Small and medium size wind generators of about 100 KW each are playing an important role in the power supplied by the Alaska Village Electric Cooperative (AVEC) -- a non-profit customer-owned electric co-op serving 52 villages throughout interior and western Alaska.
Wind power on this scale, and in these conditions, is not cheap. Unlike megawatt scale wind turbines which cost around $1,600 per KW of installed capacity, these smaller generators run around $10,000 per installed KW. Part of that cost is simply a matter of buying on a smaller scale. But according to Brent Petrie, Key Accounts Manager for AVEC, the harsh Alaska conditions are responsible for much of this cost. Building in permafrost has always been tough, especially when that permafrost undergoes seasonal melts that turns it to mush and marsh. As an environmentally sensitive utility, AVEC is careful to minimize damage during installation. Overall, electricity costs from such small scale generation are estimated by Petrie to run around 15 cents per kWh -- three to four times the price of larger scale wind farms in milder conditions.
But the same conditions that drive the price of wind electricity for the AVEC customers drive up conventional sources even more. Fuel is shipped by barge to the small isolated communities, or even flows in, meaning that electricity is supplied by diesel generators run on the most expensive of fossil fuels. Since transporting large amount of fuel is an expensive prospect, normally fuel is delivered only once a year.
According to Petrie, AVEC tries to make sure that as a cushion each village has storage capacity for 13 months of fuel. Building a diesel storage facility on permafrost is an expensive prospect too. Combined fuel purchase, shipping, and storage for diesel in these villages runs between 13 cents and 25 cents per kWh -- even before purchase and maintenance of generators is considered. Overall, electricity to these villages averages 45 cents per kWh; so the 15 cents per kWh for wind electricity represents a real savings.
The units chosen are adapted to the climate in hundreds of ways large and small. For example, the units are direct drive, rather than using gear boxes, to minimize maintenance. Blades are painted black to maximize heat gain and minimize icing. The nacelles (hubs on which the turbines rote) are enclosed to protect against cold. Since the villages are not part of a larger grid, any power the turbines generate in excess of demand boils water in dump boilers. The heat from these is used for space and hot water needs.
I think this illustrates how useful small-scale wind can be for small villages and farms where connection to a larger grid is unavailable or uneconomical. But it also illustrates why, where a larger grid is practical, large-scale wind will always out compete small-scale wind on cost.
Eric Hoffner recently posted about Edison's dream of a wind generator for every house. I think the Alaskan experience helps illustrate why that dream is no more realistic today than it was in Edison's time. Small and micro wind will, as now, be useful for certain small and micro purposes. They won't replace utilities; the economies of scale in planning, construction, and maintenance are just too large to give up.
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Comments
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Delay And Deny Posted 5:10 am
09 Jun 2007
I mean, there must be some type of sub-microscopic nano technology that would allow air to pass through it and make electricity.
Also for a place like Alaska, you could probably coat a few acres with windmills the size of oscillating desk fans and produce the same kW as these (still gargantuan) "medium" ones.
John Bailo, The "Denier Guy"
You Read It Here First
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Gar Lipow Posted 5:42 am
09 Jun 2007
As to micro turbines: a field of micro turbines would increase the price again. remember as you multiply turbines, you multiple generators, towers, a whole bunch of expenses.
That is why building integrated wind tens to play such a minor role: you can buy a small wind turbine in a vibration proof box that will integrate into a single family home. But the cost per peak KW will be much higher than a conventional wind generator; you will use a much smaller percent of that capacity than a conventional wind generator. So your cost per kWh will be as high or higher than a PV array. Wind really does have huge economies of scale. Big wind works better than medium wind. Medium wind works better than micro wind.
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amazingdrx Posted 9:44 am
09 Jun 2007
http://amazngdrx.blogharbor.com/blog
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Gar Lipow Posted 10:05 am
09 Jun 2007
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amazingdrx Posted 11:00 am
09 Jun 2007
http://amazngdrx.blogharbor.com/blog
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Gar Lipow Posted 12:04 pm
09 Jun 2007
In terms of batteries. The problem again is that these are small offgrid villages. Each village is its own little microgrid of a few hundred people. Flow batteries and capacitors are at minimum price in the ten and hundred megawatt hour range. In villages this size, they would be buying more in the 10 to 100 kWh range. That would put storage costs in the 30 cents to 40 cents per kWh range. Add that to the cost of wind electricity and you are well past the break even point to costing their customers money if they put in storage.
The problem here is one of scale. Large villages could buy cheaper wind generators and storage. Then again larger villages could get cheaper fossil fuel based electricity as well.
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amazingdrx Posted 2:22 pm
09 Jun 2007
As diesel rapidly rises some sort of combination of wind and renewable backup like biogas or storage may become cost effective.
Biogas fuel cell/microturbine would be in the right power range.
Could hydro pump storage work in a very cold climate for a small local grid with a few hundred homes? It's a facinating challenge in fact.
How about a water holding pond underground or under a dome that stores water pumped up from groundwater level that then generates power from the water dropping back down the well?
It could be economical if the wind machine were coupled directly to a shaft going down the well that ran a pump. Then the power would come directly onto the grid from a generator when the wind was blowing and the well pump would also be storing water power. When the wind slows or stops a hydro power generator could kick in.
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Gar Lipow Posted 3:44 pm
09 Jun 2007
Biogas? How do you generate it. Remember: cold climate cloudly climate north latitude not much sunlight. Biomass productivity per acre is much much lower than world average. The average household in these villages uses 400 kWh per month. Since currently about a third of this can be produced from wind in many villages, that leaves about 280 kWh to produce from renewable backup or storage if you want to further reduce diesel use. Don't think your average household will produce enough biowaste to produce biogas to generatet that many kWh.
