Volume 7 geothermal energy 7 10 – sustainable energy development the role of geothermal power

Volume 7 geothermal energy 7 10 – sustainable energy development the role of geothermal power Volume 7 geothermal energy 7 10 – sustainable energy development the role of geothermal power Volume 7 geothermal energy 7 10 – sustainable energy development the role of geothermal power Volume 7 geothermal energy 7 10 – sustainable energy development the role of geothermal power Volume 7 geothermal energy 7 10 – sustainable energy development the role of geothermal power

B Davidsdottir, University of Iceland, Reykjavík, Iceland

© 2012 Elsevier Ltd All rights reserved

7.10.1 Introduction

7.10.2 Sustainable Development: The Tale of Three Conferences

7.10.3 Sustainable Development and Energy

7.10.4.2 Definitions, Goals, and Indicators

7.10.4.3 Energy Indicators for Sustainable Development

7.10.5 Contribution of Geothermal Power to SED

7.10.5.1 The Use of Geothermal Power – Setting the Stage

7.10.5.1.1 Geothermal heat pumps

7.10.5.1.2 Direct use

7.10.5.1.3 Power generation – indirect use

7.10.5.2 Assessing the Potential Role of Geothermal Power to SED

7.10.5.2.1 The economic dimension

7.10.5.2.2 The social dimension

7.10.5.2.3 The environmental dimension

7.10.7 The MDGs and Geothermal Energy

7.10.7.1 Goal 1: Eradicate Extreme Hunger and Poverty

7.10.7.2 Goal 2: Achieve Universal Primary Education

7.10.7.3 Goal 3: Promote Gender Equality and Empower Women

7.10.7.4 Goal 4: Reduce Child Mortality Rate

7.10.7.5 Goal 5: Improve Maternal Health

7.10.7.6 Goal 6: Combat HIV/AIDs, Malaria, and Other Diseases

7.10.7.7 Goal 7: Ensure Environmental Sustainability

7.10.7.8 Goal 8: Develop a Global Partnership for Development

7.10.8 Climate Change, CDM, and Geothermal Energy

7.10.8.1 The Potential of Geothermal Power to Mitigate GHG Emissions

7.10.8.2 CDM and Geothermal Energy

7.10.9 Toward SED Using Geothermal Power

References

Glossary

Energy security Energy security refers to a resilient

energy system both in terms of supply and

infrastructure A secure energy system is capable of

withstanding threats such as attacks, supply

disruptions, and environmental threats, through a

duplication of critical equipment, diversity in fuel, other sources of energy, and reliance on less vulnerable infrastructure [51]

Millennium development goals (MDGs) The MDGs are Sustainable energy development Sustainable energy

7.10.1 Introduction

As scarcity of fossil fuels increases and the threat of climate change becomes more evident, the push amplifies each year to develop alternative energy sources that can replace fossil fuels Furthermore, over 2 billion people do not have access to high-quality fuels,

According to forecasts of future energy demand set forth by the World Energy Council, primary energy consumption is expected

Fulfilling the growing energy needs, enabling access to the billions of individuals without access to high-quality fuels, and reducing emissions of greenhouse gases (GHGs) requires a radical departure away from the fossil fuel-focused business-as-usual scenarios What needs to replace past emphasis is a new energy paradigm that will encourage transforming our current energy systems towards relying on sustainable low-carbon energy sources This new paradigm differs from the conventional energy

1 increased consideration of social, economic, and environmental impacts of energy use;

2 planetary boundaries with respect to the assimilative capacity of the Earth and the atmosphere must be respected;

3 increased emphasis on developing a wider portfolio of alternative energy resources and on cleaner energy technologies;

4 finding ways to internalize negative externalities;

5 understanding the links between the environment and the economy;

6 recognizing the need to address environmental issues at all scales (local to global);

7 emphasizing expanding energy services, widening access, and increasing efficiency; and

8 recognizing our common future and the welfare of future generations

Derived from these aspects, the core of this new paradigm is a vision for improving the provisioning and use of energy so that it

environmental impacts of energy use must be reduced, access and affordability of energy must be increased, and energy security and the efficiency of energy use and generation must increase, all in the context of alternative energy sources and in the name of sustainable energy development (SED)

