Proceedings World Geothermal Congress 2015 Melbourne, Australia, 19-25 April 2015 1 Wellhead Generating Plants: KenGen Experience Daniel Saitet, Clety Kwambai P.O Box 785 - 20117 Naivasha, Kenya dsaitet@kengen.co.ke; cbore@kengen.co.ke Keywords: wellhead generators, Geothermal, Olkaria ABSTRACT Installation of small 2-5 MWe plants on the wellhead was adopted at Olkaria in 2012 as an early generation strategy. The concept has now been expanded to involve more or less permanent units utilizing up to three wells (15 MWe) located on a single well pad. This strategy appeared quite attractive, at least at the beginning, as it was deemed to stimulate the market to invest in small plants and possible joint ventures once the concept is proven. It also assured operators of the field of early revenue pending completion of drilling and construction of power plants of the conventional type/size. Two plants were piloted, one 5 MWe plant at OW-37A in Olkaria east field and another in the virgin Eburru field both operated by KenGen. Portable wellhead units at Olkaria are condensing type and consist of turbo-generator, cooling tower, condenser, gas extraction system, electrical and control system and auxiliary equipment. Unlike conventional geothermal plants, these wellhead generating units have little permanent civil works and have shorter pipelines. They are designed to fit into containers or skid mounted to facilite easy transfer from one well pad to another as candidate well(s) may be abandoned to pave way for more permanent works. This paper discusses the strategy and offers a comparative study on the performance of such plants vis-à-vis conventional size plants operating at Olkaria. 1. INTRODUCTION Exploration for Geothermal Energy in Kenya started as early as the 1950s. The then Kenya Power Company (KPC) jointly with the Government of Kenya (GoK) and international development partners including UNDP carried out exploration for geothermal energy in many parts of the Kenyan Rift. Several prospective areas were explored and subsequently extensive works were done at the most prospective areas at Olkaria and Eburru Geothermal fields near Naivasha. In the Olkaria Central Field, several exploration wells were drilled in which wells OW-101 and OW-202 drilled in 1982 and 1996 respectively were productive wells. The wells remained shut-in until 1996 when Oserian Development Company, a flower farming company leased well OW-101 for use in electricity production and greenhouse heating. Later in 2006, Oserian entered into a contract with KenGen to extract steam from well OW-202 for electricity production. In the neighbouring Olkaria West Field, about 10 exploration wells were drilled between 1983 and 1997 with four of them producing steam. The wells remained shut-in until in 2000 when the Government of Kenya leased the wells to Ormat International for power production. In Olkaria Northwest, 22 production wells were drilled between 1985 and 1993. But it was not until 2003 (ten years later) that a generating plant was installed and commissioned. In the Olkaria Domes Field, 3 exploration wells were drilled in 1999. Two of the wells were productive. Later in 2007, appraisal and production drilling started and as at March 2010, over 100MWe equivalent of steam had been proved. Plans for constructing a power plant at the field have started but it takes at least 3 years to construct and commission the planned power plant. During that period, the available steam will be shut-in instead of generating revenue. At Eburru Geothermal Field to the North of Olkaria, KenGen carried out exploration in the area and drilled 6 wells between 1989 and 1990. One well was productive but has remained shut-in until recently when a wellhead plant was installed by KenGen. In 1990, KenGen reservoir engineers proposed the use of mobile wellhead generators for use of generation. The idea did not receive the desired support at then. However, the proposal was revisited in 2000 where a consultant was engaged to do a feasibility study. The feasibility did not support the concept. However, in 2007, KenGen contracted GDA to supply a wellhead generator for its field at Eburru. The unit was commissioned in 2011. In 2008, KenGen entered into a partnership with a developer GEG to carry out a pilot wellhead that would be customized to resource conditions. The pilot went through a series of problems but was successfully commissioned in 2012. The success of the pilot was encouraging and KenGen contractors for supply of 75MW wellheads. The project is ongoing. The success of wellheads has shown that if KenGen had invested in them much earlier, it would have reaped lots of revenue ahead of installation of the main power plant. This paper shows that a lot of potential revenue is lost by having production wells sitting idle for years and presents the potential of wellhead generators as means to achieve early power and revenue generation for geothermal resources. The paper further discusses the experiences of KenGen in installation of wellhead generators and the potential benefits of investing in wellhead generators. 2. CASE OF LOST GENERATION OPPORTUNITY To estimate the economic importance of the wellhead generation concept, a look at the lost revenue generation potential is considered over the years that the steam has available but was not in use. It is assumed that if the steam from the wells had been put into use for power generation immediately the steam was acquired, significant amount of revenue could have been generated. It is also assumed that the cost of energy would have remained constant at the current feed in tariff. A conservative availability of 80% and load factor of 90% is assumed. Six cases situations where available steam remained shut-in for considerable period of time are considered in this assessment namely: