Geothermal
Energy
The Pohutu Geyser in New Zealand erupts with a natural blast
of the Earth's interior heat.
| Geothermal energy is thermal energy generated
and stored in the Earth and originates from the original
formation of the planet, from radioactive decay of minerals, from volcanic
activity, and from solar energy absorbed at the surface. The geothermal
gradient, which is the difference in temperature between the core of the planet
and its surface, drives a continuous conduction of thermal energy in the form
of heat from the core to the surface. Geothermal
Energy is relatively
emission-free,
and unlike other renewables, isn’t tied to the sun’s energy as a
source.
Currently producing only 0.3% of global energy it is gaining greater
consideration
to meet future needs. Although
initial
investment is high for geothermal, natural gas and geothermal are still
economically comparable over a long term. But as with any energy
source, there are problems, in the case of geothermal with
drilling.
|
Recent news -
August 31 2011: The
“world’s first” hybrid solar, geothermal plant to land in Nevada. Nevada will be home to the “world’s first” hybrid solar,
geothermal plant, according to the power companies involved in the project. The
new, combined 24 MW solar photovoltaic and geothermal power plant will take about a
year to build. Eventually, the site will have 7,000 poles to support solar
panels, and 81,000 panels. The idea behind combining solar and geothermal is
that geothermal is a so-called baseload power source, so it can provide
electricity 24/7. link
_____________________________________________________ Below:
- What geothermal energy is
- Limitations
geographically
- Geothermal
energy in the USA
- Geothermal around the world
- The future
potential for geothermal
- Are there downsides?
| What geothermal energy is |
The
Earth has molten core. About 3-6km below the surface of the Earth in
some places are layers of super hot granite that can be as hot as 250
degrees centigrade. One cubic kilometre of hot granite at 250 degrees
centigrade has as much energy in it as 40 million barrels of oil. Although areas with
telltale signs like hot springs are more obvious and are often the
first places geothermal resources are used, the heat of the earth is
available everywhere, and we are learning to use it in a broader
diversity of circumstances. It is considered a renewable resource
because the heat emanating from the interior of the Earth is
essentially limitless. The heat continuously flowing from the Earth’s
interior, which travels primarily by conduction, is estimated to be
equivalent to 42 million megawatts of power, and is expected to
remain so for billions of years to come, ensuring an inexhaustible
supply of energy. Because no burning takes
place, only steam is emitted from geothermal facilities. (Pictured is a Geothermal plant in Iceland where thousands of
megawatts of electricity are generated.)
Worldwide,
about 10,715 megawatts of geothermal power is online in 24 countries. An
additional 28 gigawatts of direct geothermal heating capacity is installed for
district heating, space heating, spas, industrial processes, desalination and
agricultural applications.
Geothermal
power has historically been limited to areas near tectonic plate boundaries.
Geothermal
wells release greenhouse gases trapped deep within the earth, but these
emissions are much lower per energy unit than those of fossil fuels. As a
result, geothermal power has the potential to help mitigate global warming if
widely deployed in place of fossil fuels. Although there are emissions of
nitrous oxide, hydrogen sulfide, sulfur dioxide, particulate matter,
and carbon dioxide they are extremely low, especially when compared to
fossil fuels
Wet Geothermal and Hot Fractures Rock (HFR) Geothermal.
By nature of its geology, Australia has a lot of hot granite that’s within
3-5km of the surface of the earth. One Australian company has a proven technology that turns the heat stored in that hot
granite into clean electric power. It’s called Hot Fractured Rock (HFR)
geothermal power. HFR is different from what you might call “wet” geothermal power. “Wet”
geothermal happens when you find a volcanically active area of the Earth where
super hot water or steam already exists on or close to the surface. In New
Zealand, for example, between Rotorua and Auckland you’ll find a geothermal
facility that turns the hot steam from the surrounding countryside into
electricity via steam powered turbines. Australia is
not volcanically active, hence HFR. link
How a Geothermal Power Plant Works (Simple)
| How
geography determines geothermal supply |
The
most active geothermal resources are usually found along major plate
boundaries where earthquakes and volcanoes are concentrated. Most of
the geothermal activity in the world occurs in an area called the Ring
of Fire. This area encircles the Pacific Ocean.
