Researchers at the University of California San Diego are working on a mini-data center made from 2000 used smartphones. Because they are cooperating with Google, they are using Pixel smartphones for this. However, they are only using the mainboards of the old smartphones, omitting batteries and displays.

The computing power of the older smartphone processors is sufficient for many tasks encountered in teaching, such as for Jupyter Notebooks. The CPU performance is even better than some cheap cloud instances, especially in single-threading. However, for some applications, the main memory of the smartphones is too limited; it is between 8 and 12 GByte for the devices used.

The research group of Prof. Ryan Kastner at the University of San Diego has been researching the reuse of old smartphones as servers for several years. Several papers have already been published on this, such as “Reducing the Carbon Footprint of EdTech with Repurposed Devices” and “Junkyard Computing: Repurposing Discarded Smartphones to Minimize Carbon”.

According to a blog post by Google Research, the current project groups 20 smartphone mainboards each into a subsystem whose performance roughly corresponds to that of a typical general-purpose server. The performance is sufficient for the projects of about 75 students simultaneously. The goal is to manage 100 of these subsystems centrally.

The mainboard, including the processor or system-on-chip as well as RAM and flash memory, accounts for the largest share of the resources required to produce a smartphone. This is because the production of semiconductor chips requires a lot of energy and thousands of raw and auxiliary materials.