15 pages report (1)

The hydropower scheme in the
Alps
Group 18:
Mazin Al Abri
BartholomewAloni
ChristoforosKatsigiannis
NikolasLoizou
ArtemLukianov
HamishA MacDonald
KingsleyOkafor

Contents
Introduction.......................................................................................................................................3
Environmental Impact ........................................................................................................................5
Land impact...................................................................................................................................5
Wild life impact..............................................................................................................................5
Changing Temperatures..................................................................................................................6
Methane emissions (from reservoirs)...............................................................................................6
Turbine specifications.........................................................................................................................7
Power............................................................................................................................................7
Penstock design..............................................................................................................................8
Available head................................................................................................................................8
Design of the turbine.................................................................................................................... 10
Improvement................................................................................................................................... 12
Conclusion....................................................................................................................................... 14
References....................................................................................................................................... 15
Bibliography..................................................................................................................................... 15
Appendix......................................................................................................................................... 16
Matlab scripts............................................................................................................................... 16
Contributions............................................................................................................................... 19
Minutes ....................................................................................................................................... 19

Brief:
The aim of this project is to design a hydropower scheme in the Alps with a site for a potential
reservoir 750 m above the turbine house of a catchment area of 10 km by 25 km.
Introduction
Hydropower plants are one of the most efficient ways of generaing electricity in the world. The
hydropower is a reliable source of renewable energy. The hydropower converts the kinetic and
potential energy of the water into useful mechanical or electrical energy. Moreover,
hydropower plant is known to have high conversion efficiency, which could be over 90%,
depending on the type of scheme used. [1]
There are different types of hydropower schemes such as large scheme, pumped-storage and
run-of-the-river. In the large scheme hydropower plant, a large reservoir or dam is constructed
across a river in order to store huge amount of water. The water is then made to flow through a
turbine so as to generate electricity. One of the main advantages of the large scheme is that
high capacity turbines could be installed which will generate more flexible power through the
whole seasons. Furthermore, this type of hydropower scheme attracts a lot of tourist and it
could serve as a location for water sports.
The pumped-storage hydropower scheme uses the excess electricity produced during the off-
peak period to pump water into the upper reservoir. This water stored in the upper reservoir is
then used to power the turbine during peak time. The pumped-storage plant is one of the best
solutions for the power management where the power is generated when needed.[2]
The run-of-the-river schemes use the natural water flowing through the river and elevation
drop of the river to power a turbine, which then generates electrical energy. A portion of the
river water is diverted through a channel, which leads to a hydropower station, usually located
below the actual level of the river in order to provide higher potential energy. The water is then
released back to the river. This type of hydropower scheme does not require any large
construction; therefore it is cheaper than the other hydropower schemes. [1]
We have decided to construct a large hydropower scheme with a catchment area of 10km by
25km and an elevation of 750km in the Alps due to the design brief.

The hydropower scheme proposed will be
constructed above the Lac de Serre-
Ponçon in the South French Alps. The Lac
de Serre-Ponçon in itself is an artificial
reservoir which is fed by two rivers, the
Ubaye and Durance, and supplies water to
sixteen hydropower stations. The
hydropower scheme we are proposing will
dam the Ubaye River which runs
through the Barcelonnette Basin and
create an artificial reservoir with a proposed max surface elevation of approximately 1650m.
This Barcelonnete Basin has a catchment area of approximately 253m2. This region benefits
from consistent inter annual rainfall, especially during the summer/autumn months where
storms can reach
approximately 50mm/hour.
Annual rainfall in the region is
typically 733±412mm which,
depending on the drainage
percentage taken, means a
flow rate into the reservoir of
between 1.7 - 4.1 m3/s. The
turbine house for the power
scheme will be located on the
Lac de Serre-Ponçon itself, approximately 850m below the new reservoir, and the water will
flow back into the Lac de Serre-Ponçon so as to cause minimal disruption to the other sixteen
power stations.
Figure2: Lac de Serre-Poncon and Surrounding Area
Figure 1: Scheme located in South French Alps

