Small wind power for rural locations - part 2

Wind energy harvesting basics,
resource assessment and
application for off grid systems.
part 2
Hanan Einav-Levy M.Sc.

Thursday, November 10, 2011

Outline


Outline
• part II (2 hours)


Outline
• Example project


Outline
• Example project
• Estimating the wind resource (5)


Outline
• Example project

• Estimating the needs (10)


Outline
• Example project

• Sizing the turbine (5)


Outline
• Example project


• AC or DC (5)


Outline
• Example project


• AC or DC (5)
• Sizing the battery bank (10)


Outline
• Example project


• AC or DC (5)

• Sizing the inverter (5)


Outline
• Example project


• AC or DC (5)

• Economics (10)


Outline
• Example project


• AC or DC (5)

• Economics (10)
• Small wind turbine product comparison (10)


Outline
• Example project


• AC or DC (5)

• Economics (10)
• Case studies


Outline
• Example project


• AC or DC (5)

• Economics (10)
• Case studies
• Practical action - Peru (10)


Outline
• Example project


• AC or DC (5)

• Economics (10)
• Case studies
• AWP - Zimbabwe (10)


Outline
• Example project


• AC or DC (5)

• Economics (10)
• Case studies
• WindAid - Peru (10)


Outline
• Example project


• AC or DC (5)

• Economics (10)
• Case studies
• WindAid - Peru (10)
• CometME - Israel / Palestinian authority (10)


Resource: ITDG_2001_bookletwind.pdf

Example project

Small wind development by technology
transfer


transfer
• ITDG (now called Practical Action)


transfer
• One method to develop wind turbines for rural communities -
there are others.


transfer
there are others.
• We will use this to study the design of the system


transfer
there are others.
• Estimating the wind resource


transfer
there are others.
• Estimating the needs


transfer
there are others.
• Sizing the turbine


transfer
there are others.
• AC or DC


transfer
there are others.
• AC or DC
• Sizing the battery bank


transfer
there are others.
• AC or DC
• Sizing the battery bank
• Sizing the inverter


Current situation
• 12V Car batteries are used for
radios and TVs

• 60Ah or 90Ah battery typically
used

• A large market for existing
battery users (300,000
households)

• Monthly battery cost 6.5$ (5$
battery replacement, 1$ travel,
0.5$ charging)


Estimating the wind
• Anecdotal evidence

• The local vegetation

• The Beaufort scale

• Wind map

• Installing an anemometer+data
logging equipment - 200-1000$

• Installing a wind turbine with data
logging equipment with the same
funds


Beaufort scale


Siting the
wind turbine
• The highest
point

• Open to
prevailing winds

• Not too far
from load

• On a tall
tower!


Siting the Highest
point
wind turbine
• The highest
point

• Open to
prevailing winds

• Not too far
from load

• On a tall
tower!


Siting the Highest
Too far from loads point
wind turbine
• The highest
point

• Open to
prevailing winds

• Not too far
from load

• On a tall
tower!


Choosing AC vs. DC
• For a wind turbine installed far from
the load normally the battery voltage
will be as high as possible (48V)

• If not enough - using an DC-AC
inverter at the tower makes sense

• Allows to work at 230 volts, and
therefor less current

• Losses are proportional to the
current squared

• Beneﬁt: Allows to work with regular
230V AC loads


Choosing AC vs. DC

• But cost of DC-AC inverter
can be substantial

• Alternative - site wind
turbine close to load

• Shorter cables - less loss

• Downside: only DC loads


Conservative estimate of monthly
electricity production
• Assuming efﬁciency is 15%
(see previous lecture for
more reﬁned estimate by
Paul Gipe)
D × V ⎡ kWh ⎤2 3

• E=
10 ⎢ month ⎥
⎣ ⎦
V = average wind speed [m/s]
D = diameter [m]


Estimating the loads
• What the wind shouldn’t power:

• Electric heaters

• Electric cookers

• For whom will the system be
designed?

• Single household

• Several households


Single household


Single household
Rule of thumb -
battery charging losses


Breaking down the load for a typical day


3 households sharing a turbine


Sizing the turbine
In an ideal world -
1. Identify wind resource

2. Identify electricity needs

3. Size turbine accordingly

4. Size battery bank according
to measured wind pattern


Sizing the turbine for our two examples



Enough spare energy



Not enough energy


Sizing the battery
• The battery is charged and discharged
over a period of hours or days.

• This is a cycle
• Two parameters important in a battery
life:

• Number of cycles
• The depth of discharge


Sizing the battery


Sizing the Battery
• Calculate Ep, the daily consumption in
Wh
(for example Ep = 400 Wh/day)

• Choose N, number of days of autonomy,
typically 3-5 days
(for example N = 3 days)

• Choose maximum allowable depth of
discharge, D
(for example D = 0.5, which means 50%)

• Choose U, battery voltage (typically
12,24 or 48 volts)
(for example U = 12V)


Sizing the Battery Calculate C, battery capacity:

• Calculate Ep, the daily consumption in Ep × N
Wh C= [Ah]
(for example Ep = 400 Wh/day) D ×U
400 × 3
• Choose N, number of days of autonomy, = = 200[Ah]
typically 3-5 days
(for example N = 3 days)
0.5 × 12

