Download - Summer School on Energy Giacomo Ciamician Hydro Power ......ing. Nicola Fergnani 4 Electric power generation from hydro potential is the most significant renewable source in the world

Aula Magna – Rettorato

Mercoledì 27 maggio 2015

Hydro Power Plants

Ing. Nicola Fergnani

Summer School on Energy Giacomo Ciamician

ing. Nicola Fergnani

2Renewable energy & Hydropower

Solar Energy

Wind Energy

Hydraulic

Energy

Fossil Fuels

Tidal EnergyGeothermal

Energy

Nuclear

Energy

Energy from

sea currents

Energy from

waves


3

The hydro power potential comes from the rain…

….then it’s an “energy condensate” of solar radiation

Renewable energy & Hydropower


4

Electric power generation from hydro potential is the most significant

renewable source in the world in terms of energy production. In Italy

13-16% of electrical power generation comes from hydro (average production

of 45.7 TWh/year).

Rapporto statistico GSE 2015

Hydropower: statistics


5Hydropower in the world


6

Is it possible a further development of

small hydro in developed countries?

Small

HydroRevamp of

existing plants

In almost every European country there are only few possibilities or

no possibilities for new big hydro plants:

• most of the good location have already been exploited

• environmental impact

• opposition (NIMBY)

Hydropower


7Small Hydro: permitting procedures


8

Power potential is evaluated as:

• WATED HEAD (H)

• AVAILABLE FLOW (Q)

Hydro Power

𝑃𝑖𝑑 𝑊 = ሶ𝑚 ∙ 𝑔 ∙ 𝐻

= 𝜌 ∙ 𝑄 ∙ 𝑔 ∙ 𝐻

𝐸𝑖𝑑 𝐽 = 𝑚 ∙ 𝑔 ∙ 𝐻


9Classification

I. - Weir integrated plant - Diversion Channel plants

II. - Storage plants - Run-of-river plants

III. - High head- Medium head- Low and very low head

IV. - Pumped storage plants- Top power plants


10I Classification

Weir integrated plant

A = B

Powerhouse

integrated in

the weir

A = intake point

B = discharge point


11

Q Ecological

Flow (DMV )

Q = 100%

Q = 100%

Q = 100% - DMV

I Classification

Diversion channel plantsA = intake point

B = discharge point

Ecological flow :

Maintains the essential

processes required to

support healthy river

ecosystems


12I classification (weir-integrated)


13I classification (weir-integrated)


14I classification (diversion channel)

Powerhouse cavern

Intake weir

Settling basin

Surge tank

(forebay tank)

Tailrace tunnel

Video

https://www.youtube.c

om/watch?v=S3MQJS

DoTuw

https://www.youtube.com/watch?v=S3MQJSDoTuw


15

Water storage

Storage plants

• Pond plants [bacino]: filling rate 2~400h (storage

capacity/average river flow rate)

• Reservoir plants [serbatoio]: filling rate > 400h

Run-of river plants: filling rate < 2h

II classification


16

Hydraulic head

• High head (>100m)diversion channel needed (both storage or run-of-river)

• Medium head (30 – 100 m)diversion channel needed (both storage or run-of-river)

• Low head (2 - 30 m)both weir-integrated (very low head) or with diversion channel in most cases run-of-river

III classification


17

Energy storage capability

Pumped-storage hydroelectricity (PSH) • Only pumped

• Pumped + river

Non-pumping plants

IV classification PSH


18IV classification PSH


19IV classification PSH


20

Energy stored in PHPS

IV classification PSH


21

Decreasing hydraulic

head

Hydraulic machines


22Hydraulic machines


23

The entire pressure drop of the turbine occurs

in the nozzle, where pressure head is

converted to velocity

The turbine operates at atmospheric

pressure

Impulse turbines

R=0


24

High head: 60 - 1300 m

Relatively small flows: 0.02 - 7 m3/s

Video

https://www.youtube.com/watch?v=3PoeMQeHePo

Pelton turbine

https://www.youtube.com/watch?v=3PoeMQeHePo


25

Example of a 4 nozzles

pelton turbine

High specific power

Very high efficiency (y>90%)

High efficiency at partial loads (exclusion

or flow reduction on the single nozzle)

The stream should impact one blade per

time

Very fast run-away in case of

grid/generator failure

Pelton turbine


26Pelton turbine


27

50%

55%

60%

65%

70%

75%

80%

85%

90%

95%

0.0 0.2 0.4 0.6 0.8 1.0

Re

nd

ime

nto

Portata / Portata nominale

Pelton 1 getto

Pelton 2 getti

Pelton 4 getti

Pelton turbine


28

The pressure drop occurs partially on

the stator and partially on the rotor

The turbine is completely

submerged in the flow

A pressurized (or depressurized)

discharge is possible

Reaction turbines


29

Reaction turbine suitable for low range heads and flows

Flow range: 0.2-100 m3/s

Head range: 20-500 m

Francis turbine


30

Video

https://www.youtube.com/watch?v=pbliwh4-R2I

Francis turbine

https://www.youtube.com/watch?v=pbliwh4-R2I


31Francis turbine


32

Reaction turbine

Up to very high flows per

single turbine 2-100 m3/s

Head: 2.5 – 40 m

High efficiency at nominal

flow-rate

Expensive regulation devices

required to achieve good

partial load efficiency

A well shaped diffuser is

required

Susceptible to cavitation

Thin intake screen required

Kaplan turbine


33

Video

Kaplan turbine

https://youtu.be/0p03UTgpnDU

https://youtu.be/0p03UTgpnDU


34

Different possibilities for partial load regulation:

