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January 29, 2009
Wind Energy for Peaks Island
Summary Background Information
for the Peaks Island Council
A sub-group of the Peaks Island Environmental Action Team (PEAT) is interested in exploring the feasibility of and options for developing one or more wind energy generators on Peaks Island. This summary document presents some of the information that we think we know, and identifies the need for more information. (The terms wind generator and wind turbine are used interchangeably in this report.)
Wind Resource on Peaks Island
It feels like there is enough wind on Peaks Island to support a wind generator project, but this will need to be confirmed with better data than we have been able to find. The U.S. National Renewable Energy Laboratory publishes a map of the wind resource in Maine, based on computer models. This map is included in a report titled "Small Wind Electric Systems" for Maine at: http://www.windpoweringamerica.gov/pdfs/small_wind/small_wind_me.pdf
This map shows average wind speeds for Peaks Island at heights of 10 meters (33 feet) to be 11.5 to 12.5 mph. At a height of 50 meters (165 feet) , the average wind speed for Peaks Island is shown to be in the range of 14.3 to 15.7 mph: http://www.windpoweringamerica.gov/images/windmaps/me_50m_800.jpg.
This wind resource is considered to have "fair" potential for wind generation.
Back in 1981, the STAR Foundation installed a wind speed meter (anemometer) and recorder on Battery Steele; this data has been lost, but it was believed to have shown an average speed of just over 10 mph at a height of only 20 feet above the top of the structure (just barely above the tree/ brush height, but lower than some of the taller spruce trees on the north side of the Battery.) (The top of Battery Steele is somewhat less than 60 feet above sea level, so the anemometer was at an elevation of less than 80 feet.)
It will be necessary to get more information on the wind resource. The most prudent strategy for doing this is to erect a meteorological tower with anemometers mounted at several heights, and to record velocity and direction for at least one year. Wind data can also be purchased from a company called Truewind, but it is expensive. There are several local options for computer modeling of wind data that would be free or cost less.
Electrical Demand on Peaks Island
Detailed data from CMP for the whole island has not yet been obtained. However, a gross analysis would assume that each house uses about 1,000 kw-hours a month (including commercial and municipal uses for the purpose of estimating the total use on the Island,) and there are about 600 houses on the island. That would result in a monthly demand of about 600 mega watts-hours, or 7,200 mega watt-hours per year. Obviously, it would be necessary to obtain more detailed information, including the seasonal variation of this demand, if a large wind generator project is pursued.
As a potential demonstration/ municipal site, data was obtained for the Transfer Station. The electrical usage is lowest in the summer and fall, the lowest value in 2007 being 2,636 kw-hrs in August; the highest usage is in the winter, the highest value being 6,380 kw-hrs for December, 2007; the annual average is about 4,100 kw-hrs per month, or 49 megawatts per year. We believe that a municipal wind generator located at the Transfer Station could also be used to offset the electrical use at other municipal buildings on the island, such as the Community Center or School. Without knowing the usage at these locations, it is guessed that the total municipal electricity usage is less than 200 megawatts per year (which is the typical amount produced by a 100 kilowatt turbine.)
Wind Generator Types and Sizes
There are basically three "scales" of wind generators:
Small is less than 100 kw
Medium is from 100 kw up to 1,000 kw (1 megawatt)
Large is 1 megawatt or more
A small "house scale" wind generator would typically have less than a 5 kw rating, with a rotor diameter of about 15 feet, and a tower height of 50 to 75 feet. A 50 to 100 kw "small" machine typically has a rotor diameter of about 40 to 60 feet, and it would be installed on a tower from 80 to 125 feet tall. A 400 kw machine has a rotor diameter of about 100 feet, and it is typically installed on a tower that is about 150 feet tall. An example of a large wind generator would be a GE 1.5 megawatt wind turbine that has a rotor diameter of over 230 feet (70 meters) about 3/4 of the length of a football field. The hub can be on a tower that varies between 170 feet (52 meters) and 230 feet (85 meters) above the ground. These are the machines soon to be installed on Vinalhaven.
