Solar Ice Prototype

section – schematic design of the solar ice facility paired with an aquaponics system

{Insert a condensed version of mission statement here}

This prototype synthesizes the typically separate locations for production and storage within the food market into one facility. Perhaps the facility could also become apart of the distribution process by turning into a community food hub.

In building this prototype, we hope to provide a model community farm that could pair rural/suburban/and urban communities with locally-sourced produce and fish. However, we see the technology having the most benefit for users without existing access to electricity, stable food security, or an efficient means of producing food.

Project Goals:

– use locally available knowledge, man-power, and resources to design and build a solar ice facility that will test the theories put forth in the Solar Ice project [link]
– run the facility entirely off of energy harvested and produced on-site
– design and build the energy flows to operate at high levels of efficiency
– maximize the conditions for food production and food storage within the facility boundaries
– document the making of this facility so the idea can be sourced and used by other solar ice enthusiasts
– make suggestions for future models of solar ice that may better the performance of the system

Personal Goals:

– learn to design and maintain a productive aquaponic food production system
– learn to build using sustainable building techniques and materials

Design

Overview:

The facility will be a well-insulated building, equipped with solar panels on the sunny side of the building that will convert solar energy into DC power. The electricity gathered will be used to run the entire gamut of operations on the facility, however the majority of the electricity will be used to power a freezer to freeze units of water. The freezer will be used as a typical container for food storage. However, unlike a typical freezer design, this freezer’s hot coils will be extended and relocated to the adjacent underground aquaponics system tank. The pond will act as a heat sink, cooling the freezer coils and thus improving the performance of the freezer. The building will also incorporate an integrated ventilation system that will naturally cool the solar panels on top of the building (increasing their efficiency) and provide ventilation for the building.

The design of the facility seeks to pursue the ideals of permaculture, and may change to incorporate other methods of integrating the building systems to work together.

Specifics

Producing Ice with Solar Power-

The backbone of the system consists of the solar panels and freezer. The freezer must generate enough ice to keep the freezer cold while the sun is down and the freezer is off. Research on creating the solar ice facility can be found here.

One key benefit to this system is that the electrical energy can stay in DC form without the need for inefficient AC conversion. This is only possible when the freezer implemented is a DC freezer. Most commercially available freezers are not DC freezers, so sourcing a DC freezer is one of the main challenges for implementation.

Depending on the complexity of the freezer found locally, additional circuitry may be required to regulate the electricity coming from the solar panels. This additional circuitry may include a cutoff switch, to turn off the freezer if needed, as well as a regulator which will protect the freezer from trying to turn on if there is not enough power coming from the solar panels.

Pairing Solar Ice and Aquaponics-

Natural Cooling of the Solar Panels–

One aim of the project is to increase the efficiency of the solar
panels by cooling them to optimal temperatures using natural ventilation. The efficiency of solar panels is affected negatively by increases in temperatures. For example, in a popular model of PV panel, for every degree above 25 Celsius, the solar panel loses about .5% efficiency. In the rolling hills of central California, we need to be wary of how the higher temperatures are affecting our power output.

The solution we would like to explore is a natural ventilation system whereby cool air would run underneath the panels. The ventilation intake would exist at the bottom of the aquaponics pond so as to be cooled by the relatively stable cool temperature. The vent would run the length of the bottom of the pond (protected by a waterproof material), and be pulled into the facility which houses the solar panels so as to direct the cool air underneath the panels and up through a ventilation stack that heats the air as it pulled through. The air would be heated naturally by the sun and increase the movement of air through the system, because hot air would rise more quickly and pull more air through the system.

Pictured to the right is a schematic drawing explaining the flow of air within the freezer facility:

Increasing the Efficiency of the Freezer

By relocating the cooling coils of a typical freezer to close proximity with
the aquaponics pond, we can keep the heating coils cooler than they would be on the back of a typical freezer. Reducing the temperature difference between the hot coils and the cold coils within the freezer would increase the coefficient of performance of the freezer (COP). Here is a rudimentary review of how freezers function, according to a simplification produced by Pete Schwartz.

Materials –

The thermal storage within the freezer itself will be enhanced by building the facility with thermally massive building materials. A number of building materials would work to provide this level of insulation. Perhaps the availability of styrofoam will be explored as the building’s insulating layer.

We are also looking at and comparing the benefits of ferrocement and papercrete. In the pursuit of sustainable technologies, we plan to pursue a building plan that 1) retains the freezer’s internal coolth 2) internalizes the smallest amount of embodied energy in the creation of the building materials and construction methods.

Below are examples of ferrocrete in Pabal Domes in India. And papercrete blocks currently produced by Texas manufacturer, Mason Greenstar.

Location

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Progress link

Project Development and Effects

Group Members

Miranda Mills
Harrison Waschura
Megan Braun
Petra Knapp
Incredible Supporters:
Peter Schwartz, the Polyponics Crew