Nvidia just announced a hot water cooling system that can significantly reduce the amount of water used in data centers. NVIDIA executives said in a press release that it can reduce “nearly all water usage” in data centers.
Josh Parker, Nvidia’s chief sustainability officer, recently told Axios that “the data center water consumption challenge is largely solved.”
But that’s only part of the water story. As long as AI data centers run on fossil fuels (which is increasingly the choice of tech companies), the savings stop at the data center walls.
The central question is how Nvidia measures water usage in its data centers. According to the company’s blog post, the company is essentially drawing a line around its data centers. Everything inside is counted, everything outside is ignored.
To be fair, Nvidia’s system appears to be delivering on its promise at the facility level. The coolant operates in a closed loop, being charged once and recirculated for the life of the facility, so no new water is consumed to cool the chip. The company says it can reduce on-site water usage by 100% in favorable weather conditions.
TechCrunch has asked Nvidia for clarification on this matter and will update this article if we receive a response.
The problem is that water use outside the data center (primarily for power generation and chip manufacturing) can double or triple a facility’s total water usage. This means that Nvidia’s solution addresses approximately one-quarter to one-third of an AI data center’s total water consumption.
The new system is smart and pumps coolant into the racks at 45°C (113°F). This is a big deal for humans, but not for computer chips. Nvidia says that after the coolant passes through the server, it comes out at 55°C (131°F), drawing a significant amount of heat from the hardware.
At that temperature, the outside air in most climates can draw heat away from passive radiators without the use of evaporative cooling or, in some cases, fans. Data centers without fans or chillers not only use less water, but are also more efficient and quieter.
But without electricity, data centers cannot operate, and many types of power plants themselves rely on water as a primary consumer.
According to the U.S. Geological Survey, fossil fuel power plants are among the largest users of water in the United States, consuming 2.7 billion gallons per day, most of which is used for evaporative cooling. According to a recent study, natural gas power plants use 1.17 liters of water for every kilowatt-hour of electricity produced. Coal-fired power plants are even more water intensive, using 2.2 liters per kilowatt hour. According to the IEA, fossil fuel power plants generate about half of the electricity in all data centers today.
Hydroelectric dams, which provide about 10% of a data center’s electricity, similarly do not consume water directly, but lose 6.8 liters per kilowatt-hour of power generation to evaporation from the reservoir. There are a variety of geothermal sources that tech companies are beginning to explore, and they can be higher or lower depending on the specific technology. Some enhanced geothermal startups, like Fervo, promise to use most of the “degraded” water that would otherwise go unused.
Wind and solar power, on the other hand, use only a tiny amount of water, about 0.01 and 0.03 liters per kilowatt-hour, respectively. This figure also includes the water needed to manufacture and clean solar panels.
According to IEA forecasts, natural gas and coal are expected to provide more than 40% of the new electricity needed to meet data center demand by 2030, although the share of new electricity capacity from renewables is increasing. Without a major change in that trajectory, data centers will still consume large amounts of water, regardless of what Nvidia is doing behind the walls.
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