Do you always use the gym in the hotel you’re staying at to keep fit? The Crowne Plaza Hotel in Copenhagen is trying to offer you more incentive to exercise, as the hotel has hooked up a few exercise bikes to a generator. Guests who are interested can pedal for about fifteen minutes, generating 10Wh of electricity, and earning themselves a $36 meal voucher. Just to keep in touch with the latest tech, these bikes also feature iPhones attached to the handlebars, displaying the amount of power being generated. Aside from the exercise bikes, the hotel also has installed 2,400 solar panels and uses low-energy lighting and a groundwater-based cooling and heating system, boosting its eco-credentials.