Saturday, January 28, 2012

Power #2: How Well Do Our Solar/Wind Power and Communications Work?

(I welcome your comments and questions through the "comments" option below any entry. --Laura)

Power #2: With the bases and tower built over the prior two seasons (see blog entry, “Building the Power Tower,”)  the second summer’s project focused on installing the power and communications components that we bought from Susitna Energy of Anchorage.  These items were hoisted, tested, repaired, and in some cases, replaced over the next few seasons by the skillful remote power team at H and K Energy of Anchorage who flew out with every conceivable tool they might possibly need for each project they anticipated, as well as for troubleshooting any surprises (since the only way back to their shop or Home Depot was by plane).  We all know how important it is to trust and maybe even like the repair people who work in your home.  It is even more important when, in a remote situation, they sleep on your living room floor and eat with the family!  H and K Energy has stayed with us for several days each, once or twice a year, remaining until like magic, I could call my mother and turn on a lamp.  Over the years, I have come to look forward to their companionability as well as yet another high-tech enhancement.  

(Note:  the following article is much more technical than any other on the site.)

The Power Technology We Initially Installed

Onto the very top of the slim 120 foot tower, H and K Energy hauled a Whisper 200 wind turbine with  4 foot blades, built by Southwest Wind Power.   Below that, they attached four Solarworld 75 watt DC solar panels, facing southeast.  Further down are two communications components.  One is a Hughes 74CM Ku/Ka antenna and HN7000S 1 watt modem for Internet reception.  Lowest on the tower is a SmoothTalker to boost cell phone performance.  We estimate that the wind turbine will last about 5 years, the batteries 5 years, the solar panels and other components ten years or until technology changes enough for us to want to upgrade.   Altogether, the tower, its components and the labor invoices I could find added up to about $20,000.   What sort of pay back would that compare to for a single family home in Anchorage?  Although it isn’t an “apples-to-apples” match, it looks like five years, shorter than I thought (see third Power Article).  The overall lesson was how much human and financial effort is required to provide relatively little power, and how much I took for granted in a city.  

Solar and Wind Performance Assessments and “Plan B” Modifications

Because H and K Energy set up Internet access by which we can monitor our power production and usage, we found that although the solar panels were much lower maintenance and lower cost than wind, they also generated less power under optimum summer conditions than we expected.  Perhaps this is due to the fact that we are so far north.  The sun does not progress across the sky in the more or less straight line seen closer to the equator.  Rather, the sun moves in a J or C shape swath overhead, so  perhaps a fixed set of panels captures a narrower range of sunlight.   However, we were delighted to discover that the panels performed better than we expected during the winter.  Although there are fewer hours of daylight, the snow reflected it, increasing the “uptake” during those hours.  Since massive Chinese investment has dropped the price of solar panels that they – and their American competitors – produce, we decided to buy more panels.  But instead of installing static additions on the tower, we chose to build a manual tracker.  This past summer, Bryan and H and K energy dug out a deep pit in which they cemented a really heavy 19.5 foot, 6 inch thick, schedule 40 metal post.  (21 feet would have been preferable, but we couldn’t fit that on the plane, even though this post was strapped under the plane, to the floats).  Over the next few years, we will buy an array of larger panels to attach to a manual tracker.  In this way, we can position the panels to take advantage of the daylight later than our current panels capture, and perhaps by being lower, they will be particularly responsive to snow reflection. We’ll see how that works. 

The wind turbine was more problematic, and that was disappointing because it was so much more expensive, even before solar prices started dropping.  Although we bought a system built to withstand wind and temperature ranges anticipated by our Alaskan service providers, the fact is that Alaska is a land of extremes, and because of the mountains and bodies of water, each eco-system has its own micro-climate.  Over the first two winters while we were gone, our weather must have exceeded tolerances, because there were several breakdowns.   The main problem seems to have been that wind speeds reached such a peak (over 65 mph) that the turbine could not turn out of the stream.  This caused the blades to spin much faster than they were designed for, generate more power than was intended, and overload the electrical system.  As Murphy’s Law would have it, the weakest link in the system is the metal brushes that slide on the cylinder of the turbine's mount to allow the wind turbine to turn toward or away from the wind.  At excessive speed, not only could they not perform, they also burned up.   Furthermore, replacing them would require removal of the entire kit and caboodle which we did not want to do!   Another problem was that when the brushes failed, the shaft had too much play, causing metal to grind against metal which would shorten the life expectancy of the whole system.    

Every Alaskan I know is clever at fixing things before buying something new.  H and K Energy researched modification possibilities for each problem.  We tried the cheapest ones first.  One challenge was to “brake” the turbine from speeding up in excessive wind.  First we tried to create a manual brake, even one as simple as tying down the four foot blades when we left for the coldest and windiest part of the winter, but aside from the difficulty of climbing all the way to the top of the tower, we couldn’t figure out a reliable way to “lasso” the blades to anything without ripping both apart in a wind.    A second challenge was to tighten up the shaft without having to take the entire thing apart.  For this, H and K simply climbed to the top and dripped solder between the pieces that weren't supposed to be moving.  We’ll assess that approach after a winter.  Finally, we agreed to the third and most expensive solution.  It will be a "charge controller" which has three advantages:  it can optimize power production at low speeds, it can read high wind speeds and turn the blades out of the wind and, finally, it can also absorb the excess energy that overwhelmed the electrical system before.   They will install the upgrade this summer.

Communications Assessment and Plan B Modifications

The Hughes 74CM Ku/Ka antenna and HN7000S 1 watt modem have been completely reliable for Internet reception in all weather.  Because Hughes Net has a high priced virtual monopoly in Alaska, we pay for a modest service of 2.0 Mbpsdownload and 300 Kbps upload.  This is slow for loading pictures, and totally inadequate for streaming video, but we never were big TV watchers, so we don’t miss that functionality.  Since most of our Internet usage is for text transmissions, this works well for us and we anticipate no changes.
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My husband's "office"
The SmoothTalker was less reliable.  When it worked, we could plug our cell phones into the power shed and enjoy fine reception anywhere we called.  However, we were stymied by many hours per day or per week when we had no signal at all, and for no predictable reason, like rain, around which we could have scheduled phone meetings.  After two years of variable service, with my husband trying to conduct business calls dressed up like a polar bear in an unheated shed in winter or wearing a head net surrounded by mosquitoes in June, he was ready for a change.  H and K installed a new system which not only expanded reliable reception for many more hours per day and per month but also could be installed in our cabin (after Bryan hand dug a 500 foot trench for the wiring through heavily rooted soil, between the power tower and the cabin).  It was much more expensive than the SmoothTalker, but a huge quality of life enhancement.        

If you visited us at our cabin, your first impression would be that it is much more primitive than a suburban or city home.  Propane lights hang in two corners, a woodstove heats the rooms.  The kitchen lacks a refrigerator, microwave, and dishwasher and the living area features no TV or stereo.  But if you look further, you’ll see a phone cradle tucked in a corner upstairs, two laptop computers recharging on a low bookcase, and electric lamps we light in the winter.   

Only 20 years ago, most Americans had neither Internet nor cell phone, and yet they have become such an entrenched presence in our lives today, haven't they, for learning, business, pleasure, relationships.  On the one hand, this sort of technology seems SO out of place in a log cabin in the middle of nowhere!  But on the other hand, without it, Bryan and I would not have been able to move out to the middle of the woods until after he retired.  I’m grateful that because of such innovations, we can live and work here while we are younger and healthier.  The SmoothTalker and wind turbine may have been unpredictable, but certainly so is our future.     

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