S.T.E.V.E.N.
Sustainable Technology and Energy for Vital Economic Needs
414
Triphammer Road, Ithaca, NY 14850 USA.Email jv19@cornell.edu.
Website:
http://www.virtualithaca.com/francis/stevenhomepage.html
NEWSLETTER 2005
Introduction
Greetings from the STEVEN Foundation!
This year we have continued to pursue a mixture of research and educational
outreach. Our newsletter includes discussion of the solar oven, solar
refrigerator, collaboration with Cornell students, and other types of outreach.
Collaboration with students at Cornell University, and public presentations
in the Ithaca area
We continue to collaborate with Cornell
students who are involved with the Engineers for a Sustainable World organization,
in particular on the testing of solar ovens. In May of 2005 the students
produced a draft technical paper presenting results from parametric testing
of the solar ovens. They are continuing to run new parametric tests
during the fall of 2005, to be added to the paper in the future.
They have also developed a modified design of the solar oven with a door
in the back of the oven, so that food can be moved in and out without needing
to pass through the top of the oven. Work on this prototype is ongoing,
and the modified oven will hopefully develop into a mature technology with
ongoing work by the students on refining and testing.
During the Fall of 2005, Francis also
made presentations about appropriate technology to the Bovay Seminar Series
on Engineering Ethics at Cornell, to the Engineers for a Sustainable World
course in the engineering school, and to the Natural Builder’s Network
of the Ithaca area.
Results from a summer of intensive testing of the solar oven
During July and August of 2005 in Ithaca,
only 4 inches of rain fell, compared to an expected rainfall amount of
7 inches expected. Along with this lack of rain came abundant sunshine,
so while the weather may have been bad for many crops, it was excellent
for solar cooking.
For the summer of 2005 Francis borrowed
a test oven built by Cornell students during the 2004-05 academic year,
and used it for cooking between June 8th and September 28th. Over
this 112 day period, the oven was used 32 times, or roughly once every
four days. Usage went up during the sunniest months of July and August,
to roughly once every three days. The most frequently cooked
dish was rice (120 cups total), and in addition we cooked beans, casseroles,
potatoes, and even sweet corn.
We were pleased with the durability
of the oven, as the structure held up well, and there was no perceptible
loss of cooking performance due to deterioration of the insulation or other
factors.
New insights on materials used with the solar oven
Ongoing work with the ovens has led
to the discovery that reflective mylar that is not UV resistant is not
a good material choice, as the reflectivity degrades within a few months,
when exposed to ongoing sun. We therefore do not recommend its use
in the oven design, and also do not recommend the use of scrap reflective
plastic materials such as the insides of potato chip wrappers.
A new material that we can recommend
is the use of aluminum printing plates for the reflectors in the solar
oven. We used these all summer for the test described above, and
while they are not as reflective as the 3M UV-resistant Mylar, they nevertheless
are sufficiently reflective to successfully heat the oven to an adequate
temperature. When they become discolored, they can be cleaned or
polished, as needed, to restore the best possible reflectivity.
Update on Haiti reforestation donation
Last year we reported a sizable donation
from S.T.E.V.E.N. Foundation for afforestation work in Haiti. (The
money had originally been collected for similar sustainable development
in Bolivia, but our contact person there turned to other work.) Haiti
Reborn, the organization leading this forestation project at Gros Morne
in northern Haiti, reports that it is moving forward well. About
a million trees have now been planted, and several other mini-forests elsewhere
have been started.
There are two points to note here:
first, that in a nation continually wracked by political turmoil, agricultural
development in the countryside is still possible with a strong enough base
of resources. And second, it is our hope and that of others to impact
the climate and resource base of Haiti in some small way. Anyone
who has visited there knows the devastation wrought by deforestation, which
is ongoing as the people take wood for charcoal fuel. We would like
to be part of reversing that deforestation.
