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Kicking the CO2 habit:Wedding Great Lakes Wind to Water

by ManfromMiddletown Wed Mar 8th, 2006 at 06:12:15 PM EST

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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Because climate change is everyone's baby, and because this involves wedding elements like state ownership and international cooperation that are anathema to neocons and neoliberals.  And because the pumped storage hydro might be useful in Europe as well.

And I'll give my consent to any government that does not deny a man a living wage-Billy Bragg
by ManfromMiddletown (manfrommiddletown at lycos dot com) on Wed Mar 8th, 2006 at 06:16:48 PM EST
Man, very cool set of data.

And yes, the devil is in the demand variation. I've been looking around dimensioning for replacing everything by nuclear power plants since your previous diary and the problem is just absolutely maddening (in my case, it's made worse by the fact that I'm trying to replace everything, not just change the existing electrical power plants, so current models of electricity demand are not applicable).

As electricity cannot be stored, the power generation capacity must be dimensioned as a function of peak demand. And the peak to mean ratio is huge.

Just for a rule of thumb for a substitution on existing capacity: according to EIA, in 2004, total annual net production was 3,971,000 GWh for a total generating capacity of 1,050 GW. If all power plants had been running at full capacity all year round with no maintenance stops, the total annual production in 2004 would have been around 1,050 GW x 1 yr = 9,198,000 GWh. So the peak to mean production ratio is 9,198,000 / 3,971,000 = 2.31. This ratio is not directly applicable down to the last decimal : power plant availability is different (and really bad for windmills), seasonal effects are different (thermal power plants are less efficient in hot weather), etc, etc.

But still, 2.31 ... ouch! And for a large share of production capacity in windmills with little backup from gas or coal plants, the ratio is likely to be much worse. 3? 4? May be more?

Also, the pumping stations are OK are intraday smoothing but not so OK for seasonal smoothing. Let's say we want to store 20 GW of capacity during 6 months to deliver 20 GW during the other 6 months. 20 GW seems like a lot but by the scale of the total energy demand of the Great Lakes region - where your example is located - it is actually not that much. You need to store:
  • 20 x 10^9 W x 365/2 x 24 x 3,600 s = 315.36 x 10^15 J

Assuming 2 reservoirs with a 100 m difference and assuming 100% energy restitution (I'm being very nice there) and assuming density of water is 1,000 kg/m^3. Between winter and summer, the quantity of water you need to pump up-hill is:
  • 315.36 x 10^15 J / (9.81 m/s^2 x 100 m) = 321.46 10^12 kg ~ 321.46 10^9 m^3 of water = 321.46 km^3

Let's say Lake Michigan is the lower reservoir (57,800 km^2). Just pumping this water means moving the level of Lake Michigan between summer and winter by:
  • 321.46 km^3 / 57,800 km^2 = 0.00556 km = 5.56 m = 18.2 ft...

I don't know how much the level of Lake Michigan naturally moves between seasons but some lake-shore neighbors may be a tiny bit upset.

So, not even considering actual geographic opportunities, pumping stations don't seem a good option for seasonal smoothing beyond anything but the most marginal contribution.

I'd rather look into [yes] hydrogen, with water electrolysis for production, underground geological storage of the produced hydrogen and the usual combination of combined-cycle and simple-cycle gas turbine power plants which would burn the hydrogen instead of the usual natural gas. The CCGT plants for the bulk of the production can achieve 55% efficiency, may be 60%. Simple-cycle plants (just a gas turbine, no steam turbine) only reach 40% efficiency but are only used for the maximum peaks, once in a blue moon and are really cheap. So factoring electrolysis inefficiencies, storage losses, etc, I'd guess you can get close to 50% restitution.

The economics are probably fairly lousy (you need a lot of electrolysis cells and CCGT plants aren't that cheap) but if, as for a wind-mill, your off-peak hours electricity is virtually free, it may make sense... Upside, now, if you route most of your production through this cycle, it is this part of the electricity production you need to dimension for peak hours, not the windmills, and every hours of wind are actually used. Other upside, the pure oxygen from electrolysis has plenty of nifty usages so this side of the process is not a complete loss either.

I have another objection regarding intraday variations (of electricity demand and wind) but it's really late for me (and I need to sleep) and anyway I'm not sure it's completely relevant if you assume a large intraday storage capacity either pumping stations or my aforementioned hydrogen cycle.
by Francois in Paris on Wed Mar 8th, 2006 at 09:13:19 PM EST
[ Parent ]
I'm thinking that pumped storage might be more useful on the spot market, the very limited market where you can get 100 times the normal price for electrcity.  Stored hydro would have to be principally for this spot market during summer months.  

And I think that pumping from Lake Michigan would have to be limited.  Lake Superior has almost 3 times the volume of Lake Michigan (12,100 km2 for Superior compared to 4,920 km2 for Lake Michigan.) As well, I think that there's a lot of hydropower potential in Ontario and Quebec.

As for hydrogen, I think that it's only a matter of time until it becomes cost competitve. And for geological areas suitable for large scale storage, how about a giant, abandoned salt mine beneath the city of Detroit.  With Detroit being the center of the American auto industry, the implication of having a huge hydrogen supply in close proximity to the vast majority of US auto construction should be obvious.

And I'll give my consent to any government that does not deny a man a living wage-Billy Bragg

by ManfromMiddletown (manfrommiddletown at lycos dot com) on Wed Mar 8th, 2006 at 10:25:38 PM EST
[ Parent ]
I'm afraid this one is no longer fully abandoned but, yes, salt structures are nice for gas storage: very low looses, low cushion, high throughput.
by Francois in Paris on Thu Mar 9th, 2006 at 03:56:04 PM EST
[ Parent ]
for a large share of production capacity in windmills with little backup from gas or coal plants, the ratio is likely to be much worse. 3? 4? May be more?

Around 4 is about right. A month or two ago I showed a calculation that about an eighth of the 21% of the US land area suitable for wind power development 80 m above ground would be needed with this capacity factor. (More if long-distance transmission is to be used heavily for balancing.)

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Thu Mar 9th, 2006 at 07:13:19 AM EST
[ Parent ]
Thanks for the information-rich post. Just a few things:

  • yes, hydro-pumps are the ideal companion to wind power. You just need the right location which can provide for both. If you do have it, like in your case, it should be a no-brainer

  • just so you know, GE has basically given up on the 3.6 MW model. They've had too many problems with it and have stopped promoting it to clients, and are starting from scratch on a new (larger) model

  • the reason peak prices are so "obscenely high" is that the power plant needs to make its revenue over a short period of time. Absolute amounts paid are not that big, because volumes are pretty small. Of course, 3000 $/MWh prices instead of the usual 30-50$/MWh may sound insane, but that's what it takes to clear the market, and it works. No, the real money is made when the marginal baseload plant is an expensive one and everybody starts making out like thieves for normal, regular production over long periods - and that's what's happening when all margina lproducers are gas-fired and gas gets scarce...


In the long run, we're all dead. John Maynard Keynes
by Jerome a Paris (etg@eurotrib.com) on Wed Mar 8th, 2006 at 06:41:42 PM EST
yes, hydro-pumps are the ideal companion to wind power. You just need the right location which can provide for both. If you do have it, like in your case, it should be a no-brainer

I think that this is only workable if Ontario and Quebec are on board.  Since the North American grid is unified, it can happen.

just so you know, GE has basically given up on the 3.6 MW model. They've had too many problems with it and have stopped promoting it to clients, and are starting from scratch on a new (larger) model

I choose the GE model because I thought it was off the shelf.  The Vestas 4.5 MW model they say will be out in 2009, might be even better.  The winds at 100 meters are even better than the winds at 50 Meters. The wind density maps on Astruewind are fantastic.

And I'll give my consent to any government that does not deny a man a living wage-Billy Bragg

by ManfromMiddletown (manfrommiddletown at lycos dot com) on Wed Mar 8th, 2006 at 07:49:22 PM EST
[ Parent ]
There are also two german models for 5 MW, one for 6 MW, and at least one (a Vestas) intermediate turbine for 3 MW.

*Lunatic*, n.
One whose delusions are out of fashion.
by DoDo on Thu Mar 9th, 2006 at 05:04:40 AM EST
[ Parent ]
What happens during the winter when there are lots of ice and snow storms off the Great Lakes? It seems to me that the number of days where conditions are right might not be that large.

