Creating energy from the tides, wind

By Normand Laberge, Special to the BDN
Posted June 16, 2011, at 9:07 p.m.

The coastline of Maine stretches out for thousands of miles. During earlier centuries, tidal mills existed within communities with access to coastal waters. Windmills were also used for the generation of mechanical and, eventually, electrical energy. Today, the potential for ocean energy is being investigated as a renewable source capable of reducing our dependence on fossil fuels.

Officials from the state have expressed concerns with initial estimates of nearly 30 cents per kilowatt-hour for offshore wind; however, proponents cite the presence of a learning curve to reduce the cost of electricity by approximately 10 percent every time installed capacity is doubled. The learning curve for on-land wind has been approximately 7 percent during the past decade due to technological advances associated with increasing the length of turbine blades and due to more favorable rates for the sale of electricity to utilities. Federal and local subsidies have also assisted the development of wind resources on land.

Offshore wind systems are being designed with longer blades than their on-land counterparts. Offshore wind turbines do not pose immediate impacts to visual quality and to ambient noise levels but they are more expensive than on-land turbines due the harsher environment and due to greater uncertainty in performance and construction demands. I think that 30 cents per kilowatt-hour is close enough to economic reality to justify an investment that holds the potential for substantial capacity and with the knowledge that the cost of electricity is nearly inflation-proof due to the availability of a “free” fuel and with institutional support for project financing.

The fact that offshore wind in Maine generates eight times more energy in the winter than summer should be used to spur a transition to electrical home heating as part of a totally green process. Concerns still have to be addressed for offshore wind impacts, which will be studied by the University of Maine and which will include the use of Maine’s manufacturing capabilities.

Investment should be placed on the most promising resources with proper consideration of environmental impacts. We have sufficient information to make these initial assessments if we use our scientific common sense and carefully analyze cost and impact estimates.

I have noticed that ocean thermal energy conversion has re-emerged after being seriously considered in the 1970s and 1980s. In this case, environmental concerns seem to pose unavoidable consequences that are virtual showstoppers. So, why place a great deal of hope and investment on this resource?

Five years ago, the Electric Power Research Institute published an unrealistic report on the prospects for tidal hydro-kinetic systems. It now turns out that the cost of electricity from a proposal in Cobscook Bay is expected to cost more than $1 per kilowatt-hour from a technology with some major environmental concerns and without a real potential for a favorable “learning curve” benefit for commercialization.

The true resource of Cobscook Bay is the tidal range and not the tidal currents.  Tidewalker has been working on an innovative tidal dam proposal in Half-Moon Cove that will not alter the tidal range and which will provide renewable energy for less than 15 cents per kilowatt-hour. The environmental impacts have been defined for this project and the project offers the opportunity for regional economic development by being able to use the electricity locally. By accepting a financial plan with a fixed debt for 20 years, the cost of producing electricity for this tidal project will increase by less than 0.5 cents per kilowatt-hour over 20 years and will cost less than 2 cents per kilowatt-hour after the debt has been retired after 20 years. A tidal dam has a life expectancy of at least 50 years as opposed to other renewable energy systems.

Where is the disconnect? Maine needs to assist the development of renewable energy development in order to ensure the prospects for cheaper electricity in the next generation and to reduce its dependence on resources with limited supplies, which adversely affect economic stability and environmental quality. The strategy is to invest in the most cost-effective resource by using a common sense approach to energy development and by using our scientific and engineering skills.

Normand Laberge is the founder of Tidewalker Associates and lives in Trescott.

http://bangordailynews.com/2011/06/16/opinion/contributors/creating-energy-from-the-tides-wind/ printed on August 20, 2014