The potentially sustainable low-carbon, alternative energy resources being considered range from renewable resources such as biomass, wind, wave and tidal power, hydropower, and geothermal power to non-renewable energy sources such as nuclear power

energy sources and have different energy need profiles

A renewable resource is defined as a resource in which the rate of replenishment is equal to or higher than the rate of extraction and, thus, is able to sustain production for a long time Geothermal power is a widely available, low-carbon energy source and

geothermal reservoir, which should be approximately equal to the extraction rate, securing longevity or sustained yield of the

Sustainable production or yield of geothermal energy from an individual geothermal system is defined as

For each geothermal system, and for each mode of production there exists a certain level of maximum energy production, E0 below which it will be possible to maintain constant energy production from the system for a very long time (100 to 300 years) If the production rate is greater than E0, it cannot be maintained for this length of time Geothermal energy production below or equal to E0 is termed sustainable production while production greater than E0 is termed excessive production [4]

The sustained yield of energy resources is generally agreed to be a necessary but not a sufficient requirement for sustainable

alternative energy resource to sustainable development must be viewed in a much broader context

This chapter examines the concept of sustainable development and SED in the context of geothermal utilization, with a particular focus on how the use of geothermal power can contribute to the development of sustainable energy systems and thus aid the transition toward global sustainability

The first section of this chapter briefly examines the development of the sustainable development paradigm and then introduces energy into this context The next section depicts the concept of SED, with a focus on goals and indicators that capture movement and contribution of changes in energy systems toward SED, followed by a section that introduces the development of geothermal power into this context This section illustrates the potential contribution of geothermal power to SED, followed by a section on the contributions of geothermal power to achieving the Millennium Development Goals (MDGs) and in combating climate change The chapter closes with an overall assessment

7.10.2 Sustainable Development: The Tale of Three Conferences

Throughout millennia, humans have been concerned about the relationship between the environment and human and economic development Before the early 1960s, the discussion of this relationship revolved around local resource scarcity Early writers such as Thomas Malthus, in his paper An Essay on the Principle of Population published in 1798, eloquently captured this sentiment by illustrating the relationship between population growth and increases in food supply Malthus illustrated that since the human population can grow exponentially but food production only linearly through a gradual increase in cultivated land, food supply will always set limits to the ultimate size and well-being of the human population Malthus did not account for resource degradation in his assessments, but David Ricardo added this factor into his elaboration of how to define and assess resource rent Environmental degradation did not factor into their arguments, but evolved later, as evidence mounted on the potential negative environmental and health implications of industrial development This, beginning in the early 1960s, evolved into a global discourse on the simultaneous challenge of securing economic development, while still subject to social and environmental objectives

The beginning of the contemporary movement toward a holistic analysis of economic and human development and the environ­ment is most commonly traced back to the year 1964, to the publication of the book Silent Spring written by Rachel Carson In her book, initially aimed at the general North American public, Carson brought together research on toxicology, ecology, and epidemiology to suggest that the use of agricultural pesticides was leading to build-up of chemicals in the environment, which could be linked to damage

to the environment and to human health In essence, Carson’s book vividly illustrated that nature’s capacity to absorb or dilute

In 1968, the United Nations General Assembly (UNGA) authorized the 1972 UN Conference on the Human Environment in Stockholm It was at that conference that the concept sustainable development received for the first time international attention as it was argued as a potential solution to the economic development versus the environmental dilemma Furthermore, the principal components of the sustainable development doctrine were established with a focus on (1) the interdependence of human beings and the natural environment; (2) the links between economic and social development and environmental protection; and (3) the need in this context for a global vision and common principles

The next milestone in the evolution of the sustainable development ideology was the creation of the World Commission on Environment and Development in 1983 Chaired by the former Norwegian Prime Minister Gro Harlem Brundtland, the commis­sion worked for 3 years, weaving together a report on social, economic, cultural, and environmental issues in the context of

sustainable development was defined as

Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs [7]

