Geothermal: Tapping Energy From the Earth

By Henrylito D. Tacio

“Asia’s thirst for power is to be unquenchable.” This statement from the Financial Times Survey in 1995 provides a clear view of the present energy situation in many Asian countries; and it looks that this situation will remain such for many years to come.

“In upcoming years, increased energy demands will come primarily from the developing world,” maintained Dr. Frank Pinto, of the New York-based United Nations Development Program (UNDP). “If part of this demand is not met by savings from energy efficiency, it’s going to come from increased energy production.”

“With fossil fuel prices escalating and countries searching for ways to reduce oil dependence and greenhouse gas emissions, capturing the earth’s heat for power generation is garnering new attention,” commented Jonathan Dorn, of the Washington-based Earth Policy Institute.

Dorn was referring to geothermal power. In a report released just recently, he said that in the first half of 2008, total world installed geothermal power capacity passed 10,000 megawatts and now produces enough electricity to meet the needs of 60 million people, roughly the population of the United Kingdom.

“In 2010, capacity could increase to 13,500 megawatts across 46 countries,” Dorn pointed out. That is equivalent to 27 coal-fired power plants.

Electric power is measured in units called watt. A watt is equal to one joule (the quantity of energy that can be generated from a fuel such as oil or gas) per second. The total generating capacity of a power plant is measured in kilowatts for 1,000 watts, and megawatts for one million watts.

As geothermal power is one form of renewable energy, Jejomar Binay is batting for its further development in the country. “Next to the United States, the Philippines has the second highest geothermal power capacity in the world right now,” said the head of the United Opposition. “And we have enough geothermal power on our islands to more than double our current capacity.”

This has been supported by Mitchell Stark of Chevron Philippines. During his recent talk
in a forum held at the University of the Philippines National Institute of Geological Sciences in Diliman, he said the country has a lot of untapped resources of geothermal energy.

Worldwide, 39 countries with a cumulative population of over 750 million people have geothermal resources sufficient to meet all their electricity needs, according to Dorn. The Philippines has been using geothermal energy to sustain its energy needs for over 40 years.

Ten of the top 15 countries producing geothermal electricity are in the developing world. The Philippines, which generates 23 per cent of its electricity from geothermal energy, is the world’s second biggest producer behind the United States. The Philippines aims to increase its installed geothermal capacity by 2013 by more than 60 per cent.

The Philippines is home to more than 200 volcanoes, 21 of which are active. A volcano is considered active when it has erupted within the last 600 years while dormant volcanoes are those than has not erupted in 600 years.

Given the number of active and dormant volcanoes the country has – and most of them are still unexplored – Stark believes geothermal energy will replace other kinds of energy and help save the Philippines the much needed foreign exchange.

In Greek, geo means “earth” and thermos means “heat.” Literally, geothermal implies “heat from the earth.” Its steam comes from raindrops that seep down the cracks of the earth until it reaches a rocky reservoir two to three kilometers deep, where it is heated by the earth's core of hot rocks or magma, which transform the water into steam.

According to the country’s geothermal task force, the heat source of the geothermal energy is the magma which comes close to the earth's surface in some places. The heat in a geothermal system can be harnessed in the form of steam or with water as the medium.

But how is geothermal energy generated? “Deep holes are drilled down to the reservoirs and pipes are inserted in these holes,” explains The Geo­thermal Handbook. “The mixture of hot water and steam, under its own pres­sure, will flow up the pipe.

“Upon reaching the surface,” the handbook continues, “the water and steam go through a separator which sends the steam by way of a pipeline to the power plant, passing through scrubbers and catalysts to make it as pure as possible. The hot water, on the other hand, is sent via another pipe to a reinjection well where the water is sent back to the geothermal reservoir.

“The powerful natural steam, still under pressure, is directed into the power plant where it spins the blades of a turbine. Attached to the turbine is a generator, a tightly coiled wire cylinder which rotates in a field of magnets surrounding it.

“This rotation process generates electricity, and the electric current is then sent from the transmission lines into homes, offices and other busi­ness establishments, factories and schools.”

In the Philippines, geothermal plants are using the reinjection scheme to prevent geothermal fluids - the water used in generating electricity from the geothermal steam - from escaping and to recharge the reservoir, thus making the resource renew­able.

Pipelines carrying the fluids are insulated and tightly closed to protect the environment. And to assure a continuous supply of steam, geo­thermal operators safeguard thousands of hectares of watersheds, thus preserving nature for future genera­tions.

