Students from the University of New South Wales have designed and installed a solar powered deep freezer in a remote village on Viwa Island, off the coast of Fiji.
The students, from the UNSW Engineering’s Sustainable Energy for Developing Countries course, visited the island as part of on-the-ground research offered by the University.
The class teacher, Dr Anna Bruce from the School of Photovoltaics and Renewable Energy Engineering, says the students are directed to come up with a solution that will both empower the community and allow them to be self-sufficient.
“One of the key challenges in these communities is the local capacity to maintain their own equipment,” said Dr Bruce.
“We challenge the students to ensure that they design a solar system that is technically and financially sustainable. We also ask them to consider the cultural and governance structure.”
The Najia village on Viwa Island, on the outermost of the Yasawa Island group, is renowned for its fishing culture. So the students focused on creating a sustainable way for the villagers to freeze their daily catch and sell it on the mainland for more money.
“After installing the solar freezer system, we were received in a traditional island ceremony for guests to the village,” said recent UNSW Solar and Photovoltaic and Solar Energy Engineering graduate, Darcy Small, who was part of the team that travelled to Viwa Island.
“The communities we worked with place a high value on family and community relationships, reminding me of the importance of these aspects in life back home.”
The students said they hoped their research would help inform the next group of students to further assist the communities.
Further access to cold storage for fish, as well as to clean water, household electrification or clean cooking would make a positive impact on the community, they said.
“A key learning from this trip has been the importance of engineering design with people in mind, especially for humanitarian engineering,” said Sera Tarpis, a fourth-year UNSW Renewable Energy Engineering student.
“Having the privilege to enter the community and hear and see the concerns was very illuminating.
“It demonstrated the incredible impact a well-designed project can have, but also just how quickly expensive equipment can fall into disuse if not if not implemented correctly.”
Sophie is editor of One Step Off The Grid and deputy editor of its sister site, Renew Economy. Sophie has been writing about clean energy for more than a decade.
This post was published on November 28, 2019 9:46 am
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I'd be interested in looking at the detailed design of the freezer (and the refrigerant used) - is that available?
Hi Hugh, not sure. But you can contact the UNSW team via this link: https://newsroom.unsw.edu.au/news/science-tech/solar-powered-freezer-today%E2%80%99s-catch-unsw-engineering-makes-impact-fiji
Just imagine what that would mean for maintaining medical supplies in outreach areas!
A commendable project. A requirement for clean water was mentioned and I am surprised that hydro panel technology was not mentioned. See https://www.zeromasswater.com/ap/ for a commercial solution to clean drinking water.
Please note I have no commercial interest in the solution mentioned.
you don't need refrigerant and compressors etc. You can use the Peltier effect coolers. Run on DC and no moving parts. These are used in a lot of small automotive camping fridges and freezers. Not as efficient as a compressor based refrigeration cycle but the benefit of no moving parts and no refrigerant might be worth a few extra solar panels.
I've often wondered about more use of Peltier devices. I think they only can vary the temp about 15 degrees from ambient? Perhaps they could use a cascade, box within box to attain useful temps?
Trust me, you need a compressor for successful refrigeration, especially off grid(standalone solar power). Peltier chips are fine, but aren't efficient. 5 amps of power at 12 volts can cool about a 5 litre compartment down to around 5 degerees celcius with a Peltier chip. With a low voltage/wattage compressor fridge/freezer with an inverter drive, it can cool up to a 110 litre compartment and beyond for the same 5 amps. Huge difference, 5 litres versus 110 litres for a 5 amp outlay at 12 volts.
The other problem is that Peltier chips are often constantly switched on. Meaning that 5 amps per hour(based on a that small, 5 litre compartment), would require 120 amps over 24 hours. Meaning you would need close between one to two kilowatt hours of battery storage at 12 volts to cater for it.
With the 110 litre compressor fridge as an example, 260 amphours of batteries at 12 volts is all that's needed to run it. That modest battery size will provide between 3 and 10 days autonomy(No sun days), depending on summer or winter. This is based on a portable solar power(pv) system that I have set up and runs a 110 litre dual zone fridge/freezer as a fridge and uses around 50 to 60 amps a day in Australia's hot summer(35 Celsius and then some) and barely 15 amps in winter, running as a fridge, as a freezer, the power demand is doubled. A Peltier variant at 5 amps would still use 120 amps/day, regardless of the time of year. And using them for a freezer, is near impossible without a huge outlay of amps and a massive array of Peltier chips.
That system also runs led lights at night and charges phones and headlamp batteries.
Congraulations to the team: speculate on which of several options fpr technology they have chosen. I played with a solar concentrator with an ammonia/water cycle some years ago. theory was fine however lacked the time committment and focus to refine the issues. Did find that Pascals principle requires managing with differntial valve was needed for directional cycle flow. In the end it pulsed which didnt matter. The pulse rate regulated by the solar value. Is there anyone out there in "doing stuff" land who wants to collaborate on reinvigorating this?