Could you be the Wind God?

Scenario: You have been appointed the UK Government's minister responsible for smoothing out the intermittent output from renewable wind and solar PV electricity generation. You're going to do this by specifying storage technology that can store and release power according to variations in supply, rather than relying on coal and gas power stations stopping and starting to balance the grid. Your policy will then be tested against actual 2019 daily data provided courtesy of GRIDWATCH

Unofficially your job title is THE WIND GOD

Minister, we now need you to make some policy decisions, including the total storage capacity (in MW-h) and its instantaneous power rating (in MW). The storage facility (or facilities) can either consume power to charge the storage or generate power, as the storage is discharged. For example if you specified 144,000 MW-h of storage and a 2,000 MW power rating, that is 3 days storage full-to-empty (2,000 MW x 24 h/d x 3 d)

The average power output from wind and solar PV is 6700 MW - and we'd like you to treat that as a target - but it won't be easy.

In 2019, minimum output has been as low as 1,000 MW, maximum in excess of 12,000 MW. On days when wind and solar PV power exceeds the target, the excess will be automatically put into storage, up to the maximum power rating you specified - and provided there is spare capacity in the store. On days when wind and solar PV power is below the target, power will be drawn automatically from storage, again up to the maximum power rating, on condition the store is not completely depleted at the time.

However much storage you allocate, we'll ensure it is 50% charged at the start of day 1 (January 1st 2019)

Your assessment, minister: Net output was 1000 MW or more over the target on 46 days out of 212. On such days we would have to pay generators to shut down operation. Net output fell 1000 MW or more under target on 44 days out of 212 and on these days we would have to purchase standby power most likely using fossil fuel. Your proposed storage would require 10 Coire Glas scale storage schemes at an estimated cost of £8 billion

Overall, we'd rate your performance at 50 % - quite good, Minister! Here are the full results: