Is Hydro the only acceptable sorm of generation

It has happened to me again. I was asked to help a client who wanted to install a solar PV system to generate their own electricity. No urgent need for it other than the clients "want to do their bit for the environment". Once I explained the probable costs involved, shockingly they quickly went off the idea. I suggested either wind or water but these did not meet with too much enthusiasm either. Turns out they are active in a protest group trying to stop a wind farm being built on the hill opposite their front door and having their own wind turbine did not sit too well. They have plenty of wind (which is why they are building the wind farm opposite) and it was possible to see the cogs turning - was it possible to do it and avoid being hung by their mates?

A bit of further investigation dug out that uncle, who owns the farm next door, has "a bit of a stream. Probably too small". A swift survey showed that the stream has the potential to support a 2kw turbine - enough for 3 houses. The clients, their uncle and the guy next door are now looking to club together to put the turbine in, and have free electricity for the next 20 years.

Every time I do a seminar I tell the audience to check their stream, however small it may seem. But they never do. They always think I don't mean them because their stream really is too small. But I do, and it probably isn't.