Using kids at play on a merry-go-round as a source of power is just one of the bright ideas at SWELL 2008, an ecodesign exhibit that’s part of 30 Days of Sustainability. Other innovations being presented include the LifeStraw portable water purifier, which lets people safely drink directly from rivers, and a program aimed at closing the digital divide between rich and poor by providing low-cost laptops to children. The exhibit runs until May 10 at the Pendulum Gallery in the HSBC Building (885 West Georgia Street). Hours are Monday to Wednesday, 9 a.m. to 6 p.m.; Thursday and Friday, 9 a.m. to 9 p.m.; and Saturday, 9 a.m. to 5 p.m.