Pumped storage requires a lot of land to hold the water. With people freaking out over the small footprint of the windmills I can only imagine the resistance to such a large scale project would be even greater.

Are there any windmills in development where the axis of rotation is perpendicular to the ground instead of parallel as current designs use? This would seem to lower the visual impact as well as the amount of land area needed and might even reduce the bird problem.

Policies not Politics
---- Daily Landscape

by rdf (robert.feinman@gmail.com) on Wed Mar 8th, 2006 at 08:11:00 PM EST
What happens during the winter when there are lots of ice and snow storms off the Great Lakes? It seems to me that the number of days where conditions are right might not be that large.

The technology for this was pioneered in the North Sea, enough said.

Pumped storage requires a lot of land to hold the water. With people freaking out over the small footprint of the windmills I can only imagine the resistance to such a large scale project would be even greater.

This only works if the Canadians are onboard.  Ontario and Quebec have huge hydro power capacity.  As for the NIMBY types who worry about whether this will make their beach house go down in value, when the planet is unihabitable because of climate change I hope they're happy.

Are there any windmills in development where the axis of rotation is perpendicular to the ground instead of parallel as current designs use? This would seem to lower the visual impact as well as the amount of land area needed and might even reduce the bird problem.

Bigger is better in this case. The bigger the diameter of the blade, the slower it's rotation.  Wind shear at lower elevations lowers the wind speed.  

And I'll give my consent to any government that does not deny a man a living wage-Billy Bragg

by ManfromMiddletown (manfrommiddletown at lycos dot com) on Wed Mar 8th, 2006 at 08:37:33 PM EST
[ Parent ]
why not make them communal water sporting spots while they're full?

windsurfing, sailing,child-safe beaches etc, (not jetskis and powerboats)!

aquarius the water-bearer, hmm.

'The history of public debt is full of irony. It rarely follows our ideas of order and justice.' Thomas Piketty

by melo (melometa4(at)gmail.com) on Thu Mar 9th, 2006 at 05:01:02 AM EST
[ Parent ]
From the political viewpoint, one thing to keep in mind is that the entire global Green Party movement was germinated in Tasmania in reaction to a pumped storage hydraulic system.
http://en.wikipedia.org/wiki/Tasmanian_Greens

The problem with them is that while they look like lakes (at least when full), the water level goes up and down dramatically, so they don't work like lakes from the viewpoint of Mother Nature.

Not to say that they can't be done, but there is a potential political issue...

by asdf on Wed Mar 8th, 2006 at 09:44:14 PM EST
Forgive me if I'm intolerably ignorant on the subject.  

But one of the biggest, perhaps THE biggest problem currently facing the Great Lakes is the dangerous level of mercury in the waters (we're told not to eat fish from them, and "dead zones" are appearing in areas), a result of the pollution from coal-fired electricity generation.  

Would windfarms be able to replace some of these plants, decreasing the pollution and restoring the ecosphere of the lakes?  Seems like that would be a serious incentive.

Those who can make you believe absurdities can make you commit atrocities. -Voltaire

by p------- on Wed Mar 8th, 2006 at 11:39:17 PM EST
Yes, at least on a limited basis.  At the very least it could end the argument for dismantling the Clean Air Act to build more Coal fired plants.

And I'll give my consent to any government that does not deny a man a living wage-Billy Bragg
by ManfromMiddletown (manfrommiddletown at lycos dot com) on Wed Mar 8th, 2006 at 11:50:16 PM EST
[ Parent ]
First some nitpicking: average wind speed tells you little about power output. The latter you get by a weighted average. Also, considering today's turbines which stand 80 meters or higher, the 50-m wind maps aren't a good indicator of on-shore potential (I indicated this in my own US potential calculation a month or two ago) - nor of the off-shore potential with large off-shore turbines even if placed low (say a 100 m rotor diameter turbine atop a 60 m tower).

I also note that a less enviromentally-risky alternative to pumped storage is just variable hydropower output - already practised at some places in Scandinavia.

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Thu Mar 9th, 2006 at 05:20:40 AM EST
BTW, could you reproduce your calculation for the Michigan electricity balance?

Also, could you show a seasonal power curve for that region? To my knowledge, in Nordic countries, winter can also be the season with higher demand, due to higher use of electronic devices and heating.

