Six miles off the coast of Portsmouth, New Hampshire, sits the Isles of Shoals, a set of small islands and ledges just over 200 acres in size. The largest of the Isles of Shoals is Appledore, which is home to the Shoals Marine Laboratory, an operation run by the University of New Hampshire and Cornell University. About a quarter mile directly to the west sits Star Island, which is home to an event center owned by the Star Island Corporation, a non-profit associated with the United Church of Christ. Between the two, connected to Star by a small breakwater, sits Smuttynose, the namesake of a well known craft beer company, and the site of arguably the most famous ax murder spree in New England.
(Disclaimer: This blog has nothing to do with beer or ax murders. Sorry!)
I was lucky enough to make a trip out to the Isles of Shoals last Friday (4/3/15) with a few folks from the diesel islands and elsewhere.
We departed from Portsmouth early Friday morning in a boat driven by Marshall Frye, of the Star Island Corporation. We made our way past the Portsmouth Naval Shipyard, and out the Piscataqua River, towards the Isles of Shoals.
After about twenty minutes, we arrived at Star Island. We were surprised to see that we weren’t the only ones out there; a crew from the Shoals Marine Lab were also out on the R/V John M. Kingsbury.
After docking the boat, we were given a quick tour of the buildings on Star Island. We then headed to the backside of the island to see a recently installed 130kW solar array. This array, at the time of it’s completion (April 22, 2014), was the largest off-grid solar array in New England.
The array covers about a half-acre, and consists of over 400 panels. If you look closely at the picture above, you can see that the panels are sitting on blocks of concrete. This was a solution manufactured on the fly, after the panel installers were unable to successfully drill into rock ledge. The blocks of concrete are basically a waste product from a bridge construction project, and were acquired on the cheap to be used as anchors for the panels.
This array provides a good deal of power to the island, but a complex back up system is required to insure uninterrupted electricity supply. Most of this system is housed in a shed behind the main building on the island. This system is pretty complicated, so it helps to break it down into its components:
Generator: The island currently uses one diesel generator to provide power when the sun isn’t shining. This is a relatively new Tier 3 (meaning it complies with tier 3 of the EPA’s Clean Power Plan regulations for diesel generators) Kohler.
Charge Controllers: These do exactly what they sound like they do: control the charge going into the batteries. This keeps the batteries from overcharging, which can cause serious problems.
Batteries: The batteries are the backbone of the entire system. They offer 600 kWhs of storage, and can be fed by both the generator and the solar panels. They are usually kept at about half charge.
Inverters: The inverters draw power off the batteries to feed the distribution system. They “invert” the electricity current, meaning they take it from DC (12 Volts) to AC(120 Volts). This part of the system is actually very complex, there is a whole series of inverters that do various different things. My electrical engineering expertise is pretty limited, so I’ll leave it at that, and say that there are probably some really good resources out there thatcan explain this concept better than I can.
This flow chart helps explain how this whole system works.
The system on Star powers a hotel and a handful of associated buildings, a reverse osmosis water desalinator, and a waste treatment facility, all of which are interesting projects in their own right.
After a tour of these facilities, we headed over to Appledore. We were pretty pressed for time at this point, but we still wanted to see what we could of the Appledore system.
After a quick tour of Appledore, we hopped on the boat back to New Hampshire, and then debriefed over lunch at Loco Coco’s Tacos in Kittery.
It was interesting to draw comparisons between the Isles of Shoals and Maine’s diesel islands. For example, both are completely independent from the mainland grid, and, as a result, both have historically relied on diesel generators to supply their power. The Isles of Shoals have dealt with the same issues Monhegan and Matinicus deal with: high energy costs, issues with safety and the transporation and storage of diesel fuel, and environmental effects of diesel generation. Now that they are less reliant on diesel fuel, some of these issues are less prominent.
However, there are some differences. Star and Appledore are both privately owned, and fully shut down in the winter, whereas Monhegan and Matinicus are year-round communities. This means a couple of things:
- The load profile is different. The fact that Star and Appledore shut down in the winter means that they need hardly any generation for that period of time. This makes the solar arrays, which produce more power in the summer, a very good fit for the islands. This also means that their generators don’t run all year round, which exempts them from certain regulations.
- The Isles of shoals don’t need to worry about the kind of public concerns that come up when dealing with construction in communities like Monhegan and Matinicus. If they want to do a project on Star Island, all they need is the approval of the board of the Star Island Corporation, and the nessesary permits.
Still, the systems on Star and Appledore are a good blueprint for what might work on Monhegan or Matinicus. It’s also helpful to see what kinds of issues other places run into when installing these kinds of systems, so that those problems won’t be repeated when work is done elsewhere.