Renewable and Sustainable Energy Reviews

4 (2000) 157±175
www.elsevier.com/locate/rser

Renewable energy and sustainable

development: a crucial review
Ibrahim Dincer*
Associate Professor, Department of Mechanical Engineering, King Fahd University of Petroleum and
Minerals, Box 127, Dhahran, 31261, Saudi Arabia
Received 10 February 1999; accepted 24 February 1999

Abstract

Achieving solutions to environmental problems that we face today requires long-term

potential actions for sustainable development. In this regard, renewable energy resources
appear to be the one of the most ecient and e€ective solutions. That is why there is an
intimate connection between renewable energy and sustainable development. Anticipated
patterns of future energy use and consequent environmental impacts (focussing on acid
precipitation, stratospheric ozone depletion and the greenhouse e€ect) are comprehensively
discussed in this paper. Also, potential solutions to current environmental problems are
identi®ed along with renewable energy technologies. The relations between renewable
energy and sustainable development are described with practical cases, and an illustrative
example is presented. Throughout the paper several issues relating to renewable energy,
environment and sustainable development are examined from both current and future
perspectives. It is believed that the conclusions and recommendations drawn in the present
study will be useful to energy scientists and engineers and policy makers. # 2000 Elsevier
Science Ltd. All rights reserved.

1. Introduction

Energy is the convertible currency of technology. Without energy the whole

fabric of society as we know it would crumble; the e€ect of a 24-h cut in

* Tel.: +966-3-860-4497; fax: +966-3-860-2949.

E-mail address: idincer@kfupm.edu.sa (I. Dincer).

1364-0321/00/$ - see front matter # 2000 Elsevier Science Ltd. All rights reserved.
PII: S 1 3 6 4 - 0 3 2 1 ( 9 9 ) 0 0 0 1 1 - 8
158 I. Dincer / Renewable and Sustainable Energy Reviews 4 (2000) 157±175

electricity supplies to a city shows how totally dependent we are on that

particularly useful form of energy. Computers and lifts cease to function, hospitals
sink to a care and maintenance level and the lights go out. As populations grow,
many faster than the average 2%, the need for more and more energy is
exacerbated. Enhanced lifestyle and energy demand rise together and the wealthy
industrialized economies which contain 25% of the world's population consume
75% of the world's energy supply [1].
Problems with energy supply and use are related not only to global warming,
but also to such environmental concerns as air pollution, acid precipitation, ozone
depletion, forest destruction, and emission of radioactive substances. These issues
must be taken into consideration simultaneously if humanity is to achieve a bright
energy future with minimal environmental impacts. Much evidence exists, which
suggests that the future will be negatively impacted if humans keep degrading the
environment.
Other environmental considerations have been given increasing attention by
energy industries and the public. The concept that consumers share responsibility
for pollution and its cost has been increasingly accepted. In some jurisdictions, the
prices of many energy resources have increased over the last one to two decades,
in part to account for environmental costs. World population is expected to
double by the middle of the 21st century [2], and economic development will
almost certainly continue to grow. Global demand for energy services is expected
to increase by as much as an order of magnitude by 2050, while primary-energy
demands are expected to increase by 1.5±3 times [2]. Simultaneously, concern will
likely increase regarding energy-related environmental concerns such as acid
precipitation, stratospheric ozone depletion and global climate change.
One solution to the impending energy shortage is to make much more use of
renewable energy sources and technologies. This cause is sometimes espoused with
a fervor which leads to extravagant and impossible claims being made.
Engineering practicality, reliability, applicability, economy, scarcity of supply and
public acceptability should all be considered accordingly.
Ultimately, of course, all energy supplies on Earth derive from the sun and
solar energy provides a continuous stream of energy which warms us, causes crops
to grow via photosynthesis, heats the land and sea di€erentially and so causes
winds and consequently waves and, of course, rain leading to hydropower. Tidal
rise and fall is the result of gravitational pull of moon and sun and geothermal
heat the result of radioactive decay deep in the Earth. All are possible sources of
energy but though the science is understood, it does not follow that provided
enough research money is poured into the project an engineering solution should
be found appropriately [1]. The scienti®c understanding of the process is the easy
part; it is the engineering that is dicult to conduct.
In the light of preceding explanations we can point out the fact that energy is
one of the main factors that must be considered in discussions of sustainable
development. Several de®nitions of sustainable development have been put forth,
including the following common one: ``development that meets the needs of the
present without compromising the ability of future generations to meet their own
 I. Dincer / Renewable and Sustainable Energy Reviews 4 (2000) 157±175 159

