Renewable Energy: Power for a Sustainable Future

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Renewable Energy: Power For a Sustainable Future
Kamil Kaygusuz
Department of Chemistry, Karadeniz Technical University, 61080 Trabzon, Turkey
ABSTRACT
By the end of the 21st century, according to United Nations projections, the
number of people on the earth is likely to have approximately doubled. How can
a world of 10 to 12 billion people be provided with adequate supplies of energy,
cleanly, safely and substantially? There is a growing consensus that renewable
energy sources will be a very important part of the answer. The growing interest
in “renewables” has been prompted in part, by increasing concern over the
pollution, resource depletion and possible climate change implications of our
continuing use of conventional fossil and nuclear fuels. But recent technological
developments have also improved the cost-effectiveness of many of the
renewables, making their economic prospects look increasingly attractive. It
describes the achievement and progress made in hydropower, biomass
conversion, geothermal, solar thermal technology, wind energy conversion and
the increasing usage of photovoltaics. It is evident that global warming is setting
in and is going to change the climate as well as the terrain of many countries
unless drastic measures are taken. The Kyoto meeting emphasized the
importance of limiting CO2 emissions and to abide by some form of agreement
to reduce emissions. Present study concludes that renewable energy penetration
into the energy market is much faster than was expected in recent years and by
2030, 15–20 percent of our prime energy will be met by renewable energy.
INTRODUCTION
The Kyoto Protocol requires the USA and other major developed countries to reduce
greenhouse gas emissions from the Kyoto baseline, which is the 1990 emission level for
CO2, CH4, N2O and the 1995 level for SF6, HFCs and PFCs. During the 1970s and 1980s,
energy security, air pollution, acid rain, and nuclear accidents were the dominant catalysts
for renewable energy development. During the 1990s, the need to reduce emissions of
greenhouse gases has become an increasingly important impetus. With oil prices at low
levels, climate change has become a key policy driver for renewable energy. On the other
hand, the Kyoto Protocol can be expected to hasten the globalization of renewable energy
markets; any company that fails to understand this new dynamic may again lose out in the
marketplace. In the years ahead, the renewable energy markets of various countries and
continents will be increasingly integrated, driven not only by the broader dynamics of a
global economy but also by the fact that most of these markets are now being shaped to
some degree by the climate policy process (Flavin and Dunn, 1998).
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Renewable Energy: Power For a Sustainable Future
Renewable energy is an abundant, well-established technology and the main
ingredient is free. It is a well-known fact that eight countries have 81% of all world
crude oil reserves, six countries have 70% of all natural gas reserves and eight
countries have 89% of all coal reserves. More than half of Asia, Africa and Latin
America import over half of all their commercial energy. Most of these countries
export crops fetch low prices, but import energy at high prices, which leads to a drain
on foreign exchange earnings. This problem is worsened by the fact that power
generation is continuously increasing in these countries. Additionally, the world
population keeps increasing at 1.3–3.2% per year, so that we are doubling our
population every 60 years. Therefore, in the year 2060, we expect our population will
be in excess of 12 billion (Sayigh, 1999).
While there has been good progress in installing renewable energy systems in
recent years, the base is relatively small and the industry is still young. But the
industry’s strength is that it remains buoyant and optimistic. There is still much to do
if IEA countries are to effectively increase the share of renewable energy in total
energy supplies and promote renewable energy worldwide. There are several issues
that will affect the rate of market uptake of renewable energy sources (IEA, 2000):
•
•
•
•
•
Energy sector restructuring is gaining strength in many IEA countries and
increased competition will drive down costs. This will initially adversely affect
the deployment of renewable energy technologies until the regulatory process
creates a more level playing field to improve competition for all participants,
through the integration of national and international environmental targets.
Deregulation provides opportunities for promoting renewable energy because
there will be many new industry participants that will be aggressive and
innovative and because deregulation leads to greater customer choice.
While there are niche market where costs are less a factor and there have been
impressive cost reductions in recent years, more progress must be made to
reduce costs of current technologies.
Financing the installation of renewable energy technologies remains a major
concern. Several public and private funds have been created and there are many
financial support programmes in place. Small companies have higher costs, in
part, because the cost of borrowed capital is generally higher than for larger
companies. This affects manufacturers, independent power producers and
energy service companies. Financing is also a major concern for developing
countries and many national and international efforts have been undertaken to
facilitate easier access to capital.
Better information and training are important. The potential, benefits and costs
for renewable energy development needs to be well explained to a wider
audience of government officials, parliamentarians, energy industry officials,
potential investors and consumers. There is also a need to explain how
renewable energy can contribute to global climate change targets. Education and
training are also important to improve the skills and capabilities of the renewable
energy industry.
The rapidly changing marketplace needs a stronger, more resilient renewable
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energy industry. The creation and activities of industry association have been
important in creating a common approach and lobbying for more support. While
the trend is towards larger, more capitalized companies, there are still many
small and medium-sized companies that need various forms of technical,
financial and marketing support.
•
The future depends on a stable policy climate and an effective partnership
between government and industry to develop common strategies and action
plans to overcome technical and non-technical barriers. On the other hand,
energy sector restructuring needs to ensure that renewable energy has adequate
and fair access to markets in order to provide the benefits (e.g. environmental
benefits related to global climate change) that they can deliver.
•
A strong and continuing research and development effort by both government
and industry is needed to develop the next generation of renewable energy
technologies and significantly increase renewable energy’s share of total energy
supply.
Renewable energies and the technologies that drive them provide not only power
but also a vision for future. An important appeal of renewables is that they apply
sophisticated technologies with an abundant supply of low or non-polluting sources to
address modern societies’ existing and growing energy needs. The new technologies
are generally on a more ‘human’ scale, and signal progress based on basic values.
ENERGY DEMAND AND EMISSIONS PROJECTIONS
As the twentieth century ends, the prospects for the world petroleum industry, and for
U.S. companies in particular, are abundant, but with conflicting signals. The demand
for petroleum is rising both in U.S. and globally, as oil and gas continue to supply most
of the incremental energy needed to sustain world economic growth. In deed, the
continued spread of prosperity to broad areas of the globe previously mired in
economic stagnation might be interpreted as the signal of a new dawn to an industry
with such an essential role in fuelling that prosperity (Cavaney, 2000).
Oil and gas currently supply over 60% of the world’s energy needs, and are widely
expected to grow in importance in the future. As an illustration, consider the most
recent forecast of world energy demand prepared by the US Department of Energy,
shown in Table 1. Between 2000 and 2010, total energy consumption is expected to
rise about 25%, or more than 100 quads. Nearly three quarters of this increase is
expected to be in the demand for oil and gas. About three quarters of the increased
energy demand, and nearly 60% of the increased oil and gas demand, is expected to
originate in the developing countries.