Immediately upon publication of Our common future, the second major conference on the environment and development was authorized to be held in Rio in 1992 The Rio conference or the Earth Summit as it often is called was the first major international manifestation of the acceptance and importance of sustainable development The focus at the conference was on economic growth in the context of sustainable development, which was a necessary departure away from what was coined as environmentally destructive economic growth The issues addressed included, for example, systematic scrutiny of patterns of production with a particular emphasis

on (1) the production of toxic components, such as lead in gasoline, or poisonous waste; (2) alternative sources of energy to replace the use of fossil fuels that are linked to global climate change; (3) new reliance on public transportation systems to reduce vehicle emissions, congestion in cities, and the health problems caused by polluted air and smog; and (4) the growing scarcity of water The conference agreed to the Rio Declaration on Environment and Development, which includes 27 principles, intended to guide future sustainable development around the world In addition Agenda 21, which is a comprehensive blueprint of action to be taken globally, nationally, and locally, was accepted at the conference Agenda 21 categorized the primary themes and goals of sustainable development into three key dimensions (economic, social, and environmental), theorizing that the challenge for future development

In 2000, the Millennium Summit was held, where the United Nations Millennium Declaration was adopted, from which the

shifting the focus toward poverty, human rights, and protection of the vulnerable The eight MDGs are as follows:

Goal 1: Eradicate extreme hunger and poverty

Goal 2: Achieve universal primary education

Goal 3: Promote gender equality and empower women

Goal 4: Reduce child mortality

Goal 5: Improve maternal health

Goal 6: Combat HIV/AIDS, malaria, and other diseases

Goal 7: Ensure environmental sustainability

Goal 8: Develop a global partnership for development

Energy was and is not an explicit part of the MDGs, but the provision of modern energy services during their development was

The final milestone of significant importance in the development of the sustainable development concept and ideology was the World Summit on Sustainable Development held in Johannesburg in 2002 The premise of the Johannesburg conference was to

ment of the MDGs and the international agreements agreed to in Rio in 1992

The combined effect of the three conferences was to bring the sustainable development concept and ideology as a necessary and implicit part of any economic development strategy worldwide They also solidified the notion of sustainable development as having three dimensions The Stockholm conference highlighted the environmental dimension, the Rio conference focused on the economic

relationship between energy and sustainable development using the lens of the three dimensions of sustainable development

7.10.3 Sustainable Development and Energy

When assessing the relationship between sustainable development and energy, it is useful to examine its importance in the context

of the three established dimensions of sustainable development: the economic, the environmental, and the social dimensions

7.10.3.1 Economic Dimension

Energy use is an important driver of economic and social development as it provides basic services such as heat, illumination,

as human societies developed from being hunter-gatherer societies toward agricultural and then industrial societies, energy has always been at the center of economic and social development Initially, the original prime mover was the human muscle, and the

second energy transition occurred several millennia later, where prime movers shifted somewhat toward waterwheels and wind­mills, which enabled more powerful and efficient energy conversions The third energy transition codified as the Industrial Revolution was characterized by two traits: the substitution of animate prime movers by engines and biomass energy replaced by

New York Since the third transition, all developed economies have been consuming increasing shares of fossil fuels, both directly and indirectly e.g through electricity production and consumption All these major transitions have meant major changes in economic

Modern economies are energy dependent, and energy consumption per capita has been seen as an indicator of economic progress

energy is a limiting factor to economic production Energy prices are also seen to have a significant impact on economic performance indicators For example, empirical evidence links rising oil prices to economic losses, and energy prices are key determinants of

Per capita energy consumption (kgoe capita−1)

low inflation, ensuring energy security and proper planning of the development of our energy systems are essential components of planning for sustainable development

7.10.3.2 Social Dimension

The relationship between high-quality energy use and human welfare has been established as core indicators of human welfare such as income per capita, life expectancy, and literacy rates exhibit a significant logistic relationship to high-quality energy use [11, 13, 16, 17, 63]

At high levels of energy use per capita, the returns to increasing energy use per capita diminish as indicators for human welfare

At low levels of high-quality energy use per capita, literacy is low, life expectancy for both males and females is low, and infant mortality is high, with a drastic improvement in these indicators at marginally higher levels of per-capita energy use The reasoning behind these observed relationships is that energy services are a crucial input to the challenge of providing adequate food, shelter, clothing, water, sanitation, medical care, schooling, and access to information Less affluent households rely on a different set of energy carriers than those that are better off The poor use more of low-quality fuels, such as wood, dung, and other biomass fuels that, when used in poorly ventilated houses result in high levels of indoor air pollution As a result, the use of such lower quality fuels has adverse impacts on the health of household members, in particular women, children, and the elderly In addition, more time is spent on gathering low-quality fuels, reducing, for example, the time spent in school and on other more productive activities

In households that rely on collected biomass for fuels, up to 6 h is spent every day on collecting wood and dung In areas that rely on purchased charcoal or paraffin or coal, a significant fraction of the household disposable income is spent on energy

As a result, because of its linkages to social issues, the development of sustainable energy systems can contribute to increased

women is affected by four factors: the nature of the resource base, the characteristics of the household and community that directly affect

Figure 1 Energy use per capita and the human development index (HDI) Source: UNDP, UNDESA, WEC (2004) World Energy Assessment Overview:

2004 update United Nations Development Policy, New York [26]

As biomass resources are being degraded, more time and effort is required to meet the minimum household needs In many countries, women and children fulfill this role In addition, the health impacts of the incomplete burning of low-quality biomass fuels expose

Household and community characteristics in addition to energy policy affect energy choices, where, for example, high-quality energy resources are not equally available to all, with agricultural, domestic, rural, and women users receiving the least attention of policy-makers [9]

Given this, the social dimension of sustainable development thus demands that the incidence of energy deprivation be determined and tackled

7.10.3.3 Environmental Dimension

At the global level, we witness fossil fuel-derived emissions of GHGs contributing to climate change and its corollary impact on

significantly affect patterns of agricultural production as precipitation patterns will change, affect the acidity of the oceans, change the spread of diseases such as malaria, and severely affect biodiversity The energy sector is by far the largest contributor to emissions

The most commonly cited regional environmental impact of energy use is acid rain Acid rain is derived from emissions of sulfur dioxide and nitrous oxides, mostly from fossil fuel-driven power plants but also, to a smaller extent, from geothermal power plants

as they emit hydrogen sulfides Because acid rain can be transported over long distances in the atmosphere, the problem is transboundary and regional in scope The implications of acid rain include

• acidification of lakes, streams, and groundwater and resulting damage to fish and aquatic life;

• toxicity to plants due to acidic conditions and release of heavy metals;

• impact on plants and forests due to, for example, reduced frost hardiness;

• deterioration of materials – for example, buildings and fabrics; and

• health impacts

Local impacts of energy development, such as coal mining, include subsidence and acid mine drainage in addition to disturbing vast areas of natural habitat The exploration for and extraction of oil and natural gas can have a significant impact, particularly in sensitive

Large hydropower dams submerge vegetation, affecting ecosystems upstream and downstream The growing of energy crops for biofuels affects land use, water quality, and biodiversity Wind farms and high-temperature solar power systems are land intensive In addition,

Outdoor air pollution from fossil fuel-driven transportation, power stations, and industrial facilities causes urban smog containing an unhealthy mixture of volatile organic compounds (VOCs), particulate matter, ozone, and nitrous oxides Indoor air pollution includes particulate matter from low-quality biomass fuels, wood, and coal, as well as carbon monoxide and other hydrocarbons derived from

7.10.3.4 Summary

As can be derived from this overview, energy use is central to all three dimensions of sustainable development [11, 12, 14, 19], sometimes as a necessary prerequisite for sustainable development in two dimensions (e.g., social dimension and economic dimen­sion) but sometimes the culprit for movements away from sustainable development in others (e.g., environmental dimension) The challenge is to choose the energy resources and thereby develop an energy system that facilitates development toward sustainability in all three dimensions simultaneously Consequently, the development of sustainable energy systems relying on clean, low-carbon, and

7.10.4 Sustainable Energy Development

7.10.4.1 History

Initially, energy did not factor heavily into the sustainable development discussion However, it gradually became a central issue

at the three defining events, which anchor the evolution of the sustainable development paradigm as mentioned earlier: the three

Social state

Impact from energy sector

Responses of institutional dimension

State of energy sector

Impact from energy sector

Driving forces from

Driving forces from

economic dimension(disparity in income and energy)

