"Dryer balls" that will eliminate the need for scented dryer sheets and help your dryer work more efficiently.

A student-led project for a house that, just maybe, is smarter than its inhabitants.

A group that is figuring out how to best use vacant lots in Kensington.

These are three of the "green innovators" that have been selected for this year's Greenfest Philly, a free environmental fesitval being held Sept. 8 at Headhouse Square, 2nd and South streets. It's sponsored by the Clean Air Council.

Held from 10 a.m to 5 p.m., it's a great chance to browse the booths of more than 100 exhibitors and vendors, learn more about sustainability and shop for the stuff to help you get there.

This is the third year for the "innovators" program, and it's always great to see what comes out of it. The finalists were selected with the help of SCA, a global hygiene and forest-products company -- napkins from recycled paper, for instance -- and one of the region's most sustainable companies,

The annual innovators get to have a free booth at the fest, and one of them will be selected for a $750 cash prize.  Judges have a say, but the public can vote online as well on the Greenfest website. Grid Magazine will host a special edition of Grid Alive with the Innovators on the Greenfest stage at the festival. The winner will be announced on stage at the conclusion of Greenfest.

So here they all are: