Note: Descriptions are shown in the official language in which they were submitted.
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HAY-BASED FUEL LOGS AND METHOD OF MAKING THE SAME
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] This invention was made using funds obtained from the US Government
(USDA Rural
Development Grant ¨ VAPG) and the US Government therefore has certain rights
in this invention.
BACKGROUND OF THE INVENTION
Field of the Invention.
[0003] The present invention relates to alternative energy and, more
specifically, to a log
formed of hay and a binder. The log can be burned for heat.
2. Description of the Prior Art.
[0004] Stoves and other burning devices are a very desirable way of creating
heat insofar as
they can be economical, simple, effective and pleasant to experience. However,
burning wood can
be problematic because trees are a very important natural resource, they are
very water and time
intensive to grow, and don't necessarily deliver the desired heat. Moreover,
many states have laws that
limit the transport of firewood from one state to another because of bugs and
disease that the wood
may have. Hay, on the other hand, grows with a minimum investment of time and
water. There is a
surplus of hay in the United States. Moreover, because non-wood logs do not
have the same
potential bugs and disease infestation problems as do wood logs, non-wood fuel
logs can be
transported from state to state. There is a need for reducing wood-based fuel
for heating, and
increasing hay-based fuel for heating. More specifically, there is a need for
hay-based fuel.
Preferably this fuel would be easy and economical to produce, transport and
use; safe;
environmentally friendly; use materials readily available; be usable in pre-
existing burning devices;
and be capable of delivering heat at a desired level.
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SUMMARY OF THE INVENTION
[0005] It is an object of the present invention to provide a hay-based fuel.
It is also an
object to provide such a fuel that is fabricated relatively easily and
economically. Further, it is an
object of the invention to provide a hay-based fuel that can be transported
and used safely and more
easily than wood logs. Yet further, it is an object of the present invention
to provide a hay-based
fuel that is environmentally friendly and is formed of materials that are
readily available. It is an
object of the present invention to provide a hay-based fuel that can be used
in pre-existing burning
devices and delivers heat when burned of satisfactory intensity.
[0006] These objects are achieved with the present invention, which is a hay-
based fuel log
and the method of making the same. The fuel log is formed of a combination of
pieces of hay and
a binding agent. The hay pieces and the binding agent are compressed together
into a solid shape.
That shape may be selectable. One suitable shape is cylindrical so that it
appears to look like a
log. The invention is not limited thereto. It is believed that hay has not
been used as the basis for a
fuel log. Instead, available fuel logs are either natural wood, wood-based or
made of artificial
materials.
[0007] The hay-based fuel log is fabricated so that the majority of the hay-
binder
combination is made of the hay. The hay may be 70-80% by weight of the
combination but not
limited thereto. The binder is selected to be sufficient to keep the hay
pieces joined together in its
selected shape. The binder may have thermal characteristics that enhance the
thermal
characteristics of the hay. The hay-based fuel log is fabricated by mixing the
hay and the binder
together and then compressing that mixture together with sufficient pressure
to enable the binder
to retain the hay pieces together. The mixture may also be heated to increase
the binding of the
hay pieces together.
[0008] The hay and binder combination is used to establish a fuel log that
generates heat
when fired. The amount of heat generated is dependent on the binder used. In
one example, the
binder is a wax such as paraffin. A wax-hay combination for a fuel log that is
approximately four
inches in diameter and approximately 12 inches in length generates
approximately the same
amount of heat as a dried log of similar dimensions. The hay-based fuel log
can be used as a
replacement for wood logs as hay is plentiful. The hay-based logs are
relatively easily transported
and can be used safely and more easily than wood logs. The logs can be made of
a selectable shape
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and so they may be used in pre-existing burning devices.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a flow diagram depicting the major steps in producing the hay-
based fuel
log of the present invention.
[0010] FIG. 2 is a perspective view of a representation of equipment used to
make the hay-
based fuel log of the present invention.
[0011] FIG. 3 is a table showing the hay-based fuel logs fabricated using the
equipment of
FIG. 2 showing the conditions of fabrication and resultant log quality.
[0012] FIG. 4 is a table showing the results of testing done on certain ones
of the hay-
based fuel log formulations of FIG. 3.
DETAILED DESCRIPTION OF THE INVENTION
[0013] The following detailed description is of the best currently
contemplated modes of
carrying out exemplary embodiments of the invention. The description is not to
be taken in a limiting
sense, but is made merely for the purpose of illustrating the general
principles of the invention, since
the scope of the invention is best defined by the appended claims. It should
be understood that cutting
hay is an inherently imprecise endeavor. Accordingly, 1/8" hay stems should
not be construed to
mean that substantially all stems are this length - rather this is the
intended length but smaller
fragments and uncut stems will invariably be included.
[0014] Referring to FIG, 1, a method 10 of forming a hay-based fuel log of the
present
invention is shown. In step 12 in forming a hay-based fuel log is to obtain a
bale of dry hay. This bale
of dry hay should be standard, matured hay that is dried to approximately 5%-
15% moisture, and
preferably approximately 10% moisture. In step 14, the hay should be put
through a grinder,
hammer mill or other suitable machinery which reduces the stem length of the
hay to
approximately 1/8".
[0015] In step 16, approximately 70-80% by weight of processed hay is mixed
with
approximately 20-30% by weight of a binder or a blend or combination of
binders. One suitable
binder is chopped wax such as paraffin, which is commercially available as
Paraffin Slack Wax,
available from Hase Petroleum Wax Company, of Allenton Heights, Illinois.
Another suitable
binder is non-polluting plastic, which is commercially available as PETE
polyethylene, available from
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Alpha Omega Plastics, of Elk Grove Village, Illinois. It should be noted that
"non-polluting", as used
herein, means plastics that meet or exceed the Environmental Protection Agency
standards for non-
polluting. It should also be understood that recycled plastic may be used,
such as that obtained from
post-consumer water bottles, shopping bags, etc. Another suitable binder is
com starch, which is
commercially available as Com Starch Endosperm of the Corn, available from
National Starch, LLC, of
Indianapolis, Indiana. Potato starch may also be used as the binding agent.
[0016] The heat content of the log is dependent on the particular binder, or
blend of binders,
used in forming the logs. By way of example, employing wax as the binder
yields a hay-based log
with the highest British Thermal Unit (BTU, a measure of heat content) rating,
the use of a plastic
binder for the log yields a lower BTU rating than that of the wax-based log,
and corn or potato starch
binder for the log yields a BTU rating lower than that of the plastic-based
log. Those relative heat
content values are based on the same binder content-to-hay ration for each.
Logs with particular heat
content ratings may be selected by consumers as a function of desired heat
output. For example, some
heating devices, such as wood stoves, should not be fueled with fuels that
burn too hotly.
[0017] Returning to FIG. 1, in step 18, the binder and hay mixture is formed
into the hay-
based log. This is accomplished by filling a compression device, such as a
press die, with the
mixture of binder and processed hay and subsequently applying approximately 12
tons of pressure to
the mixture. The contents of the press die may also be heated to enhance
binding of the hay pieces.
The press may be a wood pellet machine press, or similar type of press,
modified to use a different die
with a larger diameter than a die used to form wood pellets. The resulting hay-
based fuel log can be
substantially cylindrical in shape, with an approximately 4" diameter and an
approximately 12"
length. The hay-based fuel log can be cooled after the compression step and
packaged or otherwise
processed for transport.
[0018] FIG. 2 shows an example system 30 for making the hay-based fuel log of
the
present invention using the steps described herein. The system 30 includes a
double-walled
containment tube 32, a first hydraulic cylinder 34, a second hydraulic
cylinder 36 with end cap 38
and re-circulation tubing 40. The containment tube 32 has a four-inch inside
diameter. The
containment tube 32 allows for a heating or cooling fluid to be re-circulated
through it to control
the temperature of the log making process. The first hydraulic cylinder 34 is
arranged to compress
material within the containment tube 32 and the second hydraulic cylinder is
arranged to cap the
opposing end of the containment tube 32 to establish substantially uniform
pressure on the contents
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within the tube 32. The re-circulation tubing 40 connects a source of heat or
cooling, such as hot
or cold water or steam, to the space between the two walls of the containment
tube 32 for
introducing heating or cooling to the hay-binder mixture within the
containment tube 32. The re-
circulation and temperature control of the heating/cooling fluid may be done
with a Delta-T oil
heater. FIG. 2 shows a hay-based fuel log 42 of the present invention being
ejected from the
containment tube 32.
