Definition
Basic
Geothermal energy refers to the utilisation of hot water and steam that are produced within the earth to produce power. These can be used to produce electricity and heating. In some instances hot water, occurring close to the earth's surface can be piped directly from the ground into buildings to provide heating.
Two Latin worlds compose ”geothermal”: -geo which means ”earth” and -thermal which means ”heat”. The heat of the Earth comes from its core, which may be around 5,000°C. This heat goes upwards through different layers, to reach the mantle and finally the crust where people live and grow. It can then be used for direct heating, and in some places where the magmatic part of the mantle is close enough to the surface, i.e. volcanic areas, engineers can use this heat to produce electricity.
Direct Heating
This is the simplest and the most common way to use geothermal energy. After geological prospections, where experts localise suitable places for extraction, holes are drilled to pump hot water up to the surface. These holes are generally some hundred meters deep. Depending on its temperature, the water is then used for house heating, industrial needs or swimming pools heating for instance.
Electricity
In the case that geothermal water reaches temperatures around 200°C or more, electricity can be produced. It is necessary to drill more (from 2kms to 4kms) to pump the very hot water. There are different types of technologies and power plants available to suit the resources which are going to be described later on, but basically the hot water is turned into steam which runs a turbine. Common steam turbines thermodynamic cycles take place in the power plants which produce electricity.
Geothermal Heat Pumps
In order to heat or even cool a building, geothermal heat pumps can be used. Geothermal heat pumps are usually very efficient. This is due to a constant temperature in the crust of the Earth at a certain depth (generally 10-20 meters) so the heat pump is set to constant variables. Using heat transfer principles, the geothermal heat pump heats the building during the winter (heating period) and cools it during the summer (cooling period).
History
Origin
Geothermal energy was discovered with hot springs and hot water coming to surface of the Earth. Archaeologists proved that the first use of geothermal resources took place more than 10,000 years ago in North America. Geothermal waters were used for bathing. Greeks and Romans also use geothermal energy and created the thermal baths. In 1830, the first known commercial use of geothermal energy occurred, when in Arkansas, USA, Asa Thompson decided to charge one dollar per person for the use of three spring-fed baths.
The first industrial use of geothermal energy began near Pisa, Italy. The steam was used to extract acid from the pools. This area, as known as the Larderello Fields, is where the first electricity generator was installed, producing enough electricity to lit four light bulbs first, in 1904, to finally produce 250kW in 1911. In 1930, the first heating system was developed in Reykjavik, Iceland. It now provides heating for almost all the population of the Icelandic capital city.
Popular Use
Direct heating became popular rapidly in the 1900’s. Geothermal Heat Pumps (GHPs) has been a fast growing sector since 1980’s. Geothermal heat is free and if used directly, the only energy needed is to run a pump and/or a compressor, which is relatively low compare to other means of heating. However, the drilling part of the installation remains an obstacle in some parts of the world.
The second geothermal power plant after the Larderello fields one was built in 1958. Geothermal power plants are not really popular yet, mainly due to their higher initial costs. Electricity produced from geothermal power plants represented less than 1% of the total electricity produced in 2008 but it is expected to reach 20% by 2050.
Money Involved
Revenue
The CCBJ (Climate Change Business Journal) estimates that the Geothermal Power industry generated global revenues of $6.8 billion in 2008, with power sales from the approximately 10 GW of geothermal power capacity currently online accounting for $4.8 billion or 71% of the total.
Use
Primary
Geothermal energy primary use is direct use with almost 28GW of installed capacity in 2005, of which geothermal heat pumps represent 15GW, bathing and swimming 5GW and space heating 4GW. Geothermal heat pumps have been increasing heavily between 2000 and 2005. They produced 260,000TJ in 2005.
Scope
Electricity production corresponds to an installed capacity of 8.9GW in 2005 and 10.7GW in 2010. As said before, electricity production is more difficult to develop because of its strong location dependence. Geothermal heat pumps can be installed everywhere in the world when geothermal power plants need particular soil characteristics.
Production
Step 1 - Area Investigation
Before building a new geothermal power plant, geologists need to investigate the area where geothermal energy can be harness. This is made by evaluating the soil’s temperature in order to estimate if geothermal waters can be found deeper in the Earth. Experts locate suitable areas with soil samplings, rock layers description and where hot springs are visible.
If the tests are positive, further investigations are made. Specialists and engineers start to drill wells to monitor soil’s temperature and composition. Computer based simulations help to determine how much energy could be possibly pumped from this area, how deep and where wells should be drilled.
