Monday, January 24, 2011

COPING WITH THE COLD WHEN OFF-GRID

Cold weather is bad at any time  but when off grid it can  really  become a problem. Heating the  living space with a wood stove  may not be the solution needed when coping with frozen pipes,  non starting vehicles  and non-functional water pumps.
Last winter, when  our pipes from the water well froze  I attempted  to use a propane  heater to warm up the place  where the pipes were located. The propane torch started off fine but within minutes the flame dwindled to nearly nothing. The temperatures were  -35F below so I brought the  torch indoors to see why it did not work.   Nothing seemed  wrong.  The tank apparently had  some gas left in it. Tried again  with same results. Finally changed tanks  and it  did work.

A post  mortem   gave me the answer. It was so cold that the liquid in the propane tank would not vaporize.  Lesson learned  propane will not  vaporize at extremely low temperature. Butane and Gasoline will continue to vaporize at -35 below.
An emergency generator  should be fuelled by gasoline, not diesel  in order for it to start  in extremely cold weather.  A diesel  relies  entirely on heat to ignite the fuel /air mixture. In extremely cold weather  most diesels require glow plugs  to assist  starting but  how to power the glow plugs when no power is available from a flat battery.

If you are going to depend on any kind of solar charger  be sure it is the kind that will work with  UV and  deliver some kind of charge even under  cloudy skies.

The  Canadian Coast Guard  has a design specification for their ice breakers  that could be adapted  for use  in off grid situations.
The design criteria  calls for  the ability  to let  a breaker  be abandoned in the ice for a year  or more. A two or three  man crew  should be able to  air lift by helicopter  and  using only a butane torch and muscle power be able to get the ship restarted and all systems  up and running  in only a few hours.  Sound crazy?  Here is how.

The key is to have a small  one cylinder  engine  that you can  pull start  by hand, even in the coldest  conditions. The hand held butane torch will ignite even  at very low temperatures. The small engine  intake manifold  is entirely metal so a blow torch can be applied directly to heat up the manifold  as a way to preheat the air  going into the  combustion chamber.  Be careful when applying  this method to  consumer engines because they use many plastic parts  instead of solid metal.

This small engine  drives a compressor to pump up the compressed air bottle  used for starting  a generator motor.  Cold diesels  will require glow plugs or  some kind  of starting fluid. ( actually vaporized fluid)  Ether is considered  too harsh for  use on a diesel so use propane or butane. With the generator started, you can now  get lights  and  drive  the bigger compressor to recharge the main engine air start bottles.  The  big electrical  generator  will also facilitate  using electric  glow plugs   for getting  cold diesels going  as well as driving big heaters for the interior of the ship.



So how does this relate to being off grid?  The ice breaker is off grid when frozen in the arctic ice.  Consider a homestead in the frozen winter after a week or so of  cloudy, snowy weather.  The battery bank  will eventually become so depleted it will not even light up an LED light never mind  power any fans for moving  warm air from the wood stove to other rooms in the house. There will not be enough power for  driving heat trace cables to thaw out frozen pipes or run the well pump.

Snow blowers  have electric start  engines for cranking in cold  weather. These  electric starters are 120V AC  based on the assumption  the house is grid connected.
I have looked  but failed to find any 12V DC starter equipped small generators  in the 2kw  size. All of them are intended  for  camping use  in warmer  climates. 
It is only when you get into bigger sizes do you get an optional electric start from a 12V battery.  For technical reasons so large a generator may not be a good bet for an emergency generator.
Bear in mind that a lead acid battery  needs regular and periodic maintenance  and use to remain usable. Sitting unused  in cold weather is  sure to  ruin a battery.

There are portable power packs available in the automotive stores  specifically intended to  boost cars  with flat batteries.  These  packs  are perfect for  starting  small generators   which  in turn are good for  recharging  the depleted battery. I have  personally started  big  V6 and V8 engines four times with such a portable power pack that was fully charged.  A solar  charger can maintain such a pack at peak charge  after being  charged up by other means.  With enough time, a solar panel could even recharge such a pack from complete discharge.

For off-grid emergency restart after  the wind or solar powered  battery bank got depleted  by a prolonged winter storm a very small gasoline fuelled  generator  is  the solution.  It will not be large enough to power your whole house hold but it will get you going again.

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