Document Redmond_doc_eddeadd2d7

Overlake Village District Energy Feasibility Study September 2015 Prepared by: Puget Sound Energy Sound Energy Investments ---PAGE BREAK--- Acknowledgements This feasibility study was the collaborative work of numerous personnel from the City of Redmond, Sound Energy Investments, and Puget Sound Energy. Their contributions to this effort are greatly appreciated. Puget Sound Energy would like especially to thank the key City of Redmond staff who made this effort possible: Lori Peckol, Cathy Beam, Jeff Churchill, and Pete Sullivan. 1 I P a g e ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Table of Contents Table of Contents Executive Summary 6 1 Introduction 11 2 Study Approach 12 2.1 Scenario Objectives and Approach 12 2.2 Assumptions 12 2.3 Pre-feasibility Study Recommendations 13 2.4 Evaluation Criteria 13 3 Data Acquisition 16 3.1 Data Acquisition Process 16 3.2 Planning and Space Use Assumptions 17 3.3 Planned 18 4 Energy Study 25 4.1 Modeling 25 4.2 Business-As-Usual Energy 27 4.3 District Energy Facility 28 4.4 District Energy Technology Assessment Results 49 5 Ownership Structures and Financing Models 55 5.1 Ownership Structures 55 5.2 Project Phases and Functional Activities 60 5.3 City of Redmond Participation Options 62 5.4 Financing Strategies and Risk Mitigation 65 5.5 Revenue Model 66 5.6 Ownership Structure Recommendation 67 6 Results 68 6.1 Scenario Criteria 68 6.2 Financial Modeling Approach 70 6.3 Financial Model Inputs 72 6.4 Discussion of Results 76 7 Conclusions and Recommendations 79 2 I P a g e ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Table of Contents Appendix A: Energy Efficiency Assessment 81 Appendix B: Distributed Generation 86 Rooftop Solar 86 Renewable Energy Credits 88 Recommendation 89 Appendix C: Renewable Energy and Storage Technologies 90 High Solid Anaerobic Digestion 90 Energy Storage Technologies 90 Appendix D: Utility Infrastructure and Related Technologies 94 Electric Utility 94 Natural Gas Utility Infrastructure 96 Advance Meter Infrastructure 98 Distribution Automation 99 Demand Response 100 Electric Vehicle Integration 102 Direct Use of Natural Gas 103 Appendix E: Tariff Rate Schedules and Applicable Laws 104 Natural Gas Tariff Rate 104 Electric Tariff Rate Schedules 105 Applicable Existing Laws 107 Summary of Affiliated Interest Rules 108 3 I P a g e ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I List of Tables List of Tables Table 1: Central Plant Design Options 7 Table 2: Development Scenarios 7 Table 3: Economic Results 8 Table 4: Recommendations from Pre-Feasibility Study 13 Table 5: Projected Land Use for Overlake Village 17 Table 6: Projected Rate of Development for Overlake Village through 2030 23 Table 7: Summary of Annual Energy Consumption for Study Area for 27 Table 8: Design Options 28 Table 9: BAU Scenario Summary 50 Table 10: Summary of District Energy Technology Assessment Results 50 Table 11: Summary of Annual Energy Consumption – Electrical Consumption (kWh) 53 Table 12: Summary of Annual Energy Consumption – Electrical Demand (kW) 53 Table 13: Summary of Annual Energy Consumption – Natural Gas (therms) 54 Table 14: Public Ownership Risk Benefit Summary 56 Table 15: Private Ownership Risk Benefit 57 Table 16: Public-Private Ownership Risk Benefit 58 Table 17: Cooperative Ownership Risk Benefit Summary 60 Table 18: Stakeholder Functional Activities 61 Table 19: Scenarios and Objectives 69 Table 20: Overview of District Energy Scenarios 70 Table 21: Blended Rate Calculation 71 Table 22: Capital Spending Curve for Central Plant and Distribution System 73 Table 23: Overlake Village New Development Forecast and Adoption Rate Curve 74 Table 24: District Energy Scenario Results 76 Table 25: 2014 Prescriptive Measures and Incentives 83 Table 26: Multi-Family Buildings 84 Table 27: Mixed-Use Buildings 84 Table 28: Technical Potential of Solar Generation in Overlake Village 87 Table 29: Applicable Energy Storage Technologies 91 Table 30: Existing Feeders Serving Overlake Village 95 Table 31: System Reliability 96 List of Figures Figure 1: Carbon Emissions Results for BAU and Selected Scenarios 9 Figure 2: Energy Use Results for BAU and Selected Scenarios 9 Figure 3: District Energy Study Geography 18 Figure 4: Planned Development Locations 19 Figure 5: GRE Bellevue Aerial Rendering 20 4 I P a g e ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I List of Tables Figure 6: GRE Bellevue Bel-Red Elevation 20 Figure 7: Esterra Park Proposed Site Plan 21 Figure 8: Esterra Park Rendering 21 Figure 9: KCC Limited Edition Rendering 22 Figure 10: Example Comparable Office Building (source Troy Block) 25 Figure 11: Example Comparable Office Building eQUEST Model 26 Figure 12: BAU Scenario Components 27 Figure 13: Example Boiler Plant Photos 29 Figure 14: Example Chiller Plant Photos 29 Figure 15: Example Central Plant Exterior Photos 30 Figure 16: Central Heating Hot Water and Chilled Water Plant Equipment System Diagram 31 Figure 17: Central Heating Hot Water and Chilled Water Plant Site Plan 32 Figure 18: Central Heating Hot Water-Only Plant Equipment System Diagram 33 Figure 19: Central Heating Hot Water-Only Plant Site Plan 34 Figure 20: Example Injection Well And Example Ground Source Heat Pump 35 Figure 21: Geothermal Plant Equipment System Diagram 36 Figure 22: Geothermal Plant Site Plan 37 Figure 23: Example Closed Loop Geothermal System 38 Figure 24: Combined Heat and Power Plant Equipment System Diagram 39 Figure 25: Combined Heat and Power Plant Site Plan 40 Figure 26: Demand Response / Thermal Energy Storage Plant Equipment System Diagram 41 Figure 27: Demand Response / Thermal Energy Storage Plant Site Plan 42 Figure 28: Waste Heat Recovery Plant Equipment System Diagram 43 Figure 29: Waste Heat Recovery Plant Site Plan 44 Figure 30: Low Temperature Condenser Water System with Distributed Heat Pumps Equipment System Diagram 45 Figure 31: Low Temperature Condenser Water System with Distributed Heat Pumps Site Plan 46 Figure 32: Central Plant Piping Schematic 47 Figure 33: Distribution Piping Example Cross Sectional Detail 48 Figure 34: Annual Carbon Emissions for BAU and District Energy Technology 51 Figure 35: Annual Energy Consumption for BAU and District Energy Technology Options 52 Figure 36: District Energy Scenario Components 68 Figure 37: Overlake Village New Development Forecast and Adoption Rate 75 Figure 38: BAU and District Energy Results 78 Figure 39: Average Energy Output (kWh) of 1 kW of Solar PV Capacity 87 Figure 40: Intermediate Pressure System for PSE Natural Gas Infrastructure 97 5 I P a g e ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Executive Summary Executive Summary The City of Redmond (the City) has investigated the feasibility of establishing a district energy system in Overlake Village as part of the City’s climate action planning efforts. District energy has the potential to reduce energy use, carbon emissions, and energy costs while creating a competitive edge in redevelopment by eliminating the need to provide onsite heating and cooling equipment. Puget Sound Energy (PSE) and the City, in partnership with and Sound Energy Investments, developed this feasibility study report to examine specific district energy system configurations and determine whether such a system would reduce energy costs, reduce carbon emissions, meet the City’s Climate Action Implementation Plan, and be economically feasible to construct and operate in Overlake Village. This report considers district energy technologies, ownership structures, operations, regulatory considerations, and financial analysis. Included are recommendations and considerations to be used in the next phase of district energy development for Overlake Village. The analysis also identifies specific energy efficiency considerations and distributed generation technologies that could be implemented in Overlake Village even without the development of the district energy system. The evaluation process. The City evaluated district energy for Overlake Village in a two-step process: a pre-feasibility study completed in late 2013, and a feasibility study completed in December 2014. The 2013 pre-feasibility study was funded by a HUD grant. This initial study indicated that a district energy system could reduce energy use by 10–30 percent, reduce heating and cooling energy costs by 10–50 percent, and reduce carbon emissions by 15–45 percent. The higher end of each of these ranges represents the reduction that might be achieved by combining generation technologies like natural gas and geothermal. The 2014 comprehensive feasibility study was performed by a partnership of the City and PSE, and was funded almost entirely by PSE. This study assessed district energy technology to help determine the economic feasibility of district energy for Overlake Village. As a baseline for the 2014 evaluation, PSE and the City defined several “business-as-usual” (BAU) scenarios to model the future energy performance of the Overlake Village study area if district energy is not implemented. The evaluation criteria for the feasibility study required that: 1. Rates are to be competitive with BAU energy rates. 