Elia Transmission Belgium gains access to MARI, the European platform for exchanging tertiary balancing energy

BRUSSELS | On 21 May, Elia Transmission Belgium (ETB) successfully accessed MARI*, the European platform for the exchange of balancing energy from frequency restoration reserves via manual activation (mFRR**). This platform enables European transmission system operators (TSOs) to exchange mFRR balancing energy. As with the PICASSO platform, which Elia joined in 2024, MARI provides access to the least costly balancing energy beyond Belgium's borders, within a wider area (depending on the interconnection capacities available). Elia's access to MARI helps to enhance socio-economic prosperity while giving market parties new opportunities to take part in the integrated European balancing energy market. Access to additional volumes of balancing energy also helps bolster grid security. 

* MARI: Manually Activated Reserves Initiative (MARI) is the European implementation project for the creation, future development, and operation of the European mFRR platform.
** mFRR: manual Frequency Restoration Reserve

A successful launch on 21 May

The European Electricity Balancing Regulation, specifically Commission Regulation (EU) 2017/2195, which establishes a guideline on electricity balancing, requires that European TSOs establish a common platform for the exchange of tertiary balancing energy (mFRR). The MARI project was launched by 29 European TSOs with the aim of implementing this platform and connecting various TSOs to it. Elia, which is responsible for balancing electricity flows on the Belgian transmission system, supervised the overhaul of balancing methods used on the Belgian electricity system in order to incorporate the changes needed in connection with this project. Belgium is now an operational member of the MARI project, along with Germany, the Czech Republic, Austria, Latvia, Lithuania, Estonia, Portugal, Slovakia, and Spain. The project marks a major step forward in international coordination for manual frequency restoration and the integration of European balancing energy markets. Elia Transmission Belgium's operational debut on the platform went well. 

More options for frequency restoration in neighbouring countries

mFRR is a frequency control service used by TSOs to manually balance electricity supply and demand. The energy requested allows the secondary reserves (aFRR) to be desaturated and supplemented in the event of major imbalances. These mFRR reserves are also known as tertiary reserves. They have a slower response time than aFRR and a market time unit of 15 minutes. Having access to the MARI platform broadens the scope of the balancing process by enabling the activation of mFRR in neighbouring countries in order to resolve imbalances in the Belgian system, and vice versa. As such, MARI has the same goals as the PICASSO platform (which Elia joined in November 2024) - but for mFRR rather than aFRR. 

mFRR provides more grid stability during the transition to a greater share of renewable energy 

The main objective of mFRR is to restore system frequency to its nominal value of 50 Hz. Frequency deviations can cause malfunctions or damage to electrical equipment, thus jeopardising grid reliability. The automatic Frequency Restoration Reserve (aFRR) intervenes in the event of minor deviations, while mFRR makes it possible to handle significant imbalances between electricity generation and consumption by manually activating flexibility or using the automatic secondary reserve. mFRR has a key role to play given the growing integration of renewable energy sources, such as wind and solar, which are by nature intermittent and can induce major fluctuations in electricity generation, and, consequently, cause greater frequency deviations. Finally, by using balancing reserves efficiently, system operators can reduce the costs associated with managing imbalances and optimise the use of available resources.

"We are proud to be able to access the MARI platform. This is a second key accomplishment, following our access to the PICASSO platform. These achievements make it possible to improve system security, enhance the integration of European balancing markets, and cut the costs linked to imbalance management."
James Matthys-Donnadieu, Elia Chief Customers, Markets & System Officer