Challenges in Sustainability | 2014 | Volume 2 | Issue 1 | Pages 18‒27
DOI: 10.12924/cis2014.02010018
Research Article
Mobile Open-Source Solar-Powered 3-D Printers for
Distributed Manufacturing in Off-Grid Communities
Debbie L. King
1
, Adegboyega Babasola
1
, Joseph Rozario
1,2
, and Joshua M. Pearce
1,2,3,*
1
The Michigan Tech Open Sustainability Technology Lab, Michigan Technological University, 601 M&M Building,
1400 Townsend Drive, Houghton, MI 49931-1295, United States; E-Mail: debbieking_98@yahoo.com (DLK),
adegboyega.babasola@gmail.com (AB), jrozario@mtu.edu (JR), pearce@mtu.edu (JMP)
2
Department of Electrical & Computer Engineering, Michigan Technological University, 601 M&M Building,
1400 Townsend Drive, Houghton, MI 49931-1295, United States
3
Department of Materials Science & Engineering, Michigan Technological University, 601 M&M Building,
1400 Townsend Drive, Houghton, MI 49931-1295, United States
* Corresponding Author: E-Mail: pearce@mtu.edu; Tel.: +1 9064871466
Submitted: 27 May 2014 | In revised form: 25 August 2014 | Accepted: 28 August 2014 |
Published: 30 September 2014
Abstract: Manufacturing in areas of the developing world that lack electricity severely restricts the
technical sophistication of what is produced. More than a billion people with no access to electricity
still have access to some imported higher-technologies; however, these often lack customization and
often appropriateness for their community. Open source appropriate technology (OSAT) can over-
come this challenge, but one of the key impediments to the more rapid development and distri-
bution of OSAT is the lack of means of production beyond a specific technical complexity. This study
designs and demonstrates the technical viability of two open-source mobile digital manufacturing
facilities powered with solar photovoltaics, and capable of printing customizable OSAT in any com-
munity with access to sunlight. The first, designed for community use, such as in schools or maker-
spaces, is semi-mobile and capable of nearly continuous 3-D printing using RepRap technology,
while also powering multiple computers. The second design, which can be completely packed into a
standard suitcase, allows for specialist travel from community to community to provide the ability to
custom manufacture OSAT as needed, anywhere. These designs not only bring the possibility of
complex manufacturing and replacement part fabrication to isolated rural communities lacking
access to the electric grid, but they also offer the opportunity to leap-frog the entire conventional
manufacturing supply chain, while radically reducing both the cost and the environmental impact of
products for developing communities.
Keywords: Appropriate Technology; Distributed Manufacturing; Open Source Hardware;
Photovoltaic; Solar Energy; 3D-Printing
© 2014 by the authors; licensee Librello, Switzerland. This open access article was published
under a Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0/).
1. Introduction
Modern energy access is still far from universal, as 1.4
billion people lack access to electricity [1], which di-
rectly contributes to multidimensional poverty through-
out these regions [2]. Although two-fifths of South
Asia's population, primarily living in rural areas, have
no access to the grid, more than three quarters of the
population of Sub-Saharan Africa (587 million people)
in both rural and urban areas are without electricity
[3]. This situation appears to be static as rural elec-
trification is a major challenge [4] and as the Inter-
national Energy Agency (IEA) estimates that if rural
electrification continues at the present rate, electricity
access will only keep pace with population growth
until 2030 [1]. Although some manufacturing occurs in
communities without access to electricity, the technical
sophistication of what is produced is limited. People
with no access to electricity still have access to some
higher-technologies, which are imported and lack all
customization and often appropriateness for the
community. Considering only energy-related devices,
for example, throughout the developing world there are
broken windmills and micro-hydropower installations,
empty biogas pits, rusting charcoal kilns, and unused
solar cookers [5] or tractors and water pumps in poor
condition [6]. Often the local failure of such tech-
nologies, which are employed in many communities, is
the lack of appropriateness for a specific community
(e.g. difficulties in access to parts and capacity to
perform repairs, evolutionary capacity of the tech-
nology, predetermining risk factors) [6‒8]. Thus there
is a need to ensure appropriate technology (AT) is
used, this can be defined as those technologies that
are easily and economically put to use from resources
readily available to local communities, whose needs
they meet [9]. The technologies must also comply
with environmental, cultural, economic, and educa-
tional resource constraints in the local community [9].
