In order to put together a geothermal power plant project, details about the resource and where and how the electricity will be consumed must be known. In the simplest possible case (similar to the case of Chena Hot Springs Resort), a small amount of power is developed and used within a small area by the owner of the resource. However, ownership is often complicated when the surface and subsurface (including the geothermal resource) are owned by different entities, or when there are numerous landowners in the vicinity of the site.
Developing a geothermal resource includes a number of critical steps that must be strictly adhered to. The first and most important step is that of identifying and characterizing the resource potential and capabilities for economic power generation. The simple occurrence of a hot or warm spring at the surface is not sufficient evidence for a developable resource. The size, flowability, sustainability, and ultimate heat flow are all difficult determinations that must be made with great care. The initial exploration phase can be costly and has a high risk of economic failure.
The exploration and development phases needed to characterize and sanction power plant construction will involve procuring permits, expertise, and equipment to collect and interpret data on geology, geochemistry, geophysics, and temperatures, so that wells can be sited and drilled into the reservoir. Once one or more wells have been drilled and the reservoir is identified, flow testing and reservoir engineering assessments are needed to determine the possible size and productivity of a reservoir, and also to determine how the reservoir will be produced and managed. At this time, the power plant can be designed and equipment can be chosen to best suit the reservoir. Adequate financing will be needed for construction of the power plant and any transmission line.
After the power plant is built and in operation, reservoir monitoring and management are needed to optimize the system and to determine strategies for maximizing the life of the resource. It commonly takes ten years from the start of exploration to the commissioning of a power plant for projects exceeding 10 megawatts in capacity. Small projects of < 1 megawatt to 2 or 3 megawatts can be completed in 2 or 3 years.
Operational geothermal power plants have an excellent worldwide record of reliably producing power for decades with modest environmental impacts and low operation and maintenance costs, provided that the resource is properly managed and not overdeveloped.
An old greenhouse at Chena Hot Springs is surrounded by naturally heated water.