On islands, fresh water and fuel are priceless and boat runs to and from the mainland are costly.

And that is why Shoals Marine Laboratory (SML) on 95-acre Appledore Island six miles off the Maine coast is switching to composting toilets and adding solar water-heating panels. The changes will reduce the lab's need for fresh water and fuel and require fewer pump trucks to be shipped across the water to empty the island's septic tanks.

Cornell partners with the University of New Hampshire to operate this remote facility where undergraduates study such subjects as marine biology, ecology and sustainability every summer.

Thanks to a $160,000 Field Stations and Marine Laboratories grant from the National Science Foundation, SML will build a 22-by-22-foot addition to Kiggins Commons to house the new composting toilets and solar panels on a south-facing roof this summer. Kiggins Commons includes the facility's main kitchen, mess hall, a bank of showers and toilets and lab space.

"Our overall goal is to reduce our dependence on diesel fuel as much as possible," said Ross Hansen, assistant director for operations at SML. "The plan is to become more alternative on the island as money and technology allow."

Much of the technical know how came from sustainable engineering interns from Cornell's College of Engineering, who played key roles in designing the new sustainable energy, water and waste systems.

The septic system separates solid and liquid waste, and the liquid is siphoned off for pumping to a leach field built for wastewater treatment last June. In years past, liquid waste was chlorine treated in a central holding tank before it was pumped out to sea. This required shipping to the island 55-gallon drums of chlorine, which were switched every two days. "That process was stopped when the leach fields were done," Hansen said.

The new composting toilets will use only three ounces of water, mixed with biodegradable soap foam, per flush, compared with 1.6 gallons of water that the existing low-flow toilets use. The lab used to use saltwater for flush toilets, but the new leach field required switching completely to fresh water from the island's well and from a water desalination machine when the well runs dry.

Currently, a sewage pumping truck must be shipped onto the island every three years to empty solids from the septic tanks, but the composting toilets should delay the need to empty septic tanks to every five years or longer, Hansen said.

Along with fewer boat runs to the mainland and less fresh water use, the lab also will save on diesel fuel to pump water around the island. The new solar panels will reduce the need for propane fuel -- which is also shipped to the island -- for heating water for sinks, showers and dishwashers.

Since a wind turbine was installed in 2007, and the leach field reduced the number of water pumps to four from nine, Shoals saved 1,800 gallons of diesel fuel last year at $4.50 a gallon. "Pumps and motors require a lot of energy," Hansen said.