Chesapeake Energy Corp,the Oklahoma-based firm is the No. 1 driller in Ohio.
Rig Count Interactive Map by Baker Hughes, an energy services company.
Shale Sheet Fracking, a Youngstown Vindicator blog.
The Ohio Environmental Council, a statewide eco-group based in Columbus.
Earthjustice, a national eco-group.
People's Oil and Gas Collaborative-Ohio, a grass-roots group in Northeast Ohio.
Concerned Citizens of Medina County, a grass-roots group.
No Frack Ohio, a Columbus-based grass-roots group.
Fracking: Gas Drilling's Environmental Threat by ProPublica, an online journalism site.
Pipeline, blog from Pittsburgh Post-Gazette on Marcellus shale drilling.
Allegheny Front, environmental public radio for Western Pennsylvania.
There is a trend away from coal and toward cleaner natural gas among American utilities, according to the Associated Press.
In the U.S., the electricity generated by gas-fired plants has risen by 50 percent over the last decade, while coal-generated electricity dropped slightly.
The gas plants generated about 600 billion kilowatt hours of electricity in 2000 and 981 billion hours in 2010, according to the U.S. Energy Information Agency.
The natural gas use for power rose 7 percent between 2009 and 2010 with the biggest jumps in North Carolina, Virginia and South Carolina.
Natural gas plants are attractive for utilities as long as the price of natural gas remains low, the experts say.
In Ohio, Columbus-based American Electric Power is completing a new gas-fired plant at Dresden. It should be done later this year. It is also switching one boiler at the Muskingtum River plant at Beverly to gas.
The company has 80 power plants with 22 percent of its power coming from natural gas.