xkcd.WTF!?

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Mouse Turbines

It's sad seeing those videos of turbine blade being torn apart in high winds, but it's the only way they can disperse their seeds.

Explanation

Beret Guy and Megan are walking during the summer, where Beret Guy expresses his appreciation for typical features of a summer day. Though, considering the rest of the comic, Beret Guy could mean there are large (or popular) server farms somewhere and that the bugs are video chatting. He also mentions "wind turbines" put up by field mice, which Megan initially assumes to be referring to dandelions (similar to the wordplay that Beret Guy utilized in 1322: Winter.) However, Beret Guy turns out to be speaking literally, as he picks up what is in fact a tiny wind turbine, says to make a wish, and blows into it. This causes the blades of the turbine to spin rapidly, generating a lot of power for the structure it is connected to, thus causing a field mouse to cheer in excitement.

The comic was published on the 40th anniversary of the film release of The Secret of NIMH,[1] a story featuring field mice and rats who escaped from a lab experiment which left them with a similar intelligence to human beings. The story takes place as the rats strive to achieve self-sufficiency, so that they no longer need to steal power from human-built electrical lines. (The novel this film was based on, Mrs. Frisby and the Rats of NIMH, describes the experiments and the rats' struggles in more detail.)

The title text builds on the similarities between small wind turbines and dandelions by claiming that turbines reproduce by dispersing their blades, in the manner of dandelion seed dispersal. Randall's suggestion of turbine seeds conflicts with Beret Guy's assertion that the turbines were built by field mice.

Efficacy

Sadly, the power output per size of wind turbines increases with their size,[2] a limitation not shared by other forms of renewable energy such as solar panels and pico hydro. According to this calculator, a 10 centimeter radius wind turbine powered by a 5.7 meter/second breath[3] would produce one watt at just 26% efficiency.

Further frustrating mouse use of wind power, windspeed increases logarithmically with height above ground. Windspeed is reported as its value 10 meters above ground, where it is 1.5 times faster than at ground level.[4] In the U.S., where Randall lives, average year-round windspeed is about 15 km/h,[5] or about 2.8 m/s at ground level, yielding only 0.11 watts from such turbines. However, a typical adult mouse weighs 25 grams,[6] compared to about 81 kilograms for humans in the U.S.,[7] so we could estimate that mouse electricity needs would be about 0.03% of people's.[dubious] The average U.S. residential customer uses 1,242 watts of electricity,[8] 0.03% of which is 0.37 watts. Therefore, the three turbines visible in this comic could serve about 89% of a mouse's needs. While this figure does not account for necessary home energy storage efficiency (92.5% for the Tesla Powerwall) overhead, mice usually live much less extravagantly than typical Americans,[citation needed] so three turbines per mouse should be sufficient.