Kicking the CO2 habit:Wedding Great Lakes Wind to Water
Wed Mar 08, 2006 at 02:07:34 PM PDT
A 1991 report by the American Wind Energy Association (AWEA) estimated potential US windpower generation at
10,777 million mWh, at that time nearly three times the electricity generated in the United States. A great deal has changed since that time, with improved technology lowering the kWh cost of electrcity generated from windpower, while the introduction of high resolution wind power density maps and growing cognizance of the need to exclude certain land types (urban areas, forested areas, environmentally sensitive lands) has limited the area available for development. Overall, the trend is towards lower costs (both economically and environmentally) and greatly expanded capacity.
I ran into windpower density maps for the first when doing research for an
earlier diary in this series, about the potential for microwindpower generation in urban areas. Generally speaking, wind power densities rated Class 4 on the
NREL wind power density scale or above are suitable for
utility scale development, however adva This
1987 map Wind Energy Resource Atlas shows that significant areas of Class 4 and Class 5 winds exist in the Great Lakes region.
Windpower Potential in the Great Lakes Region
High resolution wind power density maps of Michigan released in 2004 show that while inland areas of the state are not well suited for windpower development, coastal regions in western Michigan and Bay City are well suited for utility scale windpower development. A 2004 NREL assessment that exluded offshore potential and included Class 3 areas sutiable for development with modern turbines estimated that Michigan has the potential for 17,513 MW of installed capacity from wind. To put this into perspective the average American household uses 10,656 kWh annually. Meaning that the Michigan could potentially supply between a quarter and and half of its household energy needs from onshore wind power alone. Including offshore capacity, that percentage could grow significantly, and Lake Michigan isn't the only one of the Great Lakes with significant windpower power potential.
Michigan Wind Power Density at 50 Meters
Ohio Wind Power Density at 50 Meters
New York Wind Power Density at 50 Meters
Limitations
The principal limitation facing large scale windpower development in the best regions of the west coast of Michigan is that much of the lake is far deeper than the 20 meters needed for current offshore technology. As these graphics from the 2004 NREL assessment mentioned above show, there is a relatively limited area where the lake floor is less than 20 meters deep that is suitable for development.
Although Lake Michigan has the best wind power resources in the region, Lake Erie with an average depth of only 19 meters might be more suitable for development due to a wider distribution of sites exploitable with current technology. Cities like Detroit, Toledo, and Cleveland could have offshore turbines producing a significant portions of their electric power supply, and that very potential leads to another problem, offshore winds in the region tends to be seasonal.
As graphic above shows, wind speeds in the region drop in the region during the summer, precisely the time when peaking power is most needed.
Using the performace of GE Wind System's 3.6MW turbine as an example, we can see that while Big Sable Point can be expected to generate around 2 MW during the winter months, during the heavy load months in summer that capacity drops to only around 0.8 MW, meaning that at precisely the time that everyone goes to the lake shore and cranks up the AC, output from offshore turbines plummets.
Without a reliable way to store excess electricty produced during the winter months, the profitablity and reliability of offshore turbines is undermined. And the fabled hydrogen economy is a beautiful vision, but is just a vision at this point. There is however a tried and true techonology technology for storing excess electicity during off peak hours.
Wedding water and wind
Pumped-storage hydroelectric utlilizes power during off peak hours to pump water from low lying areas to higher elevation reservoirs, and then releases that water during peak periods to generate elecricity.
This concept has been proven in Western Michigan at the Ludington Pumped Storage Plant.
One of the world's biggest electric "batteries", Ludington can provide energy at a moment's notice. Its ability lies in its 27-billion gallon reservoir and a set of six turbines that drive electric generators. Those same turbines double as giant water pumps to fill the reservoir with water from Lake Michigan.
At night, when electric demand is low, Ludington's reversible turbines pump water 363 feet uphill from Lake Michigan. The water is pumped through six large pipes, or "penstocks", to the 842-acre reservoir. During the day, when electric demand is high, the reservoir releases water to flow downhill through the penstocks. The flowing water turns turbines and generators in the powerhouse to make electricity.
The plant can generate up to 1,872 megawatts -- enough electricity to serve a community of 1.4 million residential customers. The output is more than double the capacity of any single unit on Consumers Energy's system.
Ludington's relatively simple technology enables the plant to respond quickly to the daily, weekly and seasonal highs and lows of Michigan's energy demand. The plant also saves customers money by enabling Consumers Energy to avoid the expensive spot market when customer demand exceeds the capacity of the company's baseload plants. The immense size of Ludington and its six-unit design offers flexibility in balancing customer demand with electric output on a moment's notice.
Much of the craziness surrounding Enron resulted from the boom in peaking power plants in the 1990's that were designed to operate only during periods in which base load plants were unable to satisfy demand. The prices charged on this spot market were obscene, and only possible because Enron et al used laws passed in the 1970s to promote clean energy to build natural gas fired peaking plants that were not regulated as heavily as base load plants and could charge prices much higher than allowed in the retainil market.
The power of Great Lakes wind isn't that it's going to replace all the coal fired plants in the region, it's that it can end all the talking about the need to repeal the Clean Air Act, and build new coal fired base load plants. By wedding the windpower potential of the Great Lakes region to existing and potential hydropower facitities in the region, we can create a peaking power reserve that doesn't exacerbate our growing dependence on imported natural gas, or resort to dirty fuel sources like coal. In order to make this happen, there has to be coordinated action on the part of state and federal authorities and ideally Canadian authorities as well to develop the resources in the region. In most cases, the lake floor where these wind turbines would be located is owned by state governments, and their agreement is needed to move ahead with any project in the region.
To this end, I believe that a corporation in which state and provincial goverments have a controlling share, should develop the region's wind power potential. I suspect that Canada has far more pumped storage potential than can be found in the US since 70% of Canada's electricity comes from Hydro power, and as well in Canada, these hydro facilities are goverment owned, meaning that by including Canadian provinces there's no need to involve private utlities that focus on short term profit opportunities in the equation. Not only could governments in the region promote green power, they could also reinvest profits into education and infrastructure investments to jumpstart the region's economy.
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