The Marcellus Shale spanning from Pennsylvaniato New York State has been recently discovered to contain high amounts of natural gas. New, less expensive drilling technologies have made it more economically viable to extract the natural gas in the shale, opening up an exciting new resource for the the U.S., especially locally.

The biggest argument against this drilling is the disposal of water used in the process. Water is hydraulic pumped deep into the shale in a process called hydro fracturing. This makes getting at the natural gas easier, but the water used needs to be cleaned afterwards because it could become enriched with saline or heavy metals in the process. Recycling these materials is both problematic and expensive.

I'm always a little skeptical of sources cited, and this wasn't any different. but, I don't honestly know enough about the sources to say more.

Figure 7 is both outdated and misleading. The pictured scientist is holding a toxic gel like it's silly putty.

Why do scientists make proppants in substitution to water? Are they more effective, and are there more environmental repercussions?