Driving forces fromsocial dimension

Institutional state

Economic state

Environmental state

energy sector of economic dimension

Figure 2 Interrelationship among sustainability dimensions of the energy sector Source: IAEA/IEA [21]

global conferences on environment and development in Stockholm (1972), Rio de Janeiro (1992), and Johannesburg (2002) Each

of these three conferences had a unique and vital role in elucidating the fundamental bonds between energy use and the three

At the Stockholm conference, energy was referred to as a source of environmental stress, directly linking energy to the environmental dimension of sustainable development The Stockholm action plan directly refers to the environmental effects of

At the Rio conference in 1992, energy was not directly on the agenda; the Rio Declaration on Environment and Development did not contain any specifics on energy, and energy did not have its own chapter in Agenda 21, which sometimes has been coined as the first

growth, energy use, and its environmental impacts Indeed, prescriptions in various chapters of Agenda 21 provide guidance toward decreased energy consumption (Chapters 4 and 7), increased energy efficiency (Chapters 4 and 7), and accelerated development of cleaner sources of energy (Chapter 9) and in all cases bringing energy to the center of the economic growth versus environmental degradation dilemma The Commission for Sustainable Development (CSD) was established at the Rio conference, but it was not until

conclusions of the ninth session set the basis for the World Summit on Sustainable Development held in Johannesburg in 2002 The conclusions and recommendations from CSD9 on energy were organized both by subsectoral issues as well as cross-cutting issues Subsectoral issues addressed included access to energy, energy efficiency, renewable energy and rural energy, and cross­

a clear and direct reference to energy as a central issue of sustainable development was made at the third milestone conference, held

in Johannesburg in 2002, and repeated references were made to energy and the three dimensions of sustainable development Unlike the Rio Declaration on Environment and Development, the Johannesburg plan of implementation clearly treated energy as a specific issue rather than a facet of other issues Most importantly, though, was the strong emphasis on the social attributes of energy

social dimension, in addition to the already defined environmental and economic dimensions

The cumulative effect of these three conferences solidified the notion of SED as central to all three dimensions of sustainable development by identifying the relationship between energy and the environment (defined at Stockholm), the economy (defined at

than a subset of other concerns, cross-cutting the three dimensions of sustainable development

7.10.4.2 Definitions, Goals, and Indicators

the provision of adequate energy services at affordable cost in a secure and environmentally benign manner, in conformity with social and economic

The IEA and the OECD [8] defined it a few years later as

development that lasts and that is supported by an economically profitable, socially responsive and environmentally responsible energy sector with a global, long-term vision

Yet, given the development of the links between energy and sustainable development, it logically follows that Article 8 from the Johannesburg declaration offered the most comprehensive definition of SED as development that should involve (Article 8, Johannesburg declaration)

…improving access to reliable, affordable, economically viable, socially acceptable and environmentally sound energy services and resources, taking into account national specificities and circumstances through various means such as enhanced rural electrification and decentralized energy systems, increased use of renewable energy, cleaner liquid and gaseous fuels and enhanced energy efficiency…recognizing the specific factors for providing access

to the poor

Combining information derived from the literature (e.g., [22, 23, 26]) with these definitions, energy sources and systems that

1 Renewable or perpetual

2 Efficiently produced and used

3 Economically and financially viable

4 Secure and diverse

5 Equitable (readily accessible, available, and affordable)

6 Has positive social impacts

7 Minimizes environmental impacts

Combining these features of the Johannesburg definition with the IAEA definition, four central goals/themes of SED emerge [11]:

1 Improving energy efficiency: An increase in the technical and economic efficiency of energy use and production constitutes a move toward SED as it effectively enhances energy supply However, care must be taken that an increase in energy efficiency does not

SED It is possible to improve energy security through various means such as by decentralizing power generation and increasing redundancy, enhancing supply, shifting to renewable domestic energy resources and ensuring their sustainable use, and diversifying energy supply

3 Reduce environmental impact: Reducing the life-cycle environmental impact of energy use and production via the use of clean

7.10.4.3 Energy Indicators for Sustainable Development

In 1999, the IAEA, in collaboration with the UN Committee on Sustainable Energy and the UN Work Programme on Indicators of Sustainable Development in cooperation with other agencies initiated a project to develop energy system indicators with a twofold objective: (1) to complement the overall UN Work Programme on Indicators of Sustainable Development and (2) to foster energy

