11 Hydro-energy production, hydro-morphologic alterations and security implications Dr. János...

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Hydro-energy production, hydro-morphologic alterations and security implications

Dr. János FehérVisiting Professor, Szent István University, Gödöllő, Hungary

Member of European Topic Centre on Inland, Coastal and Marine Waters

“Future water use and the challenge of hydro-power development in Western Balkan” Workshop, 11-13 Feb 2013, Ljubljana, Slovenia

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Some thoughts

• World energy sources• Regional hydro-power potential• Utilization of hydro-power potential• Hydropower developments vs. Environmental impacts• Dilemmas


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World energy sources

Fossil

Solar

Wind

Nuclear

Geothermal

Biomass

Hydropower

“Future water use and the challenge of hydropower development in Western Balkan” Workshop, 11-13 Feb 2013, Ljubljana, Slovenia

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Regional hydro-power potential


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No arid country has become rich without extensive investment in water-retaining dams.

and

No mountainous country has become rich without tapping most of its hydroelectric potential.

Utilization of hydro-power potential


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The first fact is that dams have been the foundation for economic development in most rich countries, which have developed huge inventories of dams.

For example, arid countries like the US and Australia have around 5000 m3 of storage capacity for every citizen, and countries of the Organisation for Economic Co-operation and Development (OECD)

have developed over 70% of their economically viable hydroelectric potential.

The second fact is that poor countries have orders of magnitude of less water infrastructure.

Instead of the 5000 m3 of storage in rich arid countries, India and Pakistan have 150 m3 and Ethiopia and Kenya 50 m3 of

storage capacity per capita!

Instead of developing 70% of their hydropower potential, poor countries with large hydropower resources like Nepal have developed less than 1% of their hydro potential, and Africa as a whole less than 5%.

Utilization of hydro-power potential


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The capacity (P) of a hydro-power plant can easily be calculated from the h head, Q discharge and η efficiency, which later one incorporates losses in head caused by power canal, turbine, generator, transformer, etc.

P [kW] = Q[m3/s] * h [m] * a [kN/m3]

The coefficient a is practically constant in all cases:

a = g * ρ * η = 7500 [N/m3]

where

g is gravitational acceleration (9,81 m/sec²),

ρ is water density (1000 kg/m³) and

η is the net efficiency of the hydro-power plant, (assumed to be 76,5%)

Generator

Turbine


Hydro-power calculations

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• Hydropower is very efficient– Efficiency = (electrical power delivered to the “busbar”) ÷

(potential energy of head water)

• Typical losses are due to– Frictional drag and turbulence of flow– Friction and magnetic losses in turbine & generator

• Overall efficiency ranges from 75-95%

Boyle, Renewable Energy, 2nd edition, Oxford University Press, 2003


Efficiency of hydro-power plants

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Consider a mountain stream with an effective head of 25 meters (m) and a flow rate of 600 liters (ℓ) per minute. How much power could a hydro plant generate? Assume plant efficiency () of 83%.

H = 25 m Q = 600 ℓ/min × 1 m3/1000 ℓ × 1 min/60sec

Q = 0.01 m3/sec = 0.83

P 10QH = 10(0.83)(0.01)(25) = 2.075P 2.1 kW



Example 1a

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How much energy (E) will the hydro plant generate each year?

• E = P×tE = 2.1 kW × 24 hrs/day × 365 days/yrE = 18,396 kWh annually

About how many people will this energy support (assume approximately 3,000 kWh / person)?

• People = E÷3000 = 18396/3000 = 6.13• About 6 people



Example 1b

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Consider a second site with an effective head of 100 m and a flow rate of 6,000 cubic meters per second (about that of Niagara Falls). Answer the same questions.

