MEREDITH CARTER: Artists Heather Ackroyd and Dan Harvey are probably best known for their industrious, ephemeral grass installations. Indeed, last summer passers by saw one of their most ambitious works yet – a lawn that lived and died atop London’s National Theatre fly tower. However their latest work, a 20-metre high tower with solar panels and a wind turbine, is going to be around for quite sometime. The tower, located at the centre of Bristol’s Newfoundland Circus roundabout, was commission by the Bristol Alliance as a part of their Cabot Circus development. Look out for Ackroyd and Harvey’s totally self-sufficient sculpture as you come off the M32 into the port city and know this sight can be enjoyed for years to come.