Perhaps he means if you're using solar cells followed by Fisher-Tropsch to make actual fuel. I'm pretty sure plants beat that. But the base efficiency of plan

Perhaps he means if you're using solar cells followed by Fisher-Tropsch to make actual fuel. I'm pretty sure plants beat that. But the base efficiency of plants is horrible : 2% is relatively high in plant species (solar energy input -> produced plant matter output). The most efficient plants in the world are close to 4.5% efficient.