• P 10QH = 10(0.83)(6000)(100)P 4.98 million kW = 4.98 GW (gigawatts)

• E = P×t = 4.98GW × 24 hrs/day × 365 days/yrE = 43,625 GWh = 43.6 TWh (terrawatt hours)

• People = E÷3000 = 43.6 TWh / 3,000 kWhPeople = 1.45 million people

(This calculation assumes maximum power production 24x7)


Example 1b


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Trade-offs of hydro-power dams

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Environmental impacts

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• Fuel is not burned, so there is minimal pollution

• Water to run the power plant is provided free by nature

It's renewable - rainfall renews the water in the reservoir, so the fuel is almost always there

No waste products

High efficiency (80%)

Low cost electricity

Long life span

Provides flood control below dam

Provides year-round water for irrigation and crop land

Useful for fishing and recreation due to reservoir

Advantages


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• High construction costs• High environmental impacts

• High CO2 emissions from biomass decay in shallow reservoirs

• Floods natural areas• Converts land habitat to lake habitat• Danger of collapse• Uproots people• Decreases fish harvest below dam• Decreases flow of natural fertilizer to land below dam• Large water loss due to evaporation


Disadvantages / Environmental problems

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• Loss of forests, wildlife habitat, species• Degradation of upstream catchment areas due to inundation of

reservoir area• Rotting vegetation also emits greenhouse gases• Loss of aquatic biodiversity, fisheries, other downstream services• Cumulative impacts on water quality, natural flooding • Disrupt transfer of energy, sediment, nutrients• Sedimentation reduces reservoir life, erodes turbines

– Creation of new wetland habitat – Fishing and recreational opportunities provided by new

reservoirs


Ecological impacts

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• Land use – inundation and displacement of people• Impacts on natural hydrology

– Increase evaporative losses– Altering river flows and natural flooding cycles– Sedimentation/silting

• Impacts on biodiversity– Aquatic ecology, fish, plants, mammals

• Water chemistry changes– Mercury, nitrates, oxygen– Bacterial and viral infections

• Tropics• Seismic risks• Structural dam failure risks


Environmental and social issues

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• Energy demands in the future?• If hydro-power is to be used than - Discharge? • Conflicting demands for constrained water resources?


Dilemmas of vision makeing

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• Conflicting demands for constrained water resources

- implement IWRM.

“IWRM is a process which promotes the co-ordinated development and management of water, land and related resources, in order to maximise the resultant economic and social welfare in an equitable manner without compromising the sustainability of vital ecosystems”



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• How the three pillars of IWRM would develop in the future?


EconomicEfficiency Equity Environmental

Sustainability

Management Instruments Assessment Information Allocation

Instruments

EnablingEnvironment Policies Legislation

InstitutionalFramework Central -

Local River Basin Public -

Private

Balance “water for livelihood” and “water as a resource”


2121“Future water use and the challenge of hydo-power development in Western Balkan” Workshop, 11-13 Febr 2013, Ljubljana, Slovenia

Lake Tisza (Tisza-tó), also known as Kisköre Reservoir (Kiskörei-víztározó), is the largest artificial lake in Hungary.

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Special Areas (SAC) and Special Protection Areas (SPAs) in Hungary

2323“Future water use and the challenge of hydo-power development in Western Balkan” Workshop, 11-13 Febr 2013, Ljubljana, Slovenia

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Ecology – Lake Tisza

Trapa natans L. (Sulyom)Phragmites australis (CAVAN.) TRIN. ET STEND. (Nád)

Typha latifolia L. Széleslevelű gyékény

Nymphaeetum albo-luteaeTündérrózsa - vizitökhínár

Emys orbicularis

mocsári teknős Hód (Castor fiber)

Vízisikló(Natrix natrix)

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1400 million km3 – fresh water on Earth

71% of the Earth surface is water

0,45 million km3 – yearly water circle3000 years for a full circle

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Thank you for your attention!

“Future water use and the challenge of hydo-power development in Western Balkan” Workshop, 11-13 Febr 2013, Ljubljana, Slovenia

11 Hydro-energy production, hydro-morphologic alterations and security implications Dr. János...

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