Dennis Gilles May 31, 2013

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Forward Looking Statements

This presentation contains certain “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995. All statements other than statements of historical fact are forward-looking statements, which reflect the company’s current expectations and beliefs regarding its future results of operations, performance and achievements. These statements are subject to risks and uncertainties and are based upon assumptions and beliefs that may or may not materialize. Forward-looking statements may be identified by words such as “will”, “could”, “prospects”, “potential”, “planned”, “expected”, “estimates”, "schedule", "anticipates" and similar terms.

These forward-looking statements include, but are not limited to, statements concerning the company’s strategy; operating forecasts; capacity, financing and construction of new projects or expansions of existing projects; working capital requirements and availability; illustrative plant economics; and the use of share price value projections. Forward-looking statements are not guarantees of future performance and are subject to various risks and uncertainties that could cause the company’s actual results and outcomes to differ materially from those discussed or anticipated, including the factors set forth in the section entitled “Risk Factors” included in the company’s Annual Report on Form 10-K for the year ended December 31, 2012 and its other filings with the Securities and Exchange Commission.

The company does not assume the obligation to update any forward-looking statement.

All financial information presented in U.S. dollars unless otherwise indicated.

Geothermal Resources in the Western U.S.

Data source: United States Geological Survey. Map Credit: Billy Roberts

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Geothermal Power Background• Produced by utilizing heat that naturally exists within the

Earth’s crust• National Renewable Energy Lab (NREL) estimates that heat within 10,000

meters of earth’s surface is 50,000 times greater than energy that is available from petroleum and natural gas

• Geological anomalies create “shallow” reservoirs of geothermal fluids (steam and water) that can be economically exploited

• Typically reservoirs are 1,000 – 12,000 feet deep

• Geothermal fluids act as heat carriers. Those fluids are piped to the surface and used to drive turbine generators

• Geothermal fluid is reinjected to sustain reservoir pressure

• Geothermal power is renewable without significant output deterioration over time

Steam Power Plant

In dry steam or flash power plants, the hot steam (or flashed hot water) passes directly into a steam turbine.

The steam spins the turbine blades, which in turn spin the generator making the electricity.

Condensed steam is returned into the reservoir to be reheated.

Binary Cycle Power Generation

In a binary cycle plant, hot water from the ground is run through a heat exchanger to vaporize a working fluid (hydrocarbon or refrigerant) that powers the turbine generator.

The geothermal water is returned into the reservoir to be reheated.

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Geothermal Overview

• Large existing installed base in the United States

• 3,386 MW(2) in production as of year end 2012

• Comparative production of geothermal, wind, and solar in the United States in 2012(1) : (thousand MWh)

• Wind 140,089

• Geothermal 16,791

• Solar 4,342

(Wind surpassed geothermal in 2005)

• Globally, there is 11,224 MW(1) in production• United States is the largest producer in the world

• The first geothermal power plants in the U.S. were built in 1962 at The Geysers dry steam field in Northern California

– The Geysers are the largest producing geothermal field in the world

• Geothermal power has incredible potential as an energy source

Source: US DOE

Source: NREL

US Electric Geothermal Resource Survey

NREL Estimated US Geothermal Potential

Shallow – Identified…………………….30,000 MW

Shallow – Unidentified………………..120,000 MW

Co-production & Geo-pressure……>100,000 MW

Enhanced Geothermal Systems.. 13,000,000 MW

(1) GEA Data for 2012(2) Source: EIA Data for 2012

Geothermal Electricity Production in U.S. by State

California 2,732 Megawatts Nevada 517 Megawatts Utah 48 Megawatts Hawaii 38 Megawatts (25% of Big Island’s total energy)

Oregon 33 Megawatts Idaho 16 Megawatts Alaska 0.7 Megawatt Wyoming 0.3 Megawatt

Dry Steam: 1,585 MW Flash: 997 MW Binary: 804 MW

Total 3,386 MWSource: Geothermal Energy Association – 2013 Annual Generation Report

