| Abstract |
The Southeast Geysers Effluent Pipeline (SEGEP) Project began water deliveries to The Geysers on September 25, 1997. The Northern California Power Agency (NCPA) is the operator of the pipeline and, in the eleven-years since startup, more than 32 billion gallons of waste water has been successfully delivered and injected into The Geyser’s geothermal reservoir. The SEGEP Project is successfully helping to extend the life of NCPA’s geothermal facilities, and will be the source of water for an upcoming Engineered Geothermal System Project Demonstration later in 2009. The SEGEP Project consists of a 26-mile pipeline and five pump stations requiring 4.3 MW to deliver 6,000 gallons per minute to The Geysers. The largest of the five pump stations is located in the City of Clearlake, at the Lake County Sanitation District’s Southeast Treatment Plant. NCPA purchases up to 1.1 MW of electricity from the local utility at retail commercial rates to operate the pump station at 6,000 gpm. Since startup of the SEGEP Project, electrical rates have increased at an annual rate of 6% and are now the primary cost to deliver effluent to The Geysers. SEGEP participants are paying up to $0.1403 per kwh (Summer 2009) for peak power electricity energy alone at the pump station, with an additional $11.86/kw for peak summer capacity. The continued increase in the cost of electricity purchases threatens to affect the economics of SEGEP and The Geysers recharge options. The source of the electricity to pump effluent to The Geysers is not identifiable as renewable and detracts from the “clean and green” view of geothermal generation. NCPA developed an innovative approach that incorporates two renewable energy sources -- solar and geothermal -- to further increase generation of clean, sustainable energy. NCPA applied for and received a reservation request for performance-based incentives from the California Solar Initiative Program (CSI) that, together with electricity cost savings, brings about a positive financial return on investment on a 999.9 kw solar array for partially powering the pump station. The construction and operations of the Solar Pumps Project (“SPP”), including project economics and a levelized cost analysis of the project, are presented. The SPP consists of a ground mounted, single-axis tracking system with 6,336 polycrystalline silica photovoltaic panels mounted in six rotating arrays located just south of the Southeast Pump Station of SEGEP on LACOSAN property. The SPP is expected to generate more than 2.1 million Kwh annually at a levelized cost $0.095 per Kwh and provide 23% of the pump station’s electrical requirements. The Net Present Value of the solar array is presented as a function of future saved electrical purchases from the local utility. In addition to the financial benefits achieved with the Project, there are clear intangible benefits achieved. These include the reduction of 832 million lbs of green house gases annually. It is a great extension of the public/private partnership that has characterized the SEGEP. Actual results for the first four months of operation have far exceeded planned levels and suggest that the return of the project will be greater, and its payback period shorter, than originally planned. Due to the success of this first solar array, a second solar array supporting SEGEP has been sited and granted a CSI rebate reservation, and the project is about to enter construction. Taken together, the two solar projects will help increase the future economic viability of the SEGEP. |