A wall socket can be found just about anywhere, if you really need power quick there are fast charging powerbanks.
"While most homeless people own a phone, Talbot conducted interviews with people sleeping rough across London and found that many struggle with finding a place where they can actually charge the device."
So apparently at least part of the homeless disagree with you.
It might be a niche thing (it's a gradschool project after all), but it's pretty cool way to exploit things that are not supposed to be available for use.
“I was charging my phone :(“
It does not help homeless people or anyone to suggest they should break the law.
This device that uses bike chains is a bit cheeky but it is a smart idea and it should be legal, or at least not a crime (ianal). So nice, clever hack.
In my major Northeast US city, there are wall sockets on the outside of most buildings (if you know where to look), on every car of the subway/bus, in public concourses, etc.
This device seems a bit.. daft. Renting a Santander cycle costs 1.65 GBP. Add the high energy food required to supplement your diet after a 30 minute ride and this is looking closer to 3 or 4 quid for a phone charge, and that's before considering where the homeless person is going to securely stow their belongings while cycling. Luggage storage in Victoria is 5 GBP for 3 hours..