5.4 dre technologies

Implemented by the ACP Group of
States Secretariat
Funded by
the EU
Distributed Renewable Energy (DRE)
technologies overview
EMANUELA DELFINO / DIS / Design Department / Politecnico di Milano
LEARNING RESOURCE 5.4

Distributed Renewable Energy technologies
Emanuela Delfino/ Politecnico di Milano / Design Department / DIS
CONTENTS
2
1. SOLAR ENERGY
– Photovoltaic system
– Water Heating system
2. WIND ENERGY
3. HYDRO ENERGY
4. BIOMASS ENERGY
– Biogas Digester
– Biomass Gasifier
5. ENVIRONMENTAL IMPACT (LCA) OF RENEWABLE
ELECTRICITY

3
Types of Renewable Energy
GEOTHERMAL
HYDRO
WAVE
WIND
TIDAL
BIOMASSSOLAR

4
………
Solar energy is the most abundant of REs resources and is available
at any location.
1. Solar Energy

5
1. Solar Energy
The total solar irradiation of the sun is about 50 million GW which
is 10.000 times more than the energy used by the world population

WATER HEATING SYSTEMS
6
1. Solar Energy: technologies


SOLAR HEAT
HEATED WATER
PHOTOVOLTAIC SYSTEMS
SOLAR RADIATION
ELECTRICITY

7
Source: Africa Biogas CompanySource: Ashden Why solar is super?
1. Solar Energy: photovoltaic systems

THE PHOTOVOLTAIC PHENOMENON
8
Solar Photovoltaic systems (SPV)
convert the energy from the sun
with solar cells: the PV effect
phenomenon is related to the
electromotive force that is generated
under the action of light in the
contact zone between two layers of
semiconductor, usually silicon-
based .

PV CELLS MATERIAL
9
MONO-CRYSTALLINE
SILICON
(mono-c-Si)
High purity degree
purity ingots
Performance: 15-18%
Cells are rigid and fragile.
Size: 2,54 to 5,08 cm, 10
cm, 12.7-15.24 cm
POLY-CRISTALLINE
SYLICON
(poli-c-Si)
Lower purity ingots (from
waste silicon from the
electronics industry), cheaper
but lower performance.
Performance: 11-14 %
Cells are rigid and fragile.
Size: 2,54 to 5,08 cm, 10 cm,
12.7-15.24 cm
AMORPHOUS
SILICON
(a-Si)
Non-crystalline
structure Cheaper to
manufacture and install,
but lower return.
Performance: 5-10 %
Flexible cells.
Free sizes
The most reliable technology available on the market and is the silicon
solar cell.

THE PHOTOVOLTAIC PANEL
10
A number of solar cells are
gathered together to form a
solar module:
More modules can be combined
to form a field/array with high
degree of modularity and
scalability

11
• Photovoltaic Cell/Module
To convert solar energy in electric energy through the photovoltaic effect
• Charge Controllers
To protect and regulate the charge of batteries, interrupt the photovoltaic
field when the battery is charged and prevent
• Rechargeable Battery bank
To store the surplus of solar energy if not connected to the grid
• Inverter
To convert the DC from the photovoltaic modules in AC (necessary for
products such as appliances, computers, cars, urban lights, etc.)
• