Bring back the turbo. Banning it was the worst blow to the environment and economy. Just think what progress would have been made since then in regard to fuel consumption and power to weight ratio thingies.
In my simple opinion they should:
Cap engine size to that of a small car.
Reduce fuel available for each race to promote economic innovation.
Allow electric cars to race or promote a different series for electric cars with the profits of F1.
If we need an alternative to petrol then it should come from the people who make billions out of it. No doubt they have floating cars with engines that run on bu115h1t hidden away that will miraculously appear when the petrol runs out and sell for a sum that the average family can just afford.
Save the planet

.....whatever.
Lost the plot and its time for a bath.