A. Double regulation (stator + rotor)

B. Single regulation (rotor)

C. Single regulation (stator)

D. No regulation (Propeller)

Kaplan turbine


B. Single regulation (rotor)

Kaplan turbine


Kaplan turbine


37

Volumetric turbine

Working range H = 1 – 6m

Q < 7 m3/s

Archimedes Screw turbine

Video

https://www.youtube.com/watch?v=bGViZ4p3Fuw

https://www.youtube.com/watch?v=bGViZ4p3Fuw


38

H



39

0

10

20

30

40

50

60

70

80

90

100

0 0,2 0,4 0,6 0,8 1

Re

nd

ime

nto

%

Portata normalizzata Q/Qmax



40

Volumetric turbine

Working range H = 1 – 6m

Q < 7 m3/s

Low speed – long lasting mechanics

High efficiency at partial load

Possible transit of debris

Low cost and low maintenance

Reduction of civil works

Fish-Friendly Downstream

Cost < Kaplan and VLH

Limited flow and head range

Efficiency < than Kaplan @ Qn

Visual impact



41Archimedes Screw turbine


42Example of remote control system


43Choice of the turbine


44

43

)(gH

QK

Specific speed: = rotational speed [rad/s]

Q = nominal flow [m3/s]

H = net head [m]

Choice of the turbine

Nominal efficiency


45

The choice of the turbine should consider many aspects:

• Head and flow range (parallel turbines are possible)

• Partial load efficiency compared to the average flow-rates of the

river

• Minimum flow-rate required by the turbine n° of shut-off days

• Cost of civil works for the different available technologies

• Eventual needing of intake head regulation

• Maintenance costs due to debris transportation

• Annual energy yield VS cost of the plant

• Reliability, availability and expected life of the plant



46

https://hpp-design.com/


https://hpp-design.com/


-

10

20

30

40

50

60

70

80

90

100

- 10 20 30 40 50 60 70 80 90 100

ƞ Id

rau

lico

[%]

Q/QNOM

Hydraulic efficiency

Kaplan - Doppia Regolazione

Semi Kaplan

Propeller

Coclea

Pelton

Francis

47

Hydraulic efficiency

Mechanical power (shaft) / hydraulic available power

HgQ

CY



48Choice of the turbine

Generator

losses

Transformer

losses GridGearbox

losses

DP = f(Q) = 1 gear = f(P gen = f(P tr = f(P

Potential

energyHead losses

DH = f(hIN,H/D) y = f(Q

Inflow water

depth variation

losses

Screw hydraulic

losses

Bearingsfriction

Clearance leakage

Overflow leakage

Hydraulicfriction

Overall plant efficiceny(ɳ TOT = ɳ hydraulic· ɳ mechanical· ɳ electical)


The specific cost (€/kWh) of an hydro power plant is normally

higher than other RES due to the big civil works required but the

capacity factor could be very high

• Civil cost: 30% - 70%

Cost of the plant


50Cost of the plant - CAPEX

Source: International Renewable Energy Agency - 2012


51Environmental assessment

• Water flow impactfor diversion channel plants only

• Visual impactdam/weir

diversion channel/penstock

power house

tailrace channel/tunnel

electrical line

roads

• Noise impactturbines

• Animal impactbarrier for fish passage ( fish ladder)

penstock/channel = barrier for animal passage


52

Benefits:

• Clean energy production

• Programmable (storage plants) or predictable (run-of river plants)

energy production with smooth power variations.

• High investment cost on one hand, but very long service life and

low O&M costs on the other hand.

• Profitable investment due to feed-in tariffs (sometimes even

without!). Cost strongly dependent on location.

• Good development potential for small-hydro plants

• Environmental impact to be carefully evaluated

Critical points:

• Permitting procedure (high costs, long times, uncertain result)

• High specific cost for small plants (up to 10’000 €/kw)

Conclusions

Aula Magna – Rettorato

Mercoledì 27 maggio 2015

Thank you for your attention

Ing. Nicola Fergnani


54

Annual flow duration discharges

Potential evaluation: FLOW-RATE

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

0 50 100 150 200 250 300 350

Flo

w r

ate

[m3

/s]

Days

Flow-rate duration curve

Q [m3/s]

Qutilizz. [m3/s]

Qnom

Qmin


55

• Annual energy yield evaluation• Annual flow duration discharges (Qi)

• Eventual trend of intake (and discharge) levels over the year (Hi)

• Turbine efficiency for different flow-rates (ɳ i)

• Plant overall head losses (DHi) included in ɳ i

𝐸 =24 ∙ 𝜌 ∙ 𝑔 ∙ 𝑄𝑖

365

0∙ 𝐻𝑖 ∙ η𝑖

106=

𝑀𝑊ℎ

𝑎𝑛𝑛𝑜

Potential evaluation: ENERGY YELD