An automated storage and retrieval system comprising: - a track system (10, 16) comprising a first set of parallel tracks arranged in a horizontal plane and extending in a first direction, and a second set of parallel tracks arranged in the horizontal plane and extending in a second direction which is orthogonal to the first direction, which first and second sets of tracks (11, 12) form a grid pattern in the horizontal plane comprising a plurality of adjacent grid cells, each comprising a grid opening defined by a pair of adjacent tracks (11a, 11b) of the first set of tracks and a pair of adjacent tracks (12a, 12b) of the second set of tracks; - a plurality of stacks of storage containers arranged in storage columns located beneath the track system (10, 16), wherein each storage column is located vertically below a grid opening; - a plurality of container handling vehicles (3, 310, 320) for lifting and moving storage containers stacked in the stacks, the container handling vehicles (3, 310, 320) being configured to move laterally on the track system above the storage columns to access the storage containers via the grid openings, wherein each of the plurality of container handling vehicles (3, 310, 320) has a footprint (30, 30') with a horizontal extent which is equal to or less than the horizontal extent of a grid cell and comprises: - a wheel assembly for guiding the container handling vehicle (3, 310, 320) along the track system (10, 16); and - a container-receiving storage space arranged within the footprint of the container handling vehicle (3, 310, 320) for accommodating a storage container; and - a lifting device arranged to transport a storage container vertically between a storage position in a stack and a transport position in the storage space, the lifting device comprising: - a gripping device being configured to releasably grip a storage container; and - a lifting motor being configured to raise and lower the gripping device relative to the storage space, wherein each container handling vehicle (3, 310, 320) comprises a protruding section which extends horizontally beyond the footprint (30, 30') of the container handling vehicle (3, 103, 203) and, when the container handling vehicle (3, 103, 203) is positioned above a grid cell, into a neighbouring grid cell, characterised in that the protruding section (27, 27', 27") comprises at least one of: a rechargeable battery; a battery slot for housing a replaceable battery; and a sensor for establishing the position of the vehicle on the track system (10, 16) or vis-à-vis other vehicles on the track system (10, 16). - a track system (10, 16) comprising a first set of parallel tracks arranged in a horizontal plane and extending in a first direction, and a second set of parallel tracks arranged in the horizontal plane and extending in a second direction which is orthogonal to the first direction, which first and second sets of tracks (11, 12) form a grid pattern in the horizontal plane comprising a plurality of adjacent grid cells, each comprising a grid opening defined by a pair of adjacent tracks (11a, 11b) of the first set of tracks and a pair of adjacent tracks (12a, 12b) of the second set of tracks; - a plurality of stacks of storage containers arranged in storage columns located beneath the track system (10, 16), wherein each storage column is located vertically below a grid opening; - a plurality of container handling vehicles (3, 310, 320) for lifting and moving storage containers stacked in the stacks, the container handling vehicles (3, 310, 320) being configured to move laterally on the track system above the storage columns to access the storage containers via the grid openings, wherein each of the plurality of container handling vehicles (3, 310, 320) has a footprint (30, 30') with a horizontal extent which is equal to or less than the horizontal extent of a grid cell and comprises: - a wheel assembly for guiding the container handling vehicle (3, 310, 320) along the track system (10, 16); and - a container-receiving storage space arranged within the footprint of the container handling vehicle (3, 310, 320) for accommodating a storage container; and - a lifting device arranged to transport a storage container vertically between a storage position in a stack and a transport position in the storage space, the lifting device comprising: - a gripping device being configured to releasably grip a storage container; and - a lifting motor being configured to raise and lower the gripping device relative to the storage space, - a wheel assembly for guiding the container handling vehicle (3, 310, 320) along the track system (10, 16); and - a container-receiving storage space arranged within the footprint of the container handling vehicle (3, 310, 320) for accommodating a storage container; and - a lifting device arranged to transport a storage container vertically between a storage position in a stack and a transport position in the storage space, the lifting device comprising: - a gripping device being configured to releasably grip a storage container; and - a lifting motor being configured to raise and lower the gripping device relative to the storage space,