| Title | Development of Direct-Use Projects |
|---|---|
| Authors | John W. Lund |
| Year | 2009 |
| Conference | GeoFund Workshop |
| Keywords | |
| Abstract | A geothermal direct use project utilizes a natural resource – a flow of geothermal fluid at elevated temperatures, which is capable of providing heat and/or cooling to buildings, greenhouses, aquaculture ponds and industrial process (Lienau, 1998). Geothermal utilization requires a unique blending of skills to located and access a resource, and to concurrently match the varied needs of the user in order to develop a successful project. Each resource development projects is unique, and the flow chart (Figure 1.) of typical activities can serve as a guideline of logical steps to implement a project. The development of a project should be approached in phases so as to minimize risk and costs. The size of the project determines the amount of exploration and development of the resource that can be economically justified. For heating a single home the risk is high, as outside of gathering data on adjacent hot springs, wells and use, the well becomes the exploration tool and hopefully provides the necessary energy to the project. Larger projects, such as district heating and industrial applications can justified more investigation to better characterize the resource and thus reduce the risk. The first phase generally involves securing rights to the resource. This includes information on ownership, leasing, agencies involved, water rights, injection requirements, competition with adjacent geothermal users, and any potential royalty payments. The second phase involves interdisciplinary activities of geology, geochemistry, geophysics, drilling and reservoir engineering. These exploration activities are usually expensive and often the economics of a direct-use activity will not support an extensive program. However, a minimum exploration and resource characteristics that are necessary would include depth to the resource, temperature, flow-rate, drawdown and chemistry of the fluid to provide information to determine if a project is feasible and will meet the needs of the proposed activity. The preliminary and conceptual design of a direct-use project could start during the reservoir testing and evaluation, however, depending on the risk and financing issues, the phase may have to wait until the reservoir characteristics are confirmed. During the design phase special consideration must be given to the design and selection of equipment such as well pumps, piping, heat exchangers and space heating equipment. The cost of all these pieces of equipment must be considered, along with potential corrosion and scaling problem, to make the project viable. |