University of Wollongong students will hold an on-campus rally tomorrow in the hopes of pressuring the university into buying all its energy from renewable sources by 2015.The rally will begin outside the UOW library at 12.30pm, with students marching to the campus administration building to deliver a 3,500-signature petition in support of 100 per cent campus renewable energy.Students will also voice their opposition against university plans to build a $2.7 million trigeneration gas-fired power plant on campus from next year.UOW Environmental Collective member Bess Murphy said she applaud UOW for purchasing 15 per cent of its electricity from renewable sources, but that it was time for the university to go further. ‘‘We intend to send a strong signal that students’ demands can no longer be ignored,’’ she said.