The original set of indicators, now termed Energy Indicators for Sustainable Development (EISD), was truncated from 41 to 30 indicators in 2005 and put into the context of CSD terminology of themes and subthemes within each sustainable development

special issue in the journal Natural Resources Forum 2005) The chosen themes and subthemes align closely with the goals stated earlier, and therefore we will assess the contributing role of geothermal energy to sustainable development through the lens of the EISD indicator project

7.10.5 Contribution of Geothermal Power to SED

7.10.5.1 The Use of Geothermal Power – Setting the Stage

Geothermal resources have been identified in approximately 90 countries, and there is quantified information of use in 72

use ranged from bathing and washing of clothes since the dawn of civilization to using the hot water to treat various diseases as well

as to heat the city of Pompeii Native Americans and the Maoris of New Zealand used the heat for cooking and there is evidence of

Geothermal energy was for the first time in the twentieth century harnessed on a large scale for space heating, electricity generation, and industry Electric power was first generated from Larderello, Italy, in 1904 and commercial-scale electricity generation began in

Today, geothermal energy primarily is utilized in three technology categories:

• heating and cooling buildings via geothermal heat pumps that utilize shallow sources;

• heating structures with direct-use applications; and

• generating electricity through indirect use

In comparison, the total worldwide capacity for geothermal utilization for electricity generation in 2007 was approximately 10 GWe and for direct use it was 330 PJ yr−1 [3] Approximately one-third of the direct use is through ground source heat pumps Fridleifsson et al

7.10.5.1.1 Geothermal heat pumps

crust maintains temperatures ranging from 10 to 15.5 °C (50 to 60 °F) Consequently, most areas of the world are suitable for the

A geothermal heat pump system can have different features but, for example, consists of pipes buried in the shallow (ca 3 m) upper layers of the ground, with a connection to a ventilation system of an adjacent building, relying on the ground as a heat exchanger A liquid is passed through the pipes, and as the ground is naturally warmer than the atmosphere in the winter, it absorbs the warmth and delivers it to the building In the summer, the circulation can be reversed, cooling the building by bringing warmth

7.10.5.1.2 Direct use

Direct-use applications utilize groundwater that in most cases has been heated to less than 100 °C (212 °F) Direct use of geothermal energy includes use in urban areas such as for melting of snow, in industrial processes, in agricultural and aquaculture production by heating greenhouses, soils, and aquaculture ponds Direct use also includes use in swimming pools and spas and as such is very important to tourism, as well as in residential and regional (district) heating

In various countries, the direct use of geothermal power significantly contributes to the total energy use In Iceland, for example, approximately 90% of residential and commercial buildings are heated with geothermal water Larger countries such as China have

7.10.5.1.3 Power generation – indirect use

Indirect use of geothermal power conventionally involves the production of electricity In 2007, 24 countries produced electricity

During electric power generation from geothermal power, wells are drilled into geothermal reservoirs where temperatures may exceed 360 °C (680 °F), leading the steam or the water to a geothermal power plant

• Dry steam plants are used when geothermal steam is directly used to turn turbines In this case, steam is brought to the surface under its own pressure where the steam is utilized to turn the turbines of an electrical generator

• Flash steam plants rely on high-pressure hot water, pulling it into lower pressure tanks, creating flashed steam that is used to drive turbines

• Binary cycle plants pass (in a separate piping) moderately hot geothermal water by a secondary fluid, such as ammonia, with a much lower boiling point than water This causes the secondary fluid to create steam, which then drives the turbines onward

7.10.5.2 Assessing the Potential Role of Geothermal Power to SED

EISD can be used to organize and assess the potential contribution of energy system development to SED

In the EISD indicator set, the 30 indicators are classified by the three dimensions of sustainable development: the economic, the environmental, and the social Then each dimension is broken further into the themes and subthemes within each dimension as defined by the CSD Finally, indicators are defined for each subtheme and metric assigned to each indicator Below, the use of geothermal power will be discussed in the context of each dimension and subtheme of sustainable development

7.10.5.2.1 The economic dimension

The goal of SED within the economic dimension is to maximize the efficiency of the energy system and to ensure energy security The economic dimension, therefore, includes two broad themes: use and production patterns and energy security

use, and prices

The theme energy security contains subthemes including imports, strategic fuel stocks, sustained production, and diversification Each theme and subtheme is described and put into the context of geothermal energy below

