Geysers Field, California, USA
LOCATION Geysers Geothermal Field
Western GeoPower Unit 1 Western GeoPower is developing a 35 MWe power plant located at The Geysers geothermal field in Sonoma County, 75 miles north of San Francisco. The Unit 1 leasehold is situated in the south-western region of The Geysers field.
The Geysers Field spans an area of approximately 30 square miles in Sonoma and Lake Counties in California, located within the Mayacamas Mountains. The Geysers geothermal field has been in operation since the early 1960s. The Geysers field is one of only two dry steam fields in the world producing electricity, the other being at Larderello, Italy. The Geysers Field currently hosts 22 power plants producing approximately 900 megawatts of power – the largest producing field in the world. Currently operating at The Geysers are Calpine, Northern California Power Agency, U.S. Renewables and Western GeoPower
Unit 1 the Geysers Field, California, USA
Geothermal magazine presents: Western GeoPower Unit 1 – The Geysers
PROJECT DESCRIPTION
Project History
The Geysers Geothermal Field has produced commercial geothermal power continuously since the early 1960s and and produces “dry’ steam – a feature that reduces both capital and operating costs of power generation. Present generation from the three operating companies in the field – Calpine Corporation, U.S. Renewables and Northern California Power Agency – is about 900 megawatts (MW).
A commercial power plant of 62 MWe (gross) capacity, known as PG&E Unit 15, operated at the WGP leasehold between 1979 and 1989. It is now recognized that the Unit 15 plant was oversized for the available resource. During that time The Geysers Field experienced a decline in productivity as the fields resource was depleting, for this reason, the wells supplying the plant experienced a rapid decline in productivity. The PG&E plant was shut down in 1989 and dismantled and the wells were plugged. Since the mid-1990s, the rate of decline in well productivity at The Geysers has eased substantially and reservoir pressure has stabilized. In large part, this is due to the injection of treated municipal waste water into the reservoir.
The demonstrated production history and large database of resource information available from the leasehold, minimizes the risks of new development. GeothermEx, Inc. of Richmond, California projects that the Unit 1 leasehold will support a 35 MWe power plant for a minimum of 20 years, with generation continuing at a slightly reduced output factor for a further 10 years.
GeothermEx is a recognized international authority in the evaluation of geothermal resources and has been involved in the development of all the geothermal fields in the United States and over 750 projects worldwide. The company has been associated with the development of The Geysers Geothermal Field for over 30 years.
Project Facilities
The project involves the design, construction and operation of physical facilities comprising production and injection wells, a gathering and injection system, a power generation plant and a transmission line and inter-tie. Capital costs of design, construction, finance charges and drilling construction are estimated at US $1 50 million. A general description of the facilities follows:
Production and Injection Wells
Western GeoPower anticipates drilling eight production wells and one injection well on the property. . The drill pads require little work since the existing pads from the previous Unit 15 operations are still in good condition and the site is well served by existing access roads. The design envisions two pads with four wells each.
In April 2008 initial rig tests on the first well performed by GeothermEx, Inc. showed the well to be a strong producer with an initial steam flow rate of 140,000 lb/hr (63,500 kg/hr) at a wellhead pressure of 137 psia. This indicated an initial capacity of 10 MW (gross) and a stabilized capacity of at least 7 MW (gross).Drilling of well WGP-2 is underway.
“We note that the WGP-1 well is one of the strongest wells drilled at The Geysers during the past 20 years” said Dr. Subir Sanyal, President of GeothermEx, Inc. “In addition, the higher than expected static reservoir encountered (at least 280 psia compared to 250 psia assumed for project design) indicates that future wells may show higher capacity that had been anticipated.”
Power Plant
The power plant will consist of a 35 MW Top Exhausting Geothermal Condensing Steam Turbine Generator supplied by Fuji Electric Corporation and slated for delivery in August 2009. This is a conventional turbine proven in geothermal service worldwide.
Transmission Line
An existing 115 kilovolt (kV) transmission line that runs adjacent to the location of the proposed power plant can be accessed by tapping the line. No transmission upgrades are anticipated since the lines have been operating below capacity for a number of years.
ENVIRONMENTAL AND SOCIO-ECONOMIC
Environmental
Geothermal power plants release virtually no emissions. The power plant will include a multistage non-condensable gas extraction system using ejectors and a liquid ring vacuum pump. There will be primary and secondary hydrogen sulphide (H2S) abatement systems. (Typical Geysers plants separate, dewater and recycle sulfur as feedstock for sulfuric acid production). A mercury removal system also will be included if, after drilling and testing the resource; it is determined to be required.
(The 2,900 megawatts of electricity generated from geothermal resources in the U.S. is roughly equal to 24 million barrels of oil, 7.5 million tons of coal and 8.6 billion pounds of carbon in the form of CO2 or 152 billion cubic feet of natural gas and 4.8 billion pounds of carbon.)
Water sources and water quality are protected as excess water from the condenser and cooling tower is injected to the geothermal reservoir. Land disturbance is minimal as the project utilizes existing infrastructure including access roads, well pads and plant site and is immediately adjacent to an existing transmission line.
The project is compatible with existing surrounding land uses. Power production produces minimal noise (typically below 35-45 dBA during operation). The minimal footprint reduces visual impacts. The land surrounding The Geysers continues to support a strong wildlife population and remains a desired hunting destination.
Socio-Economic
WGP’s Unit 1 project is expected to be consistent with California’s Renewable Portfolio Standards (RPS) goals. Replacement of combustion-produced power with geothermal results in reduced burning of fossil fuels, improved environmental quality and public health, and reduces dependence on imported fuels.
Geothermal has a higher capacity factor than other renewables such as solar or wind as it is not dependent on climate, season or time of day. Geothermal power promotes stable electricity prices, creates sustainable economic development and creates new employment opportunities. Design, construction and operation of the proposed facility will bring a diversity of both short- and long-term jobs to the community.
CONTACT
Regional Office
Western GeoPower Inc.
235 Foss Creek Circle
Healdsburg, CA
USA 95448
Ph: 1-707-723-4455
Fax: 1-707-473-9618
Email: info@geopower.ca
www.geopower.ca