Step 2 - Construction and Production
Wells are drilled in order to access geothermal waters. The water goes up though the well by itself induced by the pressure difference, or is pumped. If the temperature is not high enough to produce electricity, the steam or hot water is used to heat cold water which will provide direct heating (geothermal waters contain high levels of silica and other dangerous components, and is not used directly to avoid corrosion problems for instance).
If the temperature is high enough, the steam runs a turbine which produces electricity. Geothermal power plants turbines need to be of high quality because of problems that can be induced by undesirable components in geothermal waters. There are different types of geothermal power plant, mainly depending on the water’s temperature. The difference takes place in the thermodynamic cycle that is used to produce the electricity.
Once the electricity is produced, the water (which is still hot) can provide direct heating. In that case, the power plant is very efficient. Finally geothermal water is rejected into the atmosphere on return into the ground. In both cases, monitoring is needed in order to limit pollution.
Step 3 - Distribution
Geothermal power plants are connected to grid of the region. Hot water from the wells or from the power plants is distributed through pipes for space heating. Even though the losses are small, the distance between the production and the demand should be as short as possible. In Reykjavik, some wells can be seen in the city center.
Challenges
Location
Geothermal systems are with no doubt very promising and competitive in suitable areas.
Enhanced Geothermal Systems (EGS) are under development in order to harness geothermal energy where it is not directly available. Water is injected into the ground and percolates through the rocks and the resulting hot water is pumped up. Engineers need to drill deeper for these projects.
Competitiveness
Geothermal energy is extremely price competitive in suitable areas. Capital costs are higher than many other energy sources, because of the drilling part, but running costs are much lower. Geothermal energy could become the first renewable energy if enhanced geothermal systems are developed successfully.
Possibilities
Clean Energy
Geothermal energy is a clean fuel source. However, geothermal power plants and wells (this is not applicable to geothermal heat pumps) have to be monitored carefully in order to avoid hazardous gases, like silica, to go to the atmosphere. These gases can be responsible of acid rains for instance, but are not dangerous if monitored.
Low Cost
Although its high capital cost, geothermal energy remains one of the cheapest energy for long-term projects. Especially regarding direct heating, geothermal energy is competitive other conventional energy sources, with a current cost between 0,5 and 5 US cents/kWh.
Key Countries
Installed Geothermal Power Capacity
(in megawatts, 2010)
1. USA - 3,093
2. Philippines - 1,904
3. Indonesia - 1,197
4. Mexico - 958
5. Italy - 843
National Geothermal Contribution
(percentage of national energy, 1998)
1. Philippine - 21.5
2. El Salvador - 20
3. Nicaragua - 17.2
4. Iceland - 14.7
5. Costa Rica - 10.2
This shows one of the most significant aspects of geothermal power development: the size of its contribution to certain national capacity.
Key Companies
Integrated Geothermal Operators
(installed capacity: fields/plants in megawatts, 2010)
1. Calpine - 1,310/1,310
2. Chevron - 1,329/1,087
3. Energy Development Corporation - 1,212/707
4. Comisión Federal de Electricidad - 958/958
5. Enel Green Power - 915/915
Prospects
Outlook
Electricity generated by geothermal energy is expected to increase up to 140GW by 2050, to meet 8 percent of global overall power demand. 40 countries could be 100% geothermal power (ring of fire) and the overall CO2 savings from geothermal electricity could be 1,000 millions of tons per year.
Sustainability
Overall
The geothermal energy field is by nature closely linked to the Profit, people, planet with the traits and focus of renewable energy in general.
Global Compact
At the current time, Enel Green Power and la Comisión Federal de Electricidad are the only two of the five biggest geothermal energy companies that are represented in Global Compact.
CSR
Three of the five biggest companies have specific CSR policies that are clearly visible when using their websites.
Transition to Globalisation
The Upside of Deep Stress
Australia has a new method for estimating in situ rock stress. Developed by the Commonwealth Scientific and Industrial Research Organisation, the new method could help miners reach points of geothermal energy.
Globalisation > Economy> Raw Materials > Mining
Transition to Tools
U.S. Geothermal Power Production and Development Update
GEA, Geothermal Energy Association, a trade association who support the expanded use of geothermal energy and are developing geothermal resources worldwide regularly publish updates on USA geothermal power production and development.
Tools > Institutions > National > USA> Dom. Pol. > Economy > Energy > Renewable
Transition to Actors
Chevron Steams Ahead on Geothermal in Asia-Pacific Region
Already the world's largest producer of geothermal energy, Chevron has added two new geothermal prospects to its portfolio of projects—Kalinga in the Philippines and Suoh-Sekincau in Indonesia. These prospects have the potential to support the company's strategy to double its geothermal capacity by 2020.
Actors > Business > Sustainability
