July 18 (Reuters) - ** Shares of power producer Talen Energy TLN.O rise 14% to $300.5 premarket
** Company said it is acquiring two power plants situated in Pennsylvania and Ohio for $3.5 billion
** Talen expects the move to boost the company's cash flow by over 40% in 2026
** Co will pay $1.46 billion in cash for Caithness Energy's Moxie Freedom Energy Center, in Pennsylvania, which controls 1,105 megawatts (MW) natural gas-fired combined cycle generation project
** TLN will pay $2.33 billion in cash for the 1,875 MW Guernsey power station in Ohio, which is owned by Caithness and BlackRock
** As of last day's close, stock up 31% YTD