The U.S. Geological Survey Energy Resources Program

Energy resources are an essential component 

of modern society. Adequate, reliable, and affordable energy supplies obtained using environmentally 

sustainable practices underpin economic prosperity, environmental quality and human health, and 

political stability. National and global demands for 

all forms of energy are forecast to increase significantly over the next several decades. Throughout 

its history, our Nation has faced important, often 

controversial, decisions regarding the competing 

uses of public lands, the supply of energy to sustain 

development and enable growth, and environmental 

stewardship.

The U.S. Geological Survey (USGS) Energy 

Resources Program (ERP) provides information to 

address these challenges by supporting scientific 

investigations of energy resources, such as research 

on the geology, geochemistry, and geophysics of 

oil, gas, coal, heavy oil and natural bitumen, oil 

shale, uranium, and geothermal resources, emerging 

resources such as gas hydrates, and research on the 

effects associated with energy resource occurrence, 

production, and (or) utilization. The results from these 

investigations provide impartial, robust scientific 

information about energy resources and support the 

U.S. Department of the Interior’s (DOI’s) mission 

of protecting and responsibly managing the Nation’s 

natural resources. Primary consumers of ERP information and products include the DOI land- and 

resource-management Bureaus; other Federal, State, 

and local agencies; the U.S. Congress and the Administration; nongovernmental organizations; the energy 

industry; academia; international organizations; and 

the general public.

The USGS Energy Resources 

Program provides information 

from impartial, scientific studies 

to advance the understanding 

of energy resources, contribute 

to plans for a sustainable and 

secure energy future, and 

facilitate responsible use of 

resources.

To advance the understanding of processes affecting 

the formation, accumulation, occurrence, and 

alteration of geologically based energy resources

To conduct scientifically robust assessments

To study the impact of energy resource occurrence 

and (or) production and use on environmental quality 

and human health
The U.S. Energy Mix: Current and Future Energy Needs

The United States is one of the largest users of 

energy, consuming annually about one-quarter of 

the energy resources produced in the world. In 2008 

alone, the United States consumed more than 7.1 

billion barrels of oil, 23.2 trillion cubic feet of natural gas, and 1.1 billion short tons of coal. Forecasts 

indicate the Nation’s need for energy resources will 

continue to grow, raising several questions, including:

• How might the U.S. energy mix change over time, and 

what energy resources could be added to the mix?

• How much domestic and foreign oil and gas 

resources are available to meet the growing domestic and global energy demands?

• Does the United States have coal deposits of sufficient quantity and quality to meet demand over the 

next century?

• What is the potential for increased use of, and impacts 

from, domestic renewable energy resources?

• Are there domestic uranium resources that could 

supplant reliance on imported uranium, and what are 

some important considerations of increased use?

• What factors affect linkages among energy resource 

production and use on the landscape, ecosystem processes, and environmental quality and human health?

Given the vast amounts of energy resources we 

use each year, an understanding of the volumes, quality, and availability of domestic and global energy 

resources is of critical national importance. To improve 

the understanding of energy resources, the ERP supports a research portfolio that addresses national and 

regional priorities, including those established through 

legislative directives such as the Energy Policy Act of 

2005 and the Energy Independence and Security Act of 

2007 (EISA), internal and external strategic planning, 

and customer surveys and needs.

9%

23%

37%

24%

2%

5%

Percentage of nonhydroelectric

renewable energy

Wind, 11%

Biomass and 

biofuels, 80%

Geothermal, 8%

Solar and 

photovoltaic, 2%

Figure 1. Pie chart depicting the percentage of contributions of 

energy resources to the total energy consumed in the United States in 

2008. Data are from the U.S. Energy Information Administration (2009).

Coal Resources

The United States has one of the world’s largest 

coal resource endowments. Presently, almost half of 

the electric power generated in the United States is 

derived from power plants using coal as a fuel source. 

In response to the increasing demands for coal and 

for cleaner electric power generation, USGS research 

focuses on modern geology-based, digital assessments 

of the quantity, quality, location, and accessibility of 

the Nation’s coal resources. Estimates of the portion of the in-place coal resources that are currently 

technically and economically recoverable are important for understanding how coal can contribute to the 

Nation’s energy mix. The USGS has recently refined 

its coal resource assessment methodology, which can 

now produce a systematic determination of the technically and economically recoverable coal resources 

on a regional basis, and it can be applied to all major 

coal-bearing areas in the Nation.

