Nvidia has announced a hot water cooling system that can dramatically reduce the amount of water used by data centers, eliminating “almost all water usage” inside the data centers themselves, according to an Nvidia executive in a press release.
“The problem of water consumption in data centers has been largely solved,” Nvidia Chief Sustainability Officer Josh Parker recently told Axios.
But that’s only part of the water story. As long as AI data centers run on fossil fuels (which tech companies are increasingly choosing to do), the cost savings will end at the data center walls.
The key issue is how Nvidia measures data center water use. According to the blog post, the company essentially draws a line around its data centers. Everything inside is calculated and everything outside is ignored.
To be fair, Nvidia’s system appears to deliver on its promise at the facility level. The coolant runs in a closed loop and is filled and recirculated once during the life of the facility, so no new water is consumed to cool the chips. In favorable climates, on-site water usage can be reduced by 100%, the company says.
TechCrunch has asked Nvidia to clarify the issue, and we will update this article if we receive a response.
The problem is that water use outside the data center, primarily in power generation and chip manufacturing, can double or triple a facility’s total water footprint. This means that Nvidia’s solution handles approximately one-quarter to one-third of the total water consumption of an AI data center.
The new system is a clever one that pumps coolant into the racks at a temperature of 45˚C (113˚F). That’s hot for humans, but not for computer chips. After passing through the server, the coolant vents at 55˚C (131˚F), dissipating a significant amount of heat from the hardware, Nvidia said.
At that temperature, in most climates, outside air can pull heat away from passive radiators without evaporative cooling or, in some cases, fans. A data center without fans or cooling will not only use less water, but will also be more efficient and quieter.
However, no data center can operate without a power supply, and many types of power plants are themselves major consumers of water.
Fossil fuel power plants are among the largest users of water in the United States, consuming 2.7 billion gallons a day, according to the U.S. Geological Survey. Most of them are used for evaporative cooling. A recent study found that natural gas power plants use 1.17 liters of water for every kWh of electricity produced. Coal-fired power plants are more water-intensive, using 2.2 liters per kilowatt-hour. According to the IEA, fossil fuel power plants produce about half of all data center power today.
Hydroelectric dams, which supply about 10% of data center power, do not consume water in the same direct way, but lose 6.8 liters per kilowatt-hour generated through evaporation from reservoirs. Geothermal energy, an underlying technology that technology companies are beginning to explore, is very diverse. It may be higher or lower depending on your specific skills. Some geothermal power startups, such as Fervo, have pledged to use most of the “decomposed” water that would otherwise go unused.
Wind and solar power, on the other hand, use very little water – about 0.01 liters and 0.03 liters per kilowatt hour, respectively. This figure includes the water needed to manufacture and clean solar panels.
The IEA projects that natural gas and coal will supply more than 40% of the new power needed to meet data center demand by 2030, with renewables accounting for an increasing share of new power capacity. Without major changes to that trajectory, data centers will still consume a lot of water regardless of what Nvidia does inside them.
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