These are massive changes, both in the magnitude and composition of global
energy demand. The anticipated growth in overall energy demand over the decade
from 2000 to 2010 is 72% greater than that experienced during the 1990s. The
expected growth in demand for oil and gas during the next decade is 79% higher than
in the last one. Overwhelmingly, this acceleration in demand is attributable to
economic and demographic growth in the developing countries. Energy growth in the
developing countries from 2000 to 2010 is expected to be more than 40% higher than
the growth experienced in the 1990s. Oil growth in the developing countries in the
Renewable Energy: Power For a Sustainable Future
606
next decade is expected to be more than 16% higher than the growth of the 1990s, and
gas growth about double that of the 1990s
On the other hand, world energy demand is projected to increase at an average
annual rate of 2 percent over the outlook period. This is slightly lower than the growth
rate 2.2 percent per year experienced from 1971 to 1995. In absolute terms, the annual
global demand for energy increases from 8341 million tonnes of oil equivalent (Mtoe)
in 1995 to 13,749 Mtoe in 2020. These figures do not include biomass energy
consumption in developing countries. On the other hand, a key message of this outlook
is that fossil fuels will continue to dominate the energy mix. Between 1995 and 2020,
95 percent of the additional energy demand will be met by fossil fuels. Projections of
world energy demand by fuel are illustrated in Figure 1. As shown from Fig. 1, oil
continues to dominate world energy consumption, although its share declines from
10% in 1995 to 8% by the end of the outlook period. Most of the increase in oil
demand will stem from additional demand for transportation sector (IEA, 1998a).
Demand for gas increases faster than that for oil in the OECD regions. Gas
consumption nearly doubles over the outlook period, rising from 1810 Mtoe in 1995
to 3468 Mtoe by 2020. The share of solid fuels in the primary energy mix will remain
largely unchanged over the projection period. About three-quarters of additional
demand for solid fuels will be in the power generation sector. Growth is faster in the
developing regions, such as in China, South Asia and Turkey are expected to develop
further their indigenous supplies of coal. On the other hand, world nuclear power is
stabilize. In the OECD, some new nuclear power plants are expected will be built
during the outlook period. At the same time, several plants will reach the end of their
operational life leading to an overall decline of nuclear power in the region. Outside
the OECD, growth could be higher, with nuclear power increasing in Asia and in the
Transition Economies (Birol and Argiri, 1999).
Table 1. World energy demand (quadrillion Btu)
World
Oil
Gas
Developed countries
Oil
Gas
East Europe & FSU
Oil
Gas
Developing countries
Oil
Gas
FSU: Former Soviet Union
Source: Cavaney (2000)
1990
343.8
134.9
72.0
182.7
78.7
35.5
73.6
21.0
26.0
87.5
35.2
10.5
2000
402.7
157.7
90.1
213.2
90.7
47.4
52.0
12.5
22.2
137.5
54.4
20.5
2010
504.2
190.4
130.8
240.4
100.2
60.8
61.0
13.4
30.2
202.8
76.8
39.8
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Figure 1. World energy demand by fuel, 1971–2020
Over the period 1971–1995, CO2 emissions grew at an average rate of 1.7% per
year. The outlook projects a faster growth rate of CO2 emissions for the period to
2020, at 2.2 percent per year. Contributing factors are the stabilization of nuclear
power generation and continued rapid growth in coal use in China and other Asian
countries. By 2020, the developing countries could account for half of global CO2
emissions. Table 2 shows data and projections of CO2 emissions for the four major
regional groupings presented in the outlook.
RENEWABLE ENERGY TECHNOLOGIES
The term “renewable energy” can be defined in several ways: for example, Twidel and
Weir (1986) define renewable energy as “energy obtained from the continuous or
repetitive currents of energy recurring in the natural environment”. Sorenson (1979)
defines renewable energy as “energy flows which are replenished at the same rate as
Table 2. CO2 emissions by region (million tonnes of CO 2)
1971
OECD
9,013
Transition Economies 3,029
China
875
Rest of the World
1,436
World
14,732
Source: IEA (1998)
1995
10,763
3,135
3,051
4,791
22,150
2010
13,427
3,852
5,322
8,034
31,189
2030
14,476
4,465
7,081
11,163
37,848
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Renewable Energy: Power For a Sustainable Future
they are used”, adding that the term renewable energy may be taken to include, more
broadly, the usage of any energy storage reservoir which is being refilled at rates
comparable to that of extraction. On the other hand, more recently, the UK Renewable
Energy Advisory Group (REAG) defined renewable energy as “the term used to cover
those energy flows that occur naturally and repeatedly in the environment and can be
harnessed for human benefit. The ultimate sources of most of this energy are the sun,
gravity and the earth’s rotation” (Boyle, 1998).
Most renewable energy sources (renewables) are derived from solar radiation,
including the direct use of solar energy for heating or electricity generation, and
indirect forms such as energy from the wind, waves and running water, and from
plants and animals (wood, straw, dung, and other plant wastes). Tidal sources of
energy result from the gravitational pull of the moon and sun, and geothermal energy
comes from the heat generated within the earth. Energy from wastes of all kinds is also
often included under the heading of renewables. On the other hand, in their
technological development, the renewable energy sources range from technologies
that are well established and mature to those that need further research and
development.
The use of renewables on a more significant scale than at present would at the very
least replace a further significant proportion of fossil and nuclear fuel use, thereby
reducing the associated environmental impacts. Most of the renewable energy sources
enable the forms of environmental damage discussed in the last section to be avoided,
but all have some form of local environmental impact of their own, ranging from very
minor to major in the case of the larger tidal and hydroelectric schemes. Almost none
of them releases gaseous or liquid pollutants during operation. On the other hand,
renewable energy sources are secure and inexhaustible, in the sense that there is no
problem of reserves being depleted. With some exceptions, proposed renewable
energy sources are local and so cannot be turned off by a foreign power. They can also
add diversity to energy supply. Some, such as tidal and hydroelectricity schemes, can
provide individual power plants much larger even than individual fossil or nuclear
power plants, but most are on a much smaller scale. Smaller power plants offer shorter
lead times for planning and construction, and reduced transport and transmission costs
(Boyle 1998).
Hydropower
There is a general view that hydroelectricity is the renewable energy source par
excellence, non-exhaustible, non-polluting, and more economically attractive than
other options. Hydropower plants emit much less greenhouse gas than do thermal
plants. Greenhouse gas emissions of hydropower are caused by the decay of
vegetation in flooded areas and by the extensive use of cement in the dam
construction. Unfortunately, there are local impacts of the use of rivers, social as well
as ecological, and they are gaining importance, as people become aware of how those
impacts affect living standards. Most renewable sources of energy hydroelectricity
generation are capital intensive but have lower operational costs than thermal and
nuclear options. The high initial cost is a serious barrier for its growth in developing
countries where most of the untapped economic potential is located (Kaygusuz, 2001).
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In 1997 total installed hydroelectric capacity was about 660 gigawatts (GW) of
which about 23 GW were small scale (plant capacity of less than 10 MW). About 20
percent of the world electricity is supplied by hydroelectricity and total amount of
hydroelectricity is 2,600 TWh of which about 3.5 percent (about 90 TWh) was in
small hydroelectric plants.
In some regions (North America, Western Europe, Pacific OECD countries) more
than 65% of the economically feasible potential is already in use. In others (SubSaharan Africa, centrally planned Asia, India) less than 18% of the potential is in use
(see Table 3). In Latin America and the Caribbean nearly 44% of the economically
feasible potential is already tapped. Since the OECD operational capacity is at 80% of
the economic potential, most experts believe this value to be an upper limit for
capacity installation. On the other hand, in 1997 the hydro capacity under installation
was 125 GW. Assuming these plants will have the same average capacity factors as
the units already in operation (45%), this represents another 490 TWh a year. This will
push the hydroelectricity production in the first years of the 21st century to at least
3,000 TWh a year. By the middle of this century hydroelectricity could grow to 6,000
TWh a year (UNDP, 2000).