2. Greenhouse gas emissions are to be lower than BAU greenhouse gas emission levels. 3. Energy use is to be lower than BAU energy use. 4. The system’s central plant is to be financially viable and must meet the investors’ objectives. PSE and the consultant team – and Sound Energy Investments – incorporated the following general methodology: 1. Compile energy use data for the Overlake Village. 2. Select suitable technologies for district energy systems. 3. Assess ownership structures and demarcation for district energy systems. 6 I P a g e ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Executive Summary 4. Evaluate the economic benefits, energy use, and greenhouse gas emissions of the proposed district energy systems based on assumed adoption rates. 5. Compare the proposed district energy systems to the BAU scenarios. Seven conceptual design options were considered for the central plant that would serve the Overlake Village district energy system. Table 1: Central Plant Design Options Option System design A Central heating hot water and chilled water plant consists of natural-gas-fired hot water boilers, chillers, cooling towers, and distribution pumps located in a central facility and connected to the district by a network of buried distribution piping. B Central heating hot-water-only plant consists of natural-gas-fired hot water boilers and distribution pumps located in a central facility and connected to the district by a network of buried distribution piping. C Central heating hot water and chilled water plant with geothermal would add a part-load open-loop ground source geothermal heat pump system to Option A. D Combined heat and power plant would add a combined heat and power system to Option A, sized for the minimum continuous heating load of the district energy system. E Demand response/thermal energy storage would add a thermal energy storage system with demand response controls to Option A. F Waste heat recovery plant would add waste heat recovery to Option A. G Waste heat recovery plant with distributed heat pumps would install gas-fired condensing boilers, cooling towers, and distribution pumps in a central facility connected to the district by a network of buried distribution piping. After establishing this range of design options for the central plant, the team framed four scenarios, with each scenario focusing on a particular aspect of the evaluation criteria as its main objective. The team then identified the design option that would best fit each scenario. Table 2: Development Scenarios Scenario Objective Best-fit option 1 Minimize carbon footprint. G 2 Minimize carbon footprint with geothermal. C 3 Minimize district energy implementation, operations, and maintenance costs. B 4 Hold customer rates to parity with BAU-gas heating rates. A The recommended ownership structure to ensure successful development and implementation of the district energy system is public-private ownership. The financial analysis assumed that the rate of return would be similar to PSE’s, but also compared the investment opportunities to keeping the cost in line with BAU. 7 I P a g e ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Executive Summary Economic feasibility. The economic feasibility results are shown in Table 3, below. Table 3: Economic Results BAU: Gas Heat BAU: Electric Heat Scenario 1: Low Carbon Scenario 2: Low Carbon, Geothermal Scenario 3: Low Cost Scenario 4: Rate Parity 25-year NPV total capital and O&M costs for building systems $53.5M $61.6M N/A N/A $25.6M N/A 25-year NPV total capital and O&M costs for district energy systems N/A N/A $51.7M $56.0M $24.3M $55.5M Internal rate of return N/A N/A 6.7% 12% 6.7% -0.25% Blended retail rate ($/MMBTU) $21.17 $42.92 $34.79 $50.06 $33.36 $21.17 Scenario 3 appears to be the most economical. It would reduce customer rates compared to today’s electric heating rates, which are what most customers pay since most new construction in Overlake Village uses electric heating. Scenario 3 also assumes City or PSE ownership, which reduces the required rate of return. In contrast to Scenario 3: • Scenario 1, which includes waste heat recovery, is more technically complex and more costly. • Scenario 2 assumes a private third-party owner, and because a private owner would require competitive rates of return commensurate with risk, the result would be unacceptably high customer utility rates. • Scenario 4 holds customer rates constant at today’s low natural gas costs. This results in unacceptably low returns. Environmental feasibility. Carbon emission reduction was an important success criterion, because this study is part of the City’s climate action planning efforts. As Figure 1 and Figure 2 show, the low-carbon Scenarios 1 and 2 perform best. All district energy scenarios out-perform the BAU scenarios, and do much better than the BAU electric heat scenario. Overall energy usage, including heating, cooling, and other electric loads such as appliances, is the lowest in the low-carbon scenarios. (Note that although greenhouse gas emission reductions are an important objective for the City, they are not mandated by regulation or law, and as a result have not been monetized in this study.) 8 I P a g e ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Executive Summary Figure 1: Carbon Emissions Results for BAU and Selected Scenarios Figure 2: Energy Use Results for BAU and Selected Scenarios Owning and operating a district energy system. Establishing a district energy system at reasonable customer rates would likely require the City or PSE to own the distribution system and central plant. District energy would be a new venture for both the City and PSE, requiring new resources and expertise. For PSE, this venture would represent a departure from its current technology and service models, and would serve only a very small part of PSE’s service area, thereby making it a relatively low priority. For the City, district energy has potential benefits, but the benefits do not appear sufficient to offset the resources needed to launch and maintain a new utility, considering the City’s existing service responsibilities and the other initiatives underway. The cost estimates would need to be much more detailed before any future phases of this project could be considered feasible. The Recommendation. The City’s staff does not believe that the potential benefits of district energy outweigh the potential costs and risks associated with establishing a new utility, nor does the staff - 2,000 4,000 6,000 8,000 10,000 12,000 14,000 16,000 BAU-Gas BAU-Electric Scenario 1 Scenario 2 Scenario 3 Scenario 4 Carbon Emissions from Heating/Cooling (tons/yr) - 50,000 100,000 150,000 200,000 250,000 300,000 BAU-Gas BAU-Electric Scenario 1 Scenario 2 Scenario 3 Scenario 4 Community Energy Use (MMBTUs) 9 I P a g e ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Executive Summary believe that the City is equipped to take on a new utility. If the potential benefits were spread over a much wider area, or if other partnership opportunities existed, the recommendation might be more favorable. While the City’s staff does not recommend proceeding with a district energy system, the study notes other, more feasible ways to advance economic and environmental goals. For example, natural gas heating is cheaper for customers and less carbon-intensive than electric heating, and yet electric heating is frequently included in new multifamily construction because it is less costly to install. The team recommends exploring ways to achieve natural gas, rooftop solar, and other carbon-light and economically competitive heating sources in new construction. This could yield benefits in Overlake Village and across the city. Also, the City recently won PSE’s Green Power Challenge; building on that success would also yield reductions in the community’s carbon footprint. 