Friday, 19 February
Ormat to double the Olkaria III Plant Capacity in Kenya
Ormat announced that it will expand the Olkaria III plant from 48 MW to up to 100MW.
I am always interested in the new plants being built by Ormat. It has not been announced what the new plant will look like but it will probably be similar to the existing Olkario III plant. The existing 48MW Olkaria III plant is located in Naivasha, Kenya and was built in two phases. The first phase of approximately 13 MW commenced commercial operations in August 2000 and the second phase of approximately 35 MW commenced operation in January 2009. It used a so-called recuperated two-phase cycle as shown in the following figure.
The recuperator is obviously applicable when the ORC fluid is a "dry" fluid or when dT/ds over the saturated vapour line is positive. Such fluids remain as superheated vapour after expansion and this superheat may be transferred to the condensed liquid in a recuperator as shown in the figure above. According to Ormat, a recuperator adds about 10-15% to the efficiency of a simple ORC without a recuperator.
The original plant had 3 units each at about 4-MW capacity using air-cooled forced-convection condensers. The following pictures depict one 4-MWe unit of the original Olkaria III plant (13 MWe).
Apparently, the expansion is also to be developed in two phases, as in the existing plant. Phase I comprising of 36 MW within 3.5 years from finalizing the amendment to the existing PPA (Power Purchasing Agreement with the Kenya Power&Lighting Co) with an option for phase II comprising of 16 MW within 4.5 years from commercial operation of phase I.
The temperature gradients in the Olkario region are quite high and reaches 200 oC/km in some wells. The following charts plots the temperature logging in some wells. The "a.s.l." means "above sea level". The wells from the Olkaria West region (where the Ormat plant is located) are OW-301 and OW-305. I could not find any information about the ORC fluid used in the plant.
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