[0019] The system 30 was used to make 15 examples of the fuel log 42 at the
University of
Maine Process Development Center of Orono, Maine. To produce the hay logs,
bales of hay from
Bragdon Farms of Vassalboro, Maine, were first reduced in particle size using
a Munson Machinery
screen classifying cutter. Several particle size fractions from 0.5 inches
down to 0.125 inches were
tested. There did not appear to be any improvements from varying the particle
size of the hay. All
hay particle sizes compressed well. The larger particle size did however have
a "made from hay"
look. The binders used in the fabrication process included various levels of
paraffin wax,
unmodified corn starch, dry distillers grain (DDG), glycerin, glycerin/starch
blend and recycled
plastic. A log was also made of hay pieces without any binder additive.
[0020] The process of making a log 42 using the system 30 begins by mixing
together hay
pieces and binder. The first hydraulic cylinder 34 is retracted from a first
end of the containment
tube 32 so that the interior of the containment tube 32 is accessible. The
interior of the
containment tube 32 is then filled with the hay-binder mixture. The second
hydraulic cylinder 36
and cap 38 are then moved into position at a second end of the containment
tube 32 to close off the
interior of the second end of the containment tube 32 and apply uniform
pressure to the contents of
the tube 32 that is approximately equal to the pressure applied by the first
hydraulic cylinder 34 at
the first end of the tube 32. The first hydraulic cylinder 34 is then actuated
to compress the mixture
within the tube 32 until 12 tons of pressure was achieved. The compressed log
may then be heated
to a selectable temperature for a selectable amount of time. For the
formulation examples
described herein, all examples were heated for about 30 minutes, and then
cooled for about one
hour. The second hydraulic cylinder 36 and the cap 38 were retracted and the
log 42 was ejected
from within the tube 32 by further extending the first hydraulic cylinder 34.
The table of FIG. 3
shows 15 formulations made using the system 30 and the steps described above.
The heating
temperatures applied to each fabricated log are also shown in the table.
[0021] A portion of the 15 fabricated logs were tested for moisture content,
ash content,
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BTU content and log density using standard test methods listed in FIG. 4. The
estimated
material costs for each of the tested samples were also calculated. The cost
calculation was on a
per log basis (4 inch diameter X 12 inches long) at the manufactured density.
For comparison,
a commercially produced fire log (Pine Mountain Fire Log) from Conros
Corporation Canada
was also tested. The test results are shown in the table of FIG. 4. Of the
formulations tested,
samples containing wax or plastic as binders resulted in the highest quality
logs in terms of
appearance, with no apparent cracking and remained intact. Logs produced with
20% starch as
the binder also looked satisfactory. Some of the remaining formulations
evaluated, where the
logs experienced slight cracking and breaking may also be suitable to produce
fire logs under
commercial log press conditions where the applied hydraulic pressure can in
some machines be
higher than the 12 tons generated by the hydraulic cylinders 34 and 36 of the
system 30. The
BTU values for the hay logs produced were lower than the wood-based control
sample, but that
is to be expected as the control sample contains approximately 50% wax, which
is substantially
more than used in the hay-based logs of the present invention. The petroleum-
based binders
such as the wax and the plastic significantly increased the BTU content of the
fabricated
hay-based logs when compared to the log made of hay alone. The remaining
formulations such
as 100% hay, hay with starch and hay with DDG averaged approximately 8,500
BTU/lb, which
is similar to wood pellets. These results suggest that suitable quality fuel
logs can be made with
several of the hay-based formulations tested. These values are summarized in
Table 2.
[0022] Produced hay-based fuel logs can be packaged (either individually or in
groups)
for transportation to, and use by, end users. The hay-based fuel log of the
present invention can
be used as a conventional wood log is used in a wood stove, fireplace, camp
fire or the like, as
desired. The hay-based fuel log can be used for cooking, warming water and
heating the inside
area of a building. If the log is packaged in wrapping, that wrapping may be
formed of a
material suitable for burning as well, such as the packaging used for
commercially available
burnable logs. The packaging may be useful in initiating the bum of the log of
the present
invention.
[0023] The scope of the claims should not be limited by particular embodiments
set
forth herein, but should be construed in a manner consistent with the
specification as a whole.
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