10 I P a g e ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Introduction 1 Introduction Overlake Village is an approximately 175-acre portion of the Overlake neighborhood within the city of Redmond, Washington, bounded by SR-520 to the north, 156th Avenue NE to the east, NE 20th Street to the south, and 148th Avenue NE to the west. Overlake Village is transforming into an urban mixed-use neighborhood where people may enjoy a mix of work and living space coupled with open areas to gather and explore. In accordance with Redmond’s Climate Action Strategy, the City has been investigating the implementation of district energy concepts as part of the Overlake Village redevelopment. District energy generally refers to a system of centralized heating – and optionally cooling – that can be implemented using a variety of energy sources and distribution systems. District energy systems produce steam, hot water, or chilled water at a central plant. The steam, hot water, or chilled water is then piped underground to individual buildings for space heating, domestic hot water heating, or air conditioning. As a result, individual buildings served by a district energy system don't need their own boilers or furnaces, chillers, or air conditioners. The district energy system does that work for them. There are more than 700 district energy systems in the United States, with ample opportunities for future development or expansion. At Overlake Village, district energy has the potential to reduce energy use, carbon emissions, and energy costs while creating a competitive edge in redevelopment by eliminating the need to provide onsite heating and cooling equipment. In 2013, the City received a HUD-funded Growing Transit Communities study, which included an initial evaluation of district energy concepts by Puttman Infrastructure (Puttman). Puttman’s pre-feasibility study estimated energy use, cost of fuel, and carbon emissions savings in comparison to conventional in- building heating and cooling systems for the 175-acre mixed-use area described above. Although Puttman’s assumptions, findings, and recommendations were preliminary in nature, they provided a useful basis for further investigation. This report builds on the assumptions and recommendations made in the Puttman pre-feasibility study, and clearly outlines any deviations from the Puttman study’s assumptions and results due to the more detailed feasibility analysis performed in 2014. 11 I P a g e ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Study Approach 2 Study Approach 2.1 Scenario Objectives and Approach There are many different ways to develop a district energy system. The team used a scenario approach in which district energy system scenarios were developed and evaluated based on the success criteria and priorities for the City. The economic and environmental benefits are the most important criteria for evaluating the district energy scenarios, according to the City’s Climate Action Strategy and the Comprehensive Plan. A viable scenario must result in: • A market advantage for building developers/owners. • Low customer energy rates. • A resilient infrastructure. • A sustainable community. • Greenhouse gas emission reductions. Along with the available information and future plans, numerous assumptions have been made at this feasibility level to formulate likely scenarios for Overlake Village. The general methodology used for this study can be simplified into several key elements: 1. Compile energy use data for the Overlake Village. 2. Select suitable technologies for district energy systems. 3. Assess ownership structures and demarcation for district energy systems. 4. Evaluate the economic benefits, energy use, and greenhouse gas emissions of the proposed district energy systems based on assumed adoption rates. 5. Compare the proposed district energy systems to the BAU scenarios. The BAU scenarios model what would happen in terms of heating and cooling technology in the absence of district energy. Two BAU scenarios are considered for comparison. One BAU scenario represents buildings in which a majority of the heating is provided by electricity (BAU-Electric Heat), and second BAU scenario represents a majority of heating provided by natural gas (BAU-Gas Heat). Economic and environmental benefits were evaluated for the BAU scenarios and compared against alternative district energy scenarios. Although greenhouse gas emission reductions are an important objective for the City, they are not mandated by regulation or law, and as a result have not been monetized in this study. Future legislation and participation in carbon markets may enable carbon emission reductions to be monetized. 2.2 Assumptions Several assumptions have been made in the BAU scenarios as well as the district energy scenarios. The assumptions important for the BAU scenarios are as follows: • Each building will have its own heating and cooling systems. • Heating and cooling systems are installed by individual developers at time of construction. 12 I P a g e ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Study Approach • Heating and cooling systems are ultimately owned, operated and maintained by building owners and homeowners. • Heating and cooling needs are met with a combination of electricity and natural gas, depending on the BAU scenario. • Electricity and natural gas service will be provided by PSE. • New construction maximizes conservation savings through the use of modern equipment and energy-efficient design. The following assumptions drive the district energy scenarios: • Central heating and cooling equipment is not located in the individual buildings. • Electricity and natural gas to serve the central plant and other district energy system needs are provided by PSE. • The City will enact an ordinance mandating new construction connection to a district energy system, or will provide significant incentives to guarantee connection. • If PSE owns and operates the system’s central plant, PSE will earn a return comparable to a regulated rate of return, and will operate as a regulated entity. Although thermal energy systems do not require WUTC regulation, and the provision of hot or chilled water would not require tariff schedules approved by the WUTC, an unregulated PSE ownership and operation model has not been evaluated in this analysis. 2.3 Pre-feasibility Study Recommendations The pre-feasibility study conducted by Puttman made several recommendations for the alignment of responsibility for district energy. The recommendations are summarized in Table 4, and were used in the development of scenarios in this study. Table 4: Recommendations from Pre-Feasibility Study Criterion Recommended Alignment Ownership Public-Private Partnership Funding for Central Plant District Energy Provider Funding for Distribution Network City of Redmond Design/Build/Permit District Energy Provider Policy Support City of Redmond mandates connection City Operations District Energy Provider Customer Relationship District Energy Provider Revenue Share between City/DE Provider based on ownership and risk 2.4 Evaluation Criteria To meet the City’s objectives, the district energy scenarios were compared to the BAU scenarios, and an assessment was made based on the following criteria. 