Gillette Coalfield (Powder River Basin)

The Powder River Basin (PRB) is the most important coal basin in the United 

States, supplying more than 40 percent of the total coal mined annually 

in the country. Utilizing new data, the USGS recently completed the most 

comprehensive evaluation to date of the Gillette coalfield. For the coalbeds 

evaluated, the technically and economically recoverable coal resources 

estimated for the Gillette coalfield are 10.1 billion short tons of coal at the 

current (as of January 2007) average estimated sales price of $10.47 per ton. 

This resource estimate changes, depending on coal sales price, but generally 

indicates that only a minor portion (6 percent) of the original in-place resource 

might realistically contribute to the energy mix. Photograph showing the upper part of the Wyodak-Anderson 

coal zone in the Antelope mine, located in the Gillette coalfield.
Oil and Natural Gas Resources

The Nation’s future oil and gas supplies will 

likely come from a mix of domestic oil and gas fields, 

from imports, and potentially from such resources 

as natural gas hydrates. Efforts to systematically 

evaluate the major resources around the world provide essential information as a basis for informed 

discussions on global resource supplies, geopolitical 

issues, and energy policy. The USGS addresses this 

information need by conducting global research and 

assessments of undiscovered, technically recoverable 

oil and gas resources and of those within the U.S. 

onshore and underlying State-owned waters. These 

estimated resources are not yet discovered but, if 

found, could be recovered using existing technology.

The USGS continues to update its oil and gas 

resource assessments for the United States and the world 

using a consistent, peer-reviewed methodology as authorized in section 364 of the Energy Policy Act of 2005 

(Public Law 109–58). The results from these activities, 

such as the USGS National Oil and Gas Assessment, 

provide information for a number of uses, including the 

development of domestic energy policies and the formulation of reasonably foreseeable development scenarios 

and resource management plans for multiple Federal 

land- and resource-management agencies.

“The most widely respected source of information 

on global conventional oil and gas resources is the 

U.S. Geological Survey.” 

International Energy Agency

World Energy Outlook 2009

Land surface

Water

Water

Water

Conventional 

stratigraphic gas 

accumulation

Conventional 

structural oil 

accumulation

Conventional 

structural gas 

accumulation

Transition zones

Tight-gas sands 

and gas shales 

(continuous)

Coalbed methane 

(continuous)

Conceptual figure depicting some geologic features of conventional and continuous 

resource accumulations.

Continuous (“Unconventional”) Gas Resources

Geologic analyses and industry experiences indicate that a 

significant portion of the remaining undiscovered domestic 

onshore gas resource occurs in continuous accumulations, 

such as coalbed methane and gas from geologic units called 

”tight-gas sands” and ”shale-gas” reservoirs. These resources 

are frequently referred to as unconventional gas resources 

in energy policy discussions. A better understanding of these 

unconventional gas resources—the fastest growing petroleum 

resources in terms of U.S. production—is critical, both in 

terms of responsible energy resource use and sustainability of 

domestic energy supplies. The USGS is conducting research 

on the geologic settings of these resources and has initiated 

a screening process for the presence and (or) absence of 

continuous resources (heavy oil, tight gas, shale gas, and 

coalbed methane) in priority basins of the world. This screening 

process will enable the USGS to assess continuous resources on 

a global basis, which would be the first assessment of its kind in 

the world.

Circum-Arctic Resource Appraisal

The Arctic is an area of high petroleum resource potential, low data 

density, high geologic uncertainty, and sensitive environmental 

conditions. A large portion of the remaining global endowment of oil and 

gas resources had long been thought to exist in this area, but the quality, 

quantity, and distribution of these resources are poorly understood. 

To address this knowledge gap, the USGS undertook a multiyear 

research effort, termed the Circum-Arctic Resource Appraisal 

(CARA), to produce a comprehensive, unbiased, probabilistic 

estimate of undiscovered conventional petroleum resources 

in the high northern latitudes. The CARA is the first publicly 

available petroleum resource estimate of the area north of 

the Arctic Circle in its entirety.