When magma comes close to the surface, it heats
ground water found trapped in porous rock or water running along
fractured rock surfaces and faults. These features are called
hydrothermal. They have two common ingredients: water (hydro) and heat
(thermal).
Geologists use various methods to look for geothermal reservoirs.
Drilling a well and testing the temperature deep underground is the
most reliable method for finding a geothermal reservoir. link
Naturally
occurring large areas of
hydrothermal resources are called geothermal reservoirs. Most are deep
underground with no visible clues showing above ground. But geothermal
energy
sometimes finds its way to the surface in the form of volcanoes and fumaroles (holes where volcanic gases are
released), hot springs and geysers.
July 2011: Short on
cash and know-how, U.S. geothermal industry stumbles. The
five major, publicly traded North American geothermal companies are valued at a
fraction of what they were a year ago, with operational problems at several of
them. The
geothermal industry is a capital-intensive field in which getting a new project
off the ground can take five years and drilling each well can cost between $3
million and $10 million, depending on local conditions. link
September 2010: Geothermal could provide all the energy the world will ever need.
The
Norwegian company Rock Energy wants to be an international leader in
geothermal heat and energy. A pilot plant has been planned for Oslo
that will collect heat from 5500 metres deep. Temperatures from this
depth can heat water to 90-95°C and can be used in district heating
plants. One
of the unique aspects of geothermal heat is that it is found everywhere
throughout the world. Call it a “democratic” energy source that anyone
can take advantage of, regardless of the conditions at the Earth’s
surface, such as the weather. The
United States, the Philippines, Mexico, Indonesia and Italy are the
international leaders in terms of producing electricity from geothermal
energy. Iceland comes in at a surprising 8th place. link
| Geothermal
energy in the USA |
The U.S.
Geological Survey
estimates the geothermal resource base in the United States to be
between
95,000 and 150,000 MW, of which about 22,000 MW have been identified as
suitable for electric power generation. Unfortunately,
only a
fraction of this resource is currently utilized, with an installed
capacity of
2,800 MW (worldwide capacity is approximately 10,000 MW). But thanks to
declining costs and state and federal support, geothermal development
is likely
to increase. Over the next
decade, new
geothermal projects are expected to come online to increase U.S.
capacity to between 8,000 and 15,000 MW.
The
United States
generates more
geothermal electricity than any other country, but it accounts for less
than 0.5%
of all electricity produced in United States.
Most of the geothermal
reservoirs in the United States
are located in the
western States and Hawaii.
California
generates the most
electricity from geothermal energy. "The Geysers" dry steam reservoir
in northern California
is the largest known dry
steam field in the world and has been producing electricity since 1960.
Only
five States have geothermal power plants: California
with 34, produces almost
90% of U.S.
geothermal electricity. Nevada has 15
geothermal power plants. Hawaii, Montana, and Utah each have one
geothermal plant. In
2010, the United States led the world in geothermal electricity production with
3,086 MW of installed capacity from 77 power plants. The largest group of
geothermal power plants in the world is located at The Geysers, a geothermal
field in California. The Philippines is the second highest producer, with 1,904
MW of capacity online.
March 2011:USA leads in geothermal production. In
its annual report released at the end of March, the GEA, a trade
association of U.S. geothermal companies, said total installed geothermal
capacity in the country amounts to 3,102 megawatts. The US has nine states
currently tapping and 15 states undergoing development on 123 geothermal
projects and is the leading geothermal energy source in the world, according to a
report from the country’s Geothermal Energy Association. link [The US geothermal industry showed a 26% growth in 2009.]
February 2011:The
U.S. Department of Energy looks to low-temperature geothermal.