The amount of electricity generated by each of these machines obviously depends on the amount of wind that actually blows at the site over time, not to mention the machine's specific efficiency. All of the machines need a minimum wind speed of about 9 mph to start working, and they reach maximum power at about 30 mph. Larger machines are typically more efficient at converting wind to electricity. In Maine, we have found that a 100 kw machine can generate about 200 megawatt-hrs per year; a 400 kw machine could generate about 900 megawatt-hrs per year, and a 1.5 megawatt machine could generate about 3,750 megawatt-hrs per year. If our estimate of electrical use on Peaks Island is accurate, generating all of the Island’s electrical needs would require either: thirty-five (35) 100kw turbines, eight (8) 500 kw turbines, or two (2) 1.5 megawatt turbines, (or some combination of these options, and not that any or all of these options would be possible.)
For this initial review, we can say there are two types of regulatory issues: (1) local government, and (2) state/Federal. The local regulations primarily relate to land use and siting concerns, while the state/Federal regulations would include electrical utility concerns and environmental permits. And all of these would depend on the size of the proposed wind generator. It should be stressed that local, state and federal regulations are being reassessed and are changing.
The City looks favorably on promoting alternative energy. Paragraph 6 in the "Energy Use and Facility Measures" section of Portland's Municipal Climate Action Plan states:
“The City should explore cost effective small-scale energy generation demonstration projects on City facilities. Such projects, including wind and solar power, offer credible opportunities to show how the City of Portland can play a part in reducing dependence on carbon emitting energy sources. Community support for locally produced energy is growing and the City should be open to using City land in private/public partnerships that reduce overall carbon emissions and potentially benefit the Portland taxpayer.”
However, current City ordinances were not written with wind generators in mind, and the existing height restrictions are prohibitive. The Planning Division is in the process of drafting a new ordinance for wind generators, and we have requested information regarding the approval process that would be involved in siting a wind turbine on the island.
As of today, there are ten Maine municipalities (Addison, Biddeford, Cape Elizabeth, Damariscotta, Eliot, Manchester, Saco, Topsham, and Wiscasset) that have enacted small wind energy ordinances, all since 2006. These ordinances typically apply to small wind machines, not more than 100 kilowatts. Setbacks from property lines range from 1.0 to 1.1 times the total height of the wind turbine. Noise is generally considered the limiting site factor, with requirements that range from a maximum of 45 to 65 decibels, or dB(A) at the property line. (See the table at the end of this report to relate these levels to typical sounds.) The noise generated by a particular wind generator depends on the specific machine, with newer models typically having lower sound levels. Larger wind turbines may need to have a “special exception” approval that would be more involved than these typical ordinances would allow.
At the state level, utility regulations allow a single user to install a single wind generator up to a size of 100 kw, and use the power as a credit for the power that would otherwise be purchased from the electric utility company. This credit system is called "net metering," and it effectively makes the generated power have a value equal to the retail cost of electricity. Any wind generator larger than 100 kw would require negotiating an agreement with a power generation company for purchasing the power at a wholesale rate. At face value, a net metering wind generator may be advantageous because of the higher value of the power generated. A larger project would also need to address the state and federal regulations associated with utilities, environmental impact, and organizing the project's development structure (see below under Economics, Development and Financing.) In any case, it seems clear that professional consultation will be important on any larger wind generation project.
