A data center with four banks of servers in white
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Waste Heat Comes Home

Using Big Data to Heat Homes

Daren Wang
January 30, 2024

Is Big Tech going to start heating your home?

Even as we all wrestle with the consequences of global warming, it can feel pretty discouraging that so much of the energy consumed in the world is used to make things hotter.

For industry, processes like smelting iron, making concrete, or processing food all take lots of heat and big gulps of power. For consumers, it’s keeping our homes cozy and making our meals hot that drive our power bills.

At the same time, heat is a byproduct of a lot of the other types of energy use, and that heat usually goes to waste. For example, if you drive a car with an internal combustion engine, only about 30 percent to 35 percent of the energy you burn is used to move the car. Much of the rest of it is heat energy that is just wasted and has to be dissipated by the radiator.  

But sometimes, it is reused. When you turn on the heat in your car, the warm air that comes through the vents is a byproduct of the hot motor. That’s a pretty efficient use of heat. So why don’t we use byproduct heat for our homes? It turns out that some tech giants are asking that same question.

‘Like’ this post to stay warm

Since 2020, Meta's massive hyperscale data center, covering an expansive 50,000 square meters on the outskirts of Odense, Denmark, has been channeling the warm air produced by its servers into the city's district heating network. Although the server farm effectively provides enough heat for around 11,000 residences, Meta’s hot air is actually distributed across approximately 100,000 households connected to the system.

Despite some local grievances about coexisting with one of the world's tech giants, particularly regarding tax payments and concerns about bright lights surrounding the data center, Wired Magazine reports that many residents feel the advantages of the innovative heating system outweigh these issues. Odense marks Meta’s first foray into channeling surplus heat from a data center directly into homes, but others in the tech world have already dipped their toes in the warm water. In Ireland, an Amazon data center contributes to heating the university campus of TU Dublin, while Microsoft is in the process of constructing what is anticipated to be the world's largest data center heating system in Espoo, Finland.

This trend is poised for growth, spurred by the ongoing AI boom leading to a surge in data center construction. Major players like Microsoft, Google, Meta, and Amazon anticipate investing around $1 trillion in infrastructure to meet the escalating demand for AI computing, and that means a lot of hot processors.

Several tech giants are hoping that the substantial heat generated by these data centers, usually released into the atmosphere, can be repurposed to fulfill part of their climate commitments. Governments can also tout agreements that demonstrate Big Tech's contribution to local communities.

Of course, the hot air produced in these centers isn’t exactly perfect for a district heating system’s needs. When captured by the local utilities, the air is around 80 degrees Fahrenheit (26.6 degrees Celsius.) The heating company then uses conventional means to boost it to the required 170 degrees Fahrenheit (76.6 degrees Celsius) for district heating.

It’s a Series of Tubes

District heating, a system where multiple buildings share one common heating source through a series of vents and ducts, is rare in North America, but is common in Nordic countries like Denmark, Finland, and Sweden. Those countries, which have histories of harnessing the ample geothermal energy that bubbles up across their landscapes, are seen as ideal testing grounds for these kinds of projects.

Microsoft's project in Espoo is expected to surpass Meta's Danish system in water temperature (90 degrees Fahrenheit or 32.2 degrees Celsius) and become the world's largest data center heating system. Finnish energy company Fortum will further elevate the heat to between 180- and 250 degrees Fahrenheit (82.2 and 121.1 degrees Celsius) before supplying it to homes, likely after 2025.

While the prices for this heat exchange remain undisclosed, both Meta and Microsoft confirm it's part of a commercial arrangement. Although not necessarily cheaper, the stability in prices compared to fluctuating fossil fuel costs is a notable benefit.

It’s Still About the Energy

In Ireland, where data centers have faced criticism for high energy consumption, Amazon is distributing excess heat from its data center for free to the local university and government offices. Despite these positive initiatives, concerns persist in regions with a high concentration of data centers, emphasizing the need for ongoing discussions on energy efficiency. In Denmark, data centers are projected to contribute to 14 percent of the country's total energy consumption by 2030, raising questions about the balance between sourcing energy from renewables and the energy demands of data centers connected to local homes.

Microsoft has received approval to construct a 170MW gas power plant for its Dublin data center development, as reported by Business Post. The €100 million plant, designated for backup purposes, will enable the data center to disconnect from the grid during grid constraints or outages. Positioned alongside 21 backup diesel generators, the "unprecedentedly large-scale" plant aims to minimize the facility's impact on the grid. This move comes amid Ireland's pause on new data developments in Dublin until 2028, with Microsoft's gas-powered approach aligning with the trend of data centers seeking independent power sources.

Although district heating is mostly limited to a few college campuses and corporate headquarters in the US, that hasn’t ruled out the use of byproduct heat here. Bathhouse, a Brooklyn-based massage and sauna facility that claims to be “an oasis to be fundamentally human,” uses heat generated by bitcoin mining rigs adjacent to the facilities to heat the water in its thermal pools and saunas.

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