City of Dayton Geothermal Feasibility Study
Heapy Engineering developed a feasibility study to determine the financial viability and economic benefits to the City and its downtown business district constituents of a district geothermal energy infrastructure that would support renewable heating and cooling benefits. This study was specifically desired to provide the basis for downtown building owners to understand the energy saving economic benefits of utilizing heating and air conditioning systems that rely on a dependable renewable source of energy, the water beneath their buildings. Using this uniquely overabundant resource would enable them to make their facilities more attractive to prospective owners and tenants from an energy conservation and energy cost standpoint.
The City of Dayton is located above the Great Miami Buried Valley Aquifer system. This aquifer has an estimated capacity of 1.5 trillion gallons and is composed of saturated sand and gravel deposits, which are extremely permeable and regionally connected, allowing for the transmission and storage of a vast amount of groundwater.
The proposed district was a multipurpose area with designation for commercial/business, industrial, or residential use. The City anticipated developing this geothermal district to offer businesses development incentives in the form of reduced heating and electric costs to businesses that locate within downtown Dayton.
Specific feasibility study tasks included:
• Determining logical locations for pumping stations in the project area
• Determining maximum capacity of pumped water from the selected stations and identification of any potential obstacles related to the selected locations.
• Creating opinions of probable cost associated with building and operating the required wells and pumping stations
• Determining the most likely building candidates, type of use for the district energy system and calculating potential flow requirements for the end users
• Calculating the maximum capacity of heating and cooling potential that can be provided by each of the proposed pumping stations
• Evaluating existing building systems of likely end-users to determine approximate costs for renovating their HVAC systems to accept the geo-thermal energy source
• Determining how the district system should be developed and establish potential boundaries
• Calculating potential energy savings and reduced carbon footprint for end users based on typical HVAC systems that utilize well water as an energy source
• Estimating potential energy costs for a typical end user
• Developing potential routes through the downtown area that makes the most sense economically and logistically for the utility service
• Analyzing the potential use of a single pipe delivery system with storm water effluent versus the development of a central heating and cooling plant and two or four pipe delivery systems
• Performing hydraulic calculations based on a decoupled district loop that extracts a constant flow of water from the aquifer (to maintain a constant head) and discharges it to the storm system for the most desirable route selected
• Estimating first cost dollars for three phases of loop development
• Determining potential operating costs for the plants based on 2010 electrical rates
• Calculating required utility rates for providing the geothermal water to typical users based on first costs, operating costs and utility capital recovery dollars to insure operations will be self-sustaining
• Assembling and reviewing existing data relative to geologic conditions, existing real estate and HVAC systems
• Holding interviews with Stakeholders: potential customers, city officials and real estate management firms
• Developing potential flow diagrams and maps of potential routes and end users
• Load Calculations – establishing an estimate of potential existing loads and loads of future users
• Developing a hydraulic model based on a single desired loop arrangement for establishing potential operating costs
• Analyzing existing systems for potential modifications to establish the potential costs of end-users to tie into the geothermal system
• Performing energy calculations for plant operations and typical end-users
• Estimating budget costs for proposed plants, loop installations and a typical branch connection to a client
• Analyzing cost benefits of the district system
• Preparing the comprehensive report of findings and phased cost estimates