The Benefits of Cooperation in a Highly Renewable European Electricity Network (1704.05492v2)

Abstract: To reach ambitious European CO$_2$ emission reduction targets, most scenarios of future European electricity systems rely on large shares of wind and solar photovoltaic power generation. We interpolate between two concepts for balancing the variability of these renewable sources: balancing at continental scales using the transmission grid and balancing locally with storage. This interpolation is done by systematically restricting transmission capacities from the optimum level to zero. We run techno-economic cost optimizations for the capacity investment and dispatch of wind, solar, hydroelectricity, natural gas power generation and transmission, as well as storage options such as pumped-hydro, battery, and hydrogen storage. The simulations assume a 95% CO$_2$ emission reduction compared to 1990, and are run over a full historical year of weather and electricity demand for 30 European countries. In the cost-optimal system with high levels of transmission expansion, energy generation is dominated by wind (65%) and hydro (15%), with average system costs comparable to today's system. Restricting transmission shifts the balance in favour of solar and storage, driving up costs by a third. As the restriction is relaxed, 85% of the cost benefits of the optimal grid expansion can be captured already with only 44% of the transmission volume.

• The paper demonstrates that expanding the grid to four times its current capacity achieves 85% of the optimal cost savings for a 95% CO₂ reduction.
• The paper employs a linear optimization model integrating wind, solar, hydro, OCGT, and storage technologies to minimize overall system costs.
• The paper highlights that enhanced cross-border cooperation is crucial for achieving cost-effective renewable integration despite public resistance to large-scale grid expansion.

Insights into the Benefits of Cooperation in a Highly Renewable European Electricity Network

This paper examines the techno-economic implications of different levels of cooperation within a renewable-based European electricity network context, particularly focusing on optimizing inter-country transmission line volumes. It is established that maximizing transmission capacities across Europe can significantly facilitate large-scale integration of renewable energy sources, specifically wind and solar, and achieve a target of 95% CO$_2$ emission reduction compared to 1990 levels.

Core Methodology and Assumptions

The paper employs a linear optimization model that minimizes total annual system costs, including fixed, variable, and transmission costs. The analysis considers various energy sources such as wind, solar photovoltaic (PV), hydroelectricity, and open-cycle gas turbines (OCGTs) alongside storage solutions like pumped hydro storage (PHS), batteries, and hydrogen storage. The transmission grid is modeled with constraints on power flow and line capacities, and the optimization spans over a full historical year, providing a comprehensive assessment of energy balances within the system.

Key Results and Numerical Findings

One of the paper's primary findings is the non-linear relationship between system costs and transmission grid expansion. Notably, the research reveals that considerable economic benefits of grid expansion can be realized with only moderate increases in transmission capacity. Specifically, expanding the grid to four times its current capacity can secure 85% of the cost savings achievable with the optimal expansion level (nine times today's capacity). In terms of cost composition, wind energy persists as the dominant generation source, contributing to 65% of total energy in the cost-optimal scenario, highlighting wind's efficiency in a continentally interconnected network.

Furthermore, the optimal scenario identifies an average system cost of 64.8 €/MWh, which is comparable to current system costs when neglecting CO$_2$ pricing. Despite significant expansion potential, public acceptance may limit feasible transmission grid growth, motivating the need for compromise solutions, such as the proposed quadruple capacity scenario.

Implications and Further Developments

The paper offers critical insight into potential configurations of a low-carbon European electricity network, emphasizing the substantial economic and operational value of cross-border transmission. It posits transmission as a key enabler for maximizing renewable resource efficiency, reducing dependency on long-term storage solutions, and achieving low-cost renewable integration. However, challenges remain concerning public resistance to large-scale grid expansions, hinting at a necessity for innovative solutions that balance technological merit with socio-political constraints.

The research also calls for a broader consideration of multisector integration in future studies, where coupling electricity with transport, heating, and other energy sectors can present additional flexibility and optimization possibilities. Such synergies could further alleviate the reliance on extensive inter-country electricity transmission by offering alternative storage and energy balancing mechanisms, thus enriching discussions on sustainable energy transition strategies across Europe.

In summary, the paper positions continent-spanning cooperation as a cornerstone for a low-carbon future in Europe, advocating for incremental development of shared transmission infrastructure that aligns economic efficiency with societal acceptance, while also exploring non-electricity solutions for sustainable development.