13 I P a g e ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Study Approach 1. Rates must be competitive with BAU energy rates. 2. Greenhouse gas emissions must be lower than BAU greenhouse gas emission levels. 3. Energy use must be lower than BAU energy use. 4. The central plant must be financially viable and must meet the investors’ objectives. PSE’s decision criteria for involvement in a district energy project follows the Washington Utilities and Transportation Commission (WUTC) rules regarding the acquisition of new resources (WAC 480-107). PSE is required to submit a request for proposals (RFP) when the company’s most recent biennial Integrated Resource Plan (IRP) demonstrates a need for new electric capacity resources within the next three years. The IRP guides PSE’s efforts to acquire new energy resources to meet the needs of customers at the lowest reasonable cost. PSE’s overall strategy for integrated resource planning is to: • Examine their customers’ electric and gas resource needs over the next twenty years, and analyze the mix of conservation programs and supply resources that might best meet those needs. • Establish the strategic direction to acquire a diversified, balanced electric resource portfolio that meets customer needs, results in reasonable energy supply costs, and mitigates market risks. • Identify the key factors related to various resource decisions, and establish a method for evaluating a resource acquisition in terms of cost, risk, and other factors at the time a decision needs to be made. The IRP does not commit to or preclude the acquisition of a specific resource type, project, or facility. PSE's resource evaluation process is designed to be consistent with guidance set forth in the Washington Administrative Code (WAC) and the Revised Code of Washington (RCW), which encourage utilities to seek resources that provide clean, safe and reliable power to meet their needs using lowest reasonable cost as a criterion. RCW 19.280.020 defines "lowest reasonable cost" as "the lowest cost mix of generating resources and conservation analysis of a wide range of commercially available resources." Further, WAC 480-107-035 provides guidance regarding the minimum criteria that must be considered when evaluating and comparing resources: At a minimum, the ranking criteria must recognize resource cost, market-volatility risks, demand- side resource uncertainties, resource dispatchability, resource effect on system operation, credit and financial risks to the utility, the risks imposed on ratepayers, public policies regarding resource preference adopted by Washington state or the federal government and environmental effects including those associated with resources that emit carbon dioxide. The ranking criteria must recognize differences in relative amounts of risk inherent among different technologies, fuel sources, financing arrangements, and contract provisions. The ranking process must complement power acquisition goals identified in the utility's integrated resource plan. 14 I P a g e ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Study Approach PSE's RFP process involves a two-phased approach designed to quickly identify the most promising proposals for a thorough combination of quantitative and qualitative evaluation.1 This approach enables PSE to organize its efforts efficiently and target the most promising proposals with thorough scrutiny. PSE’s most recent IRP (www.pse.com/irp) describes generally the process to create optimal portfolios and evaluate costs and risks, and offers in-depth descriptions of the AURORA model, the PSM I Screening Model, and the PSM III Optimization Model. Once the evaluation process is complete and the team has satisfactorily resolved open issues, the Resource Acquisition team lists the proposals with the lowest reasonable cost and risk that best complement PSE's resource and timing needs, and presents the list to PSE’s Energy Management Committee (EMC) for approval. PSE may then pursue negotiations with individual counterparties to establish the terms and conditions of Definitive Agreements. Individual resource acquisitions are approved by the EMC and, when appropriate, PSE’s Board of Directors. 1 According to WAC-480-107, the RFP is not the only method by which PSE may acquire new electric generation resources. Given its obligation to provide electricity at the lowest reasonable cost to customers, PSE also evaluates opportunistic proposals submitted outside the RFP process, and in-house development opportunities. PSE evaluates all resources in a consistent manner, using the same methods and criteria as the RFP process. 15 I P a g e ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Data Acquisition 3 Data Acquisition 3.1 Data Acquisition Process The first task of the feasibility study was data acquisition. Initial data was provided by the City. This information was supplemented during the study, as the City put the project team in touch with a sample of property owners and developers in the district. The project team also brought in data from its prior experience, and example information from other district energy systems including the City of Vancouver (Canada) Southeast False Creek system. The data provided the foundation for subsequent analysis and recommendations. 3.1.1 Data Provided by the City of Redmond The City provided the project team with prior studies and reports, future development estimates, and contact information for a sample of property owners. The prior studies and reports included: • A pre-feasibility report titled “Overlake Village District Energy Concepts and EcoDistrict Applicability” dated December 2013, prepared by Otak, Inc. in association with BAE Urban Economics, Nelson/Nygaard Consulting Associates, and Puttman Infrastructure. • An Overlake Village district energy concepts memo and powerpoint presentation dated November 2013, prepared by Puttman Infrastructure. • A Group Health – Overlake Village (Zone 4) Master Plan dated August 29, 2011, prepared by CollinsWoerman for Group Health Cooperative represented by Capstone Partners, with assistance from Brumbaugh & Associates Landscape Architecture, Coughlin Porter Lundeen, Davis Wright Tremaine, and Transportation Engineering NorthWest. • A KCC Limited Edition Master Plan – Overlake Village (Zone 1) dated June 5, 2014, prepared by CollinsWoerman for KCC Limited Edition represented by Melody Westerdal of the KCC Limited Edition Owners Association, with assistance from Williamson Law Office, Concept Engineering Landscape Services, Coughlin Porter Lundeen, Northwest Landscape Services, and Transportation Engineering NorthWest. • The City of Redmond Climate Action Implementation Plan dated May 7, 2013. • The City of Redmond Comprehensive Plan dated December 17, 2011. 3.1.2 Stakeholder Outreach Process and Information Acquired The feasibility of a district energy system in Overlake Village will be affected by the participation of private property owners in the area. During the feasibility study, selected property owners were contacted for information-gathering and collaboration. The purpose was to improve the accuracy of engineering and financial feasibility models. The sponsors of some major planned developments were contacted, as they have the potential to be anchor customers for a district energy system. There may also be the potential to integrate district energy equipment into their facilities as a central plant or node. This outreach is time-sensitive, as planning is already underway for some of these developments. It was found that the first few buildings 16 I P a g e ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Data Acquisition were being designed to have electric resistance space heating, which would be incompatible with a district energy system. Central natural-gas-fired boilers were being designed to serve domestic hot water loads. Beyond those first few buildings, there were no specific heating or cooling plans for the new developments. 