Pooling: how church heating systems and emergency power systems stabilise the electricity grid

Rapidly deployable reserve capacities are becoming increasingly important in the maintenance of electricity grid stability. Pooling brings together smaller providers, such as industrial plants, battery storage systems, church heating systems, emergency power systems and many other technologies, so they can operate on the market cooperatively. But how exactly does this work?

What is flexibility and why is it needed?

Flexibility is the ability to adjust or shift the supply and demand of electrical energy. It is crucial because if consumption and production are out of balance, the grid frequency deviates from 50 Hz, which in extreme cases can lead to load shedding or even a large-scale blackout.

What is pooling?

Pooling brings together several smaller providers to form a pool so they can act as a larger provider on the market. This aggregation helps to bring these smaller plants to market in the first place and thus taps their potential.

What technologies and plants are included in such a pool?

There are currently 15 different technologies in our flex pool: water storage power plants, batteries, waste incineration plants, electric cars, industrial plants, run-of-river power plants, pumped storage power plants, power-to-heat plants, photovoltaics, wind turbines, steam turbines, church heating systems, emergency power generators, combined heat and power plants, home energy management systems.

What part does the Axpo Group play in pooling?

The Axpo Group, with its subsidiary CKW, is a pioneer in the development of new sources of flexibility and currently provides the largest flex pool in Switzerland. Axpo is one of the first movers in the prequalification of new technologies for pooling, such as electric vehicles, battery storage and photovoltaic systems.

Who needs the pool's services?

Swissgrid is the transmission system operator in Switzerland and is responsible for the stable operation of the high-voltage grid. Swissgrid itself doesn’t own any large production or consumption facilities. Instead, it buys this flexibility service (control power and control energy) from companies such as the Axpo Group. Large storage power plants take part in this, as do the flexibility pools made up of smaller plants. 

Control power means keeping power available so you can react to imbalances. It's rather like a standby bonus for providing flexibility, and is awarded in weekly and daily auctions. Swissgrid receives around 1 GW of power in both directions (more energy into the grid/less energy into the grid), which is about the same as the power from the Gösgen nuclear power plant.

Control energy is the energy that is actually produced or consumed in the event of a call to balance the grid. It is also procured by Swissgrid in auctions.

The costs incurred by Swissgrid are passed on to each end consumer via the system service tariff.

What's in it for companies and owners of small plants?

Axpo pursues a profit-sharing model, allowing plant owners to share in the additional revenue from the balancing power and energy markets. This is an important source of income, particularly for large batteries, without which many investment decisions would probably not be made.

How has this service from Axpo developed in recent years?

There has been strong growth in the pooling segment. In 2017, there were 72 plants the Axpo Group pool, while in 2024 there were 1714 from 15 technologies.

What does the future hold for pooling?

We’re seeing a trend towards the connection of ever smaller plants. Homeowners and owners of electric vehicles can also contribute to the stability of the electricity grid and thus pay off their investments.