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Solar and Wind are typical but not complete choices |
Every day more and more people
are choosing to become energy independent and less dependent on
the electrical grid. Even those who choose to remain connected to the grid
(Grid Tied), are opting to add some form of alternative energy to reduce their
utility bills and become less dependent on the electrical grid. Some are
choosing to completely disconnect from the electrical grid, or may not even
have access to an electrical grid. Today, Solar Photovoltaic (PV) panels
and/or Wind turbines are becoming a primary choice as an alternative
energy source. Solar and Wind energy is quickly becoming more cost
effective than coal and natural gas that even the utility providers are using
these forms of alternative energy to power or supplement the electrical
grid. For those choosing to utilize alternative energy systems to generate
their own power, they have traditionally had three options; Solar (PV), Wind
Turbine, or a Hybrid Solar/Wind configuration. To a less extent, Micro-Hydro is
also a viable option but is very site specific and requires a steady year-round
source of water and flow such as a river, stream, or spring,
Solar (PV): The use of Solar Photovoltaic Panels (PV) to generate
electricity. The size and number of PV panels in the solar array is
dependent on several factors including; Geography, available space, power
requirements and of course, budget. A 5KW solar system installed in
Arizona will be different than a 5KW system installed in the inland NW due to
the different amount of solar energy available each day in each respective
region. More panels will be required in regions where sunlight is more
limited to capture more sunlight during more limited sunlight period. This also
translates to higher system costs in areas of reduced solar energy in higher
latitudes. Thus a system designed for the inland Northwest must take into
consideration the limited number of hours of sunlight per day,
the extended periods of limited sunlight in the winter months and storage
capacity of the battery bank to store sufficient power through these
periods. This is a much different consideration than that of the similar
size system installed in Arizona which has far more hours of sunlight and very
few days of limited sunlight all year.
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US Solar KWh Per Day by Month
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Wind Turbine: Wind Turbines are another popular choice for generating electricity
and unlike solar energy, can generate electricity anytime day or night, as long
as there is a minimal amount of wind, typically around 5-7 mph. A single wind
turbine can generate as much or more than a large solar panel array. As with
solar, there are several factors that must be taken into account when
considering a wind power system including; geography, site condition (terrain,
obstructions, trees, etc.), power requirements and budget. It is
interesting to note that the areas that are generally more suitable for wind,
also are areas that are not optimal for solar. For example, in the above solar
example for the inland Northwest, where the solar system must be built to
accommodate lower available periods of sunlight, this same area is often more
suitable for wind power with more areas of higher average wind speeds.
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US Average Wind Speeds |
Solar and Wind Turbine (Hybrid): If you were to plot the available solar energy per day by
month for almost any geography you would see that the highest periods of solar
energy are in the summer months and the lowest are in the winter months.
If you were to compare that to a plot of average wind speeds per month you
would see the opposite; that the lower wind speeds were generally in the summer
months and the higher wind speeds were in the winter months. If you overlaid
these two graphs, you would see that wind energy and solar energy generally complement
each other. In a 'Hybrid' system which would include both solar and
a wind turbine, each system would generally compliment the other. In the winter
months where there is less available sunlight, there would generally be more
wind to power the wind turbine. In the summer when there is generally less wind
there would be more solar power available. Thus, a hybrid system could be
used with a smaller solar component and smaller wind component so that the
combined system will generate the required power on a more continuous basis.
Today, hybrid systems are becoming more popular because of these synergies.
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Hybrid Solar / Wind Energy by Month |
While each of the above systems can
be designed and configured to meet almost any electrical power requirements
from a weekend cabin, to a large household with all of the standard amenities
and electrical appliances, they all have a major limitation. Solar systems
do not generate any power at night and times of no sunlight. Wind Generators
must have a minimum wind speed to generate power (often above 7 mph). So even
when using a Hybrid system, there will be times when neither the solar panels
nor a wind turbine is generating any electrical power.
The most important component to any
off grid power system is the battery storage component. Any power generated by
the solar panels, wind turbine, or any other energy source are stored in the
battery bank in the form of Direct-Current (DC) power. This DC power is
then converted to AC power through an inverter. It is this AC power that runs
our standard electrical appliances. The battery bank must be of
sufficient size to be able to handle power requirements during periods when no
new power is being generated. Systems are generally designed to only handle
short periods (2-4 days) of times when no power is being generated. When these
periods are exceeded, or when the system is not generating enough power in
excess of that power that is being used, then the battery levels will drop to a
level in which they must be recharged by another method. In this
condition, a generator is generally used to charge the batteries until such
time as the solar or wind turbines can generate enough power to maintain the
battery to the proper level. A generator is an important component to any
solar, wind or hybrid system as it will ensure that battery bank can be maintained
to the proper level in the event of a failure of one of the solar or wind
components or during periods of outages from either system.
So as you can see, regardless of
which alternative system configuration you choose, there will still be periods
when that system cannot generate power and you will need to have another means
of providing power to the battery bank. As we run these generators,
whether on diesel, gasoline, natural gas or propane, there is an
associated cost of fuel. These costs can quickly add up if there is
a requirement to run a generator for any extended period. What if we
could power these generators with fuel we created, thus eliminating these
additional fuel costs? That might very well be the missing link to
our complete and independent power system.
Wood Gas - the missing link
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Wood Gas Generator
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The process of producing energy
using the gasification method has been in use for more than 180 years. In the
early time coal and peat were used to power these plants. Initially developed
to produce town gas for lighting and cooking in the 1800s, this was replaced by
electricity and natural gas, it was also used in blast furnaces but the bigger
role was played in the production of synthetic chemicals where it has been in
use since the 1920s.
During both world wars, especially
the World War II, the need for fuel produced by gasification reemerged due to
the shortage of petroleum. Wood gas generators, called Gasogene or Gazogène,
were used to power motor vehicles in Europe. By 1945 there were trucks, buses
and agricultural machines that were powered by gasification. It is estimated
that there were close to 9,000,000 vehicles running on producer gas all over
the world.
Wood gasification also regained
popularity in the 1970's during the oil embargo which lead to severe gasoline
shortages in the US. It seems that gasification is something that gains
popularity during times of an energy crisis, only to be forgotten
when the crisis passes. It then has to be rediscovered and relearned when
the next energy crisis arises. Today, gasification is commonly used in
commercial applications, and is gaining popularity as a viable system for home
power generation and emergency backup power systems.
Wood gasification uses
a process called pyrolysis to break down organic matter into its basic
elements, carbon and gases. This process is done in a high temperature, oxygen
limited environment to breakdown the wood into its basic elements. The gas
is then extracted, cooled and filtered and may be used as a fuel for
direct heating applications or as a fuel to power a standard combustion engine.
The gas produced by wood gasification consists of Hydrogen, Methane and Carbon
dioxide, also referred to as 'Syngas' (Synthetic gas). It has similar
properties to natural gas but is not considered natural gas. The syngas
has a different air-to-fuel ratio that must be taken into consideration when
used as fuel for a standard combustion engine.
Syngas also has a lower power rating
than natural gas (50%-60%), which must also be taken into consideration when
selecting an engine or generator size in a power producing application. For
example, a 10KW propane generator would actually produce about 6KW of power
when run on wood gas.
Using proven and efficient designs,
today's wood gas generators can produce clean, abundant, and free
fuel for many application including heat generation, home power systems, and
emergency power systems when traditional fuels are not available or too costly.
Adding a wood gas generator to your
off grid power system will provide that last component to ensure you are
generating your own independent and free power, day or night, anytime it is
needed. In fact with today’s wood gas generators, it is possible to
configure a complete system using only a wood gas generator and standard
generator to charge the battery bank. Depending upon the size of the
system, running the wood gas generator every other day might be sufficient
to provide all of the power needed, without the need for solar, wind or
other alternative energy sources.
If you haven't yet considered wood
gas in your alternative energy system, or if you would like to learn more about
wood gas and its many uses, we would be glad to help you add this missing link
to your energy system.
Steven Honkus
OffGrid48°