Cost mitigation off Grid

 

Colleagues -

I started a thread a few days back about trying to use PV to reduce
costs for our off grid setup.
That thread is still continuing, but I find it a bit difficult to
follow.

I'd like to obtain your thoughts again, but this time, I feel that I
need to try to focus the discourse by giving more parameters.

We know that we use less than 8kw continuous because that is the max
continuous output of our current propane generator.
It does however have the 13500 "surge" (whatever that means).

Diesel isn't an option for us due to fuel spill and air quality and
permitting issues.

Waste Vegetable oil isn't an option for us due to cost of collection
and purification. We have members who use it already in other
(vehicle) applications, but it is not viable for our main application.

We don't have wood lots for methane converters.

Based on the above restrictions
and the group wisdom
garnered from our last thread,
two technologies seem to hold the most promise:
1) Batteries for energy storage as a first step.
2) Wind - We do have space for a sizable tower and would even find one
advantageous for other uses.

Therefore How do I best SIZE the two technologies.
Where do I find wind values for our site?

We operate normally on Sunday, Saturday, and Wednesday.
How do I size a battery bank and inverters to support the 3 days per
week load?

I see us using about 7 hours per day 3 days per week of 4000- 5000
watts continuous.
The load is primarily small 1/2 horsepower motors, with some lights
and a 600 watt fridge and a 700 watt microwave oven.

thanks again
Phil

 

wrote:


Are these separate, standard sized motors that could be replaced with
the latest high-efficiency motors? Could their tasks perhaps be done
more efficiently by electronically speed/torque/servo controlled
motors? Are your lights modern high-efficiency designs? There must be
a more efficient refrigerator...  Money spent reducing your load
generally gets you closer to your goal than money spent on more
off-grid power.

Loren

 

Phil,

Step ONE is to accurately measure your electrical usage.  Saying that it is
somewhat less than your generator output is not very useful information.

--ron

 

wrote:


I'll second that.  I've just started this page on energy auditing but there is
enough
there to get you started.

http://www.neon-john.com/Misc/Energy_Audit.htm

The reason I use a revenue watt-hour meter instead of something like a
Kill-A-Watt(KAW) is that the power meter's indication isn't lost when the power
goes
out or chugs.  Of necessity, the measurement cycle must be long to capture
several
use cycles.  A refrigerator should be measured for a couple of weeks at least to
capture both weekday and weekend use patterns.  An unmodified KAW resets when the
power goes off, even for a second.  I've developed a mod to add a backup battery
to a
KAW but they don't come from the factory that way.

John
---
John De Armond
See my website for my current email address
http://www.neon-john.com
Cleveland, Occupied TN
If stupidity hurt then there'd be Aspirin in the salt shakers.

 



?????  You can have a gas generator but not diesel?  Strange situation.


The power usage (KW) isn't nearly as important as the total energy (KWH) used
over a
period.  Power usage is primary an issue for sizing the inverter and maybe the
battery system, depending on how long the demand lasts.  The total energy
consumed is
important because it has to be equal to or less than the energy available.

For both your solar and wind options, there is little substitute for actually
doing
an energy availability audit.  That is determining how much solar and wind power
is
actually available.  The NREL database is a good place to start but if my needs
were
substantial, indicating a significant capital investment, then I'd want
site-specific
data.  If you can't find the detailed metrological data from the government then
you
have little choice other than to measure it, particularly the wind.  HomePower
magazine (back issues available on CD) have had some good articles on doing that.

probably the best situation would be to log metrological data for a year while
getting by on what you have now.  I'd take a closer look at diesel in the
meantime,
though.  Given how much more benign diesel is than gasoline if spilled (diesel is
quickly consumed by bacteria), I can't imagine any 'crat preferring gasoline over
diesel.

John
---
John De Armond
See my website for my current email address
http://www.neon-john.com
Cleveland, Occupied TN
There is room for all of God's creatures.... Right next to the mashed potatoes.