3.2 Planning and Space Use Assumptions Since the potential district energy system would primarily serve planned new construction in Overlake Village, the City provided development estimates through the year 2030. Table 5 shows the expected amount of square footage of development and number of multi-family dwelling units. Figure 3 shows the associated geography and the locations of the four Transportation Analysis Zones (TAZ). Table 5: Projected Land Use for Overlake Village Transportation Analysis Zone Land Use (sq. feet) Dwelling Units Office Retail Institutional Hotel Multi- family Hotel Rooms 371 63,575 360,261 0 0 296 0 372 159,402 341,600 7,163 23,880 629 144 373 429,124 158,862 0 0 1,767 0 374 958,123 252,646 0 75,932 2,296 200 Total 1,610,224 1,113,369 7,163 99,812 4,988 344 17 I P a g e ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Data Acquisition Figure 3: District Energy Study Geography 3.3 Planned Development Development is already underway, planned, or expected on few properties in or near Overlake Village. Figure 4 shows the locations of four of these properties: • GRE Bellevue • Esterra Park • KCC Limited Edition • Overlake Business Center 18 I P a g e " Legend A. c:J Study Area (TAZ 371-373. partial 374) Overlake Village ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Data Acquisition Figure 4: Planned Development Locations The GRE Bellevue property is under construction and approaching completion at the time of this report. The property will consist of 452 apartments with a layout as shown in Figure 5 and Figure 6. Esterra Park GRE Bellevue KCC Limited Overlake Business Center 19 I P a g e j ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Data Acquisition Figure 5: GRE Bellevue Aerial Rendering Figure 6: GRE Bellevue Bel-Red Elevation Esterra Park is also under construction at the time of this report, but only general site work and excavation for the first of several buildings has been completed. The property will consist of 1,400 apartments, 1,200,000 square feet of office space, 25,000 square feet of retail space, and a hotel and conference center. Figure 7 and Figure 8 illustrate the proposed development. 20 I P a g e .i.i. 11: II II • II II II II I II II " I~ i~ i .ij iii iii iii < ' • II • - Ii II • iiii I 1a • II _a I " H - iiiL'w I 1.u· a•:t a • f::i II II 11 II I - 11 II I 11 11 1• l 1 11 II • • • • • I Ill• 1_a_ . . . . . . • •I ~ !l!l ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Data Acquisition Figure 7: Esterra Park Proposed Site Plan Figure 8: Esterra Park Rendering KCC Limited Edition is a proposed future development which would occupy the south side of Overlake Village. As currently envisioned, the property would consist of 885 apartments, 173,000 square feet of 21 I P a g e - : : " ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Data Acquisition office space, 36,350 square feet of retail space, and 66,800 square feet of hotel space. Figure 9 illustrates the proposed development. Figure 9: KCC Limited Edition Rendering Overlake Business Center is an existing property immediately adjacent to the planned light rail station. There are no specific plans for re-development of this property at this time, but this is a likely location for a portion of the new development expected in the district energy area. 3.3.1 Existing Building Assumptions The existing buildings in the Overlake area have a variety of different ages and types of construction. The buildings range from less than 10 years old, such as The Village at Overlake Station, back to the 1960s and 70s for some of the older properties. A mix of electric and gas equipment heats the existing buildings. Most of the existing heating and cooling equipment is unitary-type, such as packaged rooftop units. Hence, there is a significant opportunity to improve the efficiency of the heating systems in both new and existing buildings when the properties are redeveloped. One of the larger existing properties is The Village at Overlake Station, a King County Housing Authority residential complex just to the south of the Esterra Park development and co-located with a King County transit center. This property has electric space heating, but it also has a central gas-fired domestic hot water boiler plant. With additional investigation of the size of this plant and the existing load profile, it may make sense to connect the district energy system to the plant for energy transfer to or from the 22 I P a g e Parking Ratio Parking 1.25/unit 875 stalls 1.0/key 205 stall,; 33,000 sf 1 .5/unit 50 slalls Office 192,000 sf 2.5/1000sf 480 stalls Retnil 50,000sf 4.0/1000 sf 200 stalls ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Data Acquisition plant. Other larger existing properties include a Sears department store, Overlake Terrace Retirement Community, a Safeway store, and White Swan Condominiums. It is assumed at this stage that there is little likelihood of connecting the district energy system to the existing buildings, due mainly to the types of heating and cooling systems already installed. There may be a greater opportunity in the future. For example, if an existing building were to undergo a major remodel or replacement of its heating and cooling systems, the building could be connected to the district energy system at that time. 3.3.2 Rate of Development Assumptions The estimated yearly rate of development through 2030 is based on short-term and long-term development projections. Currently planned developments are estimated to phase in over the next 6 years, based loosely on their current construction status. Future developments are estimated to be evenly distributed over the remaining years to allow for full build-out of the projections outlined in Table 5. The GRE Bellevue development’s square footage is added to the City’s 2030 development projections, since this is an adjacent property outside of the Overlake Village boundaries. Table 6 shows the resulting rate of development assumptions. The rate of development is used in the cost modeling of the district energy development scenarios. Section 6 discusses the assumption that new development will adopt district energy. Table 6: Projected Rate of Development for Overlake Village through 2030 Year New Development Square Footage Completed Cumulative New Development Square Footage (Forecasted) Notes 2015 450,000 450,000 GRE Bellevue 2016 506,905 956,905 Esterra Block 4, 7 2017 405,908 1,362,813 Esterra Block 1, 3 2018 940,782 2,303,595 Esterra Block 2, 5, 6 2019 940,782 3,244,377 Esterra Block 8, 9, 10 2020 542,500 3,786,877 LCC Limited Phase 1 2021 542,500 4,329,377 LCC Limited Phase 2 2022 368,077 4,697,454 Other Development 2023 368,077 5,065,531 Other Development 2024 368,077 5,433,607 Other Development 2025 368,077 5,801,684 Other Development 2026 368,077 6,169,761 Other Development 2027 368,077 6,537,838 Other Development 2028 368,077 6,905,914 Other Development 2029 368,077 7,273,991 Other Development 2030 368,077 7,642,068 Other Development 23 I P a g e ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Data Acquisition 3.3.3 Conservation for New Development Assumptions Because sustainability concepts are a feature of modern development master planning documents, particularly for some recent local construction projects used as examples, it is assumed that new developments in this area will include energy conservation strategies and designs. Energy-efficient building envelope, lighting, heating, and cooling systems will be used at the building level where applicable. A full description of baseline modeling is included in the following section, but in general it is assumed that planned new developments will exceed the Washington State Energy Code by approximately 10%. 