Large dams can have several purposes such as regulating the flows of rivers,
making water available for irrigation, drinking, industrial use, and the production of
hydroelectricity. Under some conditions, recreation, tourism, and navigation provide
additional benefits. However, the use of dams is also associated with environmental
Table 3. World hydroelectric potential and production in 1997
Region
Gross
Installed
Capacity
Theoretical Technical Economic Hydro Hydropower
Under
Potential Potential Potential Capacity Production Construction
(TWh)
(TWh)
(TWh)
(GWh)
(TWh)
(MWh)
5,817
1,509
912
141
697
882
7,533
2,868
1,199
114
519
18,331
North America
Latin America
and Caribbean
Western Europe
3,294
Central and
195
Eastern Europe
Former Soviet Union 3,258
Middle East and
304
North Africa
Sub-Saharan Africa
3,583
Pacific Asia
5,520
South Asia
3,635
Centrally planned Asia 6,511
Pacific OECD
1,134
Total
40,784
Source: UNDP (2001)
1,822
216
809
128
16
9
48
27
2,464
7,749
1,235
171
770
128
147
21
498
66
6,707
1,211
1,992
814
948
2,159
211
13,945
1,288
142
103
1,302
184
6,945
66
14
28
64
34
655
225
41
105
226
129
2,582
16,613
4,688
13,003
51,672
841
124,161
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Renewable Energy: Power For a Sustainable Future
problems. Serval hydroelectric projects in various parts of the world have been
cancelled or indefinitely postponed partly or entirely for environmental reasons. The
most controversial and publicly followed negative effect is relocation of people who
live in the areas of proposed dams. Many dams are built in remote regions, where
ethnic minorities live and have lived for centuries. Indigenous communities are
frequently very vulnerable to these intrusions have the end result of dislocations and
thus cause the ends of their cultures (Karkar and Karagöz, 1995).
The huge reservoirs created by the dams may cause extinction of unique plants and
animals. The losses of biodiversity may mean losses of world’s treasures and natural
resources, some of which could perhaps be developed as cures for deadly illnesses.
The altered ecosystems will never recover nor will extinct plants and animals reemerge. Reservoirs sometimes cause the development of water-related diseases. Large
dams influence health at not only the reservoir site but also upstream, downstream, and
at national or even regional levels. Increases in the prevalence of schistosomiasis,
malaria, encephalitis, hemorrhagic fevers, gastroenteritis, intestinal parasites, and
filariasis (including onchocerciasis and bancroftosis) have been documented after dam
and irrigation projects. Large dams also influence the health of animals through
increases in diseases such as river fluke in cattle and changes in the distribution of
trypanosomiasis. Changes in water flow, river ecology and salinity, easier travel due
to navigable dams and rivers, human proximity, pollution, canalization, and
agriculture allow vector-borne diseases to flourish in the tropical or subtropical
environments of less-developed countries, where most current dam building is taking
place (Kaygusuz, 1999).
Large dams demonstrate the interaction between public health and large-scale
engineering projects. Although development generally has positive health impacts, the
link between project expenditure and improved health is indirect and often tenuous.
Roads and construction activity bring benefits, but generally, improvements in water
supply, employment, and agriculture are short-lived, and their termination can have
catastrophic consequences. Dams often are justified as essential for “flood control”.
Unfortunately, this assumes that all floods are bad and precludes an ecosystem-based
management approach where natural flood regimes not only sustain habitats, but also
support millions of people through flood-recession agriculture, grazing, and fishing
(Lerer and Scudder, 1999).
Biomass
Biomass energy includes fuelwood, agricultural residues, animal wastes, charcoal, and
other fuels derived from biological sources. It currently accounts for about 14% of
world energy consumption. Biomass is the main source of energy for many developing
countries. Biomass energy is increasingly being associated with environmental
sustainability and climate stabilization as a large number of studies have shown that it
can have many environmental benefits if produced and used sustainably. The
reduction of potential negative impacts will depend on a combination of factors
including socio-cultural changes e.g. cooking stoves, use of gasifier, modern biogas,
etc. On the other hand, biomass resources are potentially the world’s largest and
sustainable energy source, a renewable resource comprising 220 billion even dry
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tonnes (about 4,500 EJ) of annual primary production. The annual global bioenergy
potential is estimated to be about 2900 EJ, though only 270 EJ could currently be
considered available on a sustainable basis and at competitive prices compared to
about 400 EJ of total energy currently being used of which biomass represents 55 EJ.
The use of biomass as an energy source in the industrial and developing countries
could not be more contrasting. In the EU and USA bioenergy is increasingly used in
modern applications with the highest rates being 12% of total energy in Austria, 18%
is Sweden, 23% in Finland, and 4% in the USA. Traditional uses of biomass in
developing countries represents a major proportion of energy (about 30%), this is
about 50 EJ or 1190 Mtoe (Hall, 1997).
It is also important to recognize that biomass is already an important source of
energy for many industries in many parts of the world both in industrial and
developing countries. Industrial applications in developed countries include CHP,
electricity generation, space, and domestic heating boilers in households and public
buildings, small industrial applications. In the Europe biomass supplies about 3% (45
Mtoe) of its primary energy, albeit with wide country variations. By the year 2010,
about 135 Mtoe (8.5%) of the primary energy could be derived from biomass,
representing an additional 90 Mtoe. On the other hand, in developing countries
biomass is the main source of energy for many artisan and cottage industries such as
baking, brewing, textile manufacture, tobacco and tea curing, etc. For example, in
Asia, rural industries account for at least 20% of the region’s wood energy
consumption (UNDP, 2001).
Table 4 was prepared to show the share of different woodfuel products derived
directly and indirectly from forests, as well as non-forest lands. It is difficult to assess
the fraction of wood residues used as energy; therefore all figures recorded in
FAOSTAT as wood residues have been assumed as woodfuels. Although this could be
Table 4. Total woodfuel consumption by regions (1995)
Region
Developing countries total
Africa
Asia
Oceania
Latin America and Caribbean
Developed countries total
Europe, Israel and Turkey
Former USSR
Canada and USA
Australia, N. Zealand and Japan
World
Source: D’Apote (1998)
Fuelwood
1,533
445
859
6
223
187
56
32
96
3
1,719
Woodfuels (106 CUM equivalent)
Charcoal
Residues Black liquor
31
15
34
72
2
3
25
10
12
0
0
0
34
2
19
8
43
227
2
33
51
0
3
8
4
1
146
0
6
23
138
58
262
612
Renewable Energy: Power For a Sustainable Future
questionable, the quantity is of relatively small significance (9%) compared to the total
woodfuel consumption. Only for Europe could there be some misinterpretation since
these by-products reach approximately 23% of the total woodfuel supply (Nogueira
and Trossero, 1998).
Total final consumption of biomass in developing countries is projected to continue
to increase, rising from 825 Mtoe in 1995 to 1071 Mtoe in 2020, although at a lower
rate than population and a much lower rate than conventional energy use. The rate of
growth of total biomass consumption is relatively low and slowing down: it is
projected to be 1.2% per year between 1995 and 2000, 1.1% between 2000 and 2010
and 1% between 2010 and 2020. During the same periods, final consumption of fossil
fuels is projected to grow at much faster rates 4.3%, 3.5% and 3.1% per year,
respectively). As a result, the share of biomass in total final consumption will decline
from 34% in 1995 to 22% in 2020 (D’Aptoe, 1998).
