High potential for flexibility in data centers

Studies and reports are multiplying on the digital sector to better determine its weight – both positive and negative – in the energy transition. Ademe recently showed the impact of the growth of this sector in terms of metal consumption. The Agency also highlighted the particular case of data centers whose development is currently very strong, in France as elsewhere in the world. In this study, she points out that digital data centers have ways to reduce their consumption of energy, water and fuel oil. Energy efficiency actions are listed as a solution, as well as the use of renewable energy sources.

Also implicit is the possibility for data centers to participate in the electricity demand flexibility market. The subject is far from trivial, as revealed in a white paper published at the beginning of November by Gimélec. The group of companies in the French electronics sector has in fact assessed the possible progression of data centers installed in France and estimated the share of the power of this park which could be mobilized to meet the need for flexibility of the electricity network. The average level would be 2.1 GW in 2035. Or 70% of the current level of reduction in industry in France.

A rapidly growing data center fleet

This potential is very significant even though Gimélec made very cautious assumptions and only considered commercial hosting data centers (called colocation), which excludes the centers of major digital players (GAFAM) and computer rooms hosted in businesses and administrations (estimated at around 5,000, but often small). Let’s examine these assumptions.

First of all, the installed computing power of colocation data centers is growing strongly: on average +16% per year in France since 2016. For the future, the white paper takes two options: a low one with growth of 11 % per year, and a high one with a rate of 20%. The park, which represented 566 MW in 2022, would thus increase to a power between 2.2 and 5.2 GW in 2035. The induced electricity consumption would be between 18.5 and 43.6 TWh.

These new consumptions would contribute to the electrification of the country as part of the energy transition (manufacture of hydrogen by electrolysis, electrical processes in industry, heat pumps in buildings, electric vehicles). They challenge the network manager RTE to satisfy them with a production system which will be increasingly powered by variable renewable energies. Hence a need to be able to activate demand flexibilities via electric vehicle batteries, the tertiary sector and industry… and therefore a fortiori data centers.

RTE is already considering intelligent connection offers where, to minimize its investment costs in the network, it will respond to the high connection demands of data centers, particularly in Île-de-France, in exchange for a commitment to their part in erasing part of their consumption up to 1,200 hours per year.

Use generators and batteries

Gimélec’s analysis highlights several levers of flexibility in data centers. They can be grouped into three main categories. The first is that of emergency generators whose data centers are currently equipped to compensate for any lack of electricity supply. These groups generally have an autonomy of 72 hours and could therefore be used by the network over a wide temporal range. If the question of supplying these generators with biofuels is resolved (affordable price, assured supply) to reduce their CO emissions₂they could strongly participate in electrical flexibility, as they already did before 2014 for the erasure mechanisms.

The second category is electrochemical batteries. Still to ensure the continuity of digital services, data centers already have uninterrupted power supply systems of this type: they could be used from time to time to support the network in frequency or voltage over short periods of time (5 to 15 minutes ). Other stationary storage using batteries of higher power and for longer durations (two to three hours) could be added to these existing systems. They could partly replace generators, but also support the network by injecting or withdrawing electricity, depending on whether the need for flexibility requires a reduction or increase in consumption.

Economic signal to be created

The third category is that relating to the actual functioning of computer servers. The heat they give off leads to the use of cooling systems to maintain an optimal temperature. They generally represent 40% of a data center’s electricity consumption! These systems could modulate their cold production – and therefore their electricity consumption – either by varying the set temperature in the server rooms, or by using the inertia of ice storage in the case of chilled water systems. We must add the possibility for the servers to shift their digital load either over time to take advantage of a moment when the network will be less tense, or to another more favorable geographical area.

Considering all these flexibility possibilities, Gimélec determined that each of them could be mobilized between 5 and 20% of the installed computing power (see table below).

The Gimélec white paper notes that regulatory aspects will need to be modified to allow certain flexibilities in data centers, and that an economic signal must be created between managers of colocation centers and their customers to facilitate them. The financial interest can come from remuneration for flexibility or from price optimization of electricity purchases. But, without a doubt, the operators of these data centers first have an intellectual revolution to carry out: today they are very demanding of services to the electricity network (connection capacities, network stability), they will have to transform into flexibility service providers.

Electrical flexibility capacity of colocation data centers in France in 2035 (in MW). Source: Gimélec