Powering and cooling data centres: why the grid and the chip are the limits

Two pieces of news from the same week sum up the state of data centre power and cooling. One is terrestrial and financial. The other is small, experimental and about to leave the planet.

The US Department of Energy said this week it would put $5.25 billion into grid improvements, made up of $1.9 billion in federal funds and $3.35 billion in cost-share funding. The Register reported on 25 September that the program covers 31 projects in 26 states under the department's SPARK initiative, with federal money coming from the Grid Resilience and Innovation Partnerships program.

The projects do not add generation. They aim to squeeze more out of what is already built, by reconductoring or rebuilding more than 1,500 miles of transmission lines and deploying sensors, power flow control devices and analytical tools across 21,000 miles of grid infrastructure. The Department of Energy claims this will improve reliability and lower electricity costs for roughly 100 million Americans.

Why does that matter to data centres? Because operators are trying to connect large loads faster than the grid can absorb them. The Register cited a warning from Moody's earlier in September that the pace of data centre construction exceeds the speed at which the US grid can add the required capacity. Moody's estimates US data centre electricity consumption will reach 426 TWh by 2030, nearly double the 2025 figure. That is the power wall in one number.

On-site generation is one answer, and it can go wrong. Ars Technica reported on 24 September that New Jersey fined the operator of a planned East Coast data centre $1.1 million for secretly installing and running gas generators without permits.

The details are specific. DataOne had 62 gas generators at the site, and thermal drone footage obtained by The Guardian and Floodlight News in August showed 45 of them operating, according to Ars Technica. The generators ran at 1,982-kilowatt capacity, far above the 37-kilowatt threshold at which New Jersey requires a permit. The state's Department of Environmental Protection said such generators emit carbon dioxide, nitrogen oxides, carbon monoxide and other combustion-related pollutants.

DataOne was given 45 days to apply for permits or stop operating, but it can keep running the engines while it seeks them. A company spokesperson told The New York Times it would apply for air permits for the temporary generators, disagreed with the fine and said the site is transitioning to low-emission fuel cells. Residents quoted by the Times were not satisfied, asking what they had been breathing in and why enforcement took six months.

Then there is the other direction: moving the compute off the grid entirely. Google's Project Suncatcher is an attempt to test whether AI hardware can run in orbit, and its first satellite, named MVP, is due to launch on 1 October aboard a SpaceX Falcon 9, Ars Technica reported on 24 September. The satellite is roughly the size of a refrigerator and carries four of Google's custom TPU accelerators, powered by solar panels supplying about one kilowatt.

Cooling is the hard part. Tom's Hardware reported on 26 September that the chips will only run for around 15 minutes before they must shut down to let the radiators catch up. Google's design uses a thermal interface material that connects the chips to aluminium and copper heat pipes, which conduct heat into a radiator that projects it into space. Radiation is another problem: it can flip bits, and Google's current answer is to restart the chips periodically.

Scale is the other caveat. One kilowatt is enough to run a microwave, not a data centre hall. James Manyika, Google's senior vice president of research, told The New York Times the company does not expect anything usefully operational in the next few years, comparing the effort to Google's driverless car work, which was tested about 15 years before anything shipped. Google still plans a pair of satellites in 2027 and has floated fleets of more than 80.

For anyone running a data centre on the ground today, the practical lesson is less exotic. Grid capacity is being expanded at the margin, not rebuilt overnight, and on-site power carries permitting risk. Renewable supply has its own limits: Data Center Knowledge noted that wind and solar vary with the weather and that storage is costly, so most sites still need conventional power as backup or supplement. Google's 15-minute bursts in orbit are a research result, not a roadmap.