24 I P a g e ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Energy Study 4 Energy Study 4.1 Modeling Approach The district energy system will mainly serve buildings that have yet to be designed. In order to estimate future thermal loading and energy use, assembled a portfolio of comparable newly- constructed facilities for which detailed heating and cooling load modeling is available. The portfolio includes both commerical and residential buildings. Estimated values are used for retail, hotel, and institutional categories. These comparable facilities were used first to estimate the BAU energy performance. Once the BAU performance was determined, substituted a district energy solution for the heating and cooling equipment and re-computed the energy performance. The following information demostrates this technique for the office building category. Using Block 3 of the Esterra Park development as a guide, searched for comparable recent new construction facilities. Esterra Park Block 3 is planned to be a 223,000-square-foot, 6-story office building, with a typical floorplate of 40,000 square feet. It will be designed and planned for technology companies. Figure 10 shows a comparable facility, Troy Block, which is currently under construction in Seattle. Troy Block consists of a North Tower and South Tower. The North Tower is 422,000 square feet in 13 stories, and the South Tower is 395,000 square feet in 12 stories. Both towers feature 33,000- to 34,000-square-foot floorplates, and are designed for technology companies. Figure 10: Example Comparable Office Building (source Troy Block) Detailed energy model information for this comparable facility is available for use in analysis. This information includes end-use breakdowns, peak heating and cooling loads, hourly rates of energy use, and energy use totals. This facility was modeled using eQUEST energy modeling software. Figure 11 shows the rendered eQUEST computer energy model, which illustrates the three dimensional 25 I P a g e ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Energy Study surface area and space volume programming used. This enables accurate heating and cooling estimates that account for building materials, systems, occupancy, controls, and local weather conditions. Figure 11: Example Comparable Office Building eQUEST Model The heating and cooling requirements for the BAU scenario were analyzed using the comparable facility portfolio. The BAU scenario assumes that each building has its own heating and cooling system, and is served 100% by its system. As the buildings will be heated by either electricity or natural gas in the BAU scenario, both types of heat generation were modeled. For the BAU-Gas Heat scenario, natural gas boilers and hot water coils or radiators were modeled. For the BAU-Electric Heat scenario, electric resistance duct or wall heaters were modeled. It is assumed that all other loads (e.g. cooling, lighting, plug loads) in the district are served by electricity, and use the same equipment in both BAU scenarios. The project team has provided these two BAU comparison scenarios to illustrate the gamut of mechanical systems that developers might choose for new construction. These two BAU scenarios provide upper and lower limits to the estimated costs and rates that could be experienced in Overlake Village. It is not unusual to see either of these two types of heating technologies, and other types as well, in recent building construction. Because the buildings in this area will be constructed with a variety of mechanical systems, the actual costs will fall between these two scenarios. While the construction costs for the BAU-Electric Heat scenario are lower, the operational costs for that scenario are significantly higher due to the higher cost of electricity over natural gas. Hence, when the district energy scenarios are compared against these two baseline options in Section 6.4, the economic case for choosing a district energy system is most compelling when evaluated against the BAU-Electric Heat scenario. 26 I P a g e ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Energy Study 4.2 Business-As-Usual Energy Requirements Energy consumption for the redeveloped Overlake Village under both BAU scenarios was estimated using the modeling approach described above. The energy requirements listed below represent the estimated heating, cooling, and other electric usage of the new development as outlined in Table 6. Non-heating/cooling loads for buildings such as lighting and plug/appliance loads are a significant portion of the electric energy use in the district. BAU assumptions for the size of these loads are derived from the same modeling process used for the heating/cooling loads. The other electric loads estimated for BAU are used throughout each of the scenarios in the calculation of community energy usage. The annual energy usage estimated for heating, cooling, and other electric loads is shown in Table 7. Table 7: Summary of Annual Energy Consumption for Study Area for BAU Building Type Annual Energy Electric Heating (kWh/yr) Gas Heating (therm/yr) Electric Cooling (kWh/yr) Other Electric Loads (kWh/yr) Residential (Multi-family) 24,787,577 995,300 2,806,000 13,106,000 Office 4,424,260 177,600 1,587,000 15,532,000 Retail 3,164,372 127,100 716,000 3,346,000 Hotel 556,695 22,400 64,000 300,000 Institutional 29,300 1,200 7,000 69,000 Total 32,962,204 1,323,600 5,180,000 32,353,000 Figure 12 shows the energy consumption components that make up the BAU-Electric Heat and BAU-Gas Heat scenarios. Figure 12: BAU Scenario Components Electric Heating Electric Cooling Other Electric Loads BAU- Electric Heat Gas Heating Electric Cooling Other Electric Loads BAU- Gas Heat BAU-Electric Scenario Components BAU-Gas Scenario Components 27 I P a g e + + + + ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Energy Study The estimated construction costs for distributed heating and cooling systems in the BAU-Gas Heat scenario are $35–45 million. This represents the installed cost of the mechanical and electrical systems that would be required to heat and cool all of the district energy buildings individually. The systems would include boilers, chillers, cooling towers, central system primary pumps, and switchgear. The estimated costs do not include the water-side or air-side distribution systems within the buildings. The estimated construction costs for distributed heating and cooling systems in the BAU-Electric Heat scenario are $20–30 million. Construction cost estimates are lower for this scenario because electric resistance heaters are less expensive to install than hot water heating systems, though they cost more to operate than natural-gas-based systems. 4.3 District Energy Facility 4.3.1 Central Plant Technologies After analysis of the BAU scenarios, the comparable facility portfolio was run through several conceptual design options for a district energy system. Various options were considered that would meet the following basic requirements. • Replace the need for central heating and cooling systems in the individual buildings. • Provide heating and cooling from centralized district facilities. • Connect to building water-side and air-side distribution systems via heat exchangers. • Support the combined heating and cooling loads of the entire district. The options considered are summarized in Table 8. Table 8: Design Options Option System design A Central heating hot water and chilled water plant B Central heating hot-water-only plant C Central heating hot water and chilled water plant with geothermal D Combined heat and power plant E Demand response/thermal energy storage F Waste heat recovery plant G Waste heat recovery plant with distributed heat pumps Each option is described below. 