needs`` [3]. There are many factors that can contribute to achieving sustainable
development. One of the most important is the requirement for a supply of energy
resources that is fully sustainable [4±7]. A secure supply of energy resources is
generally agreed to be a necessary but not sucient requirement for development
within a society. Furthermore, sustainable development within a society demands
a sustainable supply of energy resources (that, in the long term, is readily and
sustainably available at reasonable cost and can be utilized for all required tasks
without causing negative societal impacts) and an e€ective and ecient utilization
of energy resources. In this regard, the intimate connection between renewable
energy sources and sustainable development comes out.
The main objective of this paper is to discuss the environmental problems such
as acid precipitation, stratospheric ozone depletion, and greenhouse e€ect and the
anticipated patterns of future energy use and consequent environmental impacts
and to identify some solutions to the current environmental problems, focussing
on renewable energy sources and technologies and the linkage between renewable
energy and sustainable development.

2. Environmental problems

During the past two decades the risk and reality of environmental degradation
have become more apparent. Growing evidence of environmental problems is due
to a combination of several factors since the environmental impact of human
activities has grown dramatically because of the sheer increase of world
population, consumption, industrial activity, etc. Throughout the 1970 s most
environmental analysis and legal control instruments concentrated on
conventional pollutants such as SO2, NOx, particulates, and CO. Recently
environmental concern has extended to the control of micro- or hazardous air
pollutants, which are usually toxic chemical substances and harmful in small
doses, as well as to that of globally signi®cant pollutants such as CO2. Aside from
advances in environmental science, developments in industrial processes and
structures have led to new environmental problems. For example, in the energy
sector, major shifts to the road transport of industrial goods and to individual
travel by cars has led to an increase in road trac and hence a shift in attention
paid to the e€ects and sources of NOx and volatile organic compound (VOC)
emissions. A detailed information on these gaseous and particulate pollutants and
their impacts on the environment and human bodies has been recently presented
by Dincer [8].
Environmental problems span a continuously growing range of pollutants,
hazards and ecosystem degradation over ever wider areas. The major areas of
environmental problems may be classi®ed as follows:
. Major environmental accidents
. Water pollution
. Maritime pollution
160 I. Dincer / Renewable and Sustainable Energy Reviews 4 (2000) 157±175

. Land use and siting impact

. Radiation and radioactivity
. Solid waste disposal
. Hazardous air pollutants
. Ambient air quality
. Acid rain
. Stratospheric ozone depletion, and
. Global climate change (greenhouse e€ect).
Among these environmental issues, the internationally known most vital problems
are the acid precipitation, the stratospheric ozone depletion, and the global
climate change. In conjunction with this, we will focus on these three concerns in
detail. Before commencing, it is useful to provide a scheme of the pollutants and
their environmental impacts as tabulated in Table 1.

2.1. Acid rain

This is a form of pollution depletion in which pollutants produced by the

combustion of fossil fuels, particularly from both stationary and mobile sources
such as smelters for nonferrous ores, industrial boilers, and transportation
vehicles, are transported over great distances through the atmosphere and
deposited via precipitation on the Earth on ecosystems that are exceedingly
vulnerable to damage from excessive acidity. This acid rain deposition was found
to be mainly attributable to emissions of SO2 and NOx [8] and such gases react
with water and oxygen in the atmopshere and result in acids such as sulfuric and
nitric acids (Fig. 1). It is therefore obvious that the solution to the issue of acid
rain deposition requires an appropriate control of SO2 and NOx.
The pollutants have caused only local concerns related to health in the past.
However, as awareness of their contributions to the regional and transboundary
problem of acid precipitation has grown, attention has begun also focusing on
other substances such as volatile organic compounds (VOCs), chlorides, ozone
and trace metals that may participate in the complex set of chemical
transformations in the atmosphere resulting in acid precipitation and the
formation of other regional air pollutants. There are a number of major evidences
to show the damages of acid precipitation as follows [7]:
. Acidi®cation of lakes, streams and ground waters
. Toxicity to plants from excessive acid concentration
. Resulting in damage to ®sh and aquatic life
. Damage to forests and agricultural crops
. Deterioration of materials, e.g., buildings, metal structures and fabrics
. In¯uence of sulfate aerosols on physical and optical properties of clouds.
It is obvious that some energy-related activities are major sources of acid
precipitation. For example, electric power generation, residential heating and
industrial energy use account for 80% of SO2 emissions, with coal use alone
Table 1
Main gaseous pollutants and their impacts on the environmenta

