Monday, January 30, 2012

Power #3: Our Solar/Wind/Generator Power Compared to City Power Costs

Power #3:  Besides solar and wind power, our other fuel sources are wood and propane (and a backup generator). 

How do our costs contrast to traditional utility rates in a similar climate?  For comparison, I looked at municipal utility/service costs for an average single family home in Anchorage.  It is not an apples-to-apples comparison, because those residences are surely bigger than our little cabin, and sport a flushing toilet (those lucky people) but by adding our outbuildings (the shower/wash house, outhouse, pantry shed and tool/power shed), many of which have electricity and one of which has water service, it may be an informative comparison.  

The results of the analysis: On all utilities/services that can be accomplished by human labor or portable devices, our costs are far lower than city rates.  However, on those utilities that require infrastructure, our costs far exceed those of city folk...for the first several years.  See below for details and conclusions. Do you find any ideas for your home?


According to various websites, the following Anchorage expenses are $4064/yr as follows:    gas: $1140 (of which $960 is heating), electric: $1200, water and sewage: $1108, garbage collection: $160, and waste collection: $206.  I also added a cord of firewood for $250):   (I did not include monthly telephone and Internet service charges because we pay such fees, too.)  (FYI: Anchorage pays 35 cts per 100 cubic feet of gas, plus a monthly service of about $4.50.  The electric companies charge about 8.7 cts/kwh plus a monthly service charge of about $7). Note:  Houston, TX, the “power capital,” pays the highest electricity rate in the country: 18 cts/kwh, because it is generated from coal brought by train from Wyoming and other remote places). What are your rates for electricity and gas?      

 How much did/do our power/services cost?

For home heating, our costs are zero, other than the cost of the gasoline that powers the chainsaw Bryan uses to chop down birch trees for our small and efficient woodstove.  Since he enjoys the exercise he derives from hand chopping them into usable pieces, I did not add a cost for that labor.  It replaces a city gym membership.   A log cabin is inherently well insulated, and our logs are 12-16 inches thick.  So we surely use less wood for heat than would be needed by the skimpy plywood cabins scattered through the state, or perhaps even less than a slapdash construction in the city.     

 In the winter, I often cook on the wood stove, since it is already heating the cabin, as well as the propane range.  During the rest of the year, I cook primarily with propane.  Since filling the hundred pound propane tank that powers both the stove and an on- demand water heater costs $100 and lasts about 3 months at peak use, an annual bill would be less than $400.      

 For water heating, our costs are presumably comparable to any small family that uses an on-demand heater instead of a traditional one.  A 100 lb propane tank can heat the shower for four years (for 7 months per year, since we use lake water), or $25/yr.  I recommend an on-demand heater to any home owner anywhere.   

 Our refrigerator is powered by one 100 lb propane tank per year (we don’t run it in the winter months) at $100/yr.  The cold-hole we dug as a refrigerator alternative has no fuel costs.

 For garbage, waste, and sewage collection, we have no costs either.  We burn or mulch all trash and garbage except for glass and metal.  Glass gets hauled back to town a few times a year (but we try to avoid buying glass).  Metal, such as paint containers and construction components, we store in an old boat in the woods until we dig a deep pit for some construction project, like the solar tracker.  Then we bury it.  For human waste disposal, we have an outhouse.  Gray water from the kitchen and shower/wash house drains into perforated 55 gallon drums sunk into rock filled holes beneath the buildings.  

The lake provides plenty of fresh water.  Delivery to the cabin and shower house by hose instead of in 8 gallon jugs as we did the first two years cost $300 for a lake pump and more for hoses.  Well worth the price!  (In fact, shortly after we accomplished this, our full time neighbors dug a trench from their well to their cabin, to deliver their first interior running water in 12 years.)    To clean the water, H and K Energy  installed a multi-stage filtration system that cost about $2500, all in.  One tap delivers potable water to the kitchen sink.  The water to the shower, washing machine, and other sink for dish washing is filtered, but not drinkable.  Our only recurring cost is to replace filters each year for about $30.  What a contrast to the $1000/yr paid in Anchorage!      

