Solarpunk technology

LH2 can work well for commercial shipping. Use at pace of boil off. Ammonia toxicity is a bit overblown. The tiniest leak will smell strongly, and it leaks as a gas. The smell threshold is far below toxicity level. Go outside is a natural solution.

Ammonia and LH2 have tradeoffs. Compressed H2 in "trimaran pontoons" is an excellent solution that would permit sail assist as well. Nuclear is too expensive.