2 ms·

If it brings the net carbon footprint down, it could be relevant. Progress is typically iterative

• Robotbeat 6y ago
  But that hasn’t been established here. The aluminum produces hydrogen (at some level of inefficiency) which then produces electricity in a fuel cell (more inefficiency). Consumable electrodes are actually doing chemical work in the aluminum. It’s not just wear from use. To produce 78 grams of Aluminum directly requires 48 grams of Carbon electrodes (using made by graphitizing some tar or coke) which oxidizes to 176 grams of CO2. Aluminum is 31MJ/kg specific energy. Assuming 70% efficiency conversion from aluminum to hydrogen and 70% from hydrogen to electricity (both fairly optimistic figures), you’re talking about 535 grams of emitted CO2 for each kWh of electricity out. Ignoring the electricity input, inefficiencies and losses in making the aluminum, and assuming perfect conversion of the tar to electrodes. Worse than a good, advanced combined cycle natural gas plant (which can get as good as roughly 350 grams per kWh for record efficiency plants). I just don’t see how this is gonna be a net win without carbonfree electrodes. It seems just about impossible here. Storing hydrogen directly looks to make way more sense.