Federal researchers hope to bridge the gap
between fossil fuels and renewable energy by tapping into vast amounts of
low-temperature geothermal resources in America's oil and gas wells. “It’s
incredible the amount of energy that’s out there in terms of hot water,” said
William Gosnold, a professor at the University of North Dakota. In
a recent press release, the DOE announced that its Geothermal Technologies
Program has funded 17 projects in various geological conditions that have
combined capacities of 3 GW of power via “low-temperature, co-produced and
geopressured” resources. The resources could all be producing energy by
2020. link
February 2011: Updated
statistics for US geothermal optimistic. The U.S. installed just 15MW of utility-scale geothermal power
in 2010, down from 176MW the year before. When compared side by
side with installed capacity in other leading sectors in the U.S., particularly
wind and solar, the numbers look grim. However capacity is just that -
capacity. As a baseload resource, geothermal power plants generate far more
energy over time than an equivalent wind or solar plant according to the Energy
Information Administration. In 2009, 3,150MW of geothermal capacity generated
15.2 Gwh of electricity. That same year, around 35 GW of wind capacity
generated 70.7 Gwh of electricity. If an equivalent amount of geothermal were
online, it would generate more than double the amount of energy than wind. But
of course, that amount of geothermal is not online. Also it takes from 3 to 7
years to develop a geothermal plant, and more than 500MW of projects are in
advanced stages of development. link
October 2010: Geothermal energy could replace coal as West Virginia's power.
A
study by Google's philanthropic arm, Google.org., shows that heat
underground could provide 18,890MW of power using today's geothermal
technology, more than the state's current use of 16,350MW which comes
mostly from coal. link
July 2010: Nevada is on track to become the world's top geothermal energy producer.
The state's 86 planned or developing geothermal power plants have the
potential to add up to 3,686MW of geothermal power. link
A
September 2009 report, U.S. Geothermal Power Production and
Development Update, identifies 144 new geothermal
projects under
development in fourteen states that could represent as much as 7,100MW
of new baseload
power capacity. link
| Geothermal energy around the world |
March 2011: Geothermal in Asia. Japan
is sitting on enough untapped geothermal power to replace all its planned
nuclear stations over the next decade, but has no plans to harness its
estimated 23.5 gigawatts in geothermal potential other than to develop hot
springs. Geothermal energy, which in Asia struggles under limited government
and funding support, is likely to attract interest as investors rethink the
outlook for nuclear power following the crisis at Fukushima. Straddled along
the Pacific Ring of Fire, an arc of seismic activity, Asia's geothermal
reservoirs are among the world's largest. Indonesia alone holds 40% of the
world's total reserves, but less than 4% is being developed, leaving the sector
wide open for growth. (pictured - A Japanese geothermal power
plant.) link
Canada.
Geothermal alone could supply all Canada’s energy needs. A
"massive" store of clean, renewable energy is sitting at Canadians'
feet, according to a federal report on geothermal energy. "As few as 100
projects could meet Canada's energy needs," according to the team's
findings, with Canada's in-place geothermal power exceeding one million times
Canada's current electrical consumption. The heat is closest to the surface in
large swaths of British Columbia, Alberta, the Yukon and Northwest Territories,
but the report says geothermal energy opportunities exist across Canada. link
Iceland
Iceland is
often considered a country run on geothermal energy as it fundamentally
sits on a volcanic base (like Hawaii), and virtually every building in the
country is
heated with hot spring water. In Reykjavik,
for example (population 115,000), hot water is piped in from 25
kilometers
away, and residents use it for heating and for hot tap water. (Iceland is almost completely
powered from renewable sources - 73.4% from hydropower
and 26.5% geothermal.) Iceland's plan to export geothermal energy to Europe. Iceland’s largest energy company is
considering construction of the world’s longest underwater electric cable so
the nation can sell its vast geothermal and volcanic energy to the European
market. By the end of 2011, state-owned energy company, Landsvirkjun, will
complete a study of building a sub-sea cable that could deliver as much as five
terawatt-hours (5 billion kilowatt-hours) annually to Europe, enough
electricity to power 1.25 million homes.
