24v Truck Fans

Popped into CEF (City Electrical Factors) today as we needed a new desk fan at home and I couldn’t be ar5ed to drive into town (Industrial estate is closer) and noticed they also had USB powered fans there, seeing as most trucks have a USB socket nowadays (or at the very least you can get a USB adaptor for the ciggie socket) I wondered if they’d be a viable alternative to the 12/24v truckstop rubbish?