Earlier definitions of AT have recently been extended
by Sianipar et al. to include technical, economic,
environmental, social, cultural, judicial, and political
specifications [8]. To meet these requirements the
diffusion of information technologies (e.g. cell phones
and the Internet) has enabled a commons-based open
design or 'open source' method to accelerate
development of AT [10‒12]. In parallel to the open
source movement in software, open source ap-
propriate technology (OSAT) is gaining momentum as
it allows technology users to be developers simul-
taneously and share the open "source code" of their
physical AT designs, and to use this ability as a
science and engineering education aid [13‒20]. OSAT
is AT that is shared digitally and developed using OS
principles. Thus, rather than computer programs, the
"source code" for AT is material lists, directions,
specifications, designs, 3-D CAD, techniques, and
scientific theories needed to build, operate, and main-
tain it. One of the key impediments to the more rapid
development of OSAT is the lack of means of pro-
duction of open source technologies beyond a specific
technical complexity.
This barrier is being challenged by the rise of open
manufacturing with open-source 3-D printers [21],
affordable versions of which are capable of replicating
any three dimensional object in a number of polymers
and resins [22‒25]. The most striking of these 3-D
printers is the RepRap, so named because it can fab-
ricate roughly half of its own components and is thus
on the path of becoming a self-replicating rapid
prototyper [23‒24]. Recent work has shown enormous
potential for open-source 3-D printers to assist in
driving sustainable development via digital fabrication
and customization [26]. For example, there is cur-
rently a collection of open source designs useful for
sustainable development [27] including peristaltic
pumps, hemostats, and water wheels on Thingiverse,
a repository of digital designs of real physical objects
[28‒30]. Most importantly RepRaps allow users in any
location the ability to custom manufacture products
that meet their own needs and desires.
In order for rural communities to have access to
the benefits of 3-D printing of OSAT they will need
electric power from locally available renewable
resources such as solar photovoltaic (PV) technology
which converts sunlight directly into electricity. PV has
already been shown to be a technically viable,
environmentally benign, socially-acceptable and in-
creasingly economical method of providing electricity
to both on grid and remote communities all over the
world [31‒37]. Solar PV-generated electricity is par-
ticularly well suited for small scale off-grid applications
because of the relatively modest power draws of open-
source 3-D printers, and it will be addressed here.
This paper provides a description and analysis of i)
mobile community-scale and ii) ultra-portable open-
source solar-powered 3-D printers including component
summary, testing procedures, and an analysis of
energy performance. The devices were tested using
three case study prints of varying complexity appro-
priate for developing community applications, while
measuring electricity consumption. Results of this
preliminary proof of concept and technical evaluation of
the use of solar PV to power mobile RepRaps for
distributed customized manufacturing are evaluated
and conclusions are drawn.
2. Methods
2.1. RepRap Background
RepRaps can currently print with ABS, poly-
caprolactone, polyactic acid (PLA), and HDPE among
other plastics and generally cost between $30‒50 kg
‒1
[23,25]. PLA, which is used here for tests, fits the
definition of AT as it is derived from renewable sources,
is recyclable and bio-degradable. In addition, printed
PLA with a RepRap has been shown to be as strong as
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commercial prints [38]. The extruder intakes a
filament of the working material, heats it, and extrudes
it through a nozzle. The printer uses a three co-
ordinate system, where each axis involves a stepper
motor that makes the axis move and a limit switch
which prevents further movement along the axis. The
printing process uses sequential layer deposition,
where the extruder nozzle deposits a 2-D layer of the
working material, then the Z (vertical) axis lowers,
and the extruder deposits another layer on top of the
first. In this way it can build three dimensional models
from a series of two dimensional layers. It should be
noted that other heads are under development that
would allow for a greater range of deposition
materials [23,25,39‒42]. It should be pointed out
here that any of the RepRap class of 3-D printers can
be deemed appropriate for this application. The
FoldaRap was chosen as the final prototype here as it
is commercially available. It is a RepRap that folds
down, as its name implies, into a small footprint and
is thus relatively easy to transport. Today there are
many easily transported RepRaps.
2.2. Power Requirements
Here only standard RepRap solid polymer filament
extruders are considered. Their power requirements
based on a number of options are shown in Table 1.
The total power necessary will also be determined
by the processing options as shown in Table 2. Power
was measured with a multimeter (± 0.2%).
Table 1. Power requirements of RepRap variants.
