(Bloomberg) -- A watchdog for the Texas electric grid said new rules this year have led to more than $12 billion in additional costs, up from a previous estimate of $8 billion over the summer, the latest development in a contentious debate over power reserves in the Lone Star State.Most Read from BloombergHow Suspects Laundered Billions in Singapore for YearsWall Street’s Furious Bull Run Gets Reality Check: Markets WrapBitcoin Surges Past $42,000 Even as Stocks and Bonds Take a HitHarvard Alumn