...conducting innovative research for the Mining Industry!

The Centre for Environmental Research in Minerals, Metals, and Materials
The University of British Columbia
Department of Mining Engineering
6350 Stores Road, Vancouver,
V6T 1Z4, BC, Canada
Tel: (604) 822-6217 Fax: (604) 822-5599
Email: cerm3@mining.ubc.ca

Energy from Mother-Earth:
The Advent of Geothermal Energy as a Resource in Canada

Home

The Millennium

Plug

Bacteriophage for

ARD

Magnetic Levitation

Hoisting

Codisposal of

Tailings and Waste

Rock

Mercury

Detoxification

Growing Metals

Energy Efficiency

Bioindicators of

Pollution

Keeping the Roof from Falling

Geothermal Energy

in Canada

Industrial Growth

from Pollution

Robotics

Island Copper's

Pit Lake

Sulfate Reducing

Bacteria for

Mitigating ARD

Sustainable

Communities

Soils Research

PCIGR

Education of the

Sustainable

Engineer

Human Resources -

Training the Miner

of the 21st Century

Sustainable

Mining?

Integration of

Engineering and

Health Care

ISM - a new

NCE Program

in Canada

CERM3

Collaborations

How Geothermal Research can Play a Significant Role in Helping the Mining Industry Meet Canada's Commitment to the Kyoto Protocol

Mory Ghomshei,

Manager of Research, CERM3 and

Adjunct Professor of Mining Engineering

and

John A. Meech,

Professor of Mining Engineering and

Director of CERM3

Background

Canada is the only country on the Pacific Rim that has yet to exploit its geothermal resources. Low-, medium-, and high-temperature geothermal fluids are available across Canada with particular high-temperature resources close to Vancouver in British Columbia. Mine waters are often of sufficient warmth to be used to extract low-grade energy for use in the mine or its associated community.

This research program is targeted at three opportunities for mining companies to exploit the energy from geothermal resources:

• the high-grade thermal resource at Meager Creek located 40 kilometers north of Pemberton, British Columbia.

• the low-grade extraction of heat contained in mine effluent flowing from an underground mine such as Britannia Mine.

• the development of applications for municipalities, apartment building owners and tenants, and single-family dwellings to use the geothermal resources under their own property.

Geothermal Energy is a Clean and "Green" energy resource. There is virtually no other source of energy in the world today that does not produce pollution and which is literally of infinite supply. It is long past time that Canada began to exploit its geothermal resources. The exploitation is not limited to space heating or industrial use, it can also be used to generate electricity and contribute to a wider distribution network to supply North America's energy demands in a clean and efficient manner.

On a recent visit to New Zealand's Wairakei Geothermal Power Station, CERM3 researchers were able to see first hand the first geothermal power station in the world to use Flash Steam from geothermal waters as an energy source for electricity. The plant uses a cooling tower instead of river water and so, it conserves the Wairakei Borefield by condensate reinjection. Similar opportunities exist with the Meager Creek thermal field north of Pemberton, British Columbia under development by North Pacific Geopower Corporation.

                                       Wairakei Geothermal Power Development Project, New Zealand

Geothermal Energy and the Environment

Geothermal energy is heat contained below the earth's surface. The only type of geothermal energy that has been widely developed is hydrothermal energy, which consists of trapped hot water or steam. New technologies are being developed however, to exploit hot dry rock (accessed by drilling deep into rock), geo-pressured resources (pressurized brine mixed with methane), and magma. The various geothermal resource types differ in many respects, but they do share a common set of environmental issues. Air and water pollution are two leading concerns, along with safe disposal of hazardous waste, location of the generating station, and land subsidence. Since these resources are exploited in a highly centralized fashion, reducing their environmental impacts to an acceptable level should be straight forward. But it will be difficult to site plants in scenic or otherwise environmentally-sensitive areas.

