My alternative fuel proposal is an existing idea that needs a fresh look, so here are my design ideas for getting it to work.
Lithium batteries have cost, resourcing and recycling issues. Sodium batteries may be better in future but progress is slow. We need climate change action urgently and we need to keep researching options. Straight up, this is a neglected and "fringe" option with a lot of challenges. Maybe it has a low chance of success. But it needs attention because if it works it has a lot of advantages. Starting with the possibility of converting existing vehicles including converting their engines - to steam! The main emission is water vapour. The reaction product sodium hydroxide would be recycled back into sodium metal by electrolysis. Therefore electricity is the energy source for this "sodium cycle". A major challenge is to achieve better efficiency with the electrolysis. Read on about the many other challenges and my suggested solutions.