RepRap Name Power printing (W) Power heating (W) Time (min
−1
)*
LulzBot Mendel 35 W 140 W 1‒2 min
−1
Prusa Mendel 37 W 130 W 1‒2 min
−1
FoldaRap 40 W 135 W 1‒2 min
−1
Note: it should be noted that the tests in this study were performed on a heated
bed to represent a worst case scenario. The heated bed can be avoided by
printing on blue painters' tape with PLA or with a glue-stick on glass, but such
appropriate surfaces have not been found for all plastics.
Table 2. 3-D printer processing power requirements.
Option
Price Power (W) Operating
System
Notes/References
Raspberry
Pi [43]
$35
(+monitor)
3 W
(+monitor
draw)
Linux
Pros: very inexpensive, large online community support,
RepRap software available on Linux
Cons: potentially long delivery times
APC 8750
[44]
$49
(+monitor)
13 W
(+monitor
draw)
Android
2.3
Pros: larger processor than Raspberry Pi,
Cons: no available software, would have to write new
program, not yet readily available, high power
consumption
Efika MX
Smartbook
[45]
$199 3 W‒6 W Linux
Pros: runs Linux, battery life of up to 7 h so no extra
power draw, Wifi & 3G for downloading new designs,
lowest cost for highest functionality
Cons: higher cost
Control
through cell
phone via
Bluetooth
[46]
$29 (with
existing cell)
1 mW‒5 W Android
Pros: cell phones widespread, "cool" factor
Cons: current software needs improvement, can only
print designs already in hand
Use only an
SD card slot
[47]
$35 0 W N/A
Pros: ultra low power, very low cost
Cons: can only print designs already in hand, no
community design
Tablet $150‒500 7.5 W‒10 W Varies
Pros: no extra power draw on system, readily available
Cons: higher cost
20
Option
Price Power (W) Operating
System
Notes/References
OLPC [48] $100‒200 2 W Linux
Pros: large user community, already scaled in developing
world
Cons: expense, difficulty running some software
2.3. Designs
Here two types of designs are considered: i) mobile
community-scale and ii) ultra-portable open-source
solar-powered 3-D printers.
2.3.1. Community-Scale Mobile 3-D Printing
The community-scaled device is designed to be appro-
priate for a school or a community center that enables
many shared users in a community to utilize the equip-
ment. The first portable solar powered RepRap was a
Mendel variant using off-the-shelf components [49] and
running RAMPS1.3 with an SD card add-on which
allowed it to save power by printing without a com-
puter connection. This system was designed for heavy
usage. The 2 x 220 W PV panels, and 4 x 120 Ah
batteries give the user 35 hours of printing with a
single charge. The system uses an inverter to convert
the DC energy from the PV and batteries to a standard
AC signal. A standard power bar can be hooked up to
the inverter, so it can run/charge multiple laptops or
printers at once. The frames of the solar panels are
reinforced and hinged together so that the faces of the
PV modules fold together to prevent damage during
transport. There are adjustable, drop-down legs affixed
to the modules, so they can be angled accordingly for
maximum sun exposure. The community-scale
PV+RepRap system is shown in Figure 1a and the
design schematics are shown in Figure 1b. The complete
bill of materials and assembly is documented here in
[50].
Figure 1. a) Community-scale PV-powered open-source RepRap 3-D printer system for off-grid community
use and b) the basic schematic design. The PV are connected in parallel; a combiner box is used to combine
and drive the DC supply towards a 30 A charge controller, which maintains the controlled charging and
discharging of the batteries. The batteries are connected in two parallel lines with each line containing two
unit cells in series. During charging periods four 120 AH batteries are fed DC current while discharging
continues to power the RepRap and the laptop through a DC/AC inverter.
2.3.2. Community-Scale Mobile 3-D Printing
An ultra-portable open-source solar-powered 3-D printer
has also been designed. This system can be easily
transported in a suitcase and is intended to provide
complete mobility so as those visiting an isolated
community (e.g. doctors) can bring it with them to
print necessary products on site in the field. Although
not solar powered, a team from MIT has already re-
ported on developing a suitcase 3-D printer [51] and
there are other portable 3-D printers currently on the
market, including Printrbot Jr (v2), Portabee, Bukito
Portable, Taz, Tobeca (which comes in a case) and the
Foldarap. Here the ultra-portable system is based
around the FoldaRap shown in Figure 2a. It is a RepRap
variant, designed by French engineer, Emmanuel Gilloz
[52]. The FoldaRap is built on an extruded aluminum
base that is designed to fold into a 350 x 210 x 100 mm
frame. The ultra-portable solar-powered suitcase 3-D
printer is shown packed and deployed in Figures 2b
and c, respectively. The design schematics are shown
in Figure 2d.
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