Environmental Impact
Land impact
Building a reservoir requires the use of large land and in flat areas we need much more than
building in hilly areas. Flooding large areas to build reservoirs can result in the destruction of
forests, wildlife habitats, agricultural land, grasslands, marshlands and areas biologically rich.
Also there have been cases where, entire communities had to be relocated, like in the case of
the Three Gorges dam in China.[3]
Wild life impact
Dammed reservoirs are used for many purposes:
 Flood control
 Recreation
 Agricultural irrigation
We can't claim that every dam is associated with wildlife impacts and hydropower stations.
However, hydropower stations can cause a large impact on aquatic ecosystems because of the
turbine blades that injure organisms and fish. Apart from that ,there can be impacts inside the
reservoirs and at the lower ground of the facility. Reservoir water has bigger amount of
nutrients and sediments due to the fact that the water is more stagnant than normal river
water, thus algae and aquatic weeds be cultivated in excess amounts. These weeds can crowd
other animals and plant life. These should be controlled manually through harvesting or by
introducing organisms and fish that eat such plants.
In addition, if big amounts of water is stored behind
the reservoir, segments of the downstream river will
dry out. This is a usual phenomenon in hydropower
stations and for this reason is necessary for the
operators to release amounts of water at certain
times of year. Also reservoir water is low on
dissolved oxygen levels, thus when released there
can be a negative impact on downstream plants and animals. Aerating turbines can be installed
to increase the amount of dissolved oxygen in the water.[3]

Changing Temperatures
Temperature is another issue we have to deal with. Rivers are fairly homogenous in
temperature, whereas reservoirs are layered, meaning they are warm at the top and cold at the
bottom. When water is released downstream, it is usually from the bottom of the dam,
meaning that the river water will now have a change in temperature. Many micro organisms
depend on a regular cycle of temperatures and by changing that we can affect their life cycle if
not kill them.
If the dam is allowed to release water from its reservoir, it will often do so only once in a while,
release small floods. This leads to scouring and armoring of the riverbed. The high energy of the
sudden floods picks up and removes smaller sediments like silt, sand, and gravel, as well as
aquatic plants and animals, leafy debris, and large woody debris. By this, sets of habitats are
erased and also the riverbed below the dam becomes like a pavement of cobbles and loses its
value as a habitat for plants and other organisms.
Methane emissions (from reservoirs)
The reservoir of water for hydroelectric power station releases into the atmosphere a big
amount of methane and dioxide.Carbon emissions vary from dam to dam but despite that
emissions are still in high levels.This is because plants and trees in them start rotting and
decompose by other method without the use of oxygen.So this kind of decomposition release a
great amount of carbon and methane in atmosphere which increase pollution.[4]

Turbine specifications
Power
According to the area specifications:
Catchment area – 23 x 11 = 253 km2
Average rainfalls – 733 mm per year
Therefore, if there is no drainage, the average collected volume is:
𝑉 = 253 × 0.733 = 185.4 × 106
𝑚3
There are 365 days in one year, 24 hours in one day and 3600 seconds in one hour. Of these,
we can calculate the average volume flow rate: 𝑄 =
185 .5×106
365 ×24×3600
= 5.88 𝑚3
/𝑠
With the drainage 30-70% the flow rate might vary 1.7 - 4.1 m3/s respectively.
The level difference between turbine and reservoir is: H = 875 m.
From these data the average generated power can be calculated:
𝑃 = 𝜌𝑔𝐻𝑄 = 50.47𝑀𝑊
The energy potential: 𝐸 =
𝜌𝑔𝐻𝑉
3600
= 442 𝐺𝑊ℎ
The installed capacity is 495MW and the load factor is
50.47
495
× 100% = 10.1%.
The power depends on the volume flow rate, which depends on the rainfalls. This is
represented on the following graph:

