The talk is to show how we at PDC-HPC, KTH are using Open nebula cloud for delivering e-Science services to researchers. PDC cloud been used by researchers from Swedish e-Science Research Centre (SeRC) and other european researchers to leverage the on-demand, elastic delivery of science. We will discuss what problem we faced, challenges and how we crossed this chasm. In the end we will discuss an on-going effort for Federating cloud providers with use of interfaces such as OCCI and CDMI.