Guests pedal bikes to produce power for the Crowne Plaza Hotel in Copenhagen. 10WH gets you a free meal.
Guests staying at the 366-room Crown Plaza Copenhagen Towers will be encouraged to head down to the gym to spend time on its new fleet of electricity-generating exercise bikes.
The bikes have iPhones mounted on the handlebars which monitor how much power is being produced and fed into the mains supply of the hotel.
Any guest producing 10 watt hours or more will be rewarded with a free meal.