by Buckaroo » Sat Nov 28, 2015 7:56 pm
The vast majority of commercial hydrogen production comes not from electrolysis but from reformation of hydrocarbons, primarily natural gas. Electrolysis, despite being the method we all know from grade school, is the least efficient method by a huge margin. That chart quoted above shows 32.9 kWh/kg of H2, but that's wishful thinking. Realistic costs are about double that. Even given a bargain basement price for electricity, you're still looking at a cost that's approximately 5 times that of reformation techniques.
There's a lot of research trying to bring the cost of electrolysis down, but there's a long way to go to make it competitive. Sure, solar cells, wind farms, solar collectors, et. al. are great and improvements are happening at a good pace, but they all have issues that make them expensive to manufacture or maintenance intensive or land intensive or rare-earth intensive, etc. It's simply much more efficient to make hydrogen directly from hydrocarbons, rather than burn the hydrocarbons to make electricity to power electrolysis to produce H2 from water. The problem with producing H2 from hydrocarbons is you get lots of greenhouse gases as a byproduct.
Another issue is storage. Hydrogen is notoriously difficult and dangerous to store, especially long-term, which translates to high costs. Petroleum fuels are easy to store. Diesel fuels are nice due to low vapor pressure-- it doesn't ignite easily, a friendly trait when working around the stuff particularly in marine environments where things tends to collect in bilges and poorly ventilated compartments.
Let's say hydrogen fuel somehow becomes cheap and clean to produce. Hydrogen is still a lousy fuel in terms of energy density. That translates to weight and volume. Hydrogen fueled electric vehicles can give great economy but require considerable weight for fuel cells, compressed hydrogen tanks, batteries, electric motors, etc. And liquid hydrogen requires much more volume than petroleum-based fuels. For aircraft, weight and volume are everything.
There's a lot of cool and useful hydrogen tech being developed for terrific applications, but no commercial airline exec looking to purchase his third beach-front property is going to seriously consider hydrogen powered aircraft.
-Buck
Callsign: Buckaro(o)
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