The U.S. Department of Energy (DOE) has completed the Final Environmental Assessment (EA) for the Naknek Electric Association geothermal energy project near King Salmon, Alaska. The document presents analyses and describes the potential environmental impacts associated with the proposed construction, operation, drilling, well logging, completion, and testing of two of the exploratory geothermal wells (G2 and G3) and stimulation of one well (G1, G2, or G3), if feasible. The project is located on a 120 acre, Naknek Electric Association (NEA) owned land parcel approximately 8 kilometers (km) (5 miles [mi]) northeast of King Salmon and serviced by a 1.8 mile long gravel road. The DOE has included an Induced Seismicity report detailing the historical seismic history, geology, and potential effects of the project.

The Finding of No Significant Impact (FONSI) and EA (EA1759) are available to the public online in the DOE Electronic Public Reading Room or download them below. DOE's Golden Colorado Field Office has prepared this document in accordance with the National Environmental Policy Act.

FONSI for EA1759 (3.5MB)
Download EA1759 (49MB)
Download Induced Seismicity Report for EA1759 (9MB)

This is part of NEA's Southwest Alaska Regional Geothermal Energy Project which is designed is to provide a sustainable, affordable and clean alternative to the rising costs of diesel generated electricity. A geothermal resource could stabilize electric rates in Naknek, King Salmon and South Naknek by displacing up to 5.4 million gallons of diesel fuel currently used for electricity and space heating, potentially avoiding over $15,000,000 per year in fuel costs. In support of its goals to develop geothermal power, NEA and DOE in a cost sharing arrangement will drill up to two deep, full-diameter wells via Congressionally Directed Project (CDP) funds and competitively awarded American Recovery and Reinvestment Act of 2009 (ARRA) EGS funds. EGS incorporates stimulation techniques to increase the productivity of a low-permeability geothermal reservoir.

If natural permeability is not sufficient for commercial production, water may be injected into the well to open micro-fractures and allow greater quantities of water to circulate through the hot rock.

During the process of creating an underground heat exchanger by opening permeable space in the rock or during subsequent circulation of water to recover the heat, stress patterns in the rock may change and produce microseismic events (known as induced seismicity). In almost all cases, these events in the deep reservoir have been of such low magnitude and have so little energy relative to natural earthquakes that they pass unnoticed.

The difference between microseismic events created directly by fluid injection and a natural earthquake is significant: To the extent that they are sometimes felt, induced seismicity usually falls into the category of a nuisance, like a pneumatic hammer or the passing of a train or large truck, whereas a natural earthquake may cause extensive damage. For example, experience and scientific data indicate that the vibration at depth from a micro earthquake related to fluid injection is unlikely to cause any damage to modern buildings. However, large induced seismic events have occurred. In particular, a series of induced seismic events resulting from an EGS program in Basel, Switzerland led to the project's cancelation after a seismic hazard evaluation was performed. Additional information regarding induced seismicity can be located from the Lawrence Berkeley National Laboratory at http://esd.lbl.gov/research/projects/induced_seismicity/.

DOE requires EGS awardees to collect stress data, background seismicity, and geologic data prior to actual field stimulation. Once the data are collected, the awardee should use predictive stimulation models to estimate and forecast potential induced seismicity magnitude and potential radius of seismicity. Information submitted by awardees is used to develop site specific risk mitigation strategies.

A DOE team of experts will review these results as part of a go/no-go decision point. If judged satisfactory, awardees will be given the go-ahead to conduct field work with adequate permits from local authorities. Otherwise, they will be asked to gather more data and conduct more analysis.

In addition, DOE requires awardees to implement special conditions of approval for stimulations (if necessary) including: placement of ground motion sensors, monitoring and reporting of operational data and events, and instituting procedures for mitigating emerging seismic events up to complete shutdown, if necessary.

DOE requires adherence to induced seismicity protocol detailed in the "PROTOCOL FOR INDUCED SEISMICITY ASSOCIATED WITH ENHANCED GEOTHERMAL SYSTEMS" established by the International Energy Agency-Geothermal Implementing Agreement. An array of seismographs surrounding the drill site will be established to detect the response of the formation, including possible micro-earthquakes due to the EGS stimulation. This array will allow EGS to be safely managed. Properly monitored and analyzed, EGS has been valuable in the development of geothermal resources around the world.

http://www.iea-gia.org/documents/ProtocolforInducedSeismicityEGS-GIADoc25Feb09.pdf

DOE has conditionally awarded $12,376,000 to NEA for a competitive ARRA award to use EGS technologies to develop a geothermal resource on Pikes Ridge. Before releasing the funds, the National Environmental Policy Act (NEPA) requires an Environmental Assessment (EA) to be conducted to evaluate any potential environmental impacts, including induced seismicity. In addition, NEA will receive CDP funds totaling $5,354,500 federal funds which will be cost shared.

Please go to the following websites to find more information:

• http://www.nea.coop/about/geothermal.shtml
• http://www.eere.energy.gov/golden/Reading_Room.aspx
• http://www1.eere.energy.gov/geothermal