The
proposed cable would be as long as 1,180 miles, depending on its
destination; company officials are considering linking the cable to
Britain,
Norway, Holland, and Germany. At present, Landsvirkjun produces about
75% of Iceland’s electricity by tapping into the nation’s huge stores
of
geothermal power. link
March 2011: Iceland's plan to export geothermal energy to Europe
| In the first
half of 2008, total installed world geothermal power capacity already
surpassed
the 10,000MW mark, amounting to enough electricity to meet the
needs of
60 million people - but in practice only
0.3% of
global electricity demand. The capacity could increase to 13,500MW across 46
countries
by 2010. An additional 28,000MW of direct geothermal
heating
capacity is installed for district heating, space heating, spas,
industrial
processes, desalination and agricultural applications. At
present around 10,000MW of geothermal power plants are installed all
over the world, a figure which the European Geothermal Council (EGEC)
believes, is expected to double
to 20,000MW during the next seven years. The
EGEC, a
Pan-European industry association, believes that a draft EC Communiqué
titled
‘Financing low carbon technologies (SET-Plan)’ failed to mention
geothermal
power as a renewable energy source. It
also expressed the potential for development of geothermal energy
within the
private sector in the absence of governmental support. link |
May 2011: Kenya
goes geothermal for energy needs. The Kenyan Government has announced it has struck
commercially exploitable geothermal steam in the Rift Valley area of Menengai, successful completion of the well at the geothermal rich Menengai area could
see Kenya start generating an additional 8MW of power as early as March next
year. The Menengai Geothermal Field itself has a potential of 1,600 MW. Kenya
currently has an installed energy capacity of about 1,300 MW against an
estimated deficit of about 1,100 MW with more than 60% of energy generated
from hydro stations. By effectively increasing the amount of geothermal power
produced in the country the move is expected to consolidate Kenya’s efforts of
reducing over reliance on hydro power as well as the need to use diesel for power
generation. Kenya, East Africa’s largest economy, has over-relied on fossil
fuels for its energy demands resulting in high energy costs. Kenya is now rated
7th in the world in geothermal production but could be the leader in geothermal
resources in the world with the rate of significant progress at the site. link
February 2011: Potential 15,000MW in Eastern Africa. link
Central America
Dotted
with active volcanoes, sitting above shifting tectonic plates in the
Pacific basin known to cause earthquakes and volcanic eruptions,
Central America has huge potential for geothermal power and cut
dependence on oil imports. Guatemala,
Central America's biggest country, aims to produce 60% of its energy
from geothermal and hydroelectric power by 2022. Some 1,640 feet below
the summit of Guatemala's active Pacaya volcano, pipes carrying steam
and water at 347 degree F snake across the mountainside to one of two
geothermal plants currently operating in the country. Guatemala has
the potential to produce up to 1,000MW of geothermal energy, a third of
the projected energy needs in 2022.
El Salvador
received a fifth of its energy from two geothermal plants, and
investigations are being carried out to build a third. Costa Rica,
which has 152MW of capacity in four geothermal plants, is due to bring
a fifth plant on line in January 2011 and is looking into building two
more. Nicaragua generates 66MW currently and plans to increase to 166MW
in the next five years. link.
Australia.
While
much of the future supply of geothermal in Australia is expected to
come from HFR (hot fractured rock) the Birdsville geothermal power
station in western Queensland (pictured at right) is the only one of
its kind in Australia at present, but gets its small output from hydrothermal power. The small Birdsville geothermal power station was built in the early 1990's
and remains no more than a pimple on Australia’s vast geothermal energy
resources. Its well, tapping into the 98C hot water of the Great Artesian Basin, is 1230
metres deep and generates a modest 120 kW net power output. As geothermal plants go it is a low temperature plant. Other
hydrothermal plants use water of temperatures around 250C. link
Geodynamics
was registered as a public company in November 2000 and was listed in the
Australian Stock Exchange two years later. The company was formed specifically
to explore the potential of generating geothermal energy from hot fractured
rocks in Australia. The heat is extracted
from these heat-producing granites located below the earth’s surface by
circulating water via enhanced geothermal systems to generate steam.