Gaseous pollutant Greenhouse e€ect Stratospheric ozone depletion Acid precipitation Smog

Carbon monoxide (CO)

Carbon dioxide (CO2) + 2
Methane (CH4) + 2
Nitric oxide (NO) and nitrogen dioxide (NO2) 2 + +
Nitrous oxide (N2O) + 2
Sulfur dioxide (SO2) ÿ +
Chloro¯uorocarbons (CFCs) + +
Ozone (O3) + +

a
Where + stands for positive contribution, and ÿ stands for variation with conditions and chemistry, may not be a general contributor; source, Ref.
[17].
I. Dincer / Renewable and Sustainable Energy Reviews 4 (2000) 157±175
161
162 I. Dincer / Renewable and Sustainable Energy Reviews 4 (2000) 157±175

Fig. 1. A schematic representation of the formation, distribution, and impact of acid precipitation.

accounting for about 70% of SO2 emissions. Another source of acid precipitation
is sour gas treatment which produces H2S that reacts to form SO2 when exposed
to air. Road transport is an important source of NOx emissions, accounting for
48% of the total in OECD countries [9]. Most of the remaining NOx emissions
are due to fossil fuel combustion in stationary sources. Additionally, VOCs are
generated by a variety of sources, and comprise a large number of diverse
compounds. Of course, countries in which the energy-related activities occur
widely are likely to be signi®cant contributors to acid precipitation. The largest
contributors in the world are the United States, countries from the former Soviet
Union, and China [2].
As mentioned earlier, acid rain exerts its deleterious e€ects on the ecology of
water systems, on forests, and on historical and cultural artifacts. The acid rain
produced by some countries' emissions often happens to fall on other countries.
The problem was underrated until the evidence of its importance became
overwhelming. That is why this problem is very complex. This complexity makes
it dicult to apply the principle of ``the polluter pays'', and has already led to
 I. Dincer / Renewable and Sustainable Energy Reviews 4 (2000) 157±175 163

some acrimony between governments. Coal and high-sulphur fuel oil are the main
contributing sources to acid precipitation and considerable research is therefore
being undertaken on ``clean coal technologies''. Possible methods to reduce the
acid gas emissions attributable to these fuels include cleaning the coal before
combustion, as well as burning it more cleanly through the use of such techniques
as ¯uidized bed combustion technology. Other major contributors to acid
precipitation are the transport vehicles and their contributions will likely continue
to increase. Three-way catalytic converters can reduce the emissions of some
pollutants but, unfortunately, they increase the quantity of fuel consumed and
hence the amount of carbon dioxide released into the atmosphere. Some well
understood and e€ective measures for controlling acid precipitation include
limiting the number of vehicles through promoting ecient public transport, and
encouraging or enforcing the use of more fuel-ecient vehicles.

2.2. Stratospheric ozone depletion

It is well known that the ozone present in the stratosphere, roughly between
altitudes of 12 and 25 km, plays a natural, equilibrium-maintaining role for the
Earth, through absorption of ultraviolet (UV) radiation (240±320 nm) and
absorption of infrared radiation [8]. A global environmental problem is the
distortion and regional depletion of the stratospheric ozone layer which has been
shown to be caused by the emissions of CFCs, halons (chlorinated and
brominated organic compounds) and NOx (Fig. 2). Ozone depletion in the
stratosphere can lead to increased levels of damaging ultraviolet radiation
reaching the ground, causing increased rates of skin cancer, eye damage and other
harm to many biological species.
Energy- and non-energy related activities are only partially (directly or
indirectly) responsible for the emissions which lead to stratospheric ozone
depletion. CFCs, which are used in air conditioning and refrigerating equipment
as refrigerants and in foam insulation as blowing agents, and NOx emissions
which are produced by fossil fuel and biomass combustion processes, natural
denitri®cation, nitrogen fertilizers, and aircrafts play the most signi®cant role in
ozone depletion. Though scienti®c debate on ozone depletion has occurred for
over a decade, only in 1987 was an international landmark protocol signed in
Montreal to reduce the production of CFCs and halons. Conclusive scienti®c
evidence of the destruction of stratospheric ozone by CFCs and halons has
recently been gathered, and commitments for more drastic reductions in their
production were undertaken at the 1990 London Conference [10]. Tuck [11]
undertook a comprehensive study on the current status of stratospheric ozone
including a number of aspects such as historical review of the problem, chemical
and physical phenomena of the ozone depletion, ozone losses in the stratosphere
by giving some maps and the hypotheses on these impacts, and some crucial
concluding remarks.
Replacement equipment and technologies that do not use CFCs are gradually
coming to the fore and may ultimately allow for a total ban of CFCs. An
164 I. Dincer / Renewable and Sustainable Energy Reviews 4 (2000) 157±175