In terms of storage, one way to look at it is that wind costs 15 cents per kWh. If you store the wind storage losses will add as much as another nickel to that cost, due to electricty losses. So stored wind costs 20 cents per kWh before you add the actual capital cost and O&M of whatever you store it in. Electricity averages 45 cents per kWh in these villages, but part of that is the tiny grids within the village, the cost of administrationa and finance and so on. So you are looking for a storage means with a combined capital cost and O&M of no more than ten cents per kWh over the lifetime of the equipment (including delivery, finance charges, and end of life disposal). And even that may be high, because I'm assuming the 30 cents out of a 45 cent total cost is generation.
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GreyFlcn Posted 3:56 pm
09 Jun 2007
http://science.slashdot.org/article.pl?sid=03/08/28/14621 ...
It's large physically, but not very large in capacity.
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amazingdrx Posted 11:22 pm
09 Jun 2007
If renewables and conservation could tackle this situation, they could work anywhere? Antarctica? Well maybe this first.
The money is there to pay 45 cents per kwh and that figure is rising with fuel costs. At least they could afford a solution that comes in around 30 cents. Still fascinating. I'm not giving up. Will revisit this one. I dare you guys to do the same. A challenge, hehehey.
A dome covered pumped hydro pond could also grow algae for a biomass backup, but how to deal with the permafrost? True long winters limit algae growth, but lobng summer days would make up for it maybe? The covered pond could use a heat envelope using groundwater heat from under the permafrost layer? Hmmm...
http://amazngdrx.blogharbor.com/blog
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amazingdrx Posted 11:35 pm
09 Jun 2007
I wonder what the temperature is say 100 feet below the permafrost?
Get that heating load down, use super efficient appliances, and maybe batteries would prove economical. Heat pumps operating from underground temps and a heat envelope around each home circultating from groundwater in cold winter months might reduce that 400 kwh per month figure way down?
And rather than storing electric power to backup the 400 kwh per month per home, why not instead store heat in each home with heat storage salt compounds like sodium sulphate decahydrate? When there is extra strong wind, resistance a heat pump working from groundwater heats the heat storage salt solution in each home.
This is a great puzzle to consider while running my marathon training runs. Thanks for another great article Gar. Much appreciated.
http://amazngdrx.blogharbor.com/blog
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amazingdrx Posted 11:38 pm
09 Jun 2007
http://amazngdrx.blogharbor.com/blog
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Gar Lipow Posted 4:32 am
10 Jun 2007
>He would place a dome over the village, hehey.
I grew reading Bucky (which may explain something about me). But a dome over the village would melt the permafrost permanently.
If you can come up with a solution for these Alaskan villages, that is wonderful, and I encourage you to continue thinking about. But also consider that a very tiny percent of humanity lives in these conditions. So if worst came to worst, as long as we supply the 99% of humanity who are not in isolated villages on permafrost renewably, we can afford ecologically for those villages to run on fossil fuels. (I'm considering not just the villages in Alaska, but related cases in places like Siberia and Finland which also have a certain number of people living in small isolated groups.)
BTW 400 kwh per household per month is actually pretty efficient. Consider that typical monthly consumption for the U.S. is 800 kWh. Typical consumption for S. Cal is 600 kWh. So they are using 2/3rds of the electricity of your typical S. Cal household in Alaska. Geothermal heat? Again, you risk melting the permafrost. Because of the permafrost you want to minimize what you do underground. g
I think part of this challenge if you want to do something seriously on this is learn the particular conditions. For example, I note that they are using diesel instead of natural gas -- in spite of the fact that you could use the same barges that ship in diesel to ship in natural gas. I'll bet two things:
There is a good reason for this.
If you know that good reason you know more about conditions there.
Another question: to what extent is that 400 kWh per month devoted to heating? How much use do they make use of wood in that area? The use of dump boilers seems to imply that there is some electric heating going on, but maybe those boilers are reducing the need for wood chopping rather than electricity use. Believe me, if you have to chop wood for heat, being able to reduce that would be popular. Again, knowing local conditions is important.
If a lot of that electricity use is for heating, than one solution might be to find a cheaper way to do pure dump boilers -- wind alone or even wind and sun combined with above ground seasonal storage to provide district heating. Years ago, there were some attempts to use wind to drive giant brakes and produce heat direct from friction. The theory was that where you used wind electricity for heat,skipping the electric stage might save capital costs. As I remember, it proved to be untrue. The mechanical transmission of power proved more expensive than producing electricity and using it to drive resistance heating.
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amazingdrx Posted 10:37 pm
10 Jun 2007
Is there electric heating going on? Not sure. First thing that comes to mind now is use the cogeneration waste heat from the diesel generators. I bet they are heating homes with diesel too.
A zero diesel or other fossil fuel solution, 100 % wind would be nice. I know it is a special case, but rather than justifying diesel use (the thinking would be, they live on oil profits that follow fuel inflation, so as costs go up, so does their income, but how long will oil and oil profits from alaska last?), I think this cries out for a renewable wind solution.
Regardless of ground temperature I believe that simple resistance heating with extra wind from peak production stored in a heat storage phase change salt like sodium sulfate decahydrate could do the job. Along with a smaller higher temp molten wax storage for cooking and hot water heat storage.
The homes would need to be super insulated and use very efficient appliances. This is a lot like the 100% wind powered Antactic home thought experiment I have proposed before.
No takers then either, hehehey. Oh well.
Yep, me too on Bucky.
What about buffering between permafrost and the dome perimeter with a cooling envelope that stores cold below the normal freezing point with salt water? Then insulation between the dome and the cold storage zone?
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lvong Posted 6:33 am
14 Jun 2007
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gmunger Posted 7:14 am
14 Jun 2007
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