For the purposes of this summary, this issue would include aesthetic impacts as well as strict environmental impacts such as noise and wildlife conflicts. Data about the latter needs to be collected early on in the feasibility process before any wind generator project is pursued. The obvious reality is that a bigger wind generator will have a bigger impact. A study is now being conducted by the Fox Islands Electric Coop to evaluate the environmental impacts of three proposed large wind machines on Vinalhaven with a combined capacity of 4.5 megawatts, and it is expected to be completed in early 2009: http://www.foxislands.net/windpower/
Economics, Development and Financing
Here is where things start to get complicated. A small (100 kw) wind generator project can cost about $250,000. If the annual cost (capital, operation and maintenance) of such an installation is $25,000, and it produces 200 megawatts per year, the electricity costs $0.125 per kw-hr. This is less than the retail cost of $0.16 per kw-hr, and it may be possible to obtain grants to reduce the capital cost, and thereby further reduce the electricity cost.
Larger machines should have a lower unit cost of electrical generation, but the electricity cost needs to be compared to the wholesale cost of electricity, and then there is the whole topic of development structure for a project. It may be inadvisable to put up a turbine that generates more electricity over a year's time than the island actually uses, due to the uncertainty of pricing the excess power, which could pose a risk to investors in the project.
In general, a project could either be a public one, or a private one. One model for public projects is the concept of "community power," in which a cooperative organization is formed with public membership to finance and build a project. An option identified by consultant George Baker at a presentation on Peaks Island on January 12 would be to establish a “Competitive Energy Supply” company to sell power to members of the community at less than the CMP “standard offer” price. From the presentation, it also appears that a public organization can benefit from the same tax incentives and energy credits as a private project.
The private development model is just that: a private developer builds a project and sells the electricity to the transmission company. There are all sorts of tax incentives and development issues that need to be better understood about the range of development models that could be used. It will be important to have professional assistance in this regard so that development risks can be minimized and islanders' interests maximized.
Potential Sites and Designs
It is not just the strength of the wind resource that needs to be considered when siting a wind turbine. The proximity to an appropriate connection point to the electrical grid, and the ability to transport building materials to the building site must also be taken into consideration. A detailed site location study would need to be conducted before any wind energy project is pursued.
As an initial starting point, we could imagine that the Transfer Station site could be suitable for some size of wind generator. Another potential site could be the higher land where the old military observation towers are located. One potential problem with this area is that the City- owned land is protected from development by a conservation easement. This conservation easement does not exist in a 5-acre area that includes the Trott-Littlejohn Park, so this could be a potential site. There could be other possible locations, but they should not be too close to existing houses, so there are not a lot of them.
It is worth mentioning that the larger sizes of wind generators could possibly be installed at an offshore location (such as the ledges between Jewell Island and Outer Green?) This type of project would not be a Peaks Island project, and it would be complicated by the expense of laying underwater cables, which cost roughly one million dollars a mile. However, it may be worthwhile to begin a public dialog about the acceptability of such a project.
An immediate challenge is to figure out how to obtain adequate wind data to be able to evaluate a potential wind project. Wind data needs to be collected using a meteorological tower and computer software. We have identified several inexpensive possibilities for doing this in the near future, so it is also important for us to undertake the organizational steps that would be necessary to apply for any necessary funding. One organizational option would be to acquire not for profit status for PEAT, the Peaks Environmental Action Team.
City personnel have been helpful and supportive with our initial research, and are interested in the direction our efforts take. But until Portland develops a Zoning Ordinance for wind turbines, no project can realistically happen.
Conclusions and Recommendations
More information is needed before any type of "community scale" wind energy project is pursued. Our first priority is to collect wind resource data. Because the location of a wind monitoring tower implies that it could be a site for a wind generator, a thoughtful and reasoned site selection process is necessary. That said, the installation of a wind monitoring tower at any location on the Island will provide information that could be used for evaluating a wind generator in other locations. Any potential site will need to be tentative because all of the potential impacts, regulations, and the economics cannot be known until the wind data is obtained.
The next step should be to get this initial level of information out into the community and begin a dialog about the potential for a wind energy project on Peaks Island. Communicating with islanders about our research can help to build a sense of ownership which would make wind power on Peaks a real possibility.
Sound Pressure Level Examples for Decibel (dB) Values
From Canadian Centre for Occupational Health and Safety