Fig. 2. A schematic representation of sources of natural and anthropogenic ozone depleters.

important consideration in such a CFC ban is the need to distribute fairly the
economic burdens deriving from the ban, particularly with respect to developing
countries, some of which have invested heavily in CFC-related technologies. In
order to eliminate or minimize the impacts of the NOx emissions, the solutions
mentioned in the previous section can be implemented accordingly.

2.3. Global climate change (greenhouse e€ect)

Although the term greenhouse e€ect has generally been used for the role of the
whole atmosphere (mainly water vapor and clouds) in keeping the surface of the
Earth warm, it has been increasingly associated with the contribution of CO2
(currently, it is estimated that CO2 contributes about 50% to the anthropogenic
greenhouse e€ect). However, several other gases such as CH4, CFCs, halons, N2O,
ozone and peroxyacetylnitrate (so-called greenhouse gases ) produced by industrial
and domestic activities can also contribute to this e€ect, resulting in a rise in the
Earth's temperature (Fig. 3).
Potentially the most important environmental problem relating to energy
utilization is the greenhouse e€ect, also known as global warming. Increasing
atmospheric concentrations of greenhouse gases are increasing the manner in
which these gases trap heat radiated from the Earth's surface, thereby raising the
 I. Dincer / Renewable and Sustainable Energy Reviews 4 (2000) 157±175 165

Fig. 3. A schematic representation of greenhouse e€ect.

surface temperature of the Earth. The Earth's surface temperature has increased
about 0.68C over the last century, and as a consequence sea level is estimated to
have risen by perhaps 20 cm [12]. Such changes can have wide-ranging e€ects on
human activities all over the world. Current knowledge of the role of various
greenhouse gases is summarized in Dincer and Rosen [7]. Humankind is
contributing through many of its economic and other activities to the increase in
the atmospheric concentrations of various greenhouse gases. For example, CO2
releases from fossil fuel combustion, methane emissions from increased human
activity, CFC releases and deforestation all contribute to the greenhouse e€ect.
Most scientists agree that there is a cause±e€ect relationship between the observed
emissions of greenhouse gases and global warming. Furthermore, many scientists
predict that if atmospheric concentrations of greenhouse gases continue to
increase, as present trends in fossil fuel consumption suggest will occur, the
Earth's temperature may increase in the next century by another 28C and perhaps
by up to 48C. If this prediction is realized, sea level could rise between 30 and
60 cm before the end of the 21st century [12]. The impact of such a phenomenon
could be dramatic, including ¯ooding of coastal settlements, a displacement of
fertile zones for agriculture and food production toward higher latitudes, and a
decreasing availability of fresh water for irrigation and other essential uses. Such
consequences could jeopardize the survival of entire populations.
Crucial to discussions on averting global climate change is thorough evaluations
of the costs of reducing carbon emissions. From a developing-country perspective,
the discussion of costs and bene®ts has to take into account the need for policies
166 I. Dincer / Renewable and Sustainable Energy Reviews 4 (2000) 157±175

promoting rapid economic growth. Achieving such a balance between economic

development and emissions abatement requires the adoption of domestic policies
aimed at improving the eciency of energy use and facilitating fuel switching, and
the implementation of international policies enabling easier access to advanced
technologies and external resources.
The arguments about the magnitude of greenhouse e€ect have ranged back and
forth for some time. There are those who believe that the Earth is doomed to a
rise in temperature and there are those who believe that we can go on polluting
the atmosphere without consequence. Whatever the argument, there is no doubt
that the emissions are harmful and destroy the environment [13]. Of course, there
are several contradictory reports and arguments published recently that make this
®eld complicated to study. Furthermore, the environment should be considered to
be an extremely limited resource, and discharge of chemicals into it should be
subject to severe constraints. Nevertheless, in order to conduct a successful
environmental study we should have a clear outline and include the following
signi®cant steps:
. De®nition of the main goals both short- and long-term
. Measurement or estimation of the data needed as accurately as possible
. Evaluation of the measurements or estimations
. Generation of new and reliable data
. Reporting of the results without outraging.

3. Potential solutions to environmental problems

Recently, some potential solutions to the current environmental problems

associated with the harmful pollutant emissions have evolved, including:
. Renewable energy technologies
. Energy conservation (ecient energy utilization)
. Cogeneration and district heating
. Energy storage technologies
. Alternative energy dimensions for transport
. Energy source switching from fossil fuels to environmentally benign energy
forms
. Coal cleaning technologies
. Optimum monitoring and evaluation of energy indicators
. Policy integration
. Recycling
. Process change and sectoral shiftment
. Acceleration of forestation
. Carbon or fuel taxes
. Materials substitution
. Promoting public transport
 I. Dincer / Renewable and Sustainable Energy Reviews 4 (2000) 157±175 167

. Changing life styles

. Increasing public awareness
. Education and training.
Among the potential solutions listed, we will discuss the most important one, the
renewable energy technologies, in the following section.

4. Renewable energy resources and technologies

Since the oil crises in the early 1970 s, there has been active worldwide research
and development in the ®eld of renewable energy resources and systems. During
this time, energy conversion systems that were based on renewable energy
technologies appeared to be most attractive because of facts such as the projected
high cost of oil and the cost e€ectiveness estimates and easy implementation of
renewable energy systems. Furthermore, in more recent times, it has been realized
that renewable energy sources and systems can have a bene®cial impact on the
following essential technical, environmental, economic, and political issues of the
world [14]:
. Major environmental problems (e.g., acid rain, stratospheric ozone depletion,
greenhouse e€ect)
. Environmental degradation
. Depletion of the world's nonrenewable energy sources
. Increasing energy use in developing countries.
As pointed out by Hartley [15], renewable energy technologies produce marketable
energy by converting natural phenomena into useful energy forms. These
technologies use the energy inherent in sunlight and its direct and indirect impacts
on the Earth (photons, wind, falling water, heating e€ects, and plant growth),
gravitational forces (the tides), and the heat of the Earth's core (geothermal) as
the resources from which they produce energy. These resources represent a
massive energy potential which dwarfs that of equivalent fossil resources.
Therefore, the magnitude of these is not a key constraint on energy production.
However, they are generally di€use and not fully accessible, some are intermittent,
and all have distinct regional variabilities. Such aspects of their nature give rise to
dicult, but solvable, technical, institutional, and economical challenges inherent
in development and use of renewable energy resources. Despite having such
diculties and challenges, the research and development on renewable energy
resources and technologies has been expanded during the past two decades
because of the facts listed above. Nowadays, signi®cant progress is made by:
. Improving the collection and conversion eciencies
. Lowering the initial and maintenance costs
. Increasing the reliability and applicability
. Understanding the phenomena of renewable energy systems.
168 I. Dincer / Renewable and Sustainable Energy Reviews 4 (2000) 157±175

Table 2 gives the renewable energy technologies as a mix of several old concepts
(e.g., hydropower, geothermal, biomass) and new technologies (e.g., solar, ocean
thermal).
Renewable energy technologies become important as environmental concerns
increase, utility (hydro) costs climb and labor costs escalate [16]. The uncertain
global economy is an additional factor. The situation may be turned around with
an increase in research and development in the Hi-Tech ®elds, some of which are
closely associated with renewable energy technologies. This may lead to innovative
products and job creation that are supported by the governments. The progress in
other technologies, especially in Hi-Tech has induced some innovative ideas in
renewable energy system designs. The ubiquitous computer has provided means
for optimizing system performance, costs/bene®ts and environmental impacts even
before the engineer was o€ the drawing board!
The operating and ®nancial attributes of renewable energy technologies, which
include modularity and ¯exibility, low operating costs (suggesting relative cost
certainty), are considerably di€erent than those for traditional, fossil based
technologies, whose attributes include large capital investments, long
implementation lead times, and operating cost uncertainties, regarding future fuel
costs. The overall bene®ts of renewable energy technologies are often not well
understood and consequently they are often evaluated to be not as cost e€ective
as traditional technologies. In order to assess comprehensively renewable energy
technologies, however, some of their bene®ts that are often not considered must
be accounted for. Renewable energy technologies, in general, are sometimes seen
as direct substitutes for existing technologies so that their bene®ts and costs are

Table 2
Maturity of renewable energy technologies (source, Ref. [15])

Proven capability Transition phase Future potential

Hydropower Wind Advanced Turbines

Geothermal Geothermal Geothermal

Hydrothermal Hydrothermal Hot dry rock
Geopressure
Magma
Biomass Biofuels Biofuels
Direct combustion Ethanol from corn Methane
Gasi®cation Municipal wastes
Passive solar Active solar Solar thermal
Buildings Buildings Advanced electricity
Process heat High-temperature processes
Solar Thermal
Thermal/gas hybrid
Photovoltaics Photovoltaics Photovoltaics
Small remote Remote power Utility power
Specialty products Diesel hybrids
Ocean Thermal
 I. Dincer / Renewable and Sustainable Energy Reviews 4 (2000) 157±175 169

conceived in terms of assessment methods developed for the existing technologies.

