Re: least polluting rocket fuel

According to: http://www.stardrivedevice.com/electrolysis.html a
'gallon equivalent' is 1kg of hydrogen and would in fact cost slightly
over $4 to produce by electrolysing water. However, for rocketry
purposes this neglects the liquification costs which are quite
significant.

Last time I heard, NASA was purchasing their *liquid* hydrogen for
about $7/kg, and that wasn't even environmentally friendly hydrogen,
which is more expensive.

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