An overview of the Gilman site

The Gilman site is one of the hydro sites we're involved in. It's the biggest site we work with and it consists of four turbines of various sizes. It also happens to be attached to an old paper mill that has not run since 2007 (before we purchased the site).

There's an interesting history with the Gilman site particularly with my family (and others who work with us). When my father finished college he spend a year in Illinois (where I was born) before heading back to Northern NH where he grew up. His first job when he got back was at the Gilman paper mill. At the time it was owned by Georgia Pacific and he was working on a wood boiler generator. We're still trying to get that generator back online but the paper mill is pretty much dead (more on that later).

The hydro site is in good shape though. As I said, we've got four turbines working which put out almost 4 Mw/h when there's good water, which there is right now. What's really interesting though is the fact that the turbines provide an glimpse into the history of hydro.

We have two turbines (called #3 and #4) which were installed in the 1930s. The've been upgraded, but there's still a great deal of original stuff on them. For example, the actual generators attached to them are original and still working. They look nothing like modern generators (which look like big electric motors) but there's no reason to remove them.

(1930s Generator)

And then there's this crazy contraption, which (I believe) controls the wicket gates for the turbine. We're replacing it with a single hydraulic cylinder, but in the old days it did something a little more complicated...

The WHOLE thing is being replaced by a single hydraulic cylinder...

These first two turbines are of a style known as a double camel-back. As far as I know, it's not a style used anymore. 

The next turbine was built in the 1960s and is known as the #2 Turbine. I believe it's a vertical francis turbine and it's generator is significantly smaller and more efficient than #3 or #4. I need to get a picture of #2. It looks completely different and is in a very different section of the power house. 

The #1 Turbine is our newest (installed in the 1980s) and our most powerful. On a good day it will do 2.5 Mw/h. It is a horizontal Caplan set up very similar to the image that links to. 

This is a picture of the generator and gear box for the #1 Turbine. It's big, don't get me wrong, but considering it's generating 3x the power, it's still pretty compact. 

Overall it's a good site. We've got a pretty sweet trash-rack setup that let's an operator clean all the racks then plow the crap off the dam. It's mostly sticks and stuff and is your standard river flotsam for the most part. We'll pull out trash when we find it. 

The site also has these slick inflatable bags along the top of the dam. In good weather this allows us to increase our head by some amount (not sure how much... maybe a foot or two). More importantly though is that in heavy water, we can deflate them to allow more water over the dam to avoid flooding the power house (which seems to happen once a year anyway). It's incredible how strong water is.