Biomass is made of all aquatic vegetation and half of all daily rubbish. Solid
municipal waste is produced at a rate of one tonne per person per year, 61% is biomass
in the form of paper, yard trimmings and used wood. The U.S. biomass resources are
very large, more than 35 million acres of land are available for crop production. This
is without affecting the present agricultural and forestry crops. On the other hand,
biofuel produced from biomass includes ethanol, methanol, biodiesel and fuel
products derived from these materials. The production of ethanol in the U.S. is mainly
located in the large grain growing states of the Midwest. For example, in 1997, 5.6
billion litres of ethanol was produced in the U.S. At present, ethanol from corn is
blended with gasoline at 10 and 90% gasoline to produce the fuel product known as
gasohol. The U.S. uses 8% of this fuel in the light duty transportation fuel market.
Research is going on to produce vehicles operating on almost pure ethanol has high
octane fuel which leads to low emissions. Ethanol is also an excellent hydrogen source
and it can be used in fuel cells is now underdeveloped so that it can be used in vehicles
meeting the California zero emission requirement. The present research objective is to
produce ethanol from biomass at a cost that will be competitive with the cost of
gasoline without tax incentives (UNDP, 2001).
Biomass fuels
Biomass has an advantage over other renewable energy resources (such as sunlight)
because it can be converted directly into liquid fuels. This allows biomass energy to
help supply the fuel needs of the transportation sector (cars, trucks, buses, airplanes,
and trains), which uses nearly one-third of U.S. energy. Currently, the most commonly
used biomass fuel in the U.S. is ethanol, primarily produced from corn. Ethanol is the
same alcohol found in beer, wine, and liquor. As a fuel, ethanol is usually used as an
additive to gasoline, but cars could also be modified to run on pure ethanol. Another
possible fuel from biomass is methanol, commonly called wood alcohol. On the other
hand, diesel fuel can be replaced by a biomass fuel made from vegetable oils. In the
U.S. this “biodiesel” is now being commercially produced from soybean oil. Any of
the vegetable oils currently produced in the U.S. (soybean, corn, cottonseed,
sunflower) could be used to produce biodiesel. Researchers are also developing algae
to produce oils that can be used as biodiesel (NREL, 2000).
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Historically, biomass has provided a large share of Brazil’s energy supply. In Brazil,
sugar-cane is widely used as a source of ethanol. The fibrous-by-product (bagasse) is
mostly used as fuel in sugar and alcohol factories. Worldwide Brazil is the largest
producer of sugar-cane. The importance of this economic activity grew after the
creation of the Brazilian Alcohol Program (PROALCOOL ) in 1975, with the purpose
of producing anhydrous ethanol to be blended with gasoline. In 1999, the total alcohol
consumption is 18,000 million litres in Brazil. PROALCOOL has been successful in its
primary goals. It is estimated that about 33 billion US dollars (1996) were saved due to
reduction of oil imports and an alternative market was created, stabilizing sugar
commerce and making Brazil more competitive in this area. On the other hand, current
biomass contribution to power production is evaluated at less than 3 percent of total
electricity generation (10 TWh in 1999), this is mostly based on cogeneration units
burning sugar-cane bagasse (4.1 TWh in sugar-cane mills) and on black-liquor (2.9
TWh in pulp industries). In addition, about 3 TWh were produced by power systems
based on steam engines and steam turbines using agriculture residues (e.g. rice husks
and coconut shell), residues of wood processing and firewood (Walter, 2001).
Geothermal energy
Geothermal energy is the energy contained as heat in the Earth’s interior. The origin
of this heat is linked with the internal source of our planet and the physical processes
occurring there. In order to assess the current status of international geothermal
power generation, Hutter (2001) has reviewed the country update papers submitted to
the World Geothermal Conference 200 in Japan from nations generating or planning
to generate electricity. Salient facts in these papers have been synthesized and
summary descriptions of geothermally-related activities written. Finally, following a
brief discussion, conclusions are drawn and geothermal energy capacities are given
in Table 5. The country update reviews revealed that: (1) geothermally-fuelled
electric power is being generated in 21 nations as of February 2000; (2) the installed
capacity has reached 7974 MWe, which is a 16.7% increase since 1995; the total
energy generated during the last five years has been at least 49261 GWh; about 1165
wells more than 100 m deep have been drilled, and at least 13621 person-years of
professional geothermists’ time has been expended in the nations that reported this
statistic.
Categories of utilization of geothermal energy worldwide are given in Table 5. As
shown in Table 6, geothermal (ground source) heat pumps have had the second largest
energy use growth since 1995, over 59% almost all of which occurred in the United
States and Europe. The installed capacity is 5275 MWt and the annual energy use is
23 275 TJ/year in 26 countries. On the other hand, energy use growth in space heating
since 1995 is 12 percent as reported by 30 countries. About 75 percent of the 42 426
TJ/year utilization is estimated for district heating, and the remainder for individual
space heating. The majority of the district heating systems are in France, United
States, China, Japan and Turkey.
Greenhouse energy use increased by 13 percent or 2.5% annually. The countries
that have made maximum use of geothermal energy for heating greenhouses and
covered ground include China, Georgia, Hungary, Iceland, Italy, Russia, Tunisia and
Renewable Energy: Power For a Sustainable Future
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Table 5. Installed geothermal generating capacities some
selected countries, 1995–2000
Country
China
Costa Rica
El Salvador
Ethiopia
France
Guatemala
Iceland
Indonesia
Italy
Japan
Kenya
Mexico
New Zealand
Nicaragua
Philippines
Portugal
Russia
Thailand
Turkey
USA
Total
1995
(MWe)
28.78
55
105
0
4.2
0
50
309.75
631.7
413.7
45
753
286
70
1227
5
11
0.3
20.4
2816.7
6832
2000
(MWe)
29.17
142.5
161
8.52
4.2
33.4
170
589.5
785
546.9
45
755
437
70
1909
16
23
0.3
20.4
2228
7973
2005
(est. MWe)
n/a
161.5
200
8.52
20
33.4
186
1987.5
946
566.9
173
1080
437
145
2673
45
125
0.3
250
2376
11414
1995–2000
% increase
MWe increase
0.39
1.35
87.5
159
56
53.3
–
8.52
0
0
33.4
120
240
279.75
90.3
153.3
24.3
133.2
32.2
0
0
2
0.3
151
52.8
0
0
682
55.8
11
220
12
109
0
0
0
0
–588
n/a
1141
17
Source: Hunter (2001)
Table 6. Categories of utilization of geothermal energy worldwide
Geothermal heat pumps
Space heating
Greenhouse heating
Agriculture pond heating
Agricultural drying
Industrial uses
Bathing and swimming
Cooling and snow melting
Others
Total
Source: Lund (2001)
Capacity (MWt)
2000
1995
5275
1854
3263
2579
1246
1085
605
1097
74
67
474
544
3957
1085
114
115
137
238
15145
8664
Utilization (TJ/year)
2000
1995
23275
14617
42926
38230
17864
15742
11733
13493
1038
1124
10220
10120
79546
15742
1063
1124
3034
2249
190699
112441
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the United States. The energy use ranged from 3 to 102 TJ/year/ha, with most between
13 and 27 TJ/year/ha. Only 13 of 27 countries reported their heated area, which
totalled 417 ha. On the other hand, aquaculture use of geothermal energy dropped by
13 percent over the last 5 year period. A total of 16 countries reported installations,
with the largest use in China, Iceland, Georgia, Israel, Turkey and the United States
(Lund and Freeston, 2001).
