Quote:
Originally Posted by unclebilly
Not really, sure reforming is endothermic but if you do it on the cell like we did with SOFCs, it assists with cooling and thermal management of the fuel cell stack. In fact, we found (and I mentioned this in another thread weeks ago) that we were better off to run our anode exhaust through an eductor and a nickel bed (heat exchanger for our incoming fuel or air) and recycle part of the stream so we could get more cooling duty. This resulted in us running at a lower on cell fuel utilization but a higher overall system efficiency.
I think you are missing the conversion efficiencies related to putting that hydrogen into meaningful storage and taking it out and putting it to use. To make it meaningful storage, you need to compress it to several thousand PSI. This ain’t a free ride. The part that makes me shake my head is the notion that renewable energy from tidal, solar, wind, and hydroelectric can be wasted on inefficient processes because ‘free’... I think we’d be far better off using the off peak power from these ‘green’ energy conversion technologies wisely such as charging batteries and other useful things with better storage and power extraction efficiencies as opposed to making hydrogen out of water.
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Not missing that. Storage is a huge problem for hydrogen, especially in that the hydrogen can leak from something that methane can't. And H2 has a much wider flammability range than methane or other hydrocarbon fuel.
There are some interesting storage work on reverse pressure swing adsorption. Normal PSAs you sucking the contaminants and flow the gas, for purification. This instead absorbs the hydrogen into a mineral matrix, reducing the storage pressure for a given mass of hydrogen. Ratio is about 10:1 pressure reduction. You lose about 50% capacity by volume for the absorbent. But it is still a win. 300 psig instead of 3000 psig.
My issue on using hydrogen as a storage means is the losses are higher than batteries.
For stationary applications, I think flow batteries are going to come out on top. The latest work is an iron based system, which will be dirt cheap. Vanadium is great and already commercial, but it is expensive.