Wärtsilä published a study on 2 November that asks what it would cost to power off-grid data centres with flexible engines instead of combined-cycle gas turbine plants. Its answer for a scenario of 55 GW of off-grid capacity worldwide by 2035 is a saving of EUR 196 billion over 20 years, which the company rounds to "up to EUR 200 billion" in avoided balancing capacity. It adds that this holds with suitable grid and market arrangements.
How the numbers were built
The 55 GW is the upper end of Wärtsilä's outlook, not a forecast. It rests on third-party projections, including BloombergNEF's data centre outlooks, and on a review of announced projects and how far their development and permitting have come. The company scales up the results of an earlier project-level study on power for off-grid data centres and compares generation and storage capacity, cost, land and water for the same demand over 20 years. Wärtsilä says the technology cases are illustrations and that real projects will mix technologies.
What it claims for engines
According to the company, engines need less generating equipment and less battery storage to cover the same load, use far less cooling water and take up less land. It puts the water saving at 99.97% and the land difference at 2,200 football pitches. It also says that once a data centre is connected to the grid, the engines can serve as backup and help balance wind and solar output. Heat recovered from the plants could cover about 10% of European space-heating demand, on an International Energy Agency estimate, which Wärtsilä values at EUR 180 billion net over 20 years.
The study is from an engine maker, so read it as one side of the comparison. The release gives no matching figures for the combined-cycle plants beyond the comparisons above.
Off-grid is not the same as standby
A plant that is the only supply runs all year and is judged like a power station, not like a standby set that is tested monthly. That moves the questions to redundancy, maintenance windows, fuel supply and the exhaust and noise conditions in the air permit. If a project in your enquiry list says "on-site power", ask first which of the two it is.
Sources: Wärtsilä