Geothermal handbook: PlanninG and Financing power Generation t e c h n I c a L r e p o r t 2 / 2

F I g u r E 3 . 9 
Olkaria Power Plant, Kenya
Source | Magnus Gehringer.

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The parallel development approach will initially result in only partial utilization of each field’s productive 
capacity. Subsequently, additional plant capacity may be added so the degree of utilization of each 
field’s productive capacity will increase over time. The 50 MW plants in our example would be only the 
first step for each respective geothermal field. As the demand for electric power in the country grows, 
so does the need for additional capacity, including geothermal. Subsequent increments of geothermal 
power capacity will then be built—this time, taking advantage of the much better information about the 
resource, based on several years of operational data from the “first-step” plant in each field.
As mentioned earlier, there is a middle ground between an all-out effort to develop the country’s most 
promising field and developing several fields in parallel. For example, all fields could be developed 
in parallel until their relative merits become clearer, and then resources shifted to the most productive 
or promising field(s). Which phase in the project development cycle produces the needed information 
to justify the shift depends on the particular circumstances of the country. In most cases, completion 
of the test drilling phase should be sufficient to make the decision. However, there will always be a 
trade-off between allocation of capital to the resources that appear the most promising at the time and 
hedging the future uncertainty through the diversification of resource risks across geothermal fields.