INTEROFFICE MEMORANDUM

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INTEROFFICE MEMORANDUM Date: February 5, 2014 To: Boise Public Works Commission From: Anthony Perreira, P.E., Project Manager Subject: Energy Consumption at Major Facilities Managed by Public Works This report contains new information shown in bold.

1 INTEROFFICE MEMORANDUM Date: February 5, 2014 To: Boise Public Works Commission From: Anthony Perreira, P.E., Project Manager Subject: Energy Consumption at Major Facilities Managed by Public Works This report contains new information shown in bold. This memo is presented twice annually to update the Commission on the status of energy consumed and energy conservation projects occurring at major City-owned facilities managed by Public Works. Changes from the previous report are shown with bold font. Energy Use Narrative for Wastewater Facilities The West Boise WWTF has completed the installation of a third channel at the ultraviolet (UV) disinfection facility. This new channel is intended to be used as the primary channel at the facility. The UV system installed in the new channel should result in lower total electricity use by the UV facility. Biogas use at both facilities has been very reliable and has allowed the offset of natural gas use. A pre-design report was completed in June of 2013 for a combined heat and power (CHP) project. This design is for a facility to receive food wastes and brown grease for the purpose of digestion and gas production. Final design will begin after the completion of a facility plan update. This facility plan update will investigate the impact of food waste processing on the treatment system as well the effect of upcoming changes to the discharge permit. Construction of a thickening and fermentation building has begun at West Boise WWTF as part of the phosphorus removal project. This building will be completed in For ventilation and fresh air purposes, the building requires a high air exchange rate and therefore has a high heating demand to temper this air. There is currently not enough biogas being produced by the treatment process to provide the heating load required for this new facility. Natural gas will be used for heating the building rather than using biogas or the existing heating loop hot water. The HVAC system for the building will incorporate a heat recovery unit to capture waste heat from the exhaust stream. The heating system has been designed for easy conversion to hot water heating. When the CHP project is implemented, heat recovered from the CHP using the added biogas from brown grease and food waste would effectively provide the additional heating capacity needed. 1

2 A construction project is currently underway to add a new dual-fuel boiler (biogas or natural gas) to the Lander Street WWTF hot water loop. This boiler will increase the system heating capacity and improve equipment redundancy. Construction will be complete by July 2014 and ready for the 2014/2015 heating season. Current and Planned Projects to Reduce Utility Energy Consumption Project Name Dates Purpose West Boise new THK/PSF building Construction underway; in service May 2015 Natural gas heating system designed for easy conversion to hot water if CHP project is constructed. Lander St. boiler Construction underway; Provide capacity and redundancy for new addition West Boise Food and Grease Waste Receiving Facility completed by July 2014 Pre-design has been completed, planned to be evaluated as part of a facilities plan update. process and space heating loads Divert food waste from the landfill and grease trap waste from hazardous waste landfill for beneficial use generating biogas for CHP Energy Use Narrative for City Hall and City Hall West The City Hall Complex is comprised of three separate buildings connected by a central atrium. Electricity is used in the City Hall complex for space cooling, equipment motors and controls, lights, computer and security systems, domestic water heating, and other minor loads. Electricity is also used as a backup for space heating in the event geothermal heat is not available. Space heating for the complex is supplied primarily by geothermal water. During the summer months there is no geothermal water use, so the charts below only show the months of October through March. Geothermal water use is higher in than in due to an increase in the heating setpoint for the complex. This change was made in an effort to better utilize this resource and minimize the need for localized electric space heaters. There is an accompanying reduction in electrical use that is attributed to this change that was made in the geothermal system operation. Geothermal is less costly than electricity and this change also capitalizes on the City s use of an environmentally friendly resource. City Hall West utilizes natural gas in boilers for space heating, and in a separate boiler for domestic water heating. Electricity is used for space cooling, equipment motors and controls, lights, computer and security systems, and other minor loads. Historical data for electricity and gas use are attached. The City has only fully occupied the building since the spring of The energy use history documents the efforts of building staff to optimize energy use to meet occupancy needs with existing equipment. The solar heating demonstration project using DOE EECBG funds was put into service on December 23, Quarterly energy savings from solar are reported in a table below, but represent only a fraction of 1 percent of the total building energy consumption. Energy Use Narrative for Twenty Mile South Farm Practices at the Farm have been developed to use irrigation water efficiently with the current infrastructure. Efficient water use can be related directly to electrical usage by the irrigation well pumps delivering water to the irrigation equipment (for example, kwh per million gallons 2

3 pumped) and applying water commensurate with crop requirements. TMSF continues to monitor irrigation rates by field and crop for comparison to local evapotranspiration data. The attached TMSF electrical use chart has been updated using data from the Idaho Power website and reflects power consumption for the TMSF irrigation wells. Approximately 95% of the TMSF power consumption is used for pumping irrigation water. The attached chart shows a comparison of actual calendar year power consumption data for the irrigation wells from 2010 through 2013 (see page 12). From 2008 through 2011, we had very cool wet spring weather that helped to keep energy use down. This is especially evident in the attached chart when comparing March through May energy use for 2012 and 2013 to previous years. July, 2012 and July, 2013 were two of the hottest months on record for the Boise area. The City has contracted with SPF Water Engineering to implement an Observation and Maintenance Program for the irrigation wells at the farm, which should continue to ensure adequate water delivery in the most efficient manner possible. This program resembles the program SPF implemented for the Boise Parks and Recreation Department. The intent of the program is to document and track well system performance and efficiency to help identify abnormal or deteriorating conditions that would warrant further investigation or maintenance. The farm continues to implement measures such as this to increase power efficiency. The City has also contracted with SPF Water Engineering to conduct an efficiency study for the TMSF in The preliminary draft report was received by Public Works staff in late January, Several of the recommendations from the efficiency report were implemented during the 2013 crop season, including: - Operation of booster pumps on Well #7. This work was completed in May, Another recommendation was to modify the sequence of well operation. Well #12 is now a primary well and it was configured to be able to call Well #1 when additional water pressure was required in the system. The sequencing on primary Well #6 was also modified. This was completed in August, The TMSF also modified the bowls on Well #2 to make it run in a more efficient manner. This was completed in October, Calendar Year kw-hours Acres Irrigated kw-hr per irrigated acre ,600,410 3,327 2, ,680,920 3,327 2, ,795,120 3,327 1, ,681,958 3,327 1, ,480,959 3,088 1, ,838,052 3,088 1, ,622,586 2,814 2,040 3

4 AJP/ap Attachments: - Lander Street WWTF Unit Energy Use- Natural Gas - City Hall Electrical Use by Quarter - West Boise WWTF Unit Energy Use- Natural Gas - City Hall West Electrical Use by Quarter - Lander Street WWTF Unit Energy Use- Natural Gas Only - City Hall West Gas Usage by Quarter - Lander Street WWTF Unit Energy Use- Digester Gas Only - TMSF Electrical Usage for Irrigation Wells - West Boise WWTF Unit Energy Use- Natural Gas Only - Energy Use: Comprehensive Historical Narrative for Wastewater Facilities - West Boise WWTF Unit Energy Use- Digester Gas Only - WWTF Projects to Reduce Utility Energy Consumption - Lander Street WWTF Unit Energy Use- Electricity - Lander Street Electrical Monitoring Summary - West Boise WWTF Unit Energy Use- Electricity - West Boise Electrical Monitoring Summary - City Hall Bldg 1 - Geothermal Gallons per Heating Degree Day per square foot - City Hall Bldg 2 - Geothermal Gallons per Heating Degree Day per square foot 4

5 FY 2011 Annual Cost: $ 13,705 for 3.8 therms/mg FY 2012 Annual Cost: $ 10,870 for 3.2 therms/mg FY 2013 Annual Cost: $ 11,396 for 3.7 therms/mg FY 2014 YTD Cost: $ 5,297 for 6.8 therms/mg FY 2014 budget: $ 10,810 (spent 49.0% of budget) FY 2011 Annual Cost: $ 66,014 for 15.3 therms/mg FY 2012 Annual Cost: $ 26,287 for 6.6 therms/mg FY 2013 Annual Cost: $ 37,206 for 9.6 therms/mg FY 2014 YTD Cost: $ 24,444 for 23.3 therms/mg FY 2014 budget: $ 49,529 (spent 49.4% of budget) Wastewater Treatment Facilities Utility Energy Reduction Projects 5

6 Compare Natural Gas and Digester Gas use at Lander St WWTF Wastewater Treatment Facilities Utility Energy Reduction Projects 6

7 Compare Natural Gas and Digester Gas use at West Boise WWTF Wastewater Treatment Facilities Utility Energy Reduction Projects 7

8 FY 2011 Annual Cost: $337,590 for 1,763 kwh/mg FY 2012 Annual Cost: $349,982 for 1,744 kwh/mg FY 2013 Annual Cost: $408,767 for 1,770 kwh/mg FY 2014 YTD Cost: $114,543 for 1,920 kwh/mg FY 2013 budget: $449,425 (spent 25.5% of budget) FY 2011 Annual Cost: $659,925 for 2,891 kwh/mg FY 2012 Annual Cost: $681,003 for 2,939 kwh/mg FY 2013 Annual Cost: $797,939 for 2,737 kwh/mg FY 2014 YTD Cost: $217,171 for 2,723 kwh/mg FY 2014 budget: $741,606 (spent 29.3% of budget) Wastewater Treatment Facilities Utility Energy Reduction Projects 8

9 Wastewater Treatment Facilities Utility Energy Reduction Projects 9

10 Wastewater Treatment Facilities Utility Energy Reduction Projects 10

11 Wastewater Treatment Facilities Utility Energy Reduction Projects 11

12 Wastewater Treatment Facilities Utility Energy Reduction Projects 12

INTEROFFICE MEMORANDUM

INTEROFFICE MEMORANDUM Date: October 1, 12014 To: Boise Public Works Commission From: Anthony Perreira, P.E., Project Manager Subject: Energy Consumption at Major Facilities Managed by Public Works This