Penstock design
Assuming the slope of the mountain is at an angle of 20° then the approximate length of the
penstock can be found: =
𝐻
sin 20
= 2558 𝑚 , where H = 875 m
The diameter of the penstock can be found using ‘findD’ function in Matlab (Appendix 1).
The function is recursive and gives the diameter of 3.293 m.
However, the real condition might vary slightly and, due to safety issues, it is better to choose
the actual diameter slightly bigger, for example, 3.3 m.
Due to the fact that, Pelton wheel does not require specific dimensions for the tail race, it was
reasonably approximated to make it 50 m long and with the same diameter 3.3 m as the
penstock.
Available head
The level difference between reservoir and the turbine is 875 m. However, due to frictional
losses in the pipe the actual head is less and called available head.
The available head can be found using the following formulas.
First, we need to find the cross-sectional area of the penstock:
𝐴 =
𝜋𝐷2
4
= 8.55 𝑚2
Then we can find velocity of the water at the maximum flow rate of 70 m3/s
𝑉 =
𝑄
𝐴
= 8.17 𝑚/𝑠
Now we can find the dynamic head:
𝐻 𝑑 =
𝑉2
2𝑔
= 3.4 𝑚
And the head loss:
𝐻 𝐿 = (
4𝑓𝐿
𝐷
+ 𝐾) × 𝐻 𝑑 = 43 𝑚
Where K=5 and f is friction factor, which can be found from the Moody diagram using the
surface roughness 𝜀 𝑑 = 1 × 10−4
.
Of these, available head can be obtained:
𝐻 = 𝑍 − 𝐻 𝑑 − 𝐻𝐿 = 828.6 𝑚

Where Z is the original level difference, which is 875 m in our case.
The following graph represents different heads depending on the flow rate:
The ratio of the available head to the level difference depending on the flow rate is shown on
the following graph:

Design of the turbine
Due to the high level difference (875m), the Pelton turbine has been chosen for this scheme.
Other turbines such as Francis or Kaplan are able to work with heads below 300 m and even
lees.
The installed power capacity is 495 MW which splits between three turbines - 165 MW each.
There are 6 jets in each turbine, 55MW per jet.
The specific speed of the turbine can be found using:
𝐾 𝑁 = 𝜔
√
𝑃ℎ
𝜌
( 𝑔𝐻)5/4
= 0.112
where 𝜔 is rotational speed in rad/s, 𝜔 =
𝑟𝑝𝑚
30
∗ 𝜋 (rad/s)
The generator consists of 6 pole pairs, then the turbine should rotate at the speed of 500 rpm
in order to provide 50 Hz.
Using this formula the desirable rotation speed can be found: 𝑓𝑇 =
𝑓
𝑛 𝑝
The efficiency of the power scheme can be found using:
𝜂 =
𝑃
𝑃 𝐻
× 100%
where P = 495 MW, 𝑃 𝐻 = 𝜌𝑔𝐻𝑄 = 568.5 𝑀𝑊
Therefore the efficiency of the hydropower scheme is:
𝜂 =
𝑃
𝑃 𝐻
× 100% =
495
568.5
× 100% = 87%
The following graph shows efficiencies of different turbines including Pelton turbine:

And this graph shows the comparison real and ideal efficiencies:
The ideal efficiency can be found using:
𝜂 = 2 × (1 − cos 𝜃)(
𝑈
𝑉𝑗
) (1 −
𝑈
𝑉𝑗
) × 100% = 98%
where 𝜃 can be taken as a standard blade angle - 165°
The jet velocity can be calculated using:
𝑉𝑗 = 0.98 × √2𝑔𝐻 = 125 𝑚/𝑠
where 0.98 is velocity coefficient
The velocity of the blades is: 𝑈 =
𝑉𝑗
2
= 62.5 𝑚/𝑠
Jet diameter can be found from the cross-sectional area of the jet:
𝐴𝑗 =
𝑄𝑗
𝑉𝑗
= 0.03 𝑚2
And then the diameter:
𝐷𝑗 = √
4𝐴𝑗
𝜋
= 0.199 𝑚
Optimum wheel diameter can be found from:

