So I have been looking on ebay a lot for “permanent magnet motors” to try and find one for my turbine. There are lots on there, but it’s very hard to know whether what I am looking at will be any good for a turbine. This article answers that question:
You need 1 volt per 25 rpm, so just divide the voltage (in DC) by the top rpm and see if that’s 25 or less. If it’s not then it’s no good (unless you want to gear it, which I definitely don’t!).
Let the search continue…