The method used to convert geothermal steam or hot water to electricity directly affects the amount of waste generated. Closed-loop systems are almost totally benign, since gases or fluids removed from the well are not exposed to the atmosphere and are usually injected back into the ground after recovery of their heat. Although more expensive than conventional open-loop systems, in some cases, this technology can reduce scrubber and solid-waste disposal costs enough to provide a significant economic advantage.

Open-loop systems, on the other hand, typically generates large amounts of solid wastes as well as noxious fumes. Metals, minerals, and gases are leached from the host rock into the geothermal steam or hot water as it passes through the aquifer. The large amounts of chemicals released when geothermal fields are tapped into for commercial production can be hazardous or objectionable to people living and working nearby.

At The Geysers in California, the largest US geothermal development, steam vented at the surface contains hydrogen sulfide (H2S) which accounts for the area's "rotten egg" smell. Ammonia, methane, and carbon dioxide are also released as well. At a hydrothermal plant, carbon dioxide can make up about 10 percent of the gases trapped in geo-pressured brines. Nevertheless, for each kilowatt-hour of electricity generated, the amount of CO₂ emitted is only about 5 percent of that emitted by a coal- or oil-fired power plant.

Scrubbers reduce air emissions but a low-density sludge high in sulfur and vanadium is produced. Vanadium can be toxic in high concentrations but it can also be recovered for market from these sources. Additional sludge is generated when hydrothermal steam is condensed, causing dissolved solids to precipitate. The sludge is generally high in silica compounds but may also contain high amounts of chlorides, arsenic, mercury, nickel, and other toxic heavy metals. One costly method of waste disposal involves drying and shipping to licensed hazardous waste sites. Research into Sulfate Reducing Bacteria processes point possible recovery of commercially valuable metals while rendering the waste nontoxic. CERM3 intends to conduct such research to help support the development of geothermal energy resources in Canada.

The best disposal method is to inject liquid wastes or re-dissolved solids back into a porous stratum of a geothermal well. This technique is especially important at geo-pressured power plants because of the volume of waste produced each day. The waste must be injected well below fresh-water aquifers to ensure there is no contact between usable water and waste-water strata. Leaks in the well casing at shallow depths must also be avoided. In addition to providing safe waste disposal, injection can also help prevent land subsidence. At Wairakei, New Zealand, where wastes and condensates were not injected for many years, one area has sunk 7.5 meters since 1958. Land subsidence has not been detected at other hydrothermal plants in long-term operation. Since geo-pressured brines primarily are found along the Gulf of Mexico coast, where natural land subsidence is already a problem, even slight settling could have major implications for flood control and hurricane damage.

Most geothermal power plants require a large amount of water for cooling and other purposes. In places where water is in short supply, this need could raise conflicts with other users of water resources. Development of hydrothermal energy faces another unique problem. Many hydrothermal reservoirs are located in or near wilderness areas of great natural beauty such as Yellowstone National Park and the Cascade Mountains. Proposed developments in such areas have aroused intense opposition. If hydrothermal-electric development is to expand further in North America, recognition of the significant reduction in GHGs that result from the replacement of carbon-based energy resources is needed by our society.

Kyoto Protocol

The Kyoto Protocol was signed by many nations in Kyoto, Japan in 1997. Canada was one of the original signatories. Ratification has been slow but it is clear that the Canadian government is set to ratify this year its commitment to the promises made at Kyoto. The ramification for Canadian industry and all Canadians is significant. The cost estimates range from 25 to 100 billion dollars.

The Kyoto Protocol has several controversial sections regarding the commitment of First-World and Third-World countries to reducing Green-House-Gas emissions, but is essential requirement for Canada is to reduce our emissions of GHGs to 10 percent below that of 1990 by the year 2010. It is not our desire or interest here to discuss these controversies nor to examine if this level of decline is sufficient to really have an impact on the Global-Warming crisis. Rather, we intend to establish how the Mining Industry can play a role in meeting Canada's obligations through the use of technologies developed to exploit geothermal energy resources within our industrial processes. In addition, the actual exploitation of geothermal energy resources can also play an important role but significant investment may be necessary.

For a detailed pictorial description of the opportunities in Geothermal Energy in Canada, click here.