For example, solar and other renewable energy technologies can provide small
incremental capacity additions to the existing energy systems with short lead
times. Such power generation units usually provide more ¯exibility in incremental
supply than large, long lead-time units such as nuclear power stations.
For the 1990 s, some of the well-tried renewable energy technologies that have
been tested for years in the ®eld will continue to expand with improved designs.
The market demand for them by the developing nations will grow as they seek a
better standard of living. The impact of global use of renewable energy systems
will certainly reduce the pollution levels. During the past two decades, a
tremendous progress has been made on the solar energy technologies, particularly
in photovoltaics (PV). Solar photovoltaic energy, the direct conversion of sunlight
into electric power by a solid-state device, has progressed rapidly since the launch
of the ®rst satellite in the 1950 s. The impetus was due to the ubiquitous silicon
chip technology in the United States, Japan and Germany that has spawned the
world's electronic industries leading to the super highways on communications.
Now, large terrestrial photovoltaic power stations, some about 100 MW capacity,
feed the AC grid network or operate as stand-alone in the United States. Let us
compare it with hydro generated power; for example, the energy costs in the
United States are $0.06 to 0.20/kWh for hydro and $0.30 to 0.40/kWh for PV
[18].
Development of advanced renewable energy technologies can serve as cost-
e€ective and environmentally responsible alternatives to conventional energy
generation. Technical and market potential exists to signi®cantly increase the
current contribution of renewable energy sources to country's energy demands by
the year 2000, resulting in employment and economic bene®ts many times the
R&D investment. Many government energy institutions and agencies recognize
this opportunity and support their renewable energy industry's e€orts to exploit
near-term commercial potential by [16]:
. Analyzing opportunities for renewable energy and working in consultation with
industry to identify R&D and market strategies to meet technological goals
. Conducting R&D in cooperation with industry to develop and commercialize
technologies
. Encouraging the application of renewable energy technologies to potential
users, including utilities
. Providing technical support and advice to industry associations and government
programs that are encouraging the increased use of renewable energy.
In order to realize the energy, economic and environmental bene®ts that
renewable energy sources o€er, the following integrated set of activities should be
acted on accordingly:
. Research and development: R&D priorities should be set in close consultation
with industry to re¯ect their needs. Most research is conducted through cost-
shared agreements and falls within the short-to-medium term. Partners in R&D
170 I. Dincer / Renewable and Sustainable Energy Reviews 4 (2000) 157±175

should include a variety of stakeholders in the energy industry, such as private

sector ®rms, utilities across the country, provincial governments and other
federal departments.
. Technology assessment: Data should be gathered in the lab and through ®eld
trials on factors such as cost bene®t, reliability, environmental impact, safety
and opportunities for improvement. These data should also assist the
preparation of technology status overviews and strategic plans for R&D.
. Standards development: The development of technical and safety standards is
needed to encourage the acceptance of proven technologies in the marketplace.
Standards development should be conducted in cooperation with national and
international standards writing organizations, as well as other national and
provincial regulatory bodies.
. Technology transfer: R&D results should be transferred through sponsorship of
technical workshops, seminars and conferences, as well as through the
development of training manuals and design tools, and the publication of
technical reports.
Such activities will also encourage potential users to consider the bene®ts of
adopting renewable energy technologies. In support of developing near-term
markets, a key technology transfer area is to accelerate the use of renewable
energy technologies in a country's remote communities.