Table 1 illustrates the set of energy system indicators within the economic dimension

7.10.5.2.1(i) Use and production patterns

7.10.5.2.1(i)(a) Efficiency of use and production Energy consumption per capita and energy use per GDP capture the general relationship of energy consumption to population and economic growth At low levels of economic development, this ratio is relatively low but increases at decreasing rates at higher levels of development However, at higher levels at the income scale, achieving some decoupling between primary or secondary energy use and either per GDP or per capita will move countries toward

geothermal power and places less demanding temperature requirements on the heat resource As a result, geothermal heating is

geothermal electrical plant or from smaller wells or heat exchangers such as geothermal heat pumps In areas where natural hot springs are available, the warm water can be directly pumped into the district heating system, to industrial or other economic applications However, in areas where the ground is dry, but still warm, it is possible to use heat exchangers to capture the heat In

‘cold’ areas, this is also possible with the use of geothermal heat pumps, using the natural heat gradient of the Earth Therefore, it is

low-temperature geothermal resources are typically used in direct-use applications; nevertheless, some low-temperature resources

While direct uses of geothermal energy are very efficient, the efficiency of indirect use, for example, for electricity generation, varies depending on the temperature of the geothermal resource and the type of plant technology used Overall, the thermal efficiency of geothermal electric plants is relatively low, ranging from 9% to 23% Exhaust heat is wasted, unless cogeneration occurs and the hot water is used directly and locally, for example, in greenhouses, industrial applications, aquaculture, or district heating

7.10.5.2.1(i)(b) Prices Heat production from renewable energy is generally competitive with conventional energy sources in terms

Table 1 Energy indicators for sustainable development within the CSD conceptual framework: the economic dimension

Overall use Energy use per capita Imports Net energy import dependency

Overall productivity Energy use per GDP Strategic fuel Stocks of critical fuels per corresponding fuel

stocks consumption Supply efficiency Efficiency of energy conversion and Sustained Reserves to production ratio

distribution production

Prices End-use prices by fuel and by sector Diversification Fuel shares in energy and electricity

Renewable energy share in energy and electricity

Source: Vera I and Langlois L (2007) Energy indicators for sustainable development Energy 32: 875–882

cost of heat from geothermal energy is 0.5–5 US¢ kWh−1 Furthermore, future environmental costs of heat derived from geothermal

energy are significantly lower than for other alternative renewable energy sources, as well as conventional coal-driven power plants

Since geothermal power is not an intermittent energy source, not reliant on weather conditions, and generally available domestically, electricity and heat derived from geothermal resources are unlikely to be subject to the extreme price fluctuations

7.10.5.2.1(ii) Energy security

long-term, secure supplies of energy Therefore, energy security is seen as an integral part of sustainable development Energy security involves, for example, aiming for energy independence for a nation and thereby reducing import dependency, that is,

supply [26]

7.10.5.2.1(ii)(a) Diversification and reduced import dependency As geothermal energy is theoretically a renewable energy resource, and is in most cases used domestically, expanded investment in geothermal energy contributes to reduction in import dependency and enhances the fractional share of renewable energy of total primary energy use

Energy supply diversification by increased use of domestic renewable energy sources is one way of minimizing supply risk, where risk minimization necessitates that a given energy choice is evaluated in the context of the entire energy system and not as an individual choice An energy portfolio with favorable risk qualities should be composed of elements with, at least, partially offsetting risks [11] This can be reached by, for example, expanding the use of renewable energy sources such as geothermal energy, which with proper utilization strategies and the use of the same reservoir can be sustained over very long time periods; and unlike fossil fuels, its supply and price are not susceptible to external geopolitical issues (International Energy Agency, Contribution

of Renewables to Energy Security, 2007) An illustration of this is that the cost of geothermal energy does not fluctuate like the price

of gas and oil, which further contributes to a nation’s energy security Furthermore, geothermal power also has desirable risk attributes in the context of other renewable energy resources such as hydropower as it is not easily affected by, for example, drought

or other climate-related events Therefore, for example, in electricity generation, the use of geothermal power can enhance energy security in an electric generation system largely dominated by fossil fuels as its supply risks are very different from fossil fuel supply