Total Projects in Development by State

Total Planned Capacity Estimated

State Projects Additions (MW) Resource (MW) Low High Low High

AK 6 50 50 95 95

AZ 2 2 2 102 102

CA 33 995 1,061 1,736 1,827

CO 3 20 40 60 60

HI 3 - - - -

ID 11 83 83 439 514

ND 2 0.60 0.82 - -

NM 1 15 15 - -

NV 75 1,056 1,061 2,150 2,275

OR 18 73 77 208 270

TX 1 1 1 - -

UT 19 215 215 260 280

WA 1 - - 100 100

TOTAL 175 2,511 2,606 5,150 5,523

Source: Geothermal Energy Association – 2013 Annual Generation Report

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World’s Largest Geothermal Fields(MW capacity)

World's Largest Geothermal FieldsReference: Proceedings World Geothermal Congress April 2010

200

200

205

213

227

232

234

270

329

377

458

595

716

720

905

0 200 400 600 800 1000

Kamojang (Indonesia)

Darajat (Indonesia)

Heber (USA)

Hellisheidi (Iceland)

Wayang Windu (Indonesia)

Wairakei (NZ)

Tiwi (Philippines)

Coso (USA)

Salton Sea (USA)

Salak (Indonesia)

Mak-Ban (Philippines)

Larderello (Italy)

Tongonan (Philippines)

Cerro Prieto (Mexico)

Geysers (USA)

Megawatts

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Why Geothermal?

Versus Other Renewable Power Generation

• Clean and renewable generating source

• Cost competitive with traditional sources in many geographic areas

• No commodity risk and/or price volatility from fuel inputs

• No emissions = easier permitting process in power hungry Western US

• High availability versus all technologies

• Incentives enhance attractive project returns

• Base load power

• Not dependent on variables such as the time of day, cloud cover, etc.

• 95% utilization versus 30-35% for wind and solar

• Can constitute larger portion of a utility’s generating portfolio

• Results in lower production costs per megawatt produced

• More attractive project returns

• Smaller footprint and reduced visual impact versus wind and solar

• However longer development lead times and higher exploration risk/cost

Versus Traditional Power Generation

Wyoming Coal Plant

Natural Geyser

Specific Barriers to Geothermal Development

Drilling, Drilling, Drilling….. High risk - resource discovery (3 to 5 years) Cost per well $2 to $8 million Lack of drilling and development price incentives Need to reward investors with higher returns Need to create new era of geothermal drilling based on feed-in tariff

Other Factors….. Long development lead times for plant equipment Capital-intensive Regulatory patchwork

This is what it is all about!

Direct Use Applications

Direct use applications displace about 1.6 Million barrels of oil annually in the U.S.

• District Heating• Process heat• Agriculture• Aquaculture• Balneology

(Hot spring and water bathing)

District Heating Applications

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… a look at our company

_____________________________Vision: Building a sustainable, long-term clean

renewable energy company

Management: Proven geothermal energy development and operating experience

Assets: Three operating geothermal power plants• 22 MW plant near Vale, Oregon• 9 MW plant near Reno, Nevada• 13 MW plant near Pocatello, Idaho

Advanced development properties• El Ceibillo near Guatemala City, Guatemala• San Emidio II near Reno, Nevada

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U.S. Geothermal’s Producing Power Plants

Nevada

Idaho

Oregon

Reno

Boise

Raft River

San EmidioGerlach

Granite Creek

Operating Projects

Development Projects

Neal Hot Springs

Neal Hot Springs, Oregon

60 to 70% Owned*

22 net MW

Neal Hot Springs, Oregon

60 to 70% Owned*

22 net MW

San Emidio, Nevada

100% Owned

9 net MW

San Emidio, Nevada

100% Owned

9 net MW

Raft River, Idaho

50% Owned **

10 net MW

Raft River, Idaho

50% Owned **

10 net MW

* EP=Enbridge, % subject to final calculations

** EP= Goldman Sachs

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Neal Hot SpringsOregon’s First Commercial Geothermal Power Plant

