Volume 6 hydro power 6 01 – hydro power – introduction

Volume 6 hydro power 6 01 – hydro power – introduction Volume 6 hydro power 6 01 – hydro power – introduction Volume 6 hydro power 6 01 – hydro power – introduction Volume 6 hydro power 6 01 – hydro power – introduction Volume 6 hydro power 6 01 – hydro power – introduction

A Lejeune, University of Liège, Liège, Belgium

© 2012 Elsevier Ltd All rights reserved

6.01.1 Introduction

6.01.2 Hydroelectricity Progress and Development

6.01.2.1 Key Features of Hydroelectric Power

6.01.2.1.2 Ancillary services

6.01.2.1.3 Pumped-storage plants

6.01.2.1.4 GHG emissions

6.01.2.1.5 Environmental and social problems

6.01.2.2 Hydropower Development

6.01.2.2.1 Where the hydropower potential has been exploited

6.01.2.2.2 Where large hydropower potential has still to be exploited

6.01.2.2.3 Hydropower in integrated water resources management

6.01.2.2.4 International cooperation

6.01.2.2.5 Guidelines

6.01.3 Volume Presentation

6.01.3.1 Contributions and Authors, Affiliations of Volume 6

References

Glossary

Baseload power plant Baseload plant (also baseload

power plant or base load power station), is an energy

plant devoted to the production of baseload supply

Baseload plants are the production facilities used to meet

and produce energy at a constant rate

Energy Energy is the power multiplied by the time

Gigawatt hour (GWh) Unit of electrical energy equal to

Hydropower Hydropower, P = hrgk, where P is Power in

kilowatts, h is height in meters, r is flow rate in cubic meters

k is a coefficient of efficiency ranging from 0 to 1

Hydropower resource Hydropower resource can be

measured according to the amount of available power, or

energy per unit time

Megawatt (MW) Unit of Electrical power equal to one million (106) watt

Pumped storage plant Pumped-storage hydroelectricity is

a type of hydroelectric power generation used by some power plants for load balancing The method stores energy in the form of water, pumped from a lower elevation reservoir to a higher elevation Low-cost off-peak electric power is used to run the pumps During periods of high electrical demand, the stored water is released through turbines Although the losses of the pumping process makes the plant a net consumer of energy overall, the system increases revenue by selling more electricity during periods of peak demand, when electricity prices are highest Pumped storage is the largest-capacity form of grid energy storage now available

Tetrawatt hour (TWh) Unit of electrical energy equal to

6.01.1 Introduction

generation worldwide Thus, it is by far the most widespread form of renewable energy

hydropower is considered as a renewable resource) increased from 46.52 to 127.93 million gigawatt-hours (GWh) A gigawatt-hour is a measure of the total energy used over a period, equal to 1 million kilowatt-hours; 1 GWh is sufficient to

energy consumption was for oil, followed by coal (at 35.6% and 2\8.6%, respectively), and consumption in those areas has been growing However, their growth has been curbed by the growth in energy consumption from renewable sources, including

increase was almost constant, in the past few years this rate increased Electricity is growing faster than any other end-use source

20 000

18 000

Middle East

14 000

Asia

12 000

Latin America

Japan and Pacific

8000

4000

0

1965 1968 1972 1976 1980 1984 1988 1992 1996 2000 2004

60 000

50 000

40 000

TWh 30 000

20 000

10 000

0

Natural gas Oil Coal Nuclear Hydro

of energy; the rate of increase is currently in the order of 800 terawatt-hour (TWh) yr−1 (more than +4% yr−1), as shown in

This is related to the high rate of economic growth in emerging economies that mainly contribute to keep up energy needs and soaring prices While in Organisation for Economic Co-operation and Development (OECD) countries, accounting for half of the total electricity market, the power production continued with the usual historical trend (+2%), Asia and Middle East reported a rapid growth in their energy needs, with a special focus on the Chinese performance Asian power generation has now exceeded the

Electricity generation from coal and gas has been increasing faster than from any other sources, and counts now for >60% of total generation The future scenarios for energy have been examined by several agencies

• World energy consumption will increase by about 30%, with China and India being the two main drivers