SED calls for increased decentralization, locally available resources, and thus self-sufficiency, which can potentially create local investment and employment opportunities Geothermal energy fulfills all these attributes as most countries have an opportunity to use geothermal energy in some form, and it can be utilized in remote areas for small, decentralized energy generation

7.10.5.2.1(ii)(b) Sustained production and strategic fuel stocks Sustained production levels are depicted by nondeclining resource to production ratios as well as nondeclining reserve to production ratios, which implies assumed renewability of the resources Strategic fuel stocks must be maintained to enable energy consumption for at least 90 days The inherent storage ability of geothermal power and if used sustainably immediately contributes to the existence of sufficient strategic fuel stocks

7.10.5.2.1(ii)(c) Renewability and sustainable utilization Renewability is seen as a necessary but not sufficient characteristic of sustainable energy, as the resource must remain available for future generations, and reserve or resource production ratios should be

Experience shows that it is possible to harness geothermal power over an extended period of time A previously unexploited geothermal system can reach equilibrium after it begins to be used, and this new equilibrium can be maintained for a long time Research illustrates that pressure decline during production in geothermal systems can cause the recharge to the system to increase

geothermal system in Japan [3] Important contributing factors to renewability and sustainable utilization are utilization time,

It is possible to maintain constant but low production levels to ensure sustainable utilization Yet, this may not be economically viable As a result, other production options that enhance the economic returns from utilization as well as prolong the time frame for utilization may be used This includes production strategies such as (1) stepwise production up to the sustainable use limit; (2) periods of intense or excessive production followed by long breaks in production; or (3) greatly reduced production following a

short period of intense production [3] These types of ‘cyclical production’ can be just as economically viable as intensive

example, if a geothermal resource is used for indirect use such as electricity production, the recovery time cannot exceed 300 years In addition to this criteria, it is necessary to secure that if a system is used in an excessive manner and requires a recovery break or a rest, other systems must be ready for use in the same volcanic area As a result, when planning for sustainable utilization of geothermal resources, several geothermal systems must be taken into account simultaneously, as

requirements As illustrated earlier, two main management strategies that enable sustainable yield include (1) constant produc­

Sustainable yield in low-enthalpy systems is possible, even without reinjection An example of this is the Laugarnes geothermal field in Iceland, where increased production caused a pressure drop in the system and the naturally enhanced recharge led

Unlike low-enthalpy resources, high-enthalpy resources are in many cases used for electricity generation and, thus, are frequently subjected to excessive use Such excessive use may lead to a large drop in pressure, eventually rendering the resource not economically viable In such cases, reinjection of spent fluids may mitigate the drop in pressure Such reinjection schemes may, however, result in rapid cooling of the reservoir as well as lead to seismic events [23]

7.10.5.2.2 The social dimension

The social dimension (Table 2) contains two themes, equity and health The goal is to ensure reliable and affordable access to quality energy sources for all members of any given population, regardless of income or gender to facilitate increased employment

Nearly 2 billion people do not have access to high-quality energy sources and instead primarily rely on poor quality energy sources

however, to only provide access to high-quality energy because it also must be affordable, such that the population also has the means to purchase it

7.10.5.2.2(i) Equity

7.10.5.2.2(i)(a) Availability High-temperature geothermal energy resources currently suitable for electrical generation are only found in certain areas worldwide, near tectonic plate boundaries where the temperature is high enough, which means they are only available to populations living in these areas However, low-temperature resources are available in many areas of the world and geothermal heat pumps can be used anywhere In the year 2000, it was possible to use geothermal resources for direct and/or indirect applications in over 90 countries and 72 countries had quantified records of geothermal utilization [24]

Given the amount of geothermal power currently utilized and the available technical potential there clearly is room for

is possible to produce energy from geothermal sources with more consistency than with other variable renewable sources such as

Table 2 Energy indicators for sustainable development within the CSD conceptual framework: the social dimension

Share of households or population without electricity or commercial energy or

heavily dependent on noncommercial energy

Share of household income spent on fuel and electricity

Household energy use for each income group and corresponding fuel mix

Safety Accident fatalities per energy

produced by fuel mix

Source: Vera I and Langlois L (2007) Energy indicators for sustainable development Energy 32: 875–882