For more information: www.quixote.org/hr
Update about refrigeration research
Steven Vanek has undertaken to produce
an improved version of our solar icemaker: however, the demands of Ph.D.
research in agriculture have limited his progress. At this time,
of the three major refrigeration components the generator and condenser
tank have been constructed, and the evaporator is half finished.
We hope more progress will be possible in summer 2006.
As one part of the improved solar refrigerator,
a support is needed for a horizontal parabolic-trough collector, which
would continuously make the collector face the sun in a perpendicular manner.
For that purpose we constructed a platform supported by and rotating around
a pivot-pipe activated by a cable moved by a barbecue motor [usually rotating
at one RPM]. The tracker unwinds from a circle created at the bottom of
the rotating platform, with the radius of the circle converting the RPM
of the motor—using a half-inch threaded rod and slowly moving nut -- to
the angular motion of the sun during the day.
Solar house combining STEVEN designs
In Chapter 23 of Jaroslav Vanek’s book
UNIFIED THEORY OF SOCIAL SYSTEMS (recently published online: see URL, http://hdl.handle.net.1813.642
) is discussed a solar house combining the designs of a pagoda
and a tent, entirely powered by solar energy and providing for all thermal
and mechanical energy needs, including the possibility of plowing a small
field. While the house as a whole has not yet been tested, most of its
component parts were constructed and tested. A reduced sketch of
the design from the above noted chapter is shown herewith.
Reflection: the changing nature of solar-powered pumping
When the STEVEN Foundation began promoting
solar-powered pumping designs some 20 years ago, part of the motivation
was to provide a lower cost alternative to Photovoltaic (PV) solar powered
pumping. At the time, PV panels cost around $20 per watt, and the
high cost left room for a low cost solar option.
Since that time, the cost situation
for PV has changed markedly. PV panels now cost between $3 and $4
per watt, so the cost motivation for using the STEVEN parabolic trough
collector and steam engine no longer exists. In fact, the use of
PV is popular in many developing countries, where it is cost effective
to install in rural locations, instead of bringing in expensive grid power.
The solar parabolic trough is still
of interest in that it allows rural communities to use local know-how to
fabricate a machine that uses the sun, instead of relying on a distant,
high-tech factory to manufacture the PV panel, which is the heart of the
PV pumping system.
We must, however, be realistic about
the challenges facing rural communities that want access to water supplies
using some type of pumping. Typically, the community is under some
amount of economic pressure, and needs a system that is reliable from the
start. The solar PV system allows the community to begin pumping
quickly and reliably. We have therefore changed our approach to this
question. In the future, we will continue to make available information
about the parabolic trough collector to those who ask, but we will also
point out the viability of PV as a proven option.
WE OFFER MIRROR PLASTIC . . . . and other good
things
S.T.E.V.E.N. Foundation has a
considerable quantity of aluminized Mylar sheet plastic, and would be happy
to make it available to those working with solar energy, for solar collectors,
box oven cookers, or otherwise. Our plastic is of good quality: in
testing it proved to be more resistant to ultraviolet (UV) damage than
the product of another commercial supplier. It comes 3 mil thick.
The rolls are 62” wide and can be cut to your desired length. We
ask that the purchaser pay for shipping; an additional donation to S.T.E.V.E.N.
Foundation is welcome, but not a requirement.
To order plastic quickly: telephone us at:
607 257 7109.
Or, e-mail to: jv19@cornell.edu
In addition, we still offer the spectrum
of informational materials listed in our prospectus – videos, manuals and
other information. We would especially call attention to our manuals
for solar oven, probably the most generally useful of all our technologies;
and to the “Ten Dollar Pump” as a simple, effective water pumping device.
On our icemaker, the HOME POWER article [June 1996] gives the essential
information: we can supply photocopies. For the Superbike,
we have both written information, and (for sale) the special stem needed
to make the adaptation.
Please write/phone/e-mail us for any
materials of interest to you. Donations to our work are also most
welcome! … and are tax-deductible to the donor.