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Heating - Solar water heater - Swimming pool - Indoor / Canada (Kamloops Airport)
Case study assignment
You have been hired by an Energy Service Company (ESCO) to prepare a prefeasibility study of a solar water heating system at a municipal swimming pool. The indoor pool is part of the town recreation centre. It operates just 3.5 months per year - half of April, and all of May, June, and July. Since the town is not on the natural gas grid, the heating fuel is propane, delivered by truck. Propane is relatively expensive, so solar water heating may be cost-effective in reducing operating costs at the recreation centre.
Site information
The swimming pool is located in Lillooet, British Columbia, about 150 km west of Kamloops. The pool is 25 m long and 12.5 m wide, and has an average depth of 1.8 m. The average pool temperature is 29.4 ºC. Fresh make-up water is added at a rate of 5 m³ per day.
Due to the age of the boiler and heat exchanger used to heat the pool water, the overall heater efficiency is 60%. A pool cover is not used.
You have considered the pool site and decide that the best space available for solar collectors is the south-facing roof of the recreation centre. A roof-mounted solar system would be directly over the mechanical room and approximately 2 storeys above it. The roof has an open area of about 800 m² and a 3 in 12 pitch; you estimate that 20% of the available roof space should be reserved for pipes and walking space. All piping for the solar loop would be 76 mm PVC.
Financial information
The ESCO will build the project and then sell energy to the municipality. The solar energy will be priced at 90% of the cost of the propane producing an equivalent amount of heat. The ESCO will pay for the project with approximately $40,000 in equity, and take on no debt. They use a discount rate of 9% and have a tax rate of roughly 35%. The solar energy equipment qualifies for a 25% incentive from the federal government and an accelerated depreciation rate of 30%, calculated on a declining balance basis. The project life is assumed to be 20 years. Solar heating systems are exempt from the 7% provincial sales tax in British Columbia.
The price of propane is $0.24/L and it is expected to increase at a rate 2.8% above inflation, which is estimated at 2.2%. The current price of electricity is $0.06/kWh.
Prepare a RETScreen study, documenting any assumptions that you are required to make, and report on the significant conclusions from this analysis.
Solution
The worked-out solution is the data file selected from within the RETScreen Project Database. The user automatically downloads the Project Database file while downloading the RETScreen software.
Teacher's notes
Real project
Results
The Lillooet Recreation Centre operates its indoor pool only 3 months per year - May, June, and July. The pool building was originally built with a low slope, south-facing roof in the hopes that solar heating would one day be installed. Taylor Munro, in conjunction with its partner Yalakom Appropriate Technology, secured financing and built a solar system in May 1998.
Through an innovative financing method, the Recreation Centre did not pay for the capital cost of the system. Instead, the system is monitored for performance, and the Centre pays only for the energy used. This Energy Service Company (ESCO) arrangement limits the financial and technical risk for the Recreation Centre.
System description
The system uses sixty-three 1.2 m x 3.7 m unglazed collectors, which generate a peak output of approximately 250 kW. They are expected to last 20 years.
Pool water circulates directly through the collectors whenever there is enough solar energy to add useful heat to the pool. A booster pump, automatic 3-way valve and a differential temperature controller are used to divert water to the solar collectors. The solar heater operates automatically, requiring attention only at start up and shut down. The feed and return piping is mainly 78 mm PVC which branches off into 7 banks of 9 collectors each.
The annual energy delivered is approximately 83 MWh (300 Gigajoules) which displaces propane fuel and avoids about 29 tonnes per year of greenhouse gas (GHG) emissions.
The annual ESCO revenue from the sale of the solar energy is approximately $4,000. The total cost of installing the system today would be approximately $40,000. The cost after a 25% federal government incentive would be approximately $30,000.
Lessons learned
The big picture
Hundreds of municipal pools would benefit from solar heating to reduce operating costs and environmental impacts. Solar collector technology is efficient and well-proven for swimming pools. In addition to reducing GHG emissions, this technology helps mitigate urban smog by reducing the amount of nitrogen oxides produced during the summer.
Payback periods for indoor municipal pools are typically less than 10 years. Outdoor pools operating for a season of 3 months or longer have simple paybacks that are similar or even lower. In some circumstances it may be possible for customers to purchase solar energy under an Energy Service agreement, rather than make an outright purchase of equipment.
Photo
Recreation centre - Swimming pool - Solar water heater, British Columbia, Canada
References
Case study assignment
You have been hired by an Energy Service Company (ESCO) to prepare a prefeasibility study of a solar water heating system at a municipal swimming pool. The indoor pool is part of the town recreation centre. It operates just 3.5 months per year - half of April, and all of May, June, and July. Since the town is not on the natural gas grid, the heating fuel is propane, delivered by truck. Propane is relatively expensive, so solar water heating may be cost-effective in reducing operating costs at the recreation centre.