4.1. Illustrative example

Here, we present a case study performed by the city of Saarbrucken in

Germany which has 180,000 inhabitants. It started implementing a new energy
and environment strategy in the 1980 s in order to reduce energy consumption
and CO2 emissions mainly by undertaking the following actions: (i) advice and
information, (ii) least cost planning, (iii) district heating, (iv) seasonal energy
storage, and, the most important, (v) maximizing the use of renewable energies by
undertaking several actions including:
. Passive solar energy was promoted through advice to architects, planners, etc
. Four outdoor swimming pools were heated with active solar systems
. The 1000 kW solar roof programme for photovoltaic solar energy was initiated
and more than one-third has been installed
. For hydropower a 1 MW installation was planned and a signi®cant amount of
energy is now coming from this source.
Their achievements from 1980 to 1990 can be listed as follows:
. A 15% reduction in heating demand for the entire city
. A 45% reduction in heating consumption for the municipal buildings
. A 15% reduction in CO2 emissions from heating and electrical requirements of
the municipality.
As is evident from this illustrative example, the city Saarbrucken implemented a
 I. Dincer / Renewable and Sustainable Energy Reviews 4 (2000) 157±175 171

successful energy program and, as a result, received a Local Government Honor

at the United Nations Conference on Environment and Development in Rio de
Janeiro in June 1992 [19].

5. Sustainable development

A secure supply of energy resources is generally agreed to be a necessary but

not sucient requirement for development within a society. Furthermore,
sustainable development demands a sustainable supply of energy resources that, in
the long term, is readily and sustainably available at reasonable cost and can be
utilized for all required tasks without causing negative societal impacts. Supplies
of such energy resources as fossil fuels (coal, oil, and natural gas) and uranium
are generally acknowledged to be ®nite; other energy sources such as sunlight,
wind and falling water are generally considered renewable and therefore
sustainable over the relatively long term. Wastes (convertible to useful energy
forms through, for example, waste-to-energy incineration facilities) and biomass
fuels are also usually viewed as sustainable energy sources. In general, the
implications of these statements are numerous, and depend on how sustainable is
de®ned [7].
Environmental concerns are an important factor in sustainable development.
For a variety of reasons, activities which continually degrade the environment are
not sustainable over time, e.g., the cumulative impact on the environment of such
activities often leads over time to a variety of health, ecological and other
problems. A large portion of the environmental impact in a society is associated
with its utilization of energy resources. Ideally, a society seeking sustainable
development utilizes only energy resources which cause no environmental impact
(e.g., which release no emissions to the environment). However, since all energy
resources lead to some environmental impact, it is reasonable to suggest that some
(not all) of the concerns regarding the limitations imposed on sustainable
development by environmental emissions and their negative impacts can be in part
overcome through increased energy eciency. Clearly, a strong relation exists
between energy eciency and environmental impact since, for the same services or
products, less resource utilization and pollution is normally associated with
increased energy eciency.
While not all renewable energy resources are inherently clean, there is such a
diversity of choices that a shift to renewables carried out in the context of
sustainable development could provide a far cleaner system than would be feasible
by tightening controls on conventional energy. Furthermore, being by nature site-
speci®c, they favor a power system decentralization and locally applicable
solutions more or less independent of the national network. It enables citizens to
perceive positive and negative externalities of energy consumption. Consequently,
the small scale of the equipment often makes the time required from initial design
to operation short, providing greater adaptability in responding to unpredictable
growth and/or changes in energy demand.
172 I. Dincer / Renewable and Sustainable Energy Reviews 4 (2000) 157±175

5.1. Importance of renewable energy resources and technologies for sustainable

development

The exploitation of renewable energy resources and technologies is a key

component of sustainable development [19]. There are three signi®cant reasons for
it as follows.
1. They have much less environmental impact compared to other sources of
energy since there is no any energy sources with zero environmental impact.
There are a variety of choices available in practice that a shift to renewables
could provide a far cleaner energy system than would be feasible by tightening
controls on conventional energy.
2. Renewable energy resources can not be depleted unlike fossil fuel and uranium
resources. If used wisely in appropriate and ecient applications, they can
provide a reliable and sustainable supply energy almost inde®nitely. In contrast,
fossil fuel and uranium resources are ®nite and can be diminished by extraction
and consumption.
3. They favor power system decentralization and locally applicable solutions more
or less independent of the national network, thus enhancing the ¯exibility of
the system and the economic power supply to small isolated settlements. That is
why many di€erent renewable energy technologies are potentially available for
use in urban areas.