• Choose maximum allowable depth of
discharge, D
(for example D = 0.5, which means 50%)

• Choose U, battery voltage (typically
12,24 or 48 volts)
(for example U = 12V)


Cost of wind turbine - 2 meter
diameter, 100 watt rated


Economics
• Financing ownership by battery charging services
• Current batteries are 60 Ah car batteries (DOD 50%)
• To charge battery (with efﬁciency of charging loss of
25%) 0.5X60X12X1.25 = 450 Wh
• 2 meter diameter at 3.5 m/s site produces 17 kWh/
month or 600 Wh/day on average
• Therefor one battery charged per day
• charging 1 day a week for the owner, and the rest for
customers


Economics


Final system components



Sizing according to local
need and wind resource


Sizing according to wind
variability and “spares”
requirement


For an AC system -
according to maximum
load


Small wind turbine market

WT brochure
Proven WT6000 6kW Wind Turbine
Proven TM900 9m (or TM1500 15m)
Self-Supporting Mast
          

Performance
Cut-In Wind Speed 2.5 metres/second (5.6 mph)
Cut-Out Wind Speed none
Rated Wind Speed 12 metres/second (25 mph)

Rotor

•
Type Down-wind, Self-Regulating

Includes many details
Number of Blades 3, Flexible
Rotor Diameter 5.6 metres
Blade Material Wood/Epoxy/PU

Generator
Type Brushless, Direct Drive,

•
Permanent Magnet

Most important parameter -
(No Gear-Box, Zero Maintenance)
Output 48V/120V/240V/300V 3-phase AC
7000
(25Hz nom)
6000
Rated RPM 200 nominal

diameter, or swept area
5000
Rated Power 6000 Watts

Power Output (Watts)
4000

3000
Annual Output 7000-18 000 kWh depending on site
2000

1000
TM900 Mast
0
Type Self supporting/Tilt Down.
Hub Height 9m

•
0 5 10 15 20
Wind speed in m etres/second
(m ultiply by 2.2 for m .p.h.) Foundations 35 Newton Concrete Pad 2.5 x 2.5 x 1 m

Make sure is intended for Rotor Speed Control
Tube ∅ 175 mm top A/F
350 mm bottom A/F
530 mm square mast base

battery charging
Above 12m/s (25mph) the blade TM1500 Mast
pitch is automatically adjusted to Type Self supporting/Tilt Down.
maintain 200 rpm and full output Hub Height 15m
Foundations 35 Newton Concrete Pad 3 x 3 x 1.2 m
High Build Quality Tube ∅ 200 mm top A/F
All components are hot-dipped 440 mm bottom A/F

•
galvanised steel, stainless steel or 750 mm x 739mm mast base
plastic.

Must have aerodynamic Low Speed Equals Durability
Low rotor speed (half the speed of
Noise
<45dB
<60dB
(approximate)
At 5m/s
At 20m/s

control option
comparable machines) ensures 70-80dB Car 15m away at approx 40 mph.
extended durability of blades and
bearings. It also means that
Weight
Proven WTs are the quietest in the
world! WT6000 500 kg
TM900/6000 360 kg (+ 70kg gin pole)
TM1500/6000 656 kg (+ 240kg gin pole)

z : a l l wi n d t u r b s a l e s l i t m a n u a l w t 6 0 0 0 s s s p e c s h ee t s 6 0 0 0 s s 0 0 1 r e v 2 . d o c


Source -
American magazine.
2 mph = 1 m/s


Most important
parameter


Case studies

small wind:
0.2$-1.15$ / kWh

solar PV:
1.21$ / kWh


African Wind Power

• Example of
technology
transfer

African Wind Power

• Example of
technology
transfer
• Turbines now
installed from
Africa to
Antarctica!

African Wind Power

AWP - Zimbabwe - Masampa Village Lake Kariba
• AWP3.6 - 48V 13.5M tilt up tower, 275Ahr 48V Battery bank, 3KW sine
wave inverter, 12V battery charging station.


AWP - Zimbabwe - Masampa Village Lake Kariba
• AWP3.6 - 48V 13.5M tilt up tower, 275Ahr 48V Battery bank, 3KW sine wave inverter,
12V battery charging station.

• This ﬁshing co-operative village is on the shores of Lake Kariba, 45Km by boat from the
nearest town. Crocodiles inhabit the shore line and Hippos amble through the village at
night while foraging ( startling a hippo is not good for your health). With funds provided by
the Dutch government via the NGO ZERO, AWP implemented the entire project in all its
stages:

• (1) Initial location of the people in need

• (2) discussions with the village committee

• (3) resulting in motivation of the villagers to contribute labour to the installation,
transportation of all materials to site, construction and commissioning

• (4) and ﬁnally training of operators.

• The system provides lighting for the main thoroughfares and also a popular 12v car battery
charging center which draws customers from a 20 Km radius. Income from this activity is
used for village development.


WindAid - Peru


Comet-ME


Comet-ME
• The systems are designed for producing 2-3 kWh/
day for a large beduin family.
• Systems are DIY wind turbines and solar PV panels
• Systems used for powering:
• Lights
• Refrigirator
• Butter churn
• TV
• Cellphone charging
• Costs are between 5000$-8000$


Resources


Small wind power for rural locations - part 2

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Small wind power for rural locations - part 2