𝐷 𝑤 =
𝑉 𝑗
𝜔
= 2.39 𝑚
Improvement
A lower dam could be constructed in the river which leads to the lake. The dam could be used
as a pump storage by using Francis turbines at the lake. The water from the lake could be then
pumped to the lower dam when the excess power is available or at lower cost. The pumped
water is then released to drive the Francis turbines as shown in Figure [1].
Figure 1
The pumped-storage plant can be used to cover the high demand of the electricity when it is
required, especially in the summer at the lowest power generation for the Pelton wheels.
Another improvement which can be made to improve the power output and efficiency of system
is by introducing the Turgo turbine to the system or replacing Pelton wheel with Turgo Turbine.
The Turgo turbine is a simple impulse turbine (more like a modified Pelton Wheel) with a higher
specific speed compared to the Pelton.[5]

The design of the Turgo turbine allows a larger jet of water to be directed into the runner at a
particular angle. This is what increases the specific speed and thus a higher power output, most
of all higher efficiency. In terms of reliability, the Turgo turbine requires minimal maintenance
and most are designed to withstand worst case scenarios. [5]
When operating on a very high wave of water containing particles, the effect is very low on
Turgo turbine. The runner profile and jet of water are very important to maintain high
efficiencies. Wearing of material does occur, but this wearing is small and uniform across the
runner profile of the Turgo turbine therefore leaving the turbine with a very little effect on the
performance.[6]

Conclusion
We have designed a large hydropower scheme in the Alps, which has an average power output
of 50.47MW. Due to the size of the reservoir, it has the potential of generating up to 442GWh
of electricity with an efficiency of 87%.
Hydropower plants offer various benefits to the society. These benefits range from job creation
to tourist attraction in the nation where they are located. Additionally, Large hydroelectric
schemes can be used in flood control and for agricultural irrigation purposes. Large hydropower
reservoirs can serve as a ground for recreational and transportation purposes, thereby,
contributing immensely to the growth of the economy.
Finally, the construction of pumped-storage hydropower scheme below the main reservoir
appears to be very viable and efficacious when it comes to electricity generation as it ensures
that flexible and reliable electricity, which meets the shifting demands of the consumer is
generated at all time.

References
[1] A. Kumar, T. A. Schei, 2009, Contribution to Special Report Renewable Energy Sources
(SRREN), Hydropower, chapter 5, available at: http://cms.srren.ipcc-wg3.de/report/srren-
drafts-and-review/fod-drafts/fod-chapter-05.pdf/view [last Accessed 26/03/15].
[2] US DEPARTMENT OF THE INTERIOR, 2005, Hydroelectric Power, available at:
http://www.usbr.gov/power/edu/pamphlet.pdf [last Accessed 26/03/15].
[3] Y. Zhong,G. Power,1996, SOME ENVIRONMENTAL IMPACTS OF HYDROELECTRIC PROJECTS
ON FISH IN CANADA, available at
http://www.hardystevenson.com/Articles/SOME%20ENVIRONMENTAL%20IMPACTS%20OF%20
HYDROELECTRIC%20PROJECTS%20ON%20FISH%20IN%20CANADA.pdf [last Accessed
25/03/15].
[4] Union of Concerned Scientists ,N/A, Environmental Impacts of Hydroelectric Power, available
at: htp://www.ucsusa.org/clean_energy/our-energy-choices/renewable-energy/environmental-
impacts-hydroelectric-power.html#bf-toc-1 [last Accessed 26/03/15].
[5] GILKES. (2015, MARCH 15). HYDROPOWER. Retrieved from GILKES.COM:
http://www.gilkes.com/Turgo-Turbines
[6] Gordon, G. G. (2015). GILKES TURGO IMPULSE HYDRO TURBINEGILKES TURGO IMPULSE
HYDRO TURBINE. Kendal Cumbria: Gilbert Gilkes & Gordon Ltd.
Bibliography
Fearnside, Phillip M. 1989. Brazil's Balbina Dam: Environment versus the legacy of the Pharaohs
in Amazonia. Environmental Management, July/Aug 1989, Volume 13, Issue 4, pp 401-423.
National Renewable Energy Laboratory (NREL). 2012. Renewable Electricity Futures Study.
Hand, M.M.; Baldwin, S.; DeMeo, E.; Reilly, J.M.; Mai, T.; Arent, D.; Porro, G.; Meshek, M.;
Sandor, D. eds. 4 vols. NREL/TP-6A20-52409. Golden, CO: National Renewable Energy
Laboratory.
Yardley, Jim. November 19, 2007. Chinese Dam Projects Criticized for Their Human Costs. New
York Times.
National Renewable Energy Laboratory (NREL). 2012. Renewable Electricity Futures Study.
IPCC, 2011: IPCC Special Report on Renewable Energy Sources and Climate Change Mitigation.
Prepared by Working Group III of the Intergovernmental Panel on Climate Change [O.
Edenhofer, R. Pichs-Madruga, Y. Sokona, K. Seyboth, P. Matschoss, S. Kadner, T. Zwickel, P.
Eickemeier, G. Hansen, S. Schlömer, C. von Stechow (eds)]. Cambridge University Press,
Cambridge, United Kingdom and New York, NY, USA, 1075 pp. (Chapter 5 & 9).
National Academy of Sciences. 2010. Electricity from Renewable Resources: Status, Prospects,
and Impediments. Washington, DC: The National Academies Press. Online at
http://www.nap.edu/openbook.php?record_id=12619
[IPCC, 2011: IPCC Special Report on Renewable Energy Sources and Climate Change Mitigation.

