Modern offices are characterised by mobility and the increasing dissolution of spatial boundaries. Yill contributes to this openness through a highly ambitious design concept – mobility was the maxim that defined the language of form of this mobile energy storage unit. Featuring a round design, the device is rollable and bouncingly follows anyone who happens to need it. This mobile energy storage unit is equipped with a functionally well-designed, extricable handle for easy manoeuvring. The ability to store and deliver energy in an office entirely independently from the building power grid is an innovative and highly contemporary concept. Yill can store one kilowatt-hour of energy and provide up to 300 watts of electricity, enough to power a workstation for two to three days without cords or cables. Once empty, the unit’s lithium titanium batteries can be recharged by simply plugging into a charging station that draws power from renewably generated sources or via a standard electrical outlet. The principle of integrating renewable energy sources and making them easy to use wherever needed thus has been realised in a highly convincing way. With a design marked by a sense of lightness, Yill easily facilitates touchdown workspaces as well as out-of-office working in a “recreation zone” with a laptop – a storage unit that creates a new awareness for and experience of sustainability.