Rezachek & Associates'
Energy & Environmental Resources

GEOTHERMAL ENERGY

GEOTHERMAL ENERGY - What Is It?

Geothermal energy is the natural heat of the earth stored deep below the earth's surface. The energy is found near areas where volcanic activity has taken place, either recently or many years ago. It can be in the form of steam, hot liquid, or hot dry rock. Wells drilled deep into the ground bring steam and hot water to the surface.

Advantages

Geothermal energy can be used instead of fossil fuels to produce electricity. Replacing fossil fuels will reduce the amount of air pollutants which can cause acid rain and contribute to global warming. Reducing the amount of oil shipped to the Big Island (officially called the Island of Hawaii) for electrical generation lessens the possibility of oil spills.
Geothermal energy is believed to exist in large amounts on the Big Island and possibly the Island of Maui. It does not have to be imported from foreign countries or parts of the United States which require shipping over several thousand miles of ocean water.
Besides biomass, geothermal energy is the only large-scale, commercially mature natural alternative to fossil fuels on the Big Island which can provide a steady (i.e., baseload) amount of power 24 hours a day - every day, rain or shine.
Use of geothermal energy as a source of electricity will help reduce the Big Island's dependence on fossil fuels for electrical power generation. A 25-MW geothermal power plant on the Big Island displaces the need to burn about 480,000 barrels of fuel oil every year. It eliminates the need to ship that amount of fuel oil from the refineries on the Island of Oahu to the Big Island, thus significantly reducing the risk of oil spills. This geothermal plant also eliminates about 173,000 tons of CO2 that an equivalent oil-fired plant would have emitted.
Direct-use geothermal heat and some of its mineral by-products have been successfully demonstrated in aiding agricultural production; drying lumber, fruits and vegetables; and assisting certain manufacturing processes.
Drilling for geothermal resources, as well as building and operating electrical generating plants, has provided skilled jobs for Hawaii's people.
During normal operations, stringent permit conditions, state-of-the-art abatement systems, and process design should virtually eliminate unpleasant odors and mitigate noise impacts from new geothermal facilities.

Disadvantages

The exploration and development of geothermal resources can be permitted within conservation, agricultural, rural, and urban areas. Some geothermal resources can be found in the Wao Kele O Puna rainforest, one of Hawaii's nine lowland rainforests, and in residential areas where some residents may not want geothermal activities to occur.
An uncontrolled venting incident in June 1991 at the Puna Geothermal Venture project on the Big Island released hydrogen sulfide and other gases, causing some residents to remain concerned about potential emissions. As a result of the "blowout," a Geothermal Management Plan was developed that has enabled state and county agencies to better regulate geothermal activity and enforce permit conditions.
Geothermal wells are sometimes vented for a few hours to clear the well and pipe lines resulting in a temporary release of steam and abated gases. Such events can be noisy for a short time. Some continuous low-level noise is also generated during normal power plant operations.
Some native Hawaiians oppose the development of geothermal power as interfering with their worship of Pele, the goddess of volcanoes.

The Basic Process

In areas where geothermal steam or hot fluids are thought to be within economic reach of drilling equipment, wells are drilled to bring the steam or hot fluids to the surface. The steam, or steam produced by the fluids in a heat exchange process, is used to drive a turbine generator to make electricity. Modern technology allows spent geothermal fluids and non-condensable gases to be reinjected back into the ground, eliminating surface disposal and air pollution.

Use of Geothermal Energy in Hawaii

In 1881, King David Kalakaua and his Attorney General discussed with Thomas Edison the possibility of using power from Hawaii's volcanoes to produce electricity to light Hawaii's capital, and transmitting this power by submarine cable to the other islands.

Geothermal exploration in Hawaii began in the 1960s. The first geothermal well in Hawaii that produced steam was drilled in 1976. This well, named HGP-A, is 1,870 meters deep, and is one of the hottest wells in the world. The 3-MW generating plant which used steam from this well began producing electricity in 1982. The plant, originally designed as a two-year demonstration project, operated for nearly eight years before it was shut down at the end of 1989. Over that time, the plant produced between 15 and 19 million kWh of electricity per year. The electricity was sold to the Hawaii Electric Light Company for use by electric customers on the Big Island.

Noi'i O Puna, the Puna Research Center located next to the HGP-A well, provided a test site for direct-use demonstration projects using geothermal heat and other by-products. They included such varied projects as dyeing fabrics, using geothermal hot water for aquaculture, and drying fruits and lumber. Projects were terminated when the HGP-A plant was closed.

True/Mid-Pacific Geothermal Venture began exploratory drilling in the Wao Kele O Puna area in November 1989. The company, which had a permit to explore for 100 MW of geothermal power and to develop an initial 25 MW of geothermal power, suspended its operation on the Big Island in March 1994.

Puna Geothermal Venture (PGV), a partnership comprised of OESI Power Corporation and Constellation Energy Incorporated, was issued a permit to develop 25 MW of geothermal power in the Kapoho section of the Kilauea East Rift Zone (KERZ) in the Puna District of the Big Island. Under a Power Purchase Agreement with Hawaii Electric Light Company, PGV delivers an average of 25 MW of firm energy on a continuous basis, supplying approximately 19 percent of the total electricity needs of the Big Island with an on-line availability of over 90 percent. In helping meet the Big Island's growing demand for electrical energy, the company uses modern reinjection technology developed in its Mainland operations to dispose of spent gases and fluids from the generating process.

The Hawaii Natural Energy Institute drilled a series of small-diameter scientific observation holes in the KERZ. These observation holes continue to provide valuable information on the geothermal characteristics of the area pertinent to resource management and regulation of geothermal development activities.

From 1987 through early 1990, the State of Hawaii envisioned a large-scale 500 MW geothermal/inter-island submarine cable project as an alternative to the state's dependence on imported oil for 90 percent of its electricity generation. Currently, the state's policy supports geothermal energy as a potential energy resource exclusively for the Big Island and establishes that the state is no longer pursuing a large-scale inter-island geothermal/cable project.

Based on the state's current geothermal policy, the U.S. Department of Energy on May 16, 1994, withdrew its Notice of Intent to prepare a federal Environmental Impact Statement for a conceptual large-scale geothermal/inter-island cable project identified as the Hawaii Geothermal Project.

Renewable energy technologies such as geothermal can make a major contribution and play a significant role in satisfying the Big Island's energy needs. The long awaited production of electrical energy from our geothermal resources has alleviated some of the Big Island's energy concerns and has contributed toward greater energy diversification for the County of Hawaii.

Most of information contained in this summary was excerpted from a Fact Sheet prepared by the staff of the Energy Division of the State of Hawaii-Department of Business, Economic Development, and Tourism (DBEDT) and published with funding from the U.S. Department of Energy, Grant No. DE-FG49-94R900023. This information does not necessarily reflect the views of the State of Hawaii, the United States Government, or any agency thereof.