Geodynamics claimed that this is the only known source of renewable energy with
a capacity to carry large base loads. Geothermal energy from hot fractured
rocks could provide an estimated 6.8% of Australia’s base load power needs
by 2030. To date, Geodynamics has drilled five deep wells. Its Habanero 3 well,
with a depth of 4,200 meters, is the first commercial scale geothermal well in Australia. The company also plans
to construct a 50MW power plant, scheduled for commercial operations in 2012,
which will produce enough electricity to power approximately 50,000 households
| The future of Geothermal energy |
Geothermal energy
has the potential to play a significant role in moving the United States (and other regions of
the world) toward a cleaner, more sustainable energy system. It is one
of the
few renewable energy technologies that - like fossil fuels - can supply
continuous, base load power. The costs for electricity from geothermal
facilities
are also declining. Some geothermal facilities have realized at least
50%
reductions in the price of electricity since 1980. New facilities can
produce
electricity for between 4.5 and 7.3 cents per kilowatt-hour, making it
competitive with new conventional fossil fuel-fired power plants.
As
hot dry rock
technologies improve and become competitive, even more of the largely
untapped
geothermal resource could be developed. In addition to electric power
generation, which is focused primarily in the western United States,
there is a bright future for the direct use of geothermal resources as
a heating source for homes and businesses everywhere.
May 2010: Google invests in a new technology. A novel drill that is inspired by a jet engine and uses super-heated water to
carve through rock could help make clean energy from underground rocks more
economically viable, according to its backers at Google. A report by MIT estimated says that tapping just 2% of the potential resource from
so-called enhanced geothermal systems between 3km and 10km below the surface of
continental USA could supply more than 2,500 times the country's total annual
energy use. link
| Is there a downside to Geothermal
energy? |
December 2009: Geothermal Project in California Is Shut Down. The collapse of AltaRock project in California comes a day after Swiss government officials
permanently shut down a similar project in Basel, because of the damaging
earthquakes it produced in 2006 and 2007. Taken together, the two setbacks could
change the direction of the Obama administration’s geothermal program, which had
raised hopes that the earth’s bedrock could be quickly tapped as a clean and
almost limitless energy source - link Swiss geothermal project shut down. A $60 million project to extract renewable energy from the hot bedrock deep
beneath Basel, Switzerland, was shut down permanently on Thursday after a government study determined that
earthquakes generated by the project were likely to do millions of dollars in
damage each year.The AltaRock project in California is the Obama administration’s first major test of advanced
geothermal energy and like the Basel project, the plan is to drill miles
underground, fracture hot bedrock and circulate water through it to generate
steam. link
In
Landua, Germany, government officials here are reviewing the safety of
a geothermal energy project that scientists say set off an earthquake in mid-August
2009, shaking buildings and frightening many residents of this small
city. But
in recent months, two similar projects have stirred concerns about
their safety and their propensity to cause earthquakes. In the United
States, the Energy Department is scrutinizing a project in Northern
California run by AltaRock Energy to determine if it is safe. (The
project was
shut down by the company last month because of crippling technical
problems.) Another project, in Basel, Switzerland, was shut down
after it generated earthquakes in 2006 and 2007 and
is awaiting the decision of a panel of experts about whether it can
resume. Like
other earthquakes that have been attributed to geothermal plants, the
Landau temblor was sudden and brief and was accompanied by a sound that
in some cases has been likened to a sonic boom. The Landau
plant, which cost $30 million, went into operation in 2007 and produces
electricity for 6,000 homes by drawing heat from beneath the bedrock,
nearly two miles beneath the earth’s surface. link Australia's Geodynamics project in South Australia has been delayed
indefinitely while the company examines an incident which led to steam and water escaping from the 4.2km deep
well because of a blow out in April 2009. link Other sources
Recommended for further research on geothermal energy - GEA
