Oceans cover three quarters of the Earth's surface. Those vast waters provide food, enable global shipping and drive the global climate. They could also provide much of the world's electricity needs. Waves, tides, even differences in salinity and temperature, are all potential sources of energy. The trick is harnessing that power.

Last month, the nation's first commercial tidal power project - an underwater turbine that resembles a combine harvester installed on the floor of the Gulf of Maine - started pumping power to the grid. Eventually, Ocean Renewable Power Company hopes to install twenty such turbines around the Gulf of Maine. But other ocean energy projects are few and further behind.

TheNew England Marine Renewable Energy Center is a nonprofit umbrella organization that brings together academic researchers, government agencies, commercial entities and citizen groups with the aim of fostering sustainable development of New England's ocean energy resources. John Miller is the director of MREC. Anthony Kirincich is an assistant scientist at Woods Hole Oceanographic Institution, and Brian Howes is professor and director of the Coastal Systems Program at UMass Dartmouth. Both are working with MREC on local wave and tidal energy projects, like the Muskeget Channel Tidal Project that could make Edgartown the first energy-independent municipality in the country. They joined me for a conversation about the opportunities and challenges facing ocean energy development.

If this whets your appetite, you might check out MREC's Annual Technical Conference the week of Oct. 29 in Warwick, R.I.