• The power sector will be the biggest contributor to the world’s energy demand growth, representing about 40% of the total energy consumption increase by 2020

identified two such scenarios:

• ‘Reference Scenario’ in which renewables will only constitute ∼14% of the world’s primary energy demand by 2030

Rest of

America 6%

CIS 7%

EU-27

16%

Asia+Pac (exc China) 19%

Oil Biomass Other renewables

Nuclear Hydro Gas Coal

2007

2015

2030

TWh

generation will be modified due to the Fukushima accident

• ‘Alternative Policy Scenario’ in which renewables share rises to ∼16%, assuming the implementation of policies currently being

that 189 United Nations (UN) member states and at least 23 international organizations have agreed to achieve by 2015 The

countries, encompassing universally accepted human values and rights:

1 Eradicate extreme poverty and hunger

2 Achieve universal primary education

3 Promote gender equality and empower women

4 Reduce child mortality

5 Improve maternal health

6 Combat HIV/AIDS, malaria, and other diseases

7 Ensure environmental stability

8 Develop a global partnership for development

Though energy access is not an MDG in itself, it is evident that adequate provision of energy and energy access to all remain

use and greenhouse gas (GHG) emissions will require more efficient technologies for the supply and use of energy and a transition to cleaner and renewable energy sources Therefore, it is evident that the world needs energy, clean energy, and cheap energy

2000

1800

Japan

1000

Canada

800

800

Turkey Norway

600

400 France Spain

Germany

1971 1979 1987 1995 2003 2007

India

China

Venezuela

Brazil

Ukraine

Russia

Former URSS

Other CIS

Non OECD

6.01.2 Hydroelectricity Progress and Development

In about 60 countries, hydroelectricity is contributing >50% of the national electricity supply In absolute terms, more than half of the total hydroelectricity production is produced by five countries only: China, Canada, Brazil, United States, and Russia (Figure 7) [5]

According to the World Register of Dams, dams were built around the world primarily for irrigation purpose (38%) and secondarily for hydropower purpose (18%) But today, some 8200 large dams are currently in operation having hydropower as the main or sole purpose Some of them serve very large hydro plants The largest hydroelectric dams and plants in operation

hydropower dams construction is played by China and most of the largest hydroelectric dams under construction are constructed by the Chinese

3500

3000

2500

Middle East

Africa

2000

Asia

Latin America

1500

CIS Japan and Pacific

1000

North America

500

Europe

0

% of

total

Country

(based on first

10 producers)

electricity

generation

2005 data

IEA

2006 data

Max annual Year of Capacity production

Shushenskaya

Paraguay

a 22 500 when complete

b 6300 when complete

Table 2 Main schemes under construction

Maximum capacity Construction Scheduled

Hydropower

6.01.2.1 Key Features of Hydroelectric Power

After more than a century of experience, the strengths and weaknesses of hydropower are equally well understood

Its weaknesses (possible negative environmental and social impact, high upfront investment, etc.) are often over­ emphasized by opponents to dams and reservoirs, whereas its numerous and great benefits are not always adequately emphasized

An analysis of the advantages and disadvantages of hydropower is found in Chapter 3, Constraints of hydropower development (Hydropower: a multi benefit solution for renewable energy), from which are derived the comments given hereunder about the key features of hydropower

6.01.2.1.1 Cost

There are six different sources of renewable electricity Hydroelectricity is the principle source with an 86.3% share of the total renewable output Biomass, which includes solid biomass, liquid biomass, biogas, and renewable household waste, is the secondary source with 5.9%, a little ahead of the wind power sector with 5.7%, followed by geothermal power with 1.7%, solar

The cost of producing electricity is one fundamental criterion for decision making The high realization costs of dams, reservoirs, and

natural moving water directly into electricity and has therefore a very short and efficient energy chain, compared with fossil fuels It has

fuel plants are about 60% efficient Hydropower also has the best performance with respect to energy payback ratio, which is defined as

‘energy security’ (defined as “uninterrupted physical availability of energy products on the market, at a price which is affordable for all consumers,” Table 4)