4.3.2 Option A: Central Heating Hot and Chilled Water Plant Option A consists of natural-gas-fired hot water boilers, chillers, cooling towers, and distribution pumps located in a central facility and connected to the district by a network of buried distribution piping. The boilers would be high-efficiency condensing type. The chillers would be high-efficiency water-cooled type. The construction costs for this option are estimated at $40–50 million. The plant might be located in the parcel north of NE 24th Street and west of 152nd Ave NE. 28 I P a g e ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Energy Study Figure 13 and Figure 14 show the major components of a central heating hot water and chilled water plant. Figure 15 provides couple examples of the exterior of district energy central plants. Figure 13: Example Boiler Plant Photos Figure 14: Example Chiller Plant Photos 29 I P a g e ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Energy Study Figure 15: Example Central Plant Exterior Photos 30 I P a g e n 11 - ~ . - ~ Ii ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Energy Study Figure 16 is a major equipment system diagram for a central plant serving hot water and chilled water to typical building heat exchangers for energy transfer. Figure 16: Central Heating Hot Water and Chilled Water Plant Equipment System Diagram OPTION A FLOW DIAGRAM HWS HWR HWS HWR HWS HWR HWS HWS HWR HWS HWS HWS HWS CHS CHS CHS CHR CHS CHS CHS CHR CHR CHS CHR CHS CHR CHS CHR CHS HWR HWR HWR HWR HWR HWR HWS CHS CHR CHR CHR CHR TO COOLING TOWER FROM COOLING TOWER TO COOLING TOWER FROM COOLING TOWER TO COOLING TOWER FROM COOLING TOWER CHILLER TYPICAL BUILDNG BOILER BOILER BOILER HEAT EXCHANGER CHILLER CHILLER 31 I P a g e ~ - 1 1 J [[lJ I , I : , ~ , J 7W~, J 7U~~ l 7a l 1 ! ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Energy Study Figure 17 is a site plan for a central plant serving hot water and chilled water through major branch pipes to potential Overlake Village developments. Figure 17: Central Heating Hot Water and Chilled Water Plant Site Plan 32 I P a g e I l, 0~ f- • / ! ' I ATH iOR CHt lEDj POTENT~:G HOTWATEJ\Pff>, AIID HEAT ' EA MAlij TOEAO, AR I I ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Energy Study 4.3.3 Option B: Central Heating Hot-Water-Only Plant Option B consists of natural-gas-fired hot water boilers and distribution pumps located in a central facility and connected to the district by a network of buried distribution piping. The boilers would be high-efficiency condensing type. Cooling equipment would be installed in each of the individual buildings as was analyzed in the BAU condition. The construction costs for this option are estimated at $37.5–47.5 million. This plant might be located in the parcel north of NE 24th Street and west of 152nd Ave NE. Figure 18 shows a major equipment system diagram for a central plant serving heating hot water to a typical building heat exchanger for energy transfer. Figure 18: Central Heating Hot Water-Only Plant Equipment System Diagram HWS HWR HWS HWR HWS HWR HWS HWS HWR HWS HWS HWS HWS HWR HWR HWR HWR HWR HWR HWS OPTION B FLOW DIAGRAM TYPICAL BUILDNG BOILER HEAT EXCHANGER BOILER BOILER 33 I P a g e - LJ~ 721 J iil: i I ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Energy Study Figure 19 shows a site plan for central plant serving heating hot water through major branch pipes to potential Overlake Village developments. Figure 19: Central Heating Hot Water-Only Plant Site Plan 34 I P a g e et 1s-,i - i'fE-¾4t h-St reet I i P01£1lllALPAIBf0RillN'. I * ~OT WATER Pl~ MAINl'°EACll •REA 'oi;;.99r,a,v,,wss;,;,;,,;9'1 I ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Energy Study 4.3.4 Option C: Central Heating Hot and Chilled Water Plant with Geothermal Option C would add a part-load open-loop ground source geothermal heat pump system to Option A. A geothermal heat pump system uses heat exchange with the earth and groundwater as the source for both heating and cooling, depending on seasonal system loads. Either hot or chilled water can be generated by operating a refrigeration cycle heat pump to transfer energy and temporarily raise or lower the temperature of the groundwater. At the same time, the heat pump raises or lowers the temperature of the hydronic heating and cooling loops serving the district buildings. The preliminary sizing for this system is 1500 tons. A system of this size would provide a partial base load to the district energy system to operate as the first stage of heating or cooling. Boilers and chillers similar to those in Option A would serve the peak capacity. In this way, the investment in the geothermal system would be maximized by maintaining a high utilization rate on that portion of the plant. Figure 20 shows an example of a geothermal injection well and a ground source heat pump used in an open loop configuration. The ground souce heat pump appears similar to a chiller, but is capable of operating under different conditions. Figure 20: Example Injection Well And Example Ground Source Heat Pump The construction costs for the district energy system with open-loop geothermal option are estimated at $43–54 million. This plant might be located in the parcel north of NE 24th Street and west of 152nd Ave NE, with extraction and injection wells located nearby. 35 I P a g e ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Energy Study Figure 21 shows a major equipment system diagram for the geothermal portion of a plant serving hot water and chilled water to typical building heat exchangers for energy transfer. Figure 21: Geothermal Plant Equipment System Diagram TYPICAL BUILDNG HEAT EXCHANGER SAND FILTER HEAT PUMP TO INJECTION WELL FROM EXTRACTION WELL HPS HPS HPS GWR GWR GWS GWS GWS HPS HPR HPR OPTION C FLOW DIAGRAM HPR 36 I P a g e ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Energy Study Figure 22 shows a site plan for a central geothermal plant serving heating hot water and chilled water through major branch pipes to potential Overlake Village developments. Figure 22: Geothermal Plant Site Plan 37 I P a g e l OSSIBLf. EXTRACTION :fill LOCATION NE 2 h treet 1- NE- ,N th- Stree - - ONWELl.,(OCATKlN • FOSSl>l E INJECTI / l FOR v/ATER PIPl>I$ POTENTIAL PATH I . I !_J1'27,;:0½'. NE-2-1 .Str.eet ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Energy Study A closed-loop geothermal system is a variation on this technology that exchanges heat through a network of underground pipes connected in a continuous loop. This type of system is not recommended for an installation this large, as it would either require drilling over one thousand vertical wells to a depth of 300 feet each, or horizontal boring in an area equivalent to several football fields. Figure 23 shows a site plan of an 80,000-square-foot horizontal closed-loop ground source field and a photo of the installation of this field. This is a 200-ton system. Figure 23: Example Closed Loop Geothermal System 38 I P a g e + ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Energy Study 4.3.5 Option D: Combined Heat and Power Plant Option D would add a combined heat and power system to Option A, sized for the minimum continuous heating load of the district energy system. This would consist of a natural-gas-fired reciprocating engine generator, which would generate both electricity and circulate hot water from gas-fired boilers. The preliminary sizing for this equipment is 335 kW. The hot water would meet the base heating load for the district, with a smaller boiler plant meeting the peak loads. The construction costs for this option are estimated at $41-52 million. This plant might be located in the parcel north of NE 24th Street and west of 152nd Ave NE. Figure 24 shows an example major equipment system diagram for the generator portion of a plant serving heating hot water and chilled water to a typical building housing heat exchangers for energy transfer. Figure 24: Combined Heat and Power Plant Equipment System Diagram HWS HWR HWS HWR HWS HWR HWS HWS HWR HWS HWS HWS HWS HWR HWR HWR HWR OPTION D FLOW DIAGRAM BOILER BOILER BOILER GENERATOR TYPICAL BUILDNG HEAT EXCHANGER 39 I P a g e j_ .J _ ' J ' L_ l ! • i L ~ L ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Energy Study Figure 25 shows a site plan for a central plant with combined heat and power serving hot water and chilled water through major branch pipes to potential Overlake Village developments. Figure 