Online November 2012

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22 net MW power plant

Commercial Operation: November 2012

$130 million total cost

$33 million ITC Treasury cash grant– Possible additional $3.1 million after sequestration resolution

$7.3 million BETC Oregon tax credit – payment pending

$72 million (approx.) 22 year project term loan from DOE– Fixed APR ~2.6%

PPA with Idaho Power– long term buyer with attractive pricing and terms

Enbridge is equity partner

Neal Hot Springs:

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San Emidio Power Plant Online May 2012

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NV Energy 19.9 MW PPA Reservoir with 20 year operating

history

New 9 net MW power plant (Phase I) $44 million total project cost Received $11.75 million ITC

US Treasury cash grant $29 million construction loan - SAIC 20+ year project loan – pending

Option for second 11 MW plant

San Emidio Power Plant

Raft RiverPacific Northwest and Idaho’s First Geothermal Power Plant

Online - 2007

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Raft River Operations

13 MW net capacity– 10 MW current production

25 year Idaho Power PPA– Allows separate REC sales

Goldman Sachs tax equity partner since 2008

Excellent operating history $11 million DOE grant

– studying fracturing for increased production

Resource expansion potential

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El Ceibillo Project – GuatemalaDevelopment Drilling Started April 2013

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El Ceibillo Project

PPA MOU signed for 50 MW – Current retail market $140 per megawatt hour

Phase I: Planned 25 net MW power plant Estimated total project cost - $135 million Existing well field – 5 production wells

– Plan to re-enter 2 wells to deepen and drill new wells– Confirmation reservoir drilling underway

Adjacent to Guatemala City and main shipping port

– Transmission interconnect 2 km south Development decision tied to PPA, project

financing, and equity partner Option for Second 25 MW Plant (Phase II)

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U.S. Geothermal Growth Plan

1. Invest incrementally within existing Plant footprint for more MW

2. Add to Plant footprint by building new power plants on undeveloped acreage

3. Pursue development at currently held undeveloped sites

4. Evaluate other potential renewable growth opportunities– M&A– Greenfield

4 Options Under Evaluation for Renewable Growth 4 Options Under Evaluation for Renewable Growth

Utilize stimulus package

incentives:

Higher Focus

Lower Focus

- Investment Tax Credit of 30%

- Must be in continuous construction by 12/31/13

- DOE Cost Share Drilling

Quarterly Financial Results

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• All 3 projects online as of the middle of Q4 2012

• First two quarters with positive EBITDA, net income, and cash flow

Q3 - 2012 Q4 - 2012 Q1-2013

Revenue 2,019,749 5,299,162 7,086,990

Operating Income 270,012 1,671,619 3,979,695

Net Income (836,581) 748,072 2,235,079

Net Income - USG (766,100) 382,127 1,388,523

EBITDA - USG Share (499,337) 1,379,586 2,622,806

Cash Flow from Ops 387,787 995,206 4,253,788

Cash + AR - AP 3,345,381 13,552,295 16,119,075

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Planned 2013 Performance

Selected Metrics

Total HTM Share

Gross Project Capacity 65 MW

Net Project Capacity 44 MW 29 MW

Potential Annual Generation 340,000 MWh

Gross Revenue $26.3 million

EBITDA $12.9 million

Net Free Cash Flow $ 4.0 million

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• Traded on NYSE MKT – HTM and TSX GTH

• Recent transition from early development company to operating IPP

• Proven management team

• 10 years of successful project development and growth

• 3 modern geothermal power plants, plus two advanced development projects

• 65 MW gross generating capacity online during 2012

• Valuable, non depleting earth energy sources

• Achieved positive net income, cash flow, and EBITDA

• 2013 first year of sustainable earnings & cash flows

• Under valued stock in oversold market

Summary … a new beginning