6.01.2.1.2 Ancillary services

continue in countries where hydropower occupies a significant share in the power generation mix As other technologies are introduced, hydro production is mainly used to respond to gaps between supply and demand, allowing the optimization of base load generation from less flexible sources (such as nuclear, thermal, and geothermal plants), which can continue to operate at constant level at their best efficiency The fast response of hydro plants enables to meet sudden fluctuations due to peak demand or loss of other power supply options

These benefits are part of a large family of benefits of hydropower in assisting the stability of electricity production (ancillary services):

• Spinning reserve: ability to run at a zero load while synchronized to the electric system; when loads increase, additional power can

be loaded rapidly into the system to meet the demand

• Nonspinning reserve: ability to enter load into the system from a source not on line; other energy sources can also provide

Table 3 Structures of electricity production from renewable sources in 2008

Solar including photovoltaic,

Hydropower, 86.31%

Biomass, 5.94%

Wind power, 5.73%

Geothermal, 1.69%

0.32%

Marine energies, 0.01%

• Regulation and frequency response: ability to meet moment-to-moment fluctuations in system requirements; when a system is unable to respond properly to load changes, its frequency changes, resulting not just in a loss of power but potential damage to electrical equipment as well

• Voltage support: ability to control reactive power, thereby ensuring that power will flow from generation to load

• Black-start capability: ability to start generation without an outside source of power; this service allows to provide auxiliary power

to other generation sources that could take a long time to restart

Of course, the capability of providing these ancillary services depends on the storage capacity The full set of ancillary benefits

6.01.2.1.3 Pumped-storage plants

Pumped-storage plants are particularly well suited to manage peaks in electricity demand and to assure reserve generation In this role, they also have a remarkable environmental value: without pumped storage, to cope with unexpected peak demand or sudden loss of generating power, many thermal plants should operate at partial load as reserve generators, with increased fuel consumption and GHG emissions They also have great capability of load leveling because they can absorb power when the system has an excess Pumped-storage plants are therefore very effective means of improving ancillary services, thus playing a vital role for the reliability

of electricity systems in an increasingly deregulated power market

Base Base load Intermittent

load

267

250

205

200

150

100

27

0

Hydro with

voir Hydroiver Coal

Nucliear combined cycle

al gas Natur Fuel cell

Wind Solar km)

(H from gas ref

orming) Biomass

y 2000

plantation

aste

y w

voltaic r

(deliv

Bars indicate values that should be representative of the northeastern region of North America, for existing technologies The range of values, showed by black lines, Indicates the spread of all values found in the literature

These values are representative of different energy systems everywhere in the world

Biomass energy Electricity Heat Ethanol Wind electricity Solar photovoltaic electricity Solar thermal electricity Low-temperature solar heat Hydroelectricity

Large Small Geothermal energy Electricity Heat Marine energy Tidal Wave Current

5–15 ¢ kWh−1

1–5 ¢ kWh−1

8–25 $ GJ−1

5–13 ¢ kWh−1

25–125 ¢ kWh−1

12–18 ¢ kWh−1

3–20 ¢ kWh−1

2–8 ¢ kWh−1

4–10 ¢ kWh−1

2–10 ¢ kWh−1

0.5–5 ¢ kWh−1

8–15 ¢ kWh−1

8–20 ¢ kWh−1

8–15 ¢ kWh−1

Pumped-storage plants have some distinctive features in comparison with conventional hydropower plants:

• Greater output can be obtained with smaller reservoirs

• They do not need natural inflow to the reservoirs

• They can be built with considerably fewer hydrological and topographical restrictions

• Their impact on the surrounding ecosystems is comparatively less

Base and peak Base load options Intermittent

production

CO 600

511

400

200

118

0

Hydro with

oir Diesel Hydro iver reser

run-of-r

Hea Nuclear

combined cycle

al gas Fuel cell Biomass

Wind Solar photo voltaic

(H from gas ref

orming)