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Thu Mar 9th, 2006 at 05:22:17 AM EST
[ Parent ]
17,513 MW divided by 0.016 mWh (10,656 kWh per household annually) and there are 3.8 millions households in Michigan.

In the US the summer is the peak period because of air conditioing. In the winter the principal heating fuel for the Midwest is natural gas.  Deep lake cooling technology may have limited usefulness in the region reducing air conditioning.

And I'll give my consent to any government that does not deny a man a living wage-Billy Bragg

by ManfromMiddletown (manfrommiddletown at lycos dot com) on Thu Mar 9th, 2006 at 08:53:27 AM EST
[ Parent ]
Is that summer peak period pattern true for the Great Lakes region too, or is it true for the whole of the USA?

17,513 MW divided by 0.016 mWh (10,656 kWh per household annually) and there are 3.8 millions households in Michigan.

I can't see how your calculation works out. 10,656 kWh of electricity consumed annually would be 0.0012 MWh consumed hourly (i.e. an average power need of 0.0012 MW), not 0.016 MWh. You also seem to have forgot the capacity factor. Here is one way how it could be calculated correctly:

Taking 25% for capacity factor, those 17,513 MW would produce 17,513 MW x 24 hours x 365 days x 0.25 =  38.35 TWh annually, while households would need 10,656 kWh x 3,600,000 = 38.36 TWh annually. By pure accident, that covers demand exactly!

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Thu Mar 9th, 2006 at 09:39:05 AM EST
[ Parent ]
I'd blame this on my utter lack of math skills, but I think that the ignorance that cause this is an error in thinking Megawatts are the same as mWh.  And I seriously underestimated the potential as a result :)

Did I mention the report I cited excluded offshore potential, and was comissioned by the Michigan department of Commerce, curious the correllation between demand and supply here.  It's almost as thought they are suggesting that wind can produce all of Michigan's power needs.......

And I'll give my consent to any government that does not deny a man a living wage-Billy Bragg

by ManfromMiddletown (manfrommiddletown at lycos dot com) on Thu Mar 9th, 2006 at 08:31:29 PM EST
[ Parent ]
I think that the ignorance that cause this is an error in thinking Megawatts are the same as mWh

Yes, MW is a unit of the rate of energy production, MWh is the amount of energy produced (e.g. 1 MWh is the energy produced in one hour at a rate of 1 MW). Nevermind - but for future reference, I also note that mWh would not be Megawatt:

1 mWh = 1 milliwatt-hour = 0.000,001 kWh
1 Wh = 1 Watt-hour = 0.001 kWh
1 kWh = 1 kilowatt-hour
1 MWh = 1 Megawatt-hour = 1,000 kWh
1 GWh = 1 Gigawatt-hour = 1,000,000 kWh
1 TWh = 1 Terawatt-hour = 1,000,000,000 kWh

(Sorry for the pedantry, but I am both a chronical nitpicker and an ex-physicist.)

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Fri Mar 10th, 2006 at 04:21:55 AM EST
[ Parent ]
is the normalised way production potential is expressed in the industry - it does reflect weighted averages.

It is a bit strange, but that's how it is.

In the long run, we're all dead. John Maynard Keynes

by Jerome a Paris (etg@eurotrib.com) on Thu Mar 9th, 2006 at 10:52:22 AM EST
[ Parent ]
Average speeds is the normalised way production potential is expressed in the industry - it does reflect weighted averages.

What do you mean? Weighted with the characteristic curve of a "typical" (or test) turbine? Or <v³> averaging? Mean with Raleigh distribution of wind speeds? With Weibull distribution?

In ManfromMiddletown's link, they apparently use the mean with the Weibull distribution.

How different just the wind power densities for the same mean wind speed can be, can be seen on the example of three measuring sites in this NREL table (they used Raleigh distribution), and the first graph on page 18 of ManfromMiddletown's source is also indicative. The turbine power curve, and different turbine power curves are complications on this. Here is a graph from Answers.com, showing 2002 data from the Lee Ranch wind farm in Colorado (power is turbine power and thus includes the turbine power characteristics, the curves are the Raleigh models):



*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Fri Mar 10th, 2006 at 04:08:00 AM EST
[ Parent ]


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