Monday, April 28, 2008

Investment advice - sell gold buy lead (acid batteries)

As is, this cottage quickly becomes uninhabitable if the grid goes down. To celebrate Energy Independence Week this July 4, I want to be able to keep the place livable for a week off the grid, even if at a somewhat reduced lifestyle. I propose to do this with a battery-based solar electric and/or wind power system. I'll be dipping into my savings to buy it.

My budget is $5000. I know that the going rate for solar electric is about $10/watt installed, so I can afford about a 500-peak-watt system.

I seem to recall that the sunlight around here is the equivalent of about 5 peak-sun hours per day, so the system would produce at most 2500 watt-hours per day, or 75 kilowatt hours per month.

The average US household usage is ten times that, like 600-1000 kilowatt hours per month. So I have to reduce from that by 90%. People do this all the time for fun, it's called "camping." As camping goes, summer camping at home ought not to be too bad. In the case of this cottage, it helps a tremendous amount that a solar hot water system is already planned and partially completed. I think there's still an even chance Redbeard can get it built by the end of June. If only you can take a hot shower, you can put up with a lot of other stuff.

Energy Independence Week is only a stepping stone to Energy Independence Life. Over time it should be possible to increase efficiency and thereby improve quality of life (to more comfortable camping.) But we won't learn how unless we try.

To see what you can do with your 75 kWh per month, you do load analysis. I eliminated all forms of electric heat before I even started (water heater, dryer, oven, toaster, microwave, coffeepot.) After that, priority goes to any form of pumping, and the fridge. After that, the washer and other toys. Here is what I came up with, listed by energy use, highest first. Thanks to RREAL for the analysis format.



Load



Amps (peak)



Volts



Watts



Hrs/Day



kWH/mo



Fridge



2-6.5



120



184



7.2



40.3



Hydronic Pump



0.75



120



83



8



20.2



Computer



0.27



120



22



12



8.0



Well pump



3.5



220



456



0.5



6.9



Light



0.17



120



20



8



4.9



Internet



0.39



120



32



4



3.9



TV/DVD



 



120



165



0.6



3.0



Well controller



0.04



120



5



12



1.8



Compost vent fan



0.4



12



5



12



1.8



Toilet pump



9



120



525



0.1



1.6



Washer



 4-7



120



145



0.3



1.3



Phone chrg.



 



120



5



2



0.3



Dryer (air fluff)



3.9



120



175



0.001



0.01



Total



 



 



 



 



94.1


Yap, I'm over budget, and I've only got 20 watts of LED light and a half hour of TV a day. Notice that the fridge takes half the energy budget just by itself. Now ask yourself, what sense does it make to spend 500 kilowatt hours a year running a fridge in Minnesota, which has frost 200 days a year? I'll bet I could cut that in half by running a pair of air hoses from the inside of the fridge to the outside of the house.


The table above is sort an all-season analysis. In July I shouldn't need quite as much hydronic pumping. For the week I'm basically planning to cook outside on wood or charcoal.

1 comment:

Douglas Nuttall, P.Eng. said...

In minnesota, you should have enough cold in the winter to be able to freeze water and make ice for the year. Incidentally, you can provide a significant amount of your ventilation air air preheat, prior to the HRV.