Daniel Murray is joined by Mark Foley, chief executive of Eirgrid, for the latest episode of Five Degrees of Change.    Eirgrid operates the national electricity grid, which you use every time you turn on your lights at home, or power up your computer at work, or plug in your phone in a coffee shop. It delivers the electric lifeblood of our economy, and plans the electricity network out into the future so that power generation continues to meet projected electricity demand.   It sources and connects new power generators to the grid, and it manages the distribution of that energy carefully to prevent surges or blackouts.