Since grids need to be maintained and upgraded for a variety of reasons including efficiency lowering overal running costs, maintenance advances such as increasing fault tolerance and reliability and benefits to customers brough by smart grids regardless of energy source used

the same emissions as if they were upgraded without being used with renewable energy in mind but since renewables will be part of the use and replacing polluting sources like coal and the grid more efficient the total annual emissions should be lower compared than currently

who knows, traditional energy suppliers may preffer to pocket the revenues that should had been used to maintain it and keep upgrading it till it roots instead and then claim it is not fit for purpose, at the end of the day those corporations are there to increase shareholders profit let the next CEO and/or tax payer deal with it