APPP 506 – Master of Engineering Leadership Capstone Project, University of British Columbia
Abhijeet Singh, MEL Candidate | December 17, 2020
Abstract
This study provides a detailed comparison of hot water generation through the natural gas boiler and sewage waste heat recovery (SWHR) heat pump (HP). In the analysis, we have covered natural gas reduction, financial savings, and carbon reduction. Additionally, we worked on using PCM (Phase Change Material) with Heat Pump on the hot water storage site to downsize the buffer tanks used with heat pumps and avoid the oversizing of heat pumps. Lastly, we designed a lithium-ion based energy storage system along with the solar power plant for the SWHR Heat Pump.
Conversely, this review encloses, classifies, and describes the results of different works found in the literature that studied SWGR Heat Pump at commercial & residential site and PCM application with Heat Pump.
Introduction
The Vancouver City Council declared a Climate Emergency in 2019 as the world is experiencing the rising impact of climate change. Climate Emergency Action Plan is using our robust foundation and integrates climate preparedness measures. In contribution to this plan, waste heat recovery from sewage will play a notable role in decarbonizing the carbon footprint of urban areas. Buildings are considered the largest source of Vancouver’s emissions – 59% of the city’s total emissions in 2017 (City of Vancouver 2017). The energy used by buildings in Vancouver is from non-renewable sources, and this source is natural gas which is used for heating. To achieve net zero-emission building (NZB) means there should be no greenhouse gases from the energy it uses. City of Vancouver officials said, “Our strategy is to focus mainly on energy used for space heating and hot water, to have the largest carbon reduction impact.” For that, a comfortable and impactful solution is waste heat recovery from sewage.
The recovery of wastewater heat from individual building or municipal corporation sewer systems can reduce a significant amount of society’s reliance on fossil fuel use for domestic and space water heating. Latent heat in sewer wastewater can be recovered with specific heat exchangers and further upgraded to a useable temperature via heat pumps and distributed directly into the building or to the district heating system.
Background
For the project, we choose Doug Mitchell Thunderbird Sports Centre at the University of British Columbia. Its area is 25768 sqm and annually, approximately 112,320 people visit the sports center for playing and using other facilities such as showers and laundry. There are three areas in the Doug Mitchell Thunderbird Sports Centre: Thunderbird Arena, Father David Bauer Arena, and the Protrans Arena.
Furthermore, Arena has 84 showers in total and a separate laundry facility, which has nine washing machines. The total annual water consumption at the sports centre in water consumption 840,000 ft3/ 6,552,000.00 gallons. Annual domestic hot water consumption at showers and laundry is 2,315,250.00 gallons. It turns out that the shower and laundry is using 35.34% out of 100% (840,000 ft3) annual water. Thus, this site turns out to be a suitable site for applying sewage waste heat recovery and to save natural gas consumption.
For the application of sewage water heat recovery at Arena, we used PIRANHA T15, which is manufactured by SHARC Energy Systems. We decided to install a two-unit of PIRANHA T15 to fulfill the Arena shower and laundry hot water requirements. Secondly, we worked on the application of PCM (Phase change material) with a heat pump to make it compact and efficient. We used nano-eutectic technology bases PCM material which has advantages such as high latent heat, low supercooling, and good stability. Application of this material will be on the hot water storage side, wherewith the help of this we will be able to downsize the hot water storage tank and store heat for a significant amount of time in the PCM and it will act as Latent heat energy storage. Lastly, we designed a lithium-ion-based energy storage system along with the solar power plant for a single PIRANHA T15 unit.
Research Methods
Data Collection: We received data of how many people were using all the three sections of Arena: Thunderbird Arena, Father David Bauer Arena, and the Protrans Arena from 2nd February 2020 till 8th February 2020 which was a peak usage season. On the basis of this data, we created hot water consumption of shower and laundry for both peak (Aug-Feb) and off-peak season (March-July).
Sewage Waste Heat Recovery Analysis: We used all data shared as per the PIRANHA manufacturer specifications. Moreover, the SHARC Energy Systems team analyzed the collected data and after discussions, we came up with which type of unit we have to use from the PIRANHA Series. For comparing the natural gas boiler and PIRANHA T15 we did calculations in excel and derived the results.
For searching the required Phase Change Material (PCM) we took help from Rubitherm Technologies GmbH and Advanced Cooling Technologies, Inc. They helped us to select the PCM.
Energy Storage System: PVSyst 7.1 software was used for designing the energy storage system along with solar power plant, which can be installed for charging the batteries.
Results
Sewage Waste Heat Recovery System:After doing series of calculations, we found that by using PIRANHA T15 Units in place of natural gas boiler we receive financial savings of 42% in comparison to natural gas boiler. Natural gas boiler is producing 1267.06 times more emissions as compared to PIRANHA T15. The emissions may vary depending on the source of electricity and its emission factor.
Battery Storage System: The battery pack is of LG Chem Lithium-ion 7 Units each unit voltage 874 V and capacity 1556 Ah which can hold storage of 300 kWh units per day. The usage pattern is 37.5 kWh per hour and the assumed usage of PIRANHA is 8 hours a day. By using PVsyst 7.1 Software we designed a Photovoltaic solar plant of 262 kWp with specific production of 1083kWh/kWp/year, it is sufficient to supply regular power to the PIRANHA T15 round the year. PVsyst calculated the solar irradiance for the UBC Arena location.
Discussion and Conclusions
After calculations and reviewing the data, we concluded that sewage waste heat recovery (SWHR) heap pumps are highly efficient, and carbon emissions from their use are way lower as compare to natural gas boilers. As the world is moving towards net-zero buildings (NZB), the use of SWHR heat pumps are recommended. Moreover, wastewater heat recovery is critical for achieving a net-zero carbon footprint, which leads to the earning of significant points on sustainable building projects (LEED, Green Globes). It will also lead to savings from avoiding unnecessary power generation and optimize resource consumption for future generations
Contact
Abhijeet Singh
UBC Master of Engineering Leadership – Clean Energy Engineering
+1 236-885-1751 | abhijeet.greenenergy@gmail.com
https://www.linkedin.com/in/abhijeet-singh001/
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