History records showed that the world’s oldest geothermal district heating system is in Chaudes-Aigues, France, which has been operating since the 14th century. But the earliest industrial exploitation began in 1827 with the use of geyser steam to extract boric acid from volcanic mud in Larderello, Italy.

A deep geothermal well was used to heat greenhouses in Boise, Idaho in the United States in 1926, and geysers were used to heat greenhouses in Iceland at about the same time. Since 1943, Steam and hot water from geysers were used to heat homes in Iceland.

The 20thcentury saw the rise of electricity, and geothermal power was immediately seen as a possible generating source. Prince Piero Ginori Conti tested the first geothermal power generator on July 4, 1904, at the same Larderello dry steam field where geothermal acid extraction began. It was a small generator that lit four light bulbs. Later, in 1911, the world’s first geothermal power plant was built there. It was the world’s only industrial producer of geothermal electricity until 1958, when New Zealand built a plant of its own.

The first commercial geothermal heat pump was designed by J.D. Krocker to heat the Commonwealth Building in Portland, Oregon in 1946. Two years later, Professor Carl Nielsen of Ohio State University built the first residential heat pump two years later. The technology became popular in Sweden as a result of the 1973 oil crisis, and has been growing slowly in worldwide acceptance since then.

In 1967, Dr. Arturo P. Alcaraz and his team lit a light bulb using steam-powered electricity coming from a volcano near the town of Tiwi. This was the first geothermal power generated in the Philippines.

Through the hard work of Dr. Alcaraz – touted to be the Father of Geothermal in the country – the first geothermal power generating plant with a three megawatt capacity was opened in Leyte in 1977. By 1980, the geothermal plants in Tiwi and Mt. Makiling-Mt. Banahao (called Mac-Ban) were each capable of producing 220 megawatts, and in the first half of 1982, when another 110 megawatts were added at Tiwi, the Philippines attained the second highest geothermal generating capacity in the world.

Geothermal power is environment-friendly. It requires no fuel, and is therefore immune to fluctuations in fuel cost. In fact, the production of the electricity by geothermal plants is cheaper than the electricity produced in plants by using natural gas and coal. It is even cheaper than electricity produced by hydro power stations.

Geothermal has minimal land use requirements; existing geothermal plants use 1-10 hectares per megawatt versus 5-12 hectares per megawatt for nuclear operations and 25 hectares per megawatt for coal power plants.

Some people believe geothermal operations create earth­quakes. A handbook published by the Philippine National Oil Corporation (PNOC) explains: “Most geothermal sites are located along fault lines whose cracks and fissures allow surface water to seep down to the reservoir. Mini-seismic activity is often caused by the extraction of geothermal fluids as well as reinjection.”

Most of these activities are monitored by seismic instruments installed by the state-owned PNOC in cooperation with the Philippine Institute of Volcanolo­gy and Seismology. However, the scientific theory is that geothermal operations may trigger small seismic events but, as Dr. Alcaraz pointed out, these help relieve the pres­sure on earth in small doses and prevent the build up tension. “Better several small earthquakes,” he stressed, “than a big bang.”

Can geothermal operations cause a volcanic eruption? Not so, accord­ing to scientists. The PNOC handbook surmises: “Scientific experience has shown that no volcanic eruption was caused in any way by the drilling of wells or other geothermal operations. Geothermal drilling is too shallow at 3 kilome­ters to affect the 15-kilometer magma chamber.”

On the negative side, geothermal power still creates some environmental problems. Studies have shown that geothermal fluids drawn from the deep earth may carry a mixture of gases with them, notably carbon dioxide and hydrogen sulfide.

When released to the environment, these pollutants contribute to climate change, acid rain, and noxious smells in the vicinity of the plant. According to studies, existing geothermal electric plants emit an average of 90-120 kilograms of carbon dioxide per megawatt hour of electricity. But this is just a small fraction of the emission intensity of conventional fossil fuel plants. In some parts of the world, some geothermal power plants are equipped with emissions-controlling systems that reduces the exhaust of acids and volatiles.

In addition to dissolved gases, hot water from geothermal sources may contain trace amounts of dangerous elements such as mercury, arsenic, and antimony which, if disposed of into rivers, can render their water unsafe to drink. Geothermal plants can theoretically inject these substances, along with the gases, back into the earth, in a form of carbon sequestration.

Meanwhile, further reduction in the use of coal-based power is planned by the government in the next five years to increase alternative energy use to 85 percent to 90 percent from the current 75 percent to 78 percent.