What is that supposed to mean? A watt(= 1 J/s) is a measure power so energy per unit of time. Shouldn't this rather be given in joule?
But this is an art project and I have no idea what expertise does the artist have, and I'm not an expert either.
The first page states an estimate of 50g of CO2 per visit, but I'm pretty sure reality is nowhere near that. At ~1000lbs CO2 per MWh for home electricity in the US (https://www.epa.gov/energy/greenhouse-gases-equivalencies-ca...), that's ~0.45g per Wh. My laptop only has a ~40 Wh battery, so I can't even be using anywhere near that - and that's already two orders of magnitude smaller.
Accessing from a phone it would be even less significant - for example, this S7 replacement battery only holds 12.7 Wh (https://www.amazon.com/Galaxy-Battery-Replacement-Samsung-Co...).
Scrolling down the project page about half way, it's displaying 0.15 kcal for me. That's ~0.17 Wh, which would equate to only being able to do that ~235 times on a single charge for my laptop. That's very obviously nowhere near reality.
The good news is that in 4 billion years, the sun will explode, and we'll have to teach unit-accounting to sluggards in the dark. (Wait. That's the good news?)