Polydome Concept Overview V.3 Material and Energy Flows A polyculture system creates many opportunities for cycling materials and nutrients within the system. The map to the left shows the calculations we have made for the material flow within our model greenhouse. As stated in the original performance targets, the ultimate goal for a Polydome greenhouse is to have fully closed material and energy flows. Achieving this would mean that the production facility would not represent a source of pollution, nor would it drain non-renewable resources. Nutrients Though we have managed to close several “waste” cycles - for example, all vegetable, plant, and animal waste is beneficially reused within the system - there still remain some gaps. Fully closed nutrient loops are inherently difficult to achieve in agricultural production because the major nutrient flows are exported out of the system in the form of consumable products. The only way to close this loop is to receive a source of nutrients from the outside (green waste from parks, manure from animal production facilities, food waste from restaurants, or sewage from residential areas would all be potential examples). In this case, we have solved the nutrient deficit through the cultivation of chickens, however the chicken feed will still be coming from an outside source. The fish and chicken feed are the major sources of “nutrient import” that the current model still requires. However, these flows could be supplied internally by adding additional modules (algae production for the fish and a source of wild grain for the chickens). Water Use The modeled Polydome greenhouse has a fairly high water demand due to the predominant use of soil as a substrate. However, it is possible to reuse some of the water after it has passed through a drainage system, which we have not added into our calculations here. Additionally, a large part of the crop zone does not require much water during the winter dormancy phase, resulting in relatively lower water use than for a year-round soil greenhouse of comparable size. Energy Use Greenhouse production is typically energy intensive because of the requirements for ventilation, climate control, supplemental lighting, and the use of other electronic equipment. The goal of the Polydome greenhouse is to reduce the system’s overall energy demand by eliminating the need for many, though not all, of these system controls. The remainder of the required energy should then be from a renewable source. Whatever the exact design, the Polydome system should ideally take advantage of an appropriate combination of relevant energy technologies, such as those described in the earlier section on greenhouse technology, to achieve carbon-neutrality. Polydome: High Performance Polyculture Systems 37 Closing the Loops There are several competing priorities in the design of a Polydome system, which include yields, potential earnings, and material flows. In this case, we have optimized the system for economic returns and plant compatibility. One of our primary objectives was to examine the financial viability of the model. It would not be particularly difficult to recalibrate the system design so that all material loops are closed. This is best done with a specific location and local consumer market in mind. Pagina 36
Pagina 38Scoor meer met een webshop in uw kranten. Velen gingen u voor en publiceerden sportbladen online.
473 Lees publicatie 163Home