November 18, 2017

U.S. GEOTHERMAL INC.
U.S. Geothermal Inc. Provides Updates on the San Emidio and El Ceibillo Development Projects

October 26, 2017

U.S. Geothermal Inc. (the "Company") (NYSE American:HTM), a leading and profitable renewable energy company focused on the development, production, and sale of electricity from geothermal energy, is pleased to provide an update on two of its development projects and a new plan to increase generation at San Emidio I.

San Emidio II, Nevada
During September, a 59-hour, multi-well flow test was conducted using three of the recently drilled Southwest Zone wells. Total flow from the wells was approximately 1,590 gpm.  Testing included a step rate program with four-hour increments, whereby one well, then two wells, and finally all three wells were flowed for the 51-hour duration of the test.  Flowing temperature from the three wells ranged from 319°F to 325°F.  Pressure was also monitored on the flowing wells, which experienced pressure drawdown from 7.7 psi to 43.0 psi.  A monitoring well in the Southwest Zone, located 1,700 feet from the nearest flowing well, had a pressure drawdown of 4.3 psi.  Five additional monitoring wells located in the Phase I reservoir area recorded pressure changes of 0.9 psi to 3.2 psi.

These results continue to support the previously announced Probability Power Density model resource estimate of 25.9 megawatts at a 90% probability.  The 50% probability level estimate of 47 megawatts remains unchanged because all of these wells are inside the originally defined Southwest Zone resource area.  Future drilling to expand the resource beyond the currently defined area is planned, but cannot be implemented until the Environmental Assessment for the Phase II power plant development is approved by the BLM.

San Emidio I, Nevada
At our operating San Emidio I project, we are evaluating an enhancement program to increase generation from the power plant.  There is approximately 1 megawatt annual average that remains available under the terms of the PPA at full price, and several more megawatts that could be sold at the excess energy price.  One megawatt at full contract price is worth approximately $800,000 in additional annual revenue and each megawatt of excess energy is worth approximately $425,000.

A permit has been filed with the Bureau of Land Management (BLM) in order to drill a full-sized twin of observation well 25-21 in the Southwest Zone.  The new production well would be connected to the Phase I plant and provide 1,200 to 1,500 gpm of 320°F fluid.  Developing production from the Southwest Zone in 2018 would not only result in an increase in revenue, but would provide a long-term flow test of the Southwest Zone that will be critical to understand its full development potential.

El Ceibillo, Guatemala
On September 28th, U.S. Geothermal Guatemala S.A., a wholly owned subsidiary of U.S. Geothermal, Inc., was notified that it has been awarded a $3.42 ( 2.91) million grant from the German Development Facility for Latin America for further development drilling at the El Ceibillo project.  The grant represents an approximate 40% cost share for drilling up to three production wells, with a total estimated program cost of $8.81 ( 7.486) million.  If the GDF funding is used on the project and the power plant is constructed, the grant would be converted into a loan.  The German Development Bank may consider financing the entire project when it moves to production.  The next phase of work for the project is being considered by the management team as 2018 budgets are being developed. 

Expenditures at El Ceibillo are being carefully controlled until we see evidence that the energy market is advancing in Guatemala.  The Guatemalan Government announced earlier this year that a Request For Proposals (RFP) for 420 megawatts of energy, which included 40 megawatts for geothermal, was going to be issued in 2017.  There is still no indication of when that RFP may be issued.

"We are pleased to report on the flow test results from our San Emidio II development project, our near-term plans for increasing generation at San Emidio I, and in securing funding for the El Ceibillo project," said Douglas Glaspey, Interim Chief Executive Officer. "After increasing production at Raft River this year, and planned generation increases at Neal using hybrid cooling and San Emidio I in 2018, we will continue to work toward increasing generation from our existing power plants while we seek PPAs for our development projects." 

Geothermal Resource Council Awards
Two U.S. Geothermal professionals were presented with awards at the recent Geothermal Resources Council annual meeting in Salt Lake City, Utah.  Mr. Dennis Gilles was given a Lifetime Achievement Award recognizing his over 30 years of remarkable contributions to geothermal development and power plant operation. Mr. Kevin Kitz received the Ben Holt Award for his outstanding achievement in designing geothermal power plants.  Kevin's contributions to our innovative power plants, such as Neal Hot Springs, and the hybrid cooling design for the WGP Geysers project, place him at the peak of his profession.  We heartily congratulate Dennis and Kevin for their outstanding achievements in the geothermal industry and for U.S. Geothermal.

About U.S. Geothermal Inc.
U.S. Geothermal Inc. is a leading and profitable renewable energy company focused on the development, production and sale of electricity from geothermal energy. The Company is currently operating geothermal power projects at Neal Hot Springs, Oregon, San Emidio, Nevada and Raft River, Idaho for a total power generation of approximately 45 MWs. The Company is also developing an additional estimated 115 MWs of projects at: the Geysers, California; a second phase project at San Emidio, Nevada; at Crescent Valley, Nevada; and the El Ceibillo project located near Guatemala City, Guatemala.  U.S. Geothermal's growth goal is to reach over 200 MWs of generation by 2022 through a combination of internal development and strategic acquisitions.

The information provided in this news release may contain forward-looking statements within the definition of the Safe Harbor provisions of the US Private Securities Litigation Reform Act of 1995.  Readers are cautioned to review the risk factors identified by the company in its filings with United States Securities and Exchange Commission.  All statements, other than statements of historical fact, included herein, without limitation, statements relating to the staffing of executive positions, development schedules or estimated resources of U.S. Geothermal, are forward-looking statements. Forward-looking statements are frequently, but not always, identified by words such as "expects", "anticipates", "believes", "intends", "estimates", "potential", "possible", and similar expressions, or statements that events, conditions, or results "will", "may", "could", or "should" occur or be achieved. These forward-looking statements may include statements regarding perceived merit of properties; interpretation of the results of well tests; project development; resource megawatt capacity; capital expenditures; timelines; strategic plans; or other statements that are not statements of fact. Forward-looking statements involve various risks and uncertainties. There can be no assurance that such statements will prove to be accurate, and actual results and future events could differ materially from those anticipated in such statements. Important factors that could cause actual results to differ materially from U.S. Geothermal's expectations include the uncertainties involving the availability of financing in the debt and capital markets; uncertainties involved in the interpretation of results of well tests; the need for cooperation of government agencies in the development and operation of properties; the need to obtain permits and governmental approvals; risks of construction; unexpected cost increases, which could include significant increases in estimated capital and operating costs; and other risks and uncertainties disclosed in U.S. Geothermal's Annual Report on Form 10-K for the year ended December 31, 2016 filed with the United States Securities and Exchange Commission and Canadian securities regulatory authorities and in other U.S. Geothermal reports and documents filed with applicable securities regulatory authorities from time to time. Forward-looking statements are based on management's expectations, beliefs and opinions on the date the statements are made.  U.S. Geothermal Inc. assumes no obligation to update forward-looking statements if management's expectations, beliefs, or opinions, or other factors, should change.

The NYSE American does not accept responsibility for the adequacy of this release.

CONTACT
Scott Anderson
Director of Investor Relations and Corporate Communications
U.S. Geothermal Inc.
Tel:  208-424-1027
Fax: 208-424-1030
sanderson@usgeothermal.com

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