[en] Wastewater is an underutilized and readily available source of carbon free thermal energy. The energy derived from wastewater can be augmented using heat pumps to supply thermal energy to buildings. Due to favorable temperatures, wastewater sourced heat pumps are able to operate more efficiently than air and ground sourced heat pumps. This paper evaluates the potential of using wastewater heat recovery (WWHR) to provide heating and cooling to a mid-sized university campus located in the urban center of Toronto, Canada. (paper)

[en] Developing buildings which generate the amount of energy that they use (energy net-zero) in cold climates has the potential to significantly reduce overall energy consumption and Greenhouse Gas (GHG) emissions in these locations. This study introduces a design methodology which first iteratively reduces building loads from a synthesis of architectural, engineering, and building science strategies to achieve a minimized annual energy consumption. Then this optimized load is generated via on-site systems, and finally the overall design is validated within the goals of sustainability and high performance (as compared to benchmark designs). This strategy was applied to a detailed design-based analysis of a mid-rise, net-zero energy residential condo in Toronto, Canada. The building was developed within this iterative and computational process that draws on literature from passive house design, R2000, and ASHRAE 90.1 standards - as well as existing efficient building designs across various climates. Modelling using the eQuest building energy simulation software, relevant weather data, and hourly use profiles yielded energy consumption data which informed design modifications. Loads were systematically reduced by optimizing across building orientation, building layout and footprint, building materials, and architectural modifications. Furthermore, the use of Heat Recovery Ventilation (HRV) and Variable Refrigerant Flow (VRF) HVAC systems reduced heating and cooling demand and emissions in this mid-rise multi-unit residential building (MURB). Energy demand was further reduced by designing a high-performance building envelope with an improved window-to-wall ratio, triple glazed windows, airtight building enclosure, and high R-value insulation. On-site energy generation via the rooftop and facade solar array allowed for net-zero operation. The proposed methodology yielded a building design with annual energy consumption and GHG emissions reduced by 54.3% and 95.3% respectively. (paper)

[en] Building energy consumption accounts for approximately 36% of total energy consumption in the world. Since buildings are capable of on-site electricity generation and exhibiting predictive pattern of heating and cooling, the focus of this study is to investigate the Smart Dual Fuel Switching System (SDFSS), comprising a natural gas furnace and an air-source heat pump (ASHP), working in conjunction with on-site solar photovoltaic system. Base-case scenario using 1.5-ton rated capacity ASHP with 8.5 heating seasonal performance factor (HSPF) yielded only 4% cost savings and 15% greenhouse gas (GHG) emission reduction when compared to natural gas furnace space heating scenario. With an ASHP of 2-ton rated capacity and HSPF of 10 working in conjunction with solar photovoltaic (PV) system of 4.08 kWp, the cost savings of SDFSS increased to 12% and the GHG emissions reduction of 45%. SDFSS integrated with the grid is expected to yield significant benefits. It can help avoid situation of buildings drawing electricity all at once and reduce the overload on the grid. Also, it can redirect electricity generated from the solar PV system of a building for which using natural gas furnace is more economical to a building whose space heating demands can be met with this excess electricity. Higher ASHP performance and capacity, higher carbon pricing, and higher solar PV electricity generation will lead to the design of a more economical and sustainable SDFSS. (paper)

[en] Highlights: • Variation of the stream properties in the syngas-fueled hybrid SOFC–GT cycle. • Detailed analysis of the operation of the methane-fueled SOFC–GT cycle. • Investigate effects of inlet fuel type and composition on performance of cycle. • Comparison of system operation when operated with and without anode recirculation. - Abstract: In this paper, the hybrid solid oxide fuel cell (SOFC) and gas turbine (GT) model was applied to investigate the effects of the inlet fuel type and composition on the performance of the cycle. This type of analysis is vital for the real world utilization of manufactured fuels in the hybrid SOFC–GT system due to the fact that these fuel compositions depends on the type of material that is processed, the fuel production process, and process control parameters. In the first part of this paper, it is shown that the results of a limited number of studies on the utilization of non-conventional fuels have been published in the open literature. However, further studies are required in this area to investigate all aspects of the issue for different configurations and assumptions. Then, the results of the simulation of the syngas-fueled hybrid SOFC–GT cycle are employed to explain the variation of the stream properties throughout the cycle. This analysis can be very helpful in understanding cycle internal working and can provide some interesting insights to the system operation. Then, the detailed information of the operation of the methane-fueled SOFC–GT cycle is presented. For both syngas- and methane-fueled cycles, the operating conditions of the equipment are presented and compared. Moreover, the comparison of the characteristics of the system when it is operated with two different schemes to provide the required steam for the cycle, with anode recirculation and with an external source of water, provides some interesting insights to the system operation. For instance, it was shown that although the physical configuration of the cycle in two systems is the same, the actual configuration (the equipment actually taking part in the process) can be different. Finally, the results of the simulation for different types of the inlet fuel show that system outputs and operational parameters are greatly influenced by changes in the fuel type. Therefore, the possibility of variation of the inlet fuel type should be considered, and its impacts should be investigated before utilization of biogas, gasified biomass, and syngas as fuel in hybrid SOFC–GT cycles

[en] A new conceptual integrated two-stage biomass gasifier and solid oxide fuel cell (SOFC) system is proposed and a multi-physics model for predicting the performance of this system is developed. A method coupling the modeling equations of a quasi 2-D model for SOFC, a 1-D model for pyrolysis reactor, and 0-D model for the remaining components is applied. Several parametric studies are conducted using the model developed. With the main objective of operating this system being maximizing the net power output, the results for the parametric studies conducted show that the number of SOFC stacks, the mass ratio of air to steam entering the gasifier, and the temperature of the pre-heated air entering the gasifier should be taken as high as possible; whereas the moisture ratio of the wet biomass should be minimized; and there is an optimum point for the rotational speed of the pyrolysis reactor. For the considered input data and the range of parameters studied, the maximum net power output of the system is found to be 93 kW. At this condition, the useful heat output, the electrical efficiency of the system, and the fuel utilization efficiency are calculated as 71 kW, 25%, and 44%, respectively. -- Highlights: ► A new integrated two-stage biomass gasifier and SOFC system is proposed. ► A multi-physics model for predicting the performance of this system is developed. ► For the given data, the maximum net power output that can be achieved is 93 kW. ► At this condition, electrical efficiency of the integrated system is found as 25%.