Solar thermal energy
Heat and power from thermal conversion were used as early as 1948. Recently, almost
all countries with some industrial base are building solar water heaters. Israel saves
about 4 percent oil importation by using solar water heaters in almost all their
buildings. Turkey produces 1/4 of a million systems a year and Egypt legislated since
1990 that all newly built buildings must have solar water heaters as an integral part of
the buildings. As for the electricity generation, desalination and processed heat, many
applications exist in the USA, Asia and Africa. The main source book of Solar
Engineering of Thermal Processes written by Duffie and Beckman (1991) gives a
detailed discussion on these subjects.
The demand for solar thermal installations is growing constantly in Europe. On
average the number of glazed solar collectors sold annually grew by 18 percent from
1994 to 1999. In 1994, 480,000 m2 of glazed collectors were sold, the 890,000 m2 sold
in 1999 was almost double that. The total collector area has also almost doubled from
4.5 million m2 to 8.5 million m2. That sees the industry on a path of growth as wished
by the Commission’s White Paper. However, development must accelerate
substantially to reach the target of 100 million m2 were installed collectors by 2010;
that would require annual growth by 35%, it means that a doubling of the growth rate
(REFOCUS, 2001).
The solar thermal markets of the individual European countries contribute very
variedly to the overall European market. In 1999, almost half the 420,000 m2 are
glazed collectors installed in Europe were sold in Germany (see Table 7). Greece and
Austria follow with 160,000 m2 and 141,000 m2 respectively, amounting to market
shares of 18% and 16%. All other countries have market shares of less than 5% each,
amounting to only 19% of the European market. If one takes the size of the countries
into account, their standings change. In 1999 Austria topped the table with 17.5 m2
installed collector area per 1,000 inhabitants, followed closely by Greece with 15.2 m2
per 1,000 inhabitants. Germany has only a third of that rating and comes third with 5.1
m2 per 1,000 inhabitants. A number of countries follow with small gaps such as
Switzerland (4.4 m2), Denmark (2.6 m2) and the Netherlands (1.9 m2).
Photovoltaics
Photovoltaics, the use of semiconductor materials to convert sunlight directly into
electricity (and which has been used extensively in space programs), has seen costs
come down from approximately US $1 per kWh in 1980 to 20–30 cents per kWh
today. And with increasing scales of manufacturing and increasing emphasis on thinfilm devices, it is expected that electricity costs from photovoltaics will fall below 10
cents per kilowatt-hour early in the next decade. Current annual world production has
Renewable Energy: Power For a Sustainable Future
616
reached 150 MWp and is growing at more than twenty percent per year. This
corresponds to a doubling time of less than four years, and many new or expanded
manufacturing plants are going on line (IEA, 2000).
Solar photovoltaics (PV) technology is well established and used for a wide variety
of applications (lighting, communication/signals, battery charging, consumer
products, etc.). Annual shipments of PV modules generally increased by some
12–15% per year in the nineties but have increased sharply during the last two years
mainly due to heavily subsidized grid-connected residential programme in Japan and
programmes in the Netherlands and Germany. Total shipments of PV modules since
1971 till the end of 1998 were about 960 MW include PV modules for consumer
products (calculators, etc.). Efficiency improvement, cost reduction and high
reliability have contributed to the expansion of PV globally. Table 8 shows world PV
cell/module shipments for 1999 and before (Sayigh, 1999; IEA, 2000).
Table 7. Market data of solar thermal energy in Europe and
some non-European countries (glazed collectors)
Country
France
Belgium
Great Britain
Italy
Portugal
Spain
Sweden
Finland
Netherlands
Denmark
Switzerland
Germany
Greece
Austria
USA
India
China
Turkey
Japan
South Korea
Israel
Source: REFOCUS (2001)
Installed
in 1999
(m2)
6,000
1,500
9,000
24,000
4,500
33,000
9,000
7,000
30,000
4,000
31,000
420,000
160,000
141,000
25,000
2,000,000
4,000,000
430,000
1,000,000
500,000
400,000
Total installed
by the end of
1999
(m2)
296,000
19,500
141,000
244,000
219,500
313,000
157,000
12,000
146,000
282,000
241,000
2,290,000
2,645,000
1,476,000
–
–
–
–
–
–
–
Installed in 1999
per 1,000
inhabitants
(m2)
0.1
0.1
0.2
0.4
0.5
0.8
1.0
1.4
1.9
2.6
4.4
5.1
15.2
17.5
0.1
2.0
2.0
6.8
7.9
10.8
67.1
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The price of PV slightly increased in 1997, from 4.15 $/W to 4.20 $/W. In the USA
the biggest production as made by Siemens Solar with 24 MW, followed by Solarex
with 14.8 MW. In Europe, BP Solar International production was 11.3 MW, followed
by ASE GmbH and shell Netherlands of 2.0 MW each. In Japan the biggest production
of PV cells goes to Kyocera with 15.4 MW followed by sharp of 10.6 MW . On the
other hand, the dominating news about PV installations are that of the USA one
million roofs program by the year 2010 and the Japanese 70,000 roofs program by the
year 2000. The cost of the Japanese installations will be $18,000 for 3 MW power
systems in the year 2000. This will provide electricity at a cost of $ 0.27 per kWh is
very close to the electricity from the Japanese utility.
The developing countries keep adequate progress in cell production during 2000.
Terrestrial PV applications started in China around 1970 and total installed PV power
capacity stood at about 18 MWp by the end of 2000. The PV applications are mainly
in the areas of communication, remote electrification, professional use, and
commodities. In India, currently there is around 58 MW of installed PV capacity
(corresponding to about 750,000 systems) that is being used for various applications.
Under the PV program of Ministry of Non-conventional Energy Sources (MNES),
about 475,000 systems aggregating to over 15 MW have been installed. This includes
305,000 solar lanterns; 130,000 home lighting systems; 40,000 street lighting systems,
3,450 water pumping systems and about 1.1 MWp aggregate capacity of stand alone
power plants (REFOCUS, 2001).
Around the world there are many projects utilizing PV in such diverse climates,
cultures and economics as Germany, with 2000 homes, to the US Department of
Energy sponsoring a rural electrification project in Brazil for 500,000 homes. There
are 100,000 families in rural developing countries of Dominican Republic, Kenya, Sri
Lanka and Zimbabwe, all using PV power for lighting, radio and television. On the
other hand, since 1988, Indonesia has led the way among the developing countries in
the use of PV. The country has tens of thousands of villages scattered throughout the
thousands of islands with no electricity service. During 1992, 8000 PV systems were
installed in remote areas. Applications include street lighting, public television, radio,
telecommunications, cathodic protection, security lighting, vaccine refrigerators,
waterway lighting and individual home lighting. It is estimated that more than 100,000
people are served by the system already.