The lion’s share of our utility bill is electricity, and the generation costs are high for the little electricity we produce.  The power tower, solar panels, wind turbine, hired labor, lake pump, and backup generator totaled about $19,000.  The only recurring cost is $1-2/day or $150 - 300/summer) for ¼ - ½ gallon of gasoline to charge the batteries with the backup generator in periods of low sun and low wind in the summers (because the only absolute daily requirement is to keep the freezer cold).   So what is the delivery cost?  If I divide $20,500 (tower, pump, generator + gasoline) by the expected 5 year lifespan of the components with the briefest anticipated duration (the batteries and wind turbine), the delivery cost is $4100/yr.   In other words, our cost for electricity alone is nearly equivalent to the costs of all the municipal utilities and services offered to Anchorage homes (including a nice fire in the fireplace). 

But look again.  Because we pay very little for anything besides electricity (just $550/yr for propane and water filters), our five year amortized bill for everything is not much more than the annual bills paid by a home owner in Anchorage.  Note too that since most of our costs are nonrecurring and since upgrades and replacements will take place at 5, 8, even 20 year intervals, our utility costs could drop 80% after the first five years.  We anticipate that the differential between off-grid and on-grid utility/service budgets will widen as municipal rates (and property taxes) rise in the future, in response to declining state and federal investment in local utility infrastructure.    

In this regard, city folk whose fees are creeping up may be able to estimate attractive payback times for investments in non-recurring or infrequently replaced utility/service enhancements or alternatives for energy efficiency.

How much power do we use?

What do we get for our investment and what do we give up?  We have use of two computers, cell phones, lamps (with LED bulbs) during the winter, short-use kitchen appliances (blender and a food processor), short-use office equipment (a printer), a chest freezer (powered 3-4 hours per day), a washing machine and the lake pump.  That’s about it.  Even this modest draw needs to be staggered.  For example, if we ran the freezer, washing machine, and shower at the same time, and then the lake pump kicked in to refill the cistern, the system would overload and shut itself off.    


What do we do without?  We have no heat generating appliances, like dishwasher, dryer, iron, hair dryer, food dehydrator, coffee pot, or crock pot because any devices that create heat are THE monster gobblers of electricity of a household utility bill.  Any home owner can read startling data on the Internet or measure the difference by doing without these for a month.   Neither do we have electronic entertainment devices, like TVs, stereos, radios at our cabin, other than our computers and a ham radio.   

These decisions have required some adjustments, of course, primarily in terms of spontaneity, as we wash and cook in ways that our grandmothers may have done.  When I wash laundry, I line-dry it, which can take most of a day.  There is no quick reheating or thawing in a microwave, so food preparation and meals are planned… or changed.  However, I can pressure cook meals in 20 minutes on the stove that took 6-8 hours in an electric crock pot.   By carefully monitoring the temperature during the summer, we found that the chest freezer stays safely cold when powered only 3-4 hours a day.   Because I was so disappointed by the performance of an expensive propane powered refrigerator whose motherboard (?)  quit about a day after its warranty expired (and then cost a great deal to replace), we dug a low-tech cold-hole that keeps food between 40 – 50 degrees all summer, depending on the depth of its storage.  The structure, designed by our clever friends at H and K Energy is amazingly simple and effective.  Two – 55 gallon drums were glued together and sunk vertically in the ground.  The top few inches rise above ground level to evade flooding and snow melt.  The lid is a thick slab of polystyrene.  Food is stored on a series of clear, lexan shelves raised and lowered on a chain from a boat winch hanging on a beam above.  We need to do a better job of adjusting the humidity in the interior, but it proved its use to me its first summer, as a cool place for long storage of fruits, vegetables, and cheeses.   


In conclusion, for those who picture life in the bush like the gold miners of old, power usage could be nil and costs, other than personal labor, close to zero.  Portable enhancements like a propane powered stove, refrigerator, water heater and lake pump are not that expensive.  They add an annual “utility bill” of under $1000/yr.  It is only by adding electrical appliances that costs escalate above four digits, and if you pay that up front, the expense tails off sharply.  I am sure we will have thudding surprises as one component or another has a seizure at a terribly inconvenient time, and in anticipation of that, we have low-tech alternatives, like the cold hole for the refrigerator, camp showers for the lake pump/water heater, hand pumps for the filters, and a firepit and wood stove for the propane stove.  Overall, this analysis revealed to me a shorter pay back than I expected.  What the differential is for people in warmer climates and cheaper utility markets, particularly for people who live on a road system, is for interested readers to explore.  I’d be interested in what you find out.  

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

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