INTEROFFICE MEMORANDUM

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INTEROFFICE MEMORANDUM Date: August 31, 2015 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: August 31, 2015 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 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. For the time being this project is on hold. Construction of the thickening and fermentation building at West Boise WWTF is complete and the operations staff is working on startup of the Enhanced Biological Nutrient Removal (EBNR) process. As expected, this new process has added to the base electrical energy usage of the treatment plant. 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. If 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. The plant staff has worked over the past year to find areas in which to conserve energy in the existing plant. Energy savings have been realized by process optimization, operator awareness of energy consumption and conversion of site lighting to LED fixtures. These savings will help offset the additional energy usage from the EBNR processes, and the plant is showing no net increase in electrical usage. This will continue to be monitored over the next year to see the performance over an entire year of operation. 1

2 The Lander Street WWTF continues to use digester gas for heating of both the process and building space. They have 3 boilers using this gas as the primary heating fuel. Natural gas is required only on the coldest days of the year due to limitations in the digester gas distribution system. Lander Street WWTF and West Boise WWTF have been part of the Idaho Power WasteWater Energy Efficiency Cohort (WWEEC) since January of The staff at the Lander Street treatment plant has implemented various process changes that have resulted in average energy savings of 21.8% compared to average of the previous five years, and an annual cost of about the same dollars as in that same historical period. Changes have been made to the operation of the influent pumps, aeration basin DO control, UV treatment and to post aeration. Operations staff collected data on the effluent discharge to the river and showed that the post aeration blowers were not needed to treat the water exiting the UV treatment facility. This allowed the operators to run the process without needing to use the post aeration blowers. The effluent is being monitored and the post aeration blowers are able to be used if required for treatment. Innovative efforts also have led the Lander St plant to start operating in BNR mode, reducing chemical purchase costs. To effectively operate in this manner the plant flows were reduced by about 25 percent to approximately 10 mgd, with the treated flow increasing an equal amount at West Boise. West Boise staff has also worked to find improvements at their plant to save energy. They have optimized DO levels in the aeration basins and have seen lowered energy use with the new UV equipment that was recently installed. Sight lighting fixtures at both the Lander Street and West Boise WWTF have been converted to LED which cut the energy use of these by more than half. West Boise has discovered in the course of this program that the plant is already designed to operate very energy efficiently which limits their opportunities. They also were undergoing major construction and process changes over the past 2 years which added to overall energy use. The staff is constantly looking for new ways to save energy. One of the major benefits of participation in the WWEEC program is the interest this has generated in the plant staff to look for new and innovative ways to save energy. The WWEEC program continues until December of 2015 but it is the intent to implement a program which will continue to foster staff energy awareness. West Boise WWTF is looking into submetering the plant energy use in order to better track loads in each process train as well as allowing the ability to see when the daily peak energy usage occurs. This will allow the operations staff to factor in energy consumption when making process decisions. Current and Planned Projects to Reduce Utility Energy Consumption Project Name Dates Purpose West Boise new In service since May 2015 Natural gas heating system designed for THK/PSF building easy conversion to hot water if CHP project West Boise Food and Grease Waste Receiving Facility Pre-design has been completed summer 2013, project is on hold. 2 is constructed. Divert food waste from the landfill and grease trap waste from hazardous waste landfill for beneficial use generating biogas for CHP

3 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 that was remodeled into occupied space with the City Hall seismic upgrade. 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. The motors for all the major heating, ventilating and air conditioning (HVAC) components at City Hall Downtown were put on variable frequency drives (VFDs) at the end of FY 2013 which resulted in a 25% decrease in power consumption year to date versus last year. This was not reflected in power cost until 3 rd quarter of the fiscal year when Idaho Power reduced their annual adjustment mechanism. Space heating for the complex is supplied primarily by geothermal water. During the summer months there is no geothermal water use. Geothermal water use has allowed less 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 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 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 2011 through 2015 (see page 13). 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 3

4 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 efficiency of the irrigation system. SPF has conducted another Observation and Maintenance Study during the 2015 irrigation season. The results of this study are expected later in September, The City 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, For 2014, the following recommendations from the SPF Efficiency Study were implemented: - Installation of center pivot sprinkler irrigation systems on Fields 233 and 251. This was completed in March, Replace a mainline in Field 313 that will significantly reduce energy loss in this part of the system. In 2015, the final major recommendations from the SPF Efficiency Study are scheduled to be completed. These scheduled upgrades include the following: - Installation of flow meters on up to 8 wells (as budget allows). This will allow flow measurement on all major wells at the farm. The data collected will be used to better define the cost per gallon of water produced from each well. This information will be used to further refine well operations at the farm going forward. The flow meters are currently out for bid and will be installed during the fall of All flow meters will be functioning and collecting data for the 2016 irrigation season. -Installation of a new center pivot on Field 235 in the southeast corner of the farm. Although not explicitly called out in the SPF Report, this pivot will replace the last major wheel line section of the farm and will conserve both water and electricity. This project has started, the pivot has been constructed and power and mainline installation will take place in September and October This new pivot on field 235 will be ready to go for the 2016 irrigation season. 4

5 Calendar Year kw-hours Acres Irrigated kw-hr per irrigated acre 2015 through August 5,392,320 3,331 1, through August 5,677,404 3,327 1, through August 5,851,580 3,327 1, through August 5,016,320 3,327 1, through August 3,194,680 3, AJP/ap Attachments: - Lander Street WWTF Unit Energy Use- Natural Gas - CHW Q1-4 Power - West Boise WWTF Unit Energy Use- Natural Gas - CHW Q1-4 Electric $ - Lander Street WWTF Unit Energy Use- Natural Gas Only - CHW Gas Usage by Quarter - Lander Street WWTF Unit Energy Use- Digester Gas Only - CHW Gas Dollars by Quarter - West Boise WWTF Unit Energy Use- Natural Gas Only - TMSF Electrical Usage for Irrigation Wells - West Boise WWTF Unit Energy Use- Digester Gas Only - Lander Street WWTF Unit Energy Use- Electricity - West Boise WWTF Unit Energy Use- Electricity - City Hall power consumption by quarter FY City Hall Electricity Dollars by Quarter 5

6 FY 2012 Annual Cost: $ 10,870 for 3.2 therms/mg FY 2013 Annual Cost: $ 11,396 for 3.7 therms/mg FY 2014 Annual Cost: $ 11,435 for 3.6 therms/mg FY 2015 YTD Cost: $ 11,846 for 5.1 therms/mg FY 2015 budget: $ 10,810 (spent 109.6% of budget) FY 2012 Annual Cost: $ 26,287 for 6.6 therms/mg FY 2013 Annual Cost: $ 37,206 for 9.6 therms/mg FY 2014 Annual Cost: $ 60,414 for 14.8 therms/mg FY 2015 YTD Cost: $ 44,989 for 12.6 therms/mg FY 2015 budget: $ 49,529 (spent 90.8% of budget) Wastewater Treatment Facilities Utility Energy Reduction Projects 6

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

8 Compare Natural Gas and Digester Gas use at West Boise WWTF Wastewater Treatment Facilities Utility Energy Reduction Projects 8

FY 2012 Annual Cost: $349,982 for 1,744 kwh/mg FY 2013 Annual Cost: $408,767 for 1,770 kwh/mg FY 2014 Annual Cost: $442,553 for 1,709 kwh/mg FY 2015 YTD Cost: $315,485 for 1,642 kwh/mg FY 2015

9 FY 2012 Annual Cost: $349,982 for 1,744 kwh/mg FY 2013 Annual Cost: $408,767 for 1,770 kwh/mg FY 2014 Annual Cost: $442,553 for 1,709 kwh/mg FY 2015 YTD Cost: $315,485 for 1,642 kwh/mg FY 2015 budget: $449,425 (spent 70.2% of budget) FY 2012 Annual Cost: $681,003 for 2,939 kwh/mg FY 2013 Annual Cost: $797,939 for 2,737 kwh/mg FY 2014 Annual Cost: $925,577 for 2,737 kwh/mg FY 2015 YTD Cost: $754,841 for 2,608 kwh/mg FY 2015 budget: $741,606 (spent 101.8% of budget) 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

13 Wastewater Treatment Facilities Utility Energy Reduction Projects 13

INTEROFFICE MEMORANDUM

INTEROFFICE MEMORANDUM Date: March 3, 2015 To: Boise Public Works Commission From: Anthony Perreira, P.E., Project Manager Subject: Energy Consumption at Major Facilities Managed by Public Works This report