Table 8. World PV cell/module shipments in MW
Country
USA
Japan
Europe
ROW
Total
1993
22.44
16.70
16.55
4.40
60.09
1994
25.64
16.50
21.70
5.60
69.44
ROW = Rest of the World
Source: Sayigh (1999) and IEA (2000)
1995
34.75
16.40
20.10
6.35
77.60
1996
38.85
21.20
18.80
9.75
88.60
1997
53.00
35.00
29.30
9.40
126.70
1998
57.20
42.10
38.40
12.20
150.00
1999
63.32
48.30
50.20
16.40
178.22
Renewable Energy: Power For a Sustainable Future
618
Wind energy
Wind energy was used more than 3500 years ago, whether in boats to transport goods
in Egypt and Iraq (Mesopotamia). It is a clean source of energy, abundant in most parts
of the world, low in cost, sustainable, safe, popular and can create jobs. Wind
resources in developing countries are sufficient to produce thousands of MW of power
in Asia and Latin America. It is especially strong along coasts: western China, parts of
India, parts of Turkey, northeast and south Brazil, and North Africa. The wind energy
potential in the UK can supply all the electricity needs of all Western Europe.
During the year 2000, some 3,800 MW of new wind energy generating capacity were
installed worldwide, representing annual sales of about $4 billion and boosting total
installed capacity to about 17,300 MW. In 1999, a record-breaking total of 3,900 MW of
new wind energy generating capacity were installed globally. About 2,500 MW came
online in 1998. Table 9 shows wind energy installed capacities of some selected countries.
Table 9. Wind energy installed capacity of some selected countries (MW )
Country
Germany
USA
Denmark
Spain
India
Netherlands
Great Britain
China
Italy
Sweden
Canada
Greece
Ireland
Japan
Portugal
Austria
New Zealand
Finland
Brazil
France
Australia
Egypt
Argentina
Turkey
Source: AWEA (2001)
Installed
Capacity
(1997)
2081
1673
1148
512
940
319
319
166
103
122
25
29
53
18
38
20
4
12
3
10
11
5
9
0
Installed
Capacity
(1998)
2875
1820
1448
834
968
361
333
214
180
174
82
39
73
40
60
30
5
17
17
19
17
5
12
9
Installed
Capacity
(1999)
4444
2500
1748
1522
1077
410
343
246
227
197
125
79
73
68
60
35
35
32
25
22
17
15
13
9
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The past year’s growth remained concentrated in Europe. Some 3,500 MW of new
installed capacity went online in Europe, of which half (1,669 MW) were in Germany.
Spain installed 713 MW of new wind energy generating capacity in 2001 and
Denmark 552 MW, according to those countries’ respective trade associations.
Growth in the European wind energy market has been strong and steady that the
European Wind Energy Association (EWEA) has raised its goal for the region by 50%
from 40,000 MW to 60,000 MW of installed capacity by 2010, of which 5,000 MW
are expected to be offshore capacity (AWEA, 2001).
The slightly slower rate of growth in projects coming online worldwide in 2000 (an
increase of 28% in 200 compared to 37% in 1999) is largely due to a temporary dip in
the U.S. market. Only a handful of projects was dedicated this year in the U.S. as the
industry paused after the wind rush of 1999 and prepared for another in 2001: new
wind projects totalling some 2,000 MW are proposed for completion by the end of
2001 in Texas and other regions of the U.S. On the other hand, wind power has already
proven itself in California, where harnessing the wind now produces enough power for
about 300,000 homes. Most of the wind power comes from wind plants in mountain
passes at Altamont, east of San Francisco; at Tehachapi, northeast of Los Angeles; and
at San Gorgonio Pass, northwest of Palm Springs. But these wind plants represent only
a small portion of U.S. potential for wind power (AWEA, 2001).
The Mediterranean region is beginning to tap its wind. Just south of one of
Europe’s most dynamic wind energy markets, Spain, the kingdom of Morocco brought
50 MW of wind energy online as part of its program to diversity its energy portfolio.
Southern Italy’s province of Apulia now plays host to a new 170 MW project. Further
to the east, Egypt saw 30 MW of new wind energy go online on the Red Sea coastline
about 250 km south of Cairo. Turkey’s first wind farm was commissioned in 1998, and
has a capacity of 1.5 MW. Capacity is likely to grow rapidly, as plans have been
submitted for just under a further 600 MW of independent facilities. The majority of
·
proposed projects are located in Çe·sme, Izmir and Çanakkale regions about 750 km
west of Ankara (Kaygusuz and Kaygusuz, 2001).
By contrast, the Asian and Latin American markets (with the exception of
Argentina) remain largely inactive or uncertain. India and China, with historically the
largest amount of installed wind energy generation capacity among the developing
countries, have only developed a minute fraction of their respective wind energy
potentials so far. In India, the present total wind capacity is 1220 MW (as end of
September 2000). The wind energy growth was the highest during 1994 to 1996 with
total 617.64 MW. Due to various reasons subsequently there was a decline but it is
now slowly picking up again (Brown, 2001). China has world-class wind resources
and a future need for electricity to justify large-scale grid connected wind power
development. Large-scale wind power is viewed as having the highest
commercialization potential among new grid-connected renewable energy
technologies in China. It is estimated that there are 253 GW of exploitable wind
resources, across northern and eastern China. By the year 2001, China’s installed
capacity of grind-connected wind power totalled 345 MW, generated on 26 wind
farms in 11 of China’s 27 provinces and 5 municipalities. Many of these sites have
over a decade of operating experience. Future development and current construction
620
Renewable Energy: Power For a Sustainable Future
will expand wind power use into new locations, with predictions that wind power
installed capacity will reach 7 GW by 2015 (Graham, 2001).
ENVIRONMENTAL BENEFITS OF RENEWABLES
As the world moves into the 21st century, international dimensions of environmental
problems will become more important. Globalization of the economy, emergence of
worldwide communication and information networks, and rapid development of
biotechnology all have important consequences for the environment. One may expect
that by the middle of the next century about ten billion people will be placing stresses
on the natural resources will lead to further environmental problems. In fact, future
environmental problems will arise not only from the exhaustion of natural resources
but also from how those resources are consumed. New technologies can and will
lessen damaging environmental impacts if they are employed wisely, guided by the
market system (Dinçer, 2001).
Growing concerns about acid rain and then global climate change since the late
1980s has reinvigorated interest. Climate change created a completely new impetus for
clean energy technologies, of which renewable energy technologies are a major
component. Renewable energy technologies become important as environmental
concerns increase, utility cost climb and labour costs escalate. In addition, the
development and implementation of renewable energy technologies depends in part on
the global economy. Increased research and development in the “high-technology”
fields, some of which include, and contribute to the utilization of renewable energy
technologies. Progress in other technical fields has contributed some innovative ideas
in renewable energy system design. Advanced computational methods allow designers
to optimize system performance, cost/benefit ratios, and environmental impact
simultaneously, conveniently and quickly (IEA, 2000).
Increased use of renewable energy that displaces or delays increased use of other
fuels can help reduce the negative environmental impacts associated with these fuels.
Of course, there are also negative environmental impacts of renewable energy use,
especially if examined over the full life-cycle of production and decommissioning,
although the disbenefits are generally small in comparison to renewable energy’s
benefits. The environmental impacts of renewable energy use are discussed in the IEA
publication (IEA, 1998b) and UNDP publication (UNDP, 2000). This is often the
main reason for which renewable energy is promoted. In addition, the dispersed nature
of renewable energies means that all countries possess some indigenous renewable
energy resources (to a greater or lesser extent); harnessing those energy sources can
therefore help improved energy security.
Biomass energy can be carbon neutral when all biomass produced is used for
energy. Some of the proposals for reducing the impact of global warming have centred
on the need to fix or sequester atmospheric CO2 by tree planting on a very large scale.
