A utility with operations around Texas is planning a network of 50 to 150 charging stations for electric cars in the Houston metropolitan area to eliminate “range anxiety,” and is talking with Nissan, Toyota and others about offering auto buyers a package that includes network access and a home charger. The company, NRG, hopes to offer packages ranging from $49 a month, for cars with both electric motors and gasoline engines like the Chevy Volt that would not need access to the scattered charging stations, to $79 a month, for buyers of the Nissan Leaf. The network, called eVgo, will be the first private one for charging, said David Crane, the chief executive of NRG, which is based in Princeton, N.J. In a conference call with reporters, he said Thursday that a combination of home and public charging stations would “make the electric vehicle more affordable and practical, which we believe will significantly close the decision gap.” The plan is to have 50 charging stations installed by the middle of next year; these would deliver three or four miles of range for each minute of charging time.