This article appeared in todays Observer Reporter
http://www.observer-reporter.com/article/20130120/NEWS080101/130129986
Here is the first paragraph of the article:
HARRISBURG – Advances in hydraulic fracturing technology have powered the American natural gas boom. And now hydraulic fracturing could be increasingly powered by the very fuel it has been so successful in coaxing up from the depths.
It is a big step forward in reducing emmisions from the Diesel powered equipment being used now to drill and frack the wells.