An 11,000-square-foot poetry library called Poets House is expected to open in the Riverhouse condo in September. The space, at One Rockefeller Park in Battery Park City, is more than five times bigger than Poets House’s last location on Spring Street. The library will have two floors in the building, including an auditorium, children’s room, outside amphitheater and conference room. The Battery Park City Authority designated space for three non-profit groups in the 32-story Riverhouse, including Poets House, Mercy Corps and New York Public Library. Mercy Corps opened in the building last fall, and the public library is coming in 2010.