6.01.2.1.4 GHG emissions

The links between production of energy and climate change are now understood, and GHG emissions, mainly produced by burning fossil fuels, are known to contribute to global warming Hydropower tends to have a very low GHG footprint As water carries carbon in the natural cycle, all ecosystems (especially wetlands and seasonally flooded areas) emit GHG If the watershed contains a man-made reservoir, the preimpoundment emissions of the area would need to be compared with the emissions after the formation

of the reservoir

Studies in North America showed that hydropower reservoirs tend to increase the emissions marginally and a value of 10 000

hydropower Even so, hydropower GHG emissions amount to only a few percent of any kind of conventional fossil-fuel thermal generation (Figure 9) [6]

there is a growing concern to determine the contribution of freshwater reservoirs to the increase of GHG emissions in the atmosphere Therefore, it is important to continue the efforts for a better understanding and a quantitative definition of the subject

6.01.2.1.5 Environmental and social problems

Environmental concerns and problems related to dams and reservoirs are one of the main reasons emphasized by the opponents However, they are now a much-studied process Great efforts have been taken to understand them and to devise measures to avoid or rectify negative consequences These efforts resulted in a much greater knowledge and in the development of a broad range of mitigation strategies The integration of environmental and social considerations in the planning, design, and operation of dams is now a standard practice in many countries The analyses of possible problems and a comprehensive negotiation processes with all the involved stakeholders greatly improved the development effectiveness of the projects by eliminating unfavorable projects at an early stage Even the World Commission on Dams, who concluded that hydropower schemes had often environmental or social unaccep­ table costs, did not recommend that hydropower should be discouraged, or that only small schemes should be developed Instead,

an inclusive process was recommended in the planning, development, and management of the schemes It must also be noted that many well-conceived schemes have seen unappreciated service for several generations Some sites have been chosen as sites of special scientific interest because of the ecosystems that have become established in the reservoir areas

6.01.2.2 Hydropower Development

Europe and North America almost all the technically and economically feasible hydropower potential has been harnessed, a large unexploited hydropower potential is available in Asia, where the current production is less than one-third of the potential, and in Africa, where the ratio is even smaller

4000

Key (TWh yr−1)

Technical feasibility

3500

Current production

2500

2000

1500

1000

500

0

6.01.2.2.1 Where the hydropower potential has been exploited

In most of the countries where the hydro-potential has been extensively harnessed, the hydropower development started one century ago and many dams and plants are therefore old In these countries, the focus is therefore on

• maintaining the ageing works in safe and efficient conditions;

• managing new requirements and needs, minimizing the negative impact on the power production; and

• getting the most out of the existing infrastructures

6.01.2.2.1(i) Safety and efficiency of the existing dams and reservoirs

The modernization of existing power plants is motivated and economically supported by the consequent addition of more efficient production However, maintaining existing dams and reservoirs in good and safe conditions may require important and expensive remedial works conflicting with the available resources and the duration of the concessions

The recurring problems are those related to the considerable length of service of many works:

• Obsolete dam typologies, not corresponding to the current state of the art

• Dams designed using design criteria not fully compatible with current more demanding safety standards

• Ageing and degradation process, among which expansive phenomena in concrete are having an increasing importance

• Silting of reservoirs, with problems for the proper working of outlets and intakes, and additional loads applied to the structures Hydropower reservoirs can generally be filled by sediments to a higher percentage than nonhydropower reservoirs, as they are mainly addressed to maintain the head for the power generation, but silting remains a problem requiring in many cases important works for sediment removal

Furthermore, many countries have to face the problems of renewing the dam engineering profession, preserving the available experience, and transmitting it to young engineers

6.01.2.2.1(ii) Additional purposes/requirements

During the operating life of hydroelectric dams and reservoirs, new requirements are often introduced in addition to the initial sole hydroelectric purposes, such as flood protection, irrigation and potable supply, discharge for minimum vital flow, recrea­ tional purposes and touristic development, and wetland habitat The new needs introduce limitations and constraints in the use

of the water often conflicting with the optimization of the power production Some additional requirements apply only to some dams and reservoirs, depending on the capacity of the reservoirs and the local situation and needs The requirement of a continuous water discharge to assure the minimum vital flow and to improve the downstream ecological condition apply to many dams, potentially to all, and it can reduce the electrical production of a significant amount on a national scale (in Europe, e.g., the reduction could be estimated around 10%) Consequently, the introduction of this requirement is stimulating significant activities for the installation of mini-hydro turbines to generate a continuous discharge, thus mitigating the negative impact on