Appendix
Matlab scripts
disp('Hydro Power Scheme in Alps')
Z = 875; %elevation
angle=20;
Q = 70;% Maximum volume flow rate (approximate estimation)
L = Z/sin(20*pi/180);
%L2 = 40;
Kh = 5;
rho=1000;
g=9.81;
nt=3;
HL = 0.05*Z;% a head loss of 10% of the elevation
% Case of a single pipe
% typical parameters choses
ed = 1e-3; % Surface roughness
D0 = fzero(@(D) findD(D,Q,ed,HL,L), [0.1 10]);
D= ceil(D0*10)/10;% round upt the diameter to the nearest 100 mm
disp(['The minimum diameter of the penstock is ', num2str(D0,5),' m; so let''s take a diameter of
', num2str(D,'% 4.2f'),' m'])
PH= rho*g*Z*Q;
Qh= 0:70;
nth = nt*6;
Qnh= 23.3/6;
Pnh= 165e6/6;
rpmh= 500;
[Hh, KNh, effh] = turbine_spec(Qh, Z, L, D, Kh, nth, Qnh, Pnh, rpmh);
display(['Available head= ',num2str(Hh,4),...
' m; Specifc speed KN per jet= ', num2str(KNh,3),...
'; Specifc speed per turbine= ', num2str(sqrt(6)*KNh,3),...
'; Specifc speed total= ', num2str(sqrt(nth)*KNh,3),...
'; efficency= ', num2str(100*effh,'%3.0f'),' %']);
VJ=0.98*sqrt(2*g*Hh); % Jet velocity, assuming a velocity coefficient of 98%
disp(['Jet velocity = ', num2str(VJ,3), ' m/s'])
AJ=Qnh/VJ; % Jet area
DJ= sqrt(4*AJ/pi); % Jet diameter
disp(['Jet diameter = ', num2str(DJ,3), ' m'])
DPW = VJ / (rpmh/30*pi); % Optimum Wheel diameter
disp(['Wheel diameter = ', num2str(DPW,3), ' m'])
theta = 165;
Ub=VJ/2;
efftheor= 2*Ub/VJ*(1-Ub/VJ)*(1-cosd(theta));
turbine_spec function
function [Hn, KN, eff] = turbine_spec(Q, Z, L, D, K, nt, Qn, Pn, rpm);

