The Single Electricity Market (SEM) is the wholesale electricity market where electricity is traded in bulk across the island of Ireland. It enables electricity to be sold by power generators and purchased by suppliers, who in turn sell on to consumers.
The SEM was established in Northern Ireland and the Republic of Ireland in November 2007. The SEM operates with dual currencies (Euro and Sterling) and was the first market of its kind in the world when it opened.
The SEM is a gross mandatory pool, meaning all generators with an export capacity greater than 10 megawatts (MW) are obliged to participate in the market. Generators bid in their power to the market and suppliers buy from the pool to sell on to electricity consumers. In a given year, the SEM manages financial flows of approximately €3.5 billion, whilst maintaining a high level of efficient market services.
The SEM is operated by the Single Electricity Market Operator (SEMO), which is part of the EirGrid Group.
SEMO is designed to provide:
A new market is being developed in line with European legislation and Network Codes, called the I-SEM or Integrated-Single Electricity Market. It will replace the existing SEM on the island of Ireland in 2018.