| Zigurd, I doubt the "direct" 'gas to electricity' claim in this press release. Near the bottom the press release admits the conversion /isn't/ actually "direct", stating: If the fuel cell heater is connected to the gas network,
a reformer initially converts the natural gas into a
hydrogen-rich gas.
Ah-ha: A "reformer": That would be a 'steam reformer[1]'. Quoting [1], here's what a 'steam reformer' does: At high temperatures (700 – 1100 °C) and in the presence
of a metal-based catalyst (nickel), steam reacts with
methane to yield carbon monoxide and hydrogen. These two
reactions are reversible in nature.
CH4 + H2O ⇌ CO + 3 H2
So there it is, the 'hydrogen-rich gas' is syngas [3], one mole carbon monoxide plus 3 moles hydrogen.The syngas can either be burned directly (producing CO2 and heat of course), or continuing per [1], separated from the H2, then combined with more water: Additional hydrogen can be recovered by a lower-
temperature gas-shift reaction with the carbon monoxide
produced. The reaction is summarized by:
CO + H2O ⇌ CO2 + H2
But the article uses just one word, 'afterburner' which tells me they're burning away the carbon monoxide: The researchers were particularly responsible for the
construction of the prototype, the design of the overall
system, the design of the ceramic components and the
development of the reformer and the afterburner.
Not clear is whether the CO goes /through/ the ceramic SOFC or is separated so it can /bypass/ the SOFC then get remixed with some H2 at the 'afterburner'. No mention of a 'separator', so perhaps the CO does go straight through the SOFC along with the H2 without ruining the SOFC.In any case, we see this CHP plant with its SOFC requires water in, makes carbon monoxide in the process, which it 'afterburn[s]', certainly putting out CO2 [the Carbon from the methane can't just disappear, would you have that as carbon monoxide or carbon dioxide?], and needs some heat to run the steam reformer. There goes some of your thermal efficiency! [2] has a bit more on home CHP. So long story short, there's no free lunch here: * It can't hit 100% thermal efficiency * It releases CO2 * Its intermediate stage passes H2 through, and CO either through or around the SOFC, then burns off the CO to CO2 * It needs water as well as natural gas to work Presuming the Bloom Boxes also use SOFCs and methane, the operating chemistry would be the similar at the inputs and outputs: Natural Gas and Water in; Heat, CO2 and Electricity out. There may be an advance in materials science if the SOFC accepts syngas ( CO + 3 H2 ) directly without bypass of the CO and without cell degradation from the CO, but the press release says nothing specific about, or suggestive of that. edits for dialog form, clarity, corrections, 'afterburner' clean up the CO in the syngas to CO2, no water out, oh it says press release right at the top, no wonder it reads like one ======== [1] https://en.wikipedia.org/wiki/Steam_reforming [2] https://en.wikipedia.org/wiki/Home_fuel_cell [3] https://en.wikipedia.org/wiki/Syngas |