Ms Aoife MacEvilly:

I am not sure it is clear, at the moment, that the lowest cost is also the lowest carbon. It will take some time, as we invest significantly, to upgrade our network infrastructure to build more renewable capacity before we see the full benefits of increased low-carbon supply in the system. Time-of-use tariffs are a good way to provide that benefit to customers. There are lower charges overnight, because one is effectively supporting renewables that might run at night which might otherwise be curtailed because there is not enough demand. Options such as moving consumption to off-peak times deliver lower costs for lower carbon.