Ever dreamed of living off the grid, perhaps on a remote Island?
Star Island - Located seven miles off the coast of Rye, NH
If you've been out to Star Island, one of the Isles of Shoals, you know that it's one of New Hampshire's gems. Earlier this summer, my wife and I had the pleasure of returning to Star Island for a brief visit. Despite the Island's natural setting and the calming ocean breezes, the nerd in me couldn't help but contemplate the infrastructure required to keep this remote Island humming.
The Oceanic Hotel on Star Island
Star Island is home to an educational conference center that's run by the non-profit Star Island Corporation. Each summer, hundreds of conference attendees and vacationing day-trippers pour in, ready for a dose of Island living. The Island's nineteenth century Oceanic Hotel is quite rustic by modern standards, so much so that conference brochures describe the accommodations as "comfortable, but not modern." Still, the basics are well covered including electricity, indoor plumbing, and a fully equipped dining hall and snack bar.
Even providing just the basics can be a challenge, when you're seven miles away from the mainland. Water for the Islanders is supplied using a three-tiered approach including untreated seawater for outside washing and running the sewage treatment plant, rain water cisterns for showers and laundry, and a reverse-osmosis desalinization plant for potable water. All of the Island's wastewater is treated by an EPA approved wastewater treatment system. In addition to the water and sewer systems, the conference center provides meals for hundreds of guests which requires significant refrigeration and food preparation equipment.
All of these things require electricity, lots of electricity. In fact, according to Star Island Corporation's Island Engineer, Tietjen Hynes, during the peak season the Island uses about 1,500 kWh of electricity each day. Most of this electricity is produced by a pair of 125 kW generators that are powered by diesel engines. One generator is powered by a John Deere 4045 engine and the other by a CAT 3304b engine. To get an idea of the scale of these power plants, consider that they are about 25 times the size of a typical 5 kW emergency backup generator. In fact, the John Deere 4045 diesel has 4.5 liters of displacement and provides over 160 horsepower. Below is a sample photo of a generator that uses this engine.
So how much does it cost to produce electricity on Star Island? Island Engineer Hynes says that the generators consume around 100 gallons of fuel to produce the 1,500 kWh of electricity that's needed each day. The fuel must be brought in by boat, so Ill assume a $3.50-$4.00 per gallon delivered fuel price. That yields an "energy cost" of around 25 to 30 cents per kWh. That rate doesn't include capital costs or operating and maintenance costs which, given the short season and tough operating conditions, could easily add another 5-10 cents to that kWh rate. Even at this reasonably large scale, it's tough to even come close to power company costs with do-it-yourself electricity generation.
Given the remote location and the high cost of generating electricity with diesel, the Island seems like a great candidate for renewable energy sources like wind and solar. In fact, the non-profit that owns the Island has made a commitment to sustainability and has sought out ways to improve efficiency and reduce the environmental impact of their electricity production.
Elliott Memorial Building with five 125 watt photovoltaic panels installed
A few years ago, the Elliott Memorial Building was equipped with photovoltaic panels to provide power for the Island's winter caretakers. You can see the five 125 watt photovoltaic panels in the photo above. These are attached to a bank of eight 110 Ah deep cycle marine batteries and an inverter that converts the battery output to alternating current. The system provides the winter caretakers with the convenience of 24x7 ac power, without having to run a generator non-stop. According to Island Engineer Hynes, by using the solar panels and the batteries, the winter keepers are able to reduce generator run-time to just a couple of hours each day. It looks like the winter keepers have a more sophisticated version of the rudimentary blackout system I described in this earlier post.
In addition to the solar panels on the Elliott Memorial Building, the Island also has a new 5 kW Helix Wind S594 vertical wind turbine that was installed by Waterline Industries of Seabrook, NH.
Helix Wind S594 5kW vertical wind turbine
The turbine was just recently installed and the project has hit a small snag that shows just how tricky alternative energy systems can be when you're "off the grid." Island Engineer Hynes explained that the Helix turbine is intended to be used in grid-tied systems and must be fed relatively steady 60 Hz ac line power in order to produce electricity. This is a failsafe to protect utility workers from unexpected back-feeds on the power grid. Unfortunately, the Island's diesel generated electricity varies between 57 Hz and 62 Hz and this variation prevents the Helix turbine from reliably generating power. One other challenge in using wind power for commercial off-grid applications is that there's no option for net-metering, where unused power can be sold back to the utility. In off-grid applications, the turbine's output must be consumed when it's produced or stored in expensive and sometimes impractical battery systems.
Despite these issues, Ms. Hynes believes the new turbine will ultimately be used to provide electricity for the Island. She's working with Helix Wind and the distributor on a plan to connect the turbine to the existing solar battery bank and inverter to provide power to the Elliott Memorial Building and the Doctor's cottage.
View of the Helix Wind turbine and the solar panels on the Elliott Memorial Building
On nearby Appledore Island, the folks at the Shoals Marine Laboratory (SML) recently installed a Bergey 7.5kW wind turbine and 4.4 kW of photovoltaic panels to help reduce their generator fuel consumption. Although the prospects for the project are very promising, the project's cost was nothing to sneeze at, coming in at over $100k for just the wind turbine, tower, and related equipment.
Wind Turbine on Appledore next to WW II tower that houses weather instruments
Despite the minor technical snags and the somewhat high capital costs, the folks at Star Island and at the Shoals Marine Lab are proving that using renewables to generate standalone Island power is becoming more feasible as the technology continues to improve and prices continue to drop.