21-0512 Biofuel Use for SEE Institute
Diamond Developers is building SEE Institute in the award-winning community, The Sustainable City (TSC), Dubai. The project comprises a 5,000 sqm smart building (G+1) offering a central atrium, a VIP room, 2 lecture halls, a multi-purpose hall, and a 500-people amphitheater. The building is designed as a zero-carbon facility for advancing knowledge in sustainability through training, research, incubation, and events. Construction materials and method are carefully selected to reduce the building’s embodied carbon. During operation, all energy consumption will be from onsite renewables, and surplus electricity will be exported (to offset embodied carbon). TSC produces a significant amount of organic waste such as food residues, animal manure, and green waste. Currently, most of that waste is collected and transferred to a local waste management company (some food waste is discharged using the garbage disposal unit under the kitchen sink). An alternative system could divert the waste (called feedstock) to run a small-scale biogas plant in TSC using anaerobic digestion. DD is currently examining one such solution by the Dutch company The Waste Transformers (1). The biogas plant is designed to handle up to 3,000 kg of organic waste per day to produce biogas and a digestate) 2)There is no combustion – digestion will produce app. 320 m3/day of biogas which will be serving a direct-fired absorption chiller through a well-insulated and concealed pipe. The absorption chiller will contribute around 31% of the cooling load required in the SEE Institute which leads to a lower electrical use intensity. Moreover, the digestate will be utilized as a soil conditioner / fertilizer in community landscaping.
Conclusion: Although the absorption chiller is still under review by our design team, Diamond Developers kindly seeks ILFI preapproval of this technology for further consideration.
Biogas composition confirmed:
Q. In the "Beneficial Combustion" section it's stated that "There is no combustion." We wanted to be clear that the captured biofuel is being combusted on site to fuel the direct fire blast chiller. Can you share schematics of the system so we can understand the process in greater detail?
A. We have requested the schematics drawings from the manufacturer which might take time. Meanwhile, please note that we are pursuing consideration of several vendors.
A. The absorption chiller can only operate using biogas (60% CH4) which does not allow to connect the system to the natural gas as it consists of 95% CH4. Therefore, there will be no connection of natural gas lines to the absorption chiller.
Q. For the "Air Quality Impacts" section, it's stated that "impure biogas will generate dangerous flue gases." Does this mean then that the biogas you are burning is pure (as you provided those percentage breakdowns)? Is there any chance the biogas would ever have impurities in the future? And if so, how would they be filtered or captured such that there were no negative air quality impacts?
A. There is a two-stage filtration process. The plant will filter such elements as H2S, NH3 and water vapor which have no energy contribution in biogas. Removing these impurities is essential to maintain an appropriate energy density which will be done before the inlet of the absorption chiller.
A. One of the main advantages of absorption chillers is that the refrigerants used in them do not contribute neither to global warming nor to ozone depletion. The chiller will operate using a combination of lithium bromide (LiBr) in a liquid form and water (can be turned into a water vapor). In this case lithium bromide is the absorbent and water is the refrigerant.