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To safeguard against meat supply shortages during pandemics or other catastrophes, this study analyzed the potential to provide the average household’s entire protein consumption using either soybean production or distributed meat production at the household level in the U.S. with: 1) pasture-fed rabbits, 2) pellet and hay-fed rabbits, or 3) pellet-fed chickens. Only using the average backyard resources, soybean cultivation can provide 80%-160% of household protein and 0%-50% of a household’s protein needs can be provided by pasture-fed rabbits using only the yard grass as feed. If external supplementation of feed is available, raising 52 chickens while also harvesting the concomitant eggs or alternately 107 grain-fed rabbits can meet 100% of an average household’s protein requirements. These results show that resilience to future pandemics and challenges associated with growing meat demands can be incrementally addressed through backyard distributed protein production. Backyard production of chicken meat, eggs, and rabbit meat reduces environmental costs of protein due to savings in production, transportation, and refrigeration of meat products and even more so with soybeans. Generally, distributed production of protein was found to be economically competitive with centralized production of meat if distributed labor costs were ignored.

Land-use conflicts created by the growth of solar photovoltaics (PV) can be mitigated by applying the concept of agrivoltaics, that is, the co-development of land for both PV and agricultural purposes, to commercial-scale solar installations. In this study, we present a conceptual design for a novel agrivoltaic system based on pasture-fed rabbit farming and provide the technical, environmental and economic analyses to demonstrate the viability of the concept. Included in our analysis are the economic advantages to the PV operator of grazing rabbits at a density sufficient to control vegetative growth, thus reducing the economic and environmental costs of mowing; the dual-revenue stream from the sale of both rabbits and electricity, contrasted with estimates of the capital-investment costs for rabbits co-located with, and also independent of, PV; and the economic value to the rabbit farmer of higher colony-growth rates (made possible by the shading and predator protection provided by the PV arrays and of reduced fencing costs, which are the largest capital cost, by being able to leverage the PV systems for rabbit fencing. We also provide an environmental analysis that suggests that rabbit-PV farming is a pathway to a measurable reduction in agriculturally-generated greenhouse-gas emissions. Our calculations indicate that the co-location of solar and rabbit farms is a viable form of agrivoltaics, increasing overall site revenue by 2.5%–24.0% above projected electricity revenue depending on location and rental/ownership of rabbits, while providing a high-value agricultural product that, on a per weight basis, has significantly less environmental impact than cattle.

In the Upper Peninsula of Michigan, over 500 million tons of copper rich rock were removed from mines and treated in chemical baths to extract copper. Toxic substances have been seeping into the watersheds from the resultant waste stamp sands. Recent work on developing a circular economy using recycled plastic for distributed manufacturing technologies has proven promising, and this study investigates the potential to use this approach to form stamp sand and acrylonitrile styrene acrylate (ASA) composites. Specifically, this study found the maximum amount of stamp sand that was able to be added to waste ASA by mass with a single auger recyclebot system for compounding was below 40%. The mechanical properties of the composite were evaluated up to 40%, and the addition of stamp sand reduced the material's ultimate tensile strength by about half compared to the strength of raw recycled ASA, regardless of the percent stamp sand in the composite. However, this strength reduction plateaus and the tensile strength of the ASA and stamp sand composites can be compared favorably with acrylonitrile butadiene styrene (ABS) at any level. This makes waste ASA- stamp sand composites potential replacements for outdoor applications of ABS as well as some current ASA applications. These results are promising and call for future work to evaluate the technical, economic and environmental potential for waste ASA - stamp sand composites.

In order to accelerate deployment of distributed recycling by providing low-cost feed stocks of granulated post-consumer waste plastic, this study analyzes an open source waste plastic granulator system. It is designed, built, and tested for its ability to convert post-consumer waste, 3D printed products and waste into polymer feedstock for recyclebots of fused particle/granule printers. The technical specifications of the device are quantified in terms of power consumption (380 to 404 W for PET and PLA, respectively) and particle size distribution. The open source device can be fabricated for less than $2000 USD in materials. The experimentally measured power use is only a minor contribution to the overall embodied energy of distributed recycling of waste plastic. The resultant plastic particle size distributions were found to be appropriate for use in both recyclebots and direct material extrusion 3D printers. Simple retrofits are shown to reduce sound levels during operation by 4dB-5dB for the vacuum. These results indicate that the open source waste plastic granulator is an appropriate technology for community, library, maker space, fab lab, or small business&ndash, based distributed recycling.