rho= 1000; g= 9.81; ed= 1e-4;
A= pi*D^2/4;
V= Q/A;
Hd= V.^2/2/g;
HL= (4*fmoody(Q,D,ed)'*L/D+K).*Hd;
H= Z - Hd- HL;
%
figure(1);
plot (Q, H/Z*100,'linewidth', 2);
grid on;
set (gca, 'fontsize', 20);
xlabel('Q (m^3/s)'); ylabel ('H/Z %');
%
figure(2)
plot(Q, H, 'k-', Q, Hd, 'b--', Q, HL, 'r-.','linewidth', 2);
grid on;
xlabel('Q (m^3/s)'); ylabel ('H (m)');
legend('Available head','Dynamic head','Head loss','Location','W');
%
Pe = 0.96*rho*g*H.*Q;
figure(3)
plot (Q, Pe/1e6,'linewidth', 2);
grid on;
xlabel('Q (m^3/s)'); ylabel ('P (MW)');
rad= rpm/30*pi;
Qt= nt*Qn;
Hn = Z - (1 + 4*fmoody(Qt,D,ed)*L/D+K)*Qt^2/A^2/2/g;
KN = rad*sqrt(Pn/rho)/(g*Hn)^(5/4);
A= pi*D^2/4;
V= Qt/A;
Hd= V.^2/2/g;
HL= (4*fmoody(Qt,D,ed)'*L/D+K).*Hd;
H= Z - Hd- HL;
eff= Pn/(rho*g*Hn*Qn);
findD function
function f = findD(D,Q,ed,HL,L)
f = 4*fmoody(Q,D,ed).*L./D * 8.*Q.^2/9.81/pi^2./D.^4 - HL;
fmoody function
function f= fmoody(Q,D,ed,nu)
% Calculates the friction factor for the Moody diagram
% from either the volume flow rate, the pipe diameter, and the roughness
% Input format fmoody(Flow rate, Diameter, roughness, kinematic viscosity
% Viscosity is optional: default value for water: 10^-6
% Roughness optional; default value 10^-6
% or from the Reynolds number and the relative roughness

% Input format fmoody(Reynolds number, [], relative roughness)
% Relative roughness is optional: default 0.001
if nargin()<4, nu= 1e-6; end
if nargin()<2, D=[]; end;
if isempty(D), % all input is already nondimensional
Re= Q;
if nargin()<3, ed= 1e-3; end;
e= ed;
else
A= pi.*D^2/4;
U= Q./A;
Re= U.*D/nu;
if nargin()<3, ed= 1e-6; end;
e= ed./D;
end
f= zeros(length(Re), length(e));
idx= find (Re<=2300);
if length(idx), f(idx)= 16./Re(idx); end;
idx= find (Re>2300);
if length(idx), f(idx)= colebrook(Re(idx),e)/4; end;
%-------------------------------------------------------------------------
function f=colebrook(Re,e)
% Colebrook Equation
% f = Darcy-Weisbach friction factor
% R = Reynolds number
% r = relative roughness
f=zeros(length(Re), length(e));
for i=1:length(Re)
for j= 1: length(e)
% First part of Serghides equation to find first guess
f0 = 0;
f1 = -2*log10(e(j)/3.7+12/Re(i));
while abs(f1-f0)/f0 > 1e-5;
f0= f1;
f1= (2*log10(e(j)/3.7+2.51/Re(i)/sqrt(f0)))^-2;
end
f(i,j)=f1;
end
end

Contributions
Introduction, diagram - Mazin Al Abri
Environment - Nikolas Loizou and Zak Razi
Location and planning - Hamish Anthony MacDonald
Turbine selection, calculations - Artem Lukyanov
Improvements - Mazin Al Abri and Okafor Vicktor
Conclusion, corrections and checking - Bartholomew Aloni and Hamish Anthony MacDonald
Minutes
25/02/15
Everybody was present
 Discussed about the project
 Had some thoughts about possible hydropower schemes
 Split the research areas of the project
5/03/15
 Discussed what we have researched
 Found the suitable location
 Started to locate parts of the scheme
17/03/15
 Turbine has been selected
 Calculations have been done
 Environmental effect has been estimated
 Started preparation for the presentation
 The slide preparation process was split between memebers
20/03/15
 Final preparation before the presentation
 Everything was checked and corrected

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