determine the optimal transmission grid design, efficient methods for techno-economic analysis are required. The challenge of conducting an analysis of grid extensions involves lumpy investment decisions and the non-linear character of several restrictions in a real-data environment. The following paper introduces the application of the Benders Decomposition, dividing the problem into an extension and a dispatch problem to reduce the degree of computational complexity. The results show that lignite phase-out can significantly increase the number of grid extensions in Germany. All scenarios simulating a lignite phase-out by 2030 lead to higher overall system costs but lower CO $${}_{2}$$ emissions.

Features of a fully renewable US electricity system: Optimized mixes of wind and solar PV and transmission grid extensions

A future energy system is likely to rely heavily on wind and solar PV. To quantify general features of such a weather dependent electricity supply in the contiguous US, wind and solar PV generation data are calculated, based on 32 years of weather data with temporal resolution of 1h and spatial resolution of 40×40km2, assuming site-suitability-based and stochastic wind and solar capacity distributions. The regional wind-and-solar mixes matching load and generation closest on seasonal timescales cluster around 80% solar share, owing to the US summer load peak. This mix more than halves long-term storage requirements, compared to wind only. The mixes matching generation and load best on daily timescales lie at about 80% wind share, due to the nightly gap in solar production. Going from solar only to this mix reduces backup energy needs by about 50%. Furthermore, we calculate shifts in FERC (Federal Energy Regulatory Commission)-level LCOE (Levelized Costs Of Electricity) for wind and solar PV due to differing weather conditions. Regional LCOE vary by up to 29%, and LCOE-optimal mixes largely follow resource quality. A transmission network enhancement among FERC regions is constructed to transfer high penetrations of solar and wind across FERC boundaries, employing a novel least-cost optimization.

Transmission Network Enhancement with Renewable Energy

Wind and solar energy play an important role in the de – carbonization of electricity generation. However, high shares of these Variable Renewable Energies (VREs) challenge the power system considerably due to their temporal fluctuations and geographical dispersion. This paper systematically reviews and analyzes transmission grid extensions as an integration measure for VREs. Effects of grid extensions for fundamental properties of the power system as a function of the penetration and mix of wind coupled with solar energy were revealed in the study. The paper also provides an overview of the system implication of wind and solar PV energy and investigates a way to partly overcome transmission grid extensions.

Transmission grid extensions during the build-up of a fully renewable pan-European electricity supply

Spatio-temporal generation patterns for wind and solar photovoltaic power in Europe are used to investigate the future rise in transmission needs with an increasing penetration of the VRES (variable renewable energy sources) on the pan-European electricity system. VRES growth predictions according to the official National Renewable Energy Action Plans of the EU countries are used and extrapolated logistically up to a fully VRES-supplied power system. We find that keeping today's international NTCs (net transfer capacities) fixed over the next forty years reduces the final need for backup energy by 13% when compared to the situation with no NTCs. An overall doubling of today's NTCs will lead to a 26% reduction, and an overall quadrupling to a 33% reduction. The remaining need for backup energy is due to correlations in the generation patterns, and cannot be further reduced by transmission. The main investments in transmission lines are due during the ramp-up of VRES from 15% (as planned for 2020) to 80%. Additionally, our results show how the optimal mix between wind and solar energy shifts from about 70% to 80% wind share as the transmission grid is enhanced. Finally, we exemplify how reinforced transmission affects the import and export opportunities of single countries during the VRES ramp-up.

The role of grid extensions in a cost-efficient transformation of the European electricity system until 2050

A strong and intermeshed electricity grid allows the cost-efficient achievement of renewable energy targets by enabling the use of favorable sites and by facilitating the balancing of stochastic infeed from renewables and electricity demand. However, construction of new lines is currently proceeding slowly in Europe. This paper quantifies the benefits of optimal transmission grid extensions for Europe up to 2050 by iterating an investment and dispatch optimization model with a load flow based grid model. We find that large grid extensions, allowing the full exploitation of the most favorable RES-E sites throughout Europe, are beneficial from a least-cost perspective. If the electricity network were to be cost-optimally extended, 228,000km would be built before 2050 (+76% compared to today). Only for sites located furthest from large consumption areas in Central Europe would the value of grid extensions not always outweigh its costs. Furthermore, the capacity of transmission lines connecting favorable RES-E sites with demand centers is cost-optimally dimensioned to almost entirely export all RES-E generation that exceeds local electricity demand. Only in periods with the highest infeed of fluctuating renewables, electricity is stored. When optimal grid extensions are impeded, storage investments are chosen to a larger extent.

Transmission grid extensions for the integration of variable renewable energies in Europe: Who benefits where?

Variable renewable energy (VRE) generation from wind and sun is growing quickly in Europe. Already today, VRE's power contribution is at times close to the total demand in some regions with severe consequences for the remainder of the power system. Grid extensions are necessary for the physical integration of VRE, i.e., for power transports, but they also have important economic consequences for all power system participants.We employ a regional, power system model to examine the role of grid extensions for the market effects of VRE in Europe. We derive cost-optimal macroscopic transmission grid extensions for the projected wind and solar capacities in Europe in 2020 and characterize their effects on the power system with high regional and technological resolution.Without grid extensions, lower electricity prices, new price dynamics and reduced full load hours for conventional generation technologies result in proximity to high VRE capacities. This leads to substantial changes in the projected achievable revenues of utilities. Grid extensions partially alleviate and redistribute these effects, mainly for the benefit of baseload and the VRE technologies themselves.

Parametric study of variable renewable energy integration in Europe: Advantages and costs of transmission grid extensions

Wind and solar energy will play an important role in the decarbonization of the European electricity generation. However, high shares of these variable renewable energies (VREs) challenge the power system considerably due to their temporal fluctuations and geographical dispersion.In this paper, we systematically analyze transmission grid extensions as an integration measure for VREs in Europe. We show the effects of grid extensions for fundamental properties of the power system as a function of the penetration and mix of wind and solar energy. Backup capacity requirements and overproduction are reduced with a powerful overlay transmission grid. We determine the costs of the grid extensions in dependence of the VRE penetration and mix and find that the grid integration costs remain below 25% of the VRE investment costs for all conceivable VRE configurations. Furthermore, robust design features of future power systems in terms of grid geometry and flexibility requirements for backup technologies are identified.We apply a spatially and temporally highly resolved techno-economic model of the European power system for our analysis.