5.2. Essential factors for sustainable developments

The main concept of sustainability, which often inspires local and national
authorities to incorporate environmental considerations in setting energy
programmes, though being given many di€erent meanings in di€erent contexts,
embodies a long-term perspective. Besides, the future energy system will be largely
shaped by broad and powerful trends that have their roots in basic human needs.
In conjunction with this, the increasing world population requires the de®nition
and successful implementation of sustainable development. There are various
essential parameters that can help in achieving a successful sustainable
development in a society. Such parameters can be described as follows:
. Public awareness: This is the initial step and very crucial in making the
sustainable energy program successful. This should be carried out through the
media and by public and/or professional organizations.
. Information: Necessary informational input on energy utilization, environmental
impacts, renewable energy resources, etc. should be provided to public through
public and government channels.
. Environmental education and training: This can be implemented as a completing
part of the information. Any approach which does not have an integral
education and training is likely to fail. That is why this can be considered as the
 I. Dincer / Renewable and Sustainable Energy Reviews 4 (2000) 157±175 173

signi®cant prerequisite for a sustainable energy program. For this reason, a

wide scope of specialized agencies and training facilities should be made
available to the public.
. Innovative energy strategies: These should be provided for an e€ective
sustainable energy program and, therefore, require the ecient dissemination of
information, based on new methods and consisting of public relations, training
and counseling.
. Promoting renewable energy resources: In order to achieve environmentally
benign sustainable energy programs, renewable energy sources should be
promoted in every stage. This will create a strong basis for the short- and long-
term policies.
. Financing: This is a very important tool that can be used for reaching the main
goal and will accelerate the implementation of renewable energy systems and
technologies for sustainable energy development of the country. Some countries,
e.g., Germany, apply the support a di€erent way and simply exempt the people
who use such systems and technologies from some portion of their taxes.
. Monitoring and evaluation tools: In order to see how successfully the program
has been implemented, it is of great importance to monitor each step and
evaluate the data and ®ndings obtained. In this regard, appropriate monitoring
and evaluation tools should be used.

6. Conclusions

Renewable energy resources and their utilization are intimately related to

sustainable development. For societies to attain or try to attain sustainable
development, much e€ort should be devoted to discovering sustainable energy
resources in terms of renewables. In addition, environmental concerns should be
addressed. The following concluding remarks can be drawn from this study:
. There are a number of environmental problems that we face today. These
problems span a continuously growing range of pollutants, hazards and
ecosystem degradation over ever wider areas. The most signi®cant ones are acid
precipitation, stratospheric ozone depletion, and global climate change.
. Potentially the most important environmental problem relating to energy
utilization is the greenhouse e€ect. Increasing atmospheric concentrations of
greenhouse gases are increasing the manner in which these gases trap heat
radiated from the Earth's surface, thereby raising the surface temperature of the
Earth and as a consequence risen sea levels.
. Recently, a variety of potential solutions to the current environmental problems
associated with the harmful pollutant emissions has evolved. However,
renewable energy appears to be one of the most important solutions.
. Renewable energy technologies, in general, are sometimes seen as direct
substitutes for existing technologies so that their bene®ts and costs are
174 I. Dincer / Renewable and Sustainable Energy Reviews 4 (2000) 157±175

conceived in terms of assessment methods developed for the existing

technologies. For example, solar and other renewable energy technologies can
provide small incremental capacity additions to the existing energy systems with
short lead times. Such power generation units usually provide more ¯exibility in
incremental supply than large, long lead-time units such as nuclear power
stations.
. Development of advanced renewable energy technologies that serve as cost-
e€ective and environmentally responsible alternatives to conventional energy
generation. Technical and market potential exists to signi®cantly increase the
current contribution of renewable energy sources to country's energy demands
by the year 2000, resulting in employment and economic bene®ts many times
the R&D investment. Many government energy institutions and agencies
recognize this opportunity and support their renewable energy industry's e€orts
to exploit near-term commercial potential.
. In order to attain the energy, economic and environmental bene®ts that
renewable energy sources o€er, an integrated set of activities such as R&D,
technology assessment, standards development and technology transfer should
be conducted as required.
. Sustainable development demands a sustainable supply of energy resources that,
in the long term, is readily and sustainably available at reasonable cost and can
be utilized for all required tasks without causing negative societal impacts.
Supplies of such energy resources as fossil fuels (coal, oil, and natural gas) and
uranium are generally acknowledged to be ®nite; other energy sources such as
sunlight, wind and falling water are generally considered renewable and
therefore sustainable over the relatively long term.
. The exploitation of renewable energy resources and technologies is a key
component of sustainable development due to the facts: (i) much less
environmental impact, (ii) more ¯exibility, (iii) being undepleted, and (iv)
decentralization possibility.
. Increasing world population requires the de®nition and successful
implementation of sustainable development.

Acknowledgements

The author is grateful for the support provided for this work by King Fahd
University of Petroleum and Minerals.

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