Stable and Renewable: Assessing the Reliability of a Fully Renewable European Energy System

TL;DR

This study demonstrates that a fully renewable European energy system can achieve reliability comparable to fossil-based systems at minimal additional cost, primarily through strategic capacity increases and hydrogen backup.

Contribution

It provides the first comprehensive assessment showing that a cost-optimal, fully renewable European energy system can be reliably stable with minimal extra investment.

Findings

Reliability loss is only 0.03% in a fully renewable system.

Household supply remains largely unaffected by renewable variability.

Additional capacity of hydrogen turbines and batteries ensures system reliability at negligible cost.

Abstract

The transformation of the energy system has raised concerns about the reliability of fully renewable energy systems. We address this question for a 2050 European energy system using an economically optimal adequacy assessment. Our results show that a cost-optimal, fully renewable European system can be as reliable as a fossil-based one, with an average loss of load of only 0.03% due to variability in renewable generation. Outages primarily affect industrial and service sectors, while household supply remains largely uninterrupted. Regional differences in supply security emerge, with outages concentrated in countries with a low Value of Lost Load (VoLL). We demonstrate that system reliability can be fully ensured at negligible additional cost (+0.17%) by modestly increasing hydrogen turbine (+10%) and battery capacities (+15%) beyond the cost-optimal levels. We conclude that well-designed renewable energy systems are stable, with hydrogen-based backup being a key enabler of reliability.