Blockabgrenzung

Blockabgrenzung is a term used in the European electricity market to describe a congestion management measure applied by transmission system operators. At a cross-border interconnection or border between market areas, the available transfer capacity is divided into blocks, and certain blocks may be blocked or restricted to market participants. The aim is to ensure grid security and prevent overloads while keeping the remainder of the capacity available for trading.

How it works in practice: When a grid bottleneck is forecast or observed, the grid operator designates blocks of transfer capacity that cannot be allocated through the market. The remaining capacity is then offered to the Day-Ahead or Intraday markets, subject to the congestion situation. The process is typically carried out by German transmission system operators (TSOs) such as 50Hertz, Amprion, TenneT, and TransnetBW, in coordination with market operators. Blockabgrenzung is particularly relevant at interconnections with neighboring countries and in regions with high wind or solar generation that can stress the transmission network.

Rationale and effects: The measure helps maintain the reliability and stability of the power system during congested conditions. It can influence cross-border trade volumes and prices, sometimes reducing expected exports or imports. Critics point to potential distortions or reduced transparency in market outcomes, while supporters emphasize improved security of supply.

Regulatory context: Blockabgrenzung operates within the broader framework of EU electricity market rules and national/regulatory oversight. It is one of several congestion management tools used to handle grid constraints alongside capacity allocation and market coupling mechanisms.