Whilst there is little doubt that the halting of deforestation and the replanting of large
areas of trees would bring many environmental benefits, the adoption of a wider
biomass energy strategy may be a more cost-effective way of regulating the CO2
balance of the atmosphere. On the other hand, CO2 and H2O are never the sole
products of the use of fuels. It has been argued, for example, that although bio-diesel
ENERGY EXPLORATION & EXPLOITATION · Volume 19 · Number 6 · 2001
621
generates 65% less CO2 than the equivalent fossil fuel, its advantage falls to 35% when
other greenhouse gases such as NOx and CH4 are taken into account. In general, byproducts result from the high temperatures of combustion, and most fuels also contain
some incombustible material (ash) must be removed from the furnace. For many fuels,
careful attention to plant design, construction and operation is required to ensure that
complete combustion is achieved and prevent the emission of poisonous products of
incomplete combustion (Hall, 1997).
Further, biofuels are inherently cleaner than coal, with virtually zero sulphur
content. Their more uniform energy content and greater reactivity makes it easier to
optimize the design of combustion systems, and means there is no need for ‘scrubbing’
equipment to remove sulphur dioxide.
Biofuels are therefore ‘clean’ with respect to greenhouse gas emission (CO2) and
acid gas emissions (SO2). Another constituent of acid rain, nitrogen oxides (NOx), can
be produced by the burning of any fuel, particularly where the drive for fuel efficiency
has led to a higher combustion temperature. Their level can, however, be greatly
reduced using modified combustion systems and/or catalysts to clean up exhaust
gases.
Geothermal energy, with its proven technology and abundant resources, can make
a significant contribution toward reducing the emission of greenhouse gases worldwide. It is necessary for governments to implement a legal and institutional framework
and fiscal instruments allowing geothermal resources to complete with conventional
energy systems. International forecasts expect the share of renewable energy sources
in the world energy mix to increase very significantly in the new century (to 30–80%)
in 2100). How large the share of geothermal energy will be in the world energy at the
end of the new century is much dependant on the actions of the geothermal community
and the countries leading geothermal development (Fridleifsson, 2001).
The range in CO2 emissions from high-temperature geothermal fields used for
electricity production in the world is 13–380 g/kWh, whereas the CO2 emissions are
453 g/kWh for natural gas, 906 g/kWh for oil and 1042 g/kWh for coal (UNDP, 2000).
Sulfur emissions are also significantly less for geothermal than fossil fuel electric
power plants. On the other hand, the gas emissions from low-temperature geothermal
resources are normally only a fraction of the emissions form the high-temperature
fields used for electricity production. Conventional geothermal schemes in
sedimentary basins commonly produce brines are generally reinjected into the
reservoir and thus never released into the environment, so CO2 emission of the
geothermal energy is zero.
Wind energy can be regarded as environmentally friendly; however, it is not free of
emissions. The production of the blades, the nacelle, the tower, etc., the exploration of
the material and the transport of equipment leads to the consumption of energy
resources, hence emissions are produced as long as they energy resources are based on
fossil fuel. These emissions are known as indirect emissions. Table 10 provides an
overview of the most important emissions related to electricity production based on
different power generation technologies. The data comprises direct emissions and
indirect emissions. The calculation is based on the average German energy mix and on
typical German technology efficiency. On the other hand, wind energy has the
Renewable Energy: Power For a Sustainable Future
622
potential to play an important role in the future energy supply in many areas of the
world. Within the last 10 years, wind turbine technology has reached a very reliable
and sophisticated level. The growing international market will lead to further
improvements, such as large wind turbines. These improvements will lead to further
cost reductions, and for the medium term, wind energy will be able to compete with
conventional fossil fuel power generation technology (Ackerman and Söder, 2000).
The Kyoto Protocol promotes the eventual use of innovative approaches such Joint
Implementation (JI), the Clean Development Mechanism (CDM) and emissions
trading which will likely have an important long-term effect on the deployment of
renewable energy technologies globally. The greenhouse gas emissions reduction
targets of the Protocol imply that, once the Protocol is ratified, developed countries
will pay particular attention to renewable energy because of its great potential for
reducing global greenhouse gas emissions. But while renewables contribute to
resolving environmental issues, including global climate change, there are still some
environmental concerns, particularly at the local level, which show down renewable
energy market penetration, at least in the short-term (IEA), 1998).
Most quantification of the benefits or renewable energy relates to greenhouse gas
emissions. The European Union’s White Paper on renewable energy (EC, 1997) states
that if the target to double the share of renewable energy is achieved, CO2 emissions
would be reduced by 402 million tones per year by 2010 in the European Union.
According to the White paper, this represented approximately one-third of the
expected CO2 reduction target.
Table 10. Comparison of energy amortisation time and emissions of
various energy technologies
Technology
Coal fired
Gas (CCGT)
Large-hydro
Micro hydro
Small hydro
Wind turbine
4.5 m/s
5.5 m/s
6.5 m/s
Photovoltaic
Mon-crystalline
Multi-crystalline
Amorphous
Energy pay back
time in months
1.0–1.1
0.4
5–6
9–11
8–9
Source: Ackermann (2000)
SO2 emission
In kg/GWh
630–1370
45–140
18–21
38–46
24–29
NO2 emission
In Kg/GWh
630–1560
650–810
34–40
71–86
46–56
CO2 in
Ton/GWh
830–920
370–420
7–8
16–20
10–12
6–20
4–13
2–8
18
13–20
10–16
26–43
18–27
14–22
19–34
13–22
10–17
72–93
58–74
51–66
230–295
260–330
135–175
270–340
250–310
160–200
200–260
190–250
170–220
ENERGY EXPLORATION & EXPLOITATION · Volume 19 · Number 6 · 2001
623
CONCLUSIONS
Renewable energy is a carbon-free or carbon-neutral energy source, the increased use
of which can be part of the package of policies and measures by some developed and
developing countries work to meet their emissions commitments as set out in the
Kyoto Protocol. Increased renewable energy supply can also help governments
achieve other policy goals, including energy security and diversity. Renewable energy
encompasses a wide diversity of fuel types and fuel uses. The applicability of each of
these, and the cost of different renewable energy technologies vary greatly. Some
renewable energy sources, such as hydro and biomass, are widely used and widely
available (see Table 11). Others, such as geothermal, are widely used where they are
available. Some renewable energies such as solar and wind are not yet used on a large
scale, although they have a huge untapped potential. On the other hand, declining
renewable energy costs, improvements in renewable energy technology, and
governments’ interest in promoting renewable energy because of their positive
environmental effects, should result in the continued growth of renewable energy use
and importance. The use of renewable energy has already helped to reduce growth in
greenhouse gas emissions from the energy sector, and many countries’ governments
see an increased use of renewable energy as both feasible and desirable. The following
conclusions should be given (UNDP, 2000):
•
Biomass can make a large contribution to the future world’s energy supply. Land
for biomass production should not be bottleneck, if the modernization of
conventional agricultural production continues. Recent evaluations indicate that
if land surfaces of 400–700 million hectares were used for biomass energy
production halfway into the 21st century, there could be no conflicts with other
land-use functions and the preservation of nature.
•
Although developing countries are the main consumers of biomass, the potential,
production, and use of biomass in these countries are often poorly quantified and
documented.
