I would assume that most of that is due to PDFs weigthing a lot more than their content. If someone wants to donate IT skills and coding time (this is a thing

I would assume that most of that is due to PDFs weigthing a lot more than their content. If someone wants to donate IT skills and coding time (this is a thing that I've read several times in HN), perhaps it would be great that someone puts together a system that takes a PDF, OCRs it when necessary, detects images and graphs, and uses all of that to create a light version of the document (html/latex/markdown/whatever); and then puts all of those TB through that tool. The reduction in storage and network costs might be a lot more than a standard donation!