90o E 90o W

0° 

180o

ARCT C C RCLE

I

I

PROBABILITY (percent)

100

50–100

30–50

10–30

<10

Area of low 

petroleum potential

Assessment units (AUs) in the Circum-Arctic Resource Appraisal color coded by 

assessed probability of the presence of at least one undiscovered oil and (or) gas 

field with recoverable resources greater than 50 million barrels of oil equivalent.
Other Geologic Energy 

Resources

The forecast increase in future 

energy demand indicates all energy 

resources merit consideration to 

augment and diversify the Nation’s 

energy mix. As one example, 

updated knowledge of the geologic 

setting, occurrence, and estimates of 

the magnitude of the undiscovered 

U.S. uranium resource endowment is needed for better informed 

planning efforts about the potential 

for domestic uranium supplies to 

sustain or increase the contribution of nuclear energy to the U.S. 

energy mix. As the Nation’s energy 

mix evolves, the USGS will continue to support a research and 

assessment portfolio that includes 

a comprehensive suite of energy 

sources, including hydrocarbon- and 

nonhydrocarbon-based sources.

Geothermal Energy

The USGS recently released an updated 

national geothermal resource estimate of 

the potential for geothermal power. The 

study results indicate that full development 

of conventional, identified systems 

alone could expand geothermal power 

production by approximately 6,500 

Megawatts-electric (MWe), or about 

260 percent of the currently installed 

geothermal total of more than 2,500 MWe. 

The provisional Enhanced Geothermal 

Systems (EGS; high temperature, but low 

permeability) resources estimate indicates 

that, if successfully developed, EGS could 

support an installed geothermal electric 

power-generating capacity equivalent 

to about half the currently installed U.S. 

electric power-generating capacity. The 

USGS is working in collaboration with other 

Federal and State partners to conduct 

research to better understand the geologic 

and hydrologic aspects of EGS and provide 

a detailed framework to underpin future 

assessments of EGS resource potential.

Map showing the location of identified moderatetemperature and high-temperature geothermal systems 

in the western contiguous United States. Each system is 

represented by a black dot.

Gas Hydrates

Gas hydrates are naturally occurring, ice-like solids in which water molecules trap natural gas molecules 

in a cage-like structure. Gas hydrates are widespread in Arctic regions beneath permafrost and beneath 

the seafloor in sediments of the outer continental margins, representing an immense natural gas 

resource that has the potential to make a significant contribution to both domestic and global energy 

mixes. Recently, the USGS completed the first-ever resource estimate of undiscovered, technically 

recoverable gas hydrates in northern Alaska. This study used a geology-based assessment 

methodology and culminated in a mean estimate of about 85 trillion cubic feet of undiscovered, 

technically recoverable gas resources. The USGS is continuing to collaborate with other Federal, 

industry, academic, and international partners to further the scientific understanding and potential 

viability of this energy resource.

Sediment core sample, collected from the offshore of India as part of the National 

Gas Hydrates Program Expedition 01, showing the presence of gas hydrate (white).

Geologic Carbon Dioxide 

Sequestration

Energy resources are at the 

nexus of global change and environmental issues, particularly because 

of the linkage between energy use 

and greenhouse gas emissions. 

Fossil fuel combustion is a major 

source of carbon dioxide (CO2

), a 

greenhouse gas, to the atmosphere. 

Fossil fuels will likely continue to 

provide a significant portion of total 

energy needs in both industrialized 

and developing countries over the 

next several decades. Achieving 

an overall reduction of CO2

 emissions to the atmosphere will involve 

a combination of techniques, and 

sequestration of CO2

 in geologic 

reservoirs has the potential to make 

a significant contribution to such 

mitigation strategies.

The USGS is authorized in 

EISA to develop a methodology 

and conduct a national assessment of onshore geologic storage capacity for CO2

. The USGS 

has developed a methodology, 

which has undergone external peer 

review by technical experts, and 

is conducting an assessment of the 

Nation’s resources for geologic 

carbon sequestration in oil and gas 

reservoirs and saline formations. 

The assessment focuses on the 

technically accessible CO2

-storage resource, which is based on 

present-day geological and engineering knowledge and technology for CO2 injection into geologic 

formations.
Environmental Quality and Human 

Health Effects

Energy resources can contain toxic substances 

that, if mobilized so that exposure occurs, can 

adversely affect human health and environmental 

quality. The toxic substances include both organic 

and inorganic compounds, many of which are known 

or suspected of causing cancer and other diseases in 

humans. These toxic substances can be mobilized by 

natural processes or by human extraction and utilization. This exposure may lead to acute disease symptoms or to increased disease risk from long-term, 

chronic exposure. The USGS conducts research to 

address the potential linkages among geology, energy 

resources, and environmental quality and human 

health to enable land managers and environmental 

and medical officials to better assess human health and 

ecosystem effects, to develop cost-effective remedies, 

and to establish appropriate policies and regulations.

