How can I export all my blog posts as CSV?
If I was going to try to create a CSV of my sites content I would try to use the Views Data Export module and filter on your blog content type and include all the fields you want.


  This module is designed to provide a way to export large amounts of
  data from views. It provides a display plugin that can rendered
  progressively in a batch. Style plugins are included that support
  exporting in the following types:
  
  
  CSV
  Microsoft XLS
  Microsoft DOC
  Basic TXT
  XML