Table 11. Status of electricity production from renewable energy sources
Energy
production
in 1998
Renewables TWh(e) (%)
Hydropowera 2600 91.90
Biomass
160
5.66
Geothermal
46
1.63
Wind
18
0.64
Solar PV
0.5
0.05
Solar Ther-Elec. 1
0.10
Tidal
0.6
0.02
Operating
capacity
end 1998
GWe
(%)
663 91.71
40
5.53
8
1.11
10
1.38
0.5
0.12
0.4
0.11
0.3
0.04
Capacity
Factor
(%)
20– 70
25– 80
45– 90
20– 30
8– 20
20– 35
20– 30
Current
Future
Energy
Energy
Turnkey
cost
cost
Investment
(cent/kWh) (cent/kWh) Cost U$/kW)
2– 10
2– 8
1000– 4000
5– 15
4– 10
900– 3000
2– 10
108
800– 3000
5– 13
3– 10
110– 1700
25– 125
5– 25
5000– 10000
12– 18
4– 10
3000– 4000
8– 15
8– 15
1700– 2500
Source: UNDP (2000)
a Large hydro stations produce 2510 TWh (capacity 640 GWe) and small 90 TWh (23 GWe)
PV: Photovoltaics Ther-Elec.: Thermal electricity
624
•
•
•
•
•
•
•
•
Renewable Energy: Power For a Sustainable Future
Biomass can be used for energy production in many forms. The resource use, the
technologies applied, and the set-up of systems will depend on local conditions,
both physical and socioeconomic. Agricultural crops offer cheap and productive
biomass production, with low or even positive environmental impacts.
Although wind-generated electricity is an intermittent resource, it can be
transformed to baseload power supply if combined with energy storage. For
compressed air energy storage the additional costs may be limited to about $0.01
a kWh, opening the possibility of exploiting good wind resources remote from
markets.
The environmental impacts of wind turbines are limited, with noise and visibility
causing the most problems, increasing public resistance against the installation
of new turbines in densely populated countries.
Today photovoltaics generally cannot compete with conventional power plants
in grid-connected applications. It remains uncertain whether and when
photovoltaics will compete with fossil fuels on a large scale. This mainly
depends on the development of photovoltaics, on the price development of coal
and natural gas, and on possibilities for CO2 removal at low cost.
Supplying less than 1 percent of the world’s energy consumption, photovoltaic
systems can play a major role in rural electrification by reaching many of the 2
billion people in developing countries who do not have access to electricity.
In the sunbelt of the world, solar thermal power is one of the candidates to
provide a significant share of renewable clean energy needed in the future. Solar
thermal energy is now ready for more widespread application if we start more
intensified market penetration immediately, its application is not strongly
restricted by land area or resource limitation.
Hydropower is a clean energy source with many technical advantages over
thermal and nuclear plants: operating reserves, spinning reserves. On the other
hand, improvements and efficiency measures are needed in dam structures,
turbines, generators, substations, transmission lines, and environmental
mitigation technology to sustain hydropower’s role as a clean, renewable energy
source.
Geothermal energy, with its proven technology and abundant resources, can
make a significant contribution towards reducing the emission of greenhouse
gases. But it requires that governments implement policies and measures to
improve the competitiveness of geothermal energy systems with conventional
energy systems.
BIBLIOGRAPHY
Ackermann, T. and Söder, L. Wind energy technology and current status: a review.
Renewable and Sustainable Energy Reviews 2000; 4: 315–374.
American Wind Energy Association (AWEA ). 2001. Global wind energy market
report; http://www.awea.org
Birol, F. and Argiri, M. 1999. World energy prospects to 2020. Energy 24: 905–918.
Brown, CA. Wind power in China. Refocus April 2001: 24–29.
ENERGY EXPLORATION & EXPLOITATION · Volume 19 · Number 6 · 2001
625
Boyle, G (ed.). 1998. Renewable energy: Power for a sustainable future. Oxford
University Press: Oxford.
Cavaney, R. 2000. At the millennium: a new dawn for the petroleum industry?
In Energy 2000. Sovereign Publications: London
D’Apote, S.L. (1998. IEA biomass energy analysis and projections. Biomass Energy:
Data, Analysis and Trends. Conference Proceedings, Paris, pp. 151–179.
Dincer, I. 2001. Environmental issues: I-Energy utilization. Energy Sources 23:
69–81.
Duffie, J.A. and Beckman, W.A. 1991. Solar engineering of thermal processes.
2nd ed. New York: Wiley.
European Commission (EC). 1997. Energy for the future: renewable sources of
energy,
White Paper for a Community Strategy and Action Plan, December 1997.
Flavin, C and S. Dunn. 1998. Climate of opportunity: renewable energy after Kyoto.
Renewable Energy Policy Project. http://www.repp.org/
Fridleifsson, I.B. 2001. Geothermal energy for the benefit of the people.
Renewable and Sustainable Energy Reviews 5: 299–312.
Graham, J. Ripening renewable energy market in China. Refocus April 2001: 18–23.
Hall, D.O. 1997. Biomass energy in industrialized countries–A view of the future.
Forest Ecology and Management 91: 17–45.
Hutter, GW. The status of world geothermal power generation 1995–2000.
Geothermics 2001: 30: 1–27.
International Energy Agency (IEA ). 1998a. World Energy Outlook. Paris:
IEA/OECD.
International Energy Agency (IEA). 1998b. Benign Energy?: The Environmental
Implications of Renewables. Paris: IEA/OECD.
International Energy Agency (IEA). 2000. The evolving renewable energy market.
Paris: IEA/OECD. http://www.iea.org
Kaygusuz, K. Hydropower and biomass as renewable energy sources in Turkey.
Energy Sources 2001; 23: 775–799.
Kaygusuz, K. Hydropower potential in Turkey. Energy Sources 1999; 21: 581–588.
Kaygusuz, K and A. Kaygusuz. 2001. Renewable energy and sustainable development
in Turkey. Renewable Energy (in press).
Lerer, LB and Scudder, T. Health impacts of large dams. Environmental Impact
Assessment Reviews 1999; 19: 113–123.
Lund. JW. And Freeston, DH. World-wide direct uses of geothermal energy 2000.
Geothermics 2001; 30: 29–68.
Nogueira, L.A.H. and M.A. Trossero. 1998. Introducing WEIS : The FAO wood
energy Information system. Biomass Energy: Data, Analysis and Trends.
Conference Proceedings, Paris, March, p. 151.
626
Renewable Energy: Power For a Sustainable Future
National Renewable Energy Laboratory (NREL ). 2000. Renewable energy: a guide to
the new world of energy choices http://www.nrel.doe.gov/
REFOCUS (International Renewable Energy Magazine), June 2001, pp. 18–20 and
32–34. Netherland: Elsevier; http://www.re-focus.net
Sarkar, A.U. and Karagoz, S. 1995. Sustainable development of hydroelectric power.
Energy 20: 977–981.
Sayigh, A. 1999. Renewable energy–the way forward. Applied Energy 64: 15–30.
Sorensen, B. 1979. Renewable Energy, Academic Press: New York.
Twidel, J and A. Weir. 1986. Renewable Energy Resources. ELBS Edition: London.
United Nations Development Program (UNDP ). 2000. World Energy Assessment:
Energy and the Challenge of Sustainability, UNDP, New York.
United Nations Development Program (UNDP ). 2001. Bioenergy Primary:
Modernised Biomass Energy for Sustainable Development, UNDP, New York.
Walter, A. Biomass energy in Brazil: past activities and perspectives. Refocus Jan/Feb
2001: 26–30.