on-site construction the flows rerouted, without shutting down the whole system. The collection of data on the system’s performance will also help standardize its functioning over time and provide valuable data to the academic community. To keep the costs of this system reasonable, we have recommended that the D-SARR reactor be constructed in DIY fashion by the de Ceuvel group with the advice an oversight of an engineering firm. Some professional oversight is necessary to avoid poor mounting of the units that could lead to leaks, reactor malfunctions, or poorly executed insulation. The D-SARR system will also require regular maintenance and monitoring to ensure that it is properly functioning. Some possible ways of managing this maintenance demand are to divide maintenance responsibilities among users of the site or to allocate some of the money that would normally be paid to utilities to hire a parttime manager for various aspects of the site. COST & LABOR ESTIMATES We estimate the cost of the DIY D-SARR system at 2.700 € per renter on the de Ceuvel site. The total cost of the communal D-SARR facility is 43.000 € and will require an estimated 350 hours of labor to build and install overall (22 hours per renter). A commercial version of a reactor performing the same functions would cost an estimated 10.000 € per boat, or a total of 160.000 €. A DIY reedbed filtration system will cost an additional 1.000 € per renter and require an estimated 70 hours of labor. The management and control system is estimated to cost an additional 100 € per renter, including microcomputing equipment, sensors, and a display. Our material cost calcuations are based on the assumption that they will be purchased from inexpensive sources in Asia or Eastern Europe. With the lower cost of installation of a DIY system, the anticipated return on investment can be under five years. To arrive at this figure we consider that without the D-SARR system and solar heating, each boat would require around 2.000 € worth of new infrastructure connections. The biogas and valuable nutrients (such as struvite) can also be sold by the association for a small annual profit. For this return on investment to be achieved, maintenance costs will also need to be kept relatively low. 2 biogas production cost of the D-SARR modular reactor. The biogas produced also has a financial value, which can be recouped by the association by selling the biogas to site users or outside parties. Using the biogas on site is highly recommended to showcase the closed material flow and avoid transportation costs. The de Ceuvel site will produce 2.700 usable m3 of biogas per year, with an average calorific content of 54.000 MJ (assuming 20 MJ/m3 ) or approximately 15.000 kWh. At a market price of 0,7 euro cents per kWh, this is valued at 10.500 € in equivalent energetic value from natural gas. To arrive at these biogas production calculations, we have assumed that the site will be used by an average of 75 people, each of whom will produce an average of 100 grams of feces, 0,2 kg of kitchen waste, and 0,2 liters of urine per day. The biogas produced from the digestion of organic wastes in the D-SARR system will be used to run the D-SARR itself (for heating the pasteurizer and keeping the reactor at a suitably high temperature), and for use in the restaurant on site. The link between the biogas at the restaurant and the adjacent D-SARR treatment facility should be made transparent and educational for all visitors to the area. COST & LABOR ESTIMATES The costs of biogas production and collection are included within the overall estimates for the 52 / 146 Pagina 51
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