Site information
The swimming pool is located in Lillooet, British Columbia, about 150 km west of Kamloops. The pool is 25 m long and 12.5 m wide, and has an average depth of 1.8 m. The average pool temperature is 29.4 ºC. Fresh make-up water is added at a rate of 5 m³ per day.
Due to the age of the boiler and heat exchanger used to heat the pool water, the overall heater efficiency is 60%. A pool cover is not used.
You have considered the pool site and decide that the best space available for solar collectors is the south-facing roof of the recreation centre. A roof-mounted solar system would be directly over the mechanical room and approximately 2 storeys above it. The roof has an open area of about 800 m² and a 3 in 12 pitch; you estimate that 20% of the available roof space should be reserved for pipes and walking space. All piping for the solar loop would be 76 mm PVC.
Financial information
The ESCO will build the project and then sell energy to the municipality. The solar energy will be priced at 90% of the cost of the propane producing an equivalent amount of heat. The ESCO will pay for the project with approximately $40,000 in equity, and take on no debt. They use a discount rate of 9% and have a tax rate of roughly 35%. The solar energy equipment qualifies for a 25% incentive from the federal government and an accelerated depreciation rate of 30%, calculated on a declining balance basis. The project life is assumed to be 20 years. Solar heating systems are exempt from the 7% provincial sales tax in British Columbia.
The price of propane is $0.24/L and it is expected to increase at a rate 2.8% above inflation, which is estimated at 2.2%. The current price of electricity is $0.06/kWh.
Prepare a RETScreen study, documenting any assumptions that you are required to make, and report on the significant conclusions from this analysis.
Solution
The worked-out solution is the data file selected from within the RETScreen Project Database. The user automatically downloads the Project Database file while downloading the RETScreen software.
Teacher's notes
- The avoided cost of heating energy has been calculated by first adding 7% to the current price of propane ($0.24/L), to account for the 7% provincial sales tax levied on propane but not solar water heating systems, and then multiplying by 90%, to represent the revenue to the ESCO.
- The size of the system has been limited to 63 collectors, which is smaller than recommended by RETScreen. This has been done to match the funds available to the ESCO.
- The annual operating and maintenance labour costs account for system start up and shutdown at the beginning and end of the season, respectively. These are estimated to take 2 hours each.
Real project
Results
The Lillooet Recreation Centre operates its indoor pool only 3 months per year - May, June, and July. The pool building was originally built with a low slope, south-facing roof in the hopes that solar heating would one day be installed. Taylor Munro, in conjunction with its partner Yalakom Appropriate Technology, secured financing and built a solar system in May 1998.
Through an innovative financing method, the Recreation Centre did not pay for the capital cost of the system. Instead, the system is monitored for performance, and the Centre pays only for the energy used. This Energy Service Company (ESCO) arrangement limits the financial and technical risk for the Recreation Centre.
System description
The system uses sixty-three 1.2 m x 3.7 m unglazed collectors, which generate a peak output of approximately 250 kW. They are expected to last 20 years.
Pool water circulates directly through the collectors whenever there is enough solar energy to add useful heat to the pool. A booster pump, automatic 3-way valve and a differential temperature controller are used to divert water to the solar collectors. The solar heater operates automatically, requiring attention only at start up and shut down. The feed and return piping is mainly 78 mm PVC which branches off into 7 banks of 9 collectors each.
The annual energy delivered is approximately 83 MWh (300 Gigajoules) which displaces propane fuel and avoids about 29 tonnes per year of greenhouse gas (GHG) emissions.
The annual ESCO revenue from the sale of the solar energy is approximately $4,000. The total cost of installing the system today would be approximately $40,000. The cost after a 25% federal government incentive would be approximately $30,000.
Lessons learned
- A "low-flow" design using small pipes and pumps reduced capital and operating costs making the system more cost-effective.
- The existing building roof, specially designed for solar collectors, eliminates the need for collector racking thus significantly lowering the project cost. This forethought should be applied in the design of new pool facilities.
- Unglazed collectors are susceptible to wind induced heat loss. The site-specific wind conditions should be carefully considered when designing the solar heating system.
The big picture
Hundreds of municipal pools would benefit from solar heating to reduce operating costs and environmental impacts. Solar collector technology is efficient and well-proven for swimming pools. In addition to reducing GHG emissions, this technology helps mitigate urban smog by reducing the amount of nitrogen oxides produced during the summer.
Payback periods for indoor municipal pools are typically less than 10 years. Outdoor pools operating for a season of 3 months or longer have simple paybacks that are similar or even lower. In some circumstances it may be possible for customers to purchase solar energy under an Energy Service agreement, rather than make an outright purchase of equipment.
Photo
Recreation centre - Swimming pool - Solar water heater, British Columbia, Canada
References
- Davis, Scott, "Personal communication," Yalakom Appropriate Technology, 2000.
- Thwaites, Joe, "Personal communication," Taylor Munro Energy Systems Inc., 2000