For example, over the past several years, interest in U.S. uranium supplies has grown as demand 

for nuclear energy has increased. This recent interest 

has also raised the visibility of legacy uranium mining 

impacts, which are widespread in the Western United 

States. Scientific investigations of legacy uranium mining and milling areas and historic and ongoing uranium mining operations are needed to develop a better 

understanding of the processes operating at such sites 

in order to determine the effects of such past operations

on soils, surface water, and groundwater.

Monitoring

well

Monitoring

well

To ISR plant

(uranium enriched)

From ISR plant 

(O2/CO2 enriched)

Water table

Clay layer

Uranium ore

Confining clay layer

Host sandstone

Conceptual figure showing the geologic setting and process for in-situ recovery of 

uranium from an underground orebody.

Uranium Environmental Research

Most uranium mining has shifted away from conventional 

underground mining and milling to a potentially more 

sustainable in-situ recovery (ISR) method. The ISR method 

utilizes solutions to dissolve uranium from ore in the 

subsurface, which is monitored for potential impacts on 

groundwater. USGS scientists are conducting laboratory- and 

reaction-modeling studies to understand the feasibility of using 

natural or introduced sulfide minerals, such as mackinawite, 

as a remediation medium for groundwater restoration following 

ISR mining and for in-situ remediation of uranium-contaminated 

groundwaters.

Characterization, Uses, and Impacts 

of Produced Waters

Development and production of oil and 

gas resources can also require and yield 

significant quantities of water. Produced 

water and fluids used and recovered 

during hydrofracturing (hydrofracing) 

are likely to play an expanding role in 

energy resource considerations because 

treatment and disposal costs for produced 

and hydrofracing waters vary markedly. 

Also, the potential beneficial use of 

produced waters is an area of expanding 

interest, particularly in areas with limited 

water resources. The USGS conducts 

research to provide information on the 

volume, quality, impacts, and possible 

uses of water produced during oil, gas, 

and coalbed methane production and 

development in the United States. Examples of a coalbed methane well (inset) and a produced water impoundment from the Powder River Basin, Wyo.
Next Steps—Developing Multidisciplinary Approaches To Address 

Energy Resource Issues

Two key issues affecting current and future 

energy resource availability are the effects of globalization, and the likelihood that land, water, and 

environmental changes from energy extraction and 

consumption will factor more strongly into how 

societies use resources (USGS, 2007). Our Nation 

endeavors to balance the land, water, and environmental effects of resource development and extraction 

within this broader perspective of sustainability. These 

trends—globalization and environmental impacts—

point to a future United States with a more diversified 

energy mix (that is, less dependent on imported oil) 

and a life-cycle approach that evaluates the linkages 

between energy use and the broader effects of that 

use. A wide-ranging, multidisciplinary approach is 

needed to understand and evaluate how the complex 

energy resource “life cycle” of occurrence, formation processes, extraction methods, and use influence 

(or are influenced by) landscape, hydrology, climate, 

ecosystems, and human health. The USGS, with its 

multidisciplinary scientific expertise in hydrology, 

biology, geology, and geography, is developing better 

integrated approaches to address these challenges and 

provide a more systematic, holistic understanding of 

natural resources across the landscape.

For more information, please contact:

Energy Resources Program Coordinator

U.S. Geological Survey

915A National Center

12201 Sunrise Valley Drive

Reston, VA 20192

Telephone: (703) 648–6470

Fax: (703) 648–5464

E-mail: gd-energyprogram@usgs.gov

Internet: http://energy.usgs.gov/

References Cited

International Energy Agency, 2009, World energy outlook 

2009: Paris, France, International Energy Agency, 696 p.

U.S. Energy Information Administration, 2009, Annual 

energy review 2008: U.S. Energy Information Administration DOE/EIA–0384(2008), 446 p. (Also available at 

http://www.eia.gov/FTPROOT/multifuel/038408.pdf.)

U.S. Geological Survey, 2007, Facing tomorrow’s challenges—U.S. Geological Survey science in the decade 

2007–2017: U.S. Geological Survey Circular 1309, 81 p. 

(Also available at http://pubs.usgs.gov/circ/2007/1309/.)

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