For intermittent sources it's also important to be able to cycle on/off (or throttle to partial power) frequently. In reading about green hydrogen projects I sa

For intermittent sources it's also important to be able to cycle on/off (or throttle to partial power) frequently. In reading about green hydrogen projects I saw it mentioned that traditional alkaline electrolyzers could not safely run in an intermittent fashion, although proton exchange membrane electrolyzers could. Unfortunately, the source that mentioned this did not say why alkaline units were unsafe to run this way, and my searches for more information were not successful. My guess is something like "it relies on a certain outflow rate of gases to prevent hydrogen/oxygen mixing" but I'm not sure why that is a particular issue for traditional alkaline electrolyzers, or how difficult it is to mitigate. The alkaline units otherwise require only common materials, have been manufactured forever, and seem like the natural thing to build more of for coupling to intermittent renewables.