25: Combined Heat and Power Plant Site Plan CENTRAL CHILLER, BOILER, AND POWER PLANT POTENTIAL PATH FOR CHILLED AND HEATING HOT WATER PIPE MAIN TO EACH AREA POTENTIAL PATH FOR CHILLED AND HEATING HOT WATER PIPE MAIN TO EACH AREA 40 I P a g e ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Energy Study 4.3.6 Option E: Demand Response / Thermal Energy Storage Plant Option E would add a thermal energy storage system with demand response controls to Option A. This system would consist of a large insulated chilled water storage tank and the associated pumps and controls to provide chilled water peaking capacity or capacity to draw on when there is a need to limit demand. Demand would be reduced by operating fewer chillers for a given cooling load termporarily. This system would also have the capability of charging the tank with chilled water at night when the mechanical system operating efficiency is higher compared with the heat of the day. The preliminary sizing for this equipment is 2 million gallons. The construction costs for this option are estimated at $41–51 million. This plant might be located in the parcel north of NE 24th Street and west of 152nd Ave. NE. Figure 26 shows a major equipment system diagram for a plant with thermal energy storage serving hot water and chilled water to typical building heat exchangers for energy transfer. The storage tank could also be incorporated into an underground parking garage in an urban location. Figure 26: Demand Response / Thermal Energy Storage Plant Equipment System Diagram BOILER TYPICAL BUILDNG HEAT EXCHANGER BOILER BOILER CHILLER CHILLER CHILLER STORAGE TANK TO COOLING TOWER FROM COOLING TOWER TO COOLING TOWER FROM COOLING TOWER TO COOLING TOWER FROM COOLING TOWER OPTION E FLOW DIAGRAM CHS CHR CHR CHR CHR CHS CHR CHS HWR HWR HWR HWR HWR HWS CHS CHS CHS CHR CHS CHS CHS CHR CHR CHS CHR CHS CHR CHS CHR CHS HWS HWS HWS HWS HWS HWR HWS HWR HWS HWR HWS HWS HWR 41 I P a g e l r , ~r 7 : f.h71 l)JL J tilic 1 lQ: :i ltij kl l ' ~ ~ - - i i ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Energy Study Figure 27 shows a site plan for a central plant with thermal energy storage serving hot water and chilled water through major branch pipes to potential Overlake Village developments. Figure 27: Demand Response / Thermal Energy Storage Plant Site Plan POTENTIAL PATH FOR CHILLED AND HEATING HOT WATER PIPE MAIN TO EACH AREA POTENTIAL PATH FOR CHILLED AND HEATING HOT WATER PIPE MAIN TO EACH AREA THERMAL STORAGE TANK CENTRAL CHILLER AND BOILER PLANT 42 I P a g e ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Energy Study 4.3.7 Option F: Waste Heat Recovery Plant Option F would add waste heat recovery to Option A. Two potential waste heat sources have been identified. The first is data center waste heat from the Microsoft Troon facility, which is located just north of Esterra Park Block 2. The second is wastewater heat recovery from the sewer main that runs down 152nd Avenue. These sources would provide base load heating for the district, with associated improvements in energy efficiency and a reduction in traditional mechanical equipment sizing. The preliminary sizing for the heat recovery equipment is 1 MW. The construction costs for this option are estimated at $41–51 million. This plant might be located within or near the Esterra Park development. Figure 28 shows a major equipment system diagram for a plant with waste heat recovery serving hot water and chilled water to typical building heat exchangers for energy transfer. Figure 28: Waste Heat Recovery Plant Equipment System Diagram CHILLER TYPICAL BUILDNG BOILER HEAT EXCHANGER BOILER BOILER CHILLER CHILLER HEAT PUMP HWS HWR HWS HWR HWS HWR HWS HWS HWR HWS HWS HWS HWS CHS CHS CHS CHS CHS CHS CHR CHR CHS CHR CHS CHR CHS CHR CHS HWR HWR HWR HWR HWR HWR HWS CHS CHR CHR CHR TO COOLING TOWER FROM COOLING TOWER TO COOLING TOWER FROM COOLING TOWER TO COOLING TOWER FROM COOLING TOWER TO WASTE HEAT SOURCE/SEWER SYSTEM FROM WASTE HEAT SOURCE OPTION F FLOW DIAGRAM 43 I P a g e lio • -g~r , -1 i WI[ I , . ,ii_ J . - I ! i I i i ! _J ! I I t i ~ [lftr_r ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Energy Study Figure 29 shows a site plan for a central plant with waste heat recovery serving hot water and chilled water through major branch pipes to potential Overlake Village developments. Figure 29: Waste Heat Recovery Plant Site Plan CENTRAL CHILLER AND BOILER PLANT POTENTIAL PATH FOR HEATING HOT WATER PIPE MAIN TO EACH AREA POTENTIAL PATH FOR HEATING HOT WATER PIPE MAIN TO EACH AREA POTENTIAL PATH FOR HEAT RECOVERY PIPING POTENTIAL PATH FOR HEAT RECOVERY PIPING 44 I P a g e ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Energy Study 4.3.8 Option G: Waste Heat Recovery Plant with Distributed Heat Pumps Option G would install gas-fired condensing boilers, cooling towers, and distribution pumps in a central facility connected to the district by a network of buried distribution piping. Water would be distributed at low temperatures and boosted or dropped to heating and cooling temperatures at nodes closer to or within the end-use buildings. This option also includes the waste heat recovery described above. The construction costs for this option are estimated at $42–52 million. Option G provides more flexibility in plant location and the number of plants. Plants could be located near potential waste heat recovery sources. Figure 30 shows a major equipment system diagram for a low-temperature system with heat recovery serving condenser water to a typical building heat pump. Figure 30: Low Temperature Condenser Water System with Distributed Heat Pumps Equipment System Diagram CWR CWR CWR CWR CWR CWR TO WASTE HEAT SOURCE FROM WASTE HEAT SOURCE CWS TYPICAL BUILDNG BOILER BOILER BOILER HEAT PUMP COOLING TOWER COOLING TOWER COOLING TOWER HEAT EXCHANGER OPTION G FLOW DIAGRAM CWS CWR CWS CWR CWS CWR CWS CWS CWR CWS CWS CWS CWS 45 I P a g e ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Energy Study Figure 31 shows a site plan for a for a low-temperature system with heat recovery serving condenser water through major branch pipes to potential Overlake Village developments. Figure 31: Low Temperature Condenser Water System with Distributed Heat Pumps Site Plan 46 I P a g e I \I , _ I LOW13.IPERAT'JR:. Cl 40E-.SEI\ WATER ~ POTJ:" 4l ~Ttf-FM fVT=\IP LI ~ ---PAGE BREAK--- Overlake Village District Energy Feasibility Study I Energy Study 4.3.9 Hot/Chilled Water Distribution System All of the district energy technology options will requre a network of buried distribution piping to distribute thermal energy around Overlake Village. The following distribution system requirements provide additional detail to the site plan pipe routing examples presented above. Figure 32 shows a schematic piping flow diagram for a central plant serving hot water and chilled water to the four Transportation Analysis Zones identified in Figure 1. The right-of-way (ROW) requirements for the distribution piping specify that: • The top of the pipe should be buried 4 feet deep. • There are supply and return lines for both hot and chilled water (4 pipes total). • Pipes should be separated in the trench by 1 foot of horizontal clearance on each side. • Pipe diameter may range from 10 inches to 24 inches, requiring up to 12 feet of horizontal ROW for the main loop; branch loops may require as little as 8 feet 4 inches of horizontal ROW. • Pipes should be separated from other utilities by a certain distance which will depend on the final system design temperatures. Figure 32: Central Plant Piping Schematic Pipe sizes are shown for a full build-out of the district energy system. Figure 33 shows an example cross- sectional detail of buried distribution piping for the corresponding main loop pipe sizes with required insulation and spacing. 47 I P a g e / 374PAACEL 10"'CHIL1.EDWATER 10"HEATir\GHOTWATER c-r- 1U'CHILLEDWATER 1/ l'ZCHIUEOWATER 1fr'CHUEOWATffi 17HEATltl.GHOTWA r WHfA11~GliOTWATER 24"HEATI/\GHOTWATER I I ~ ~ 1 I I L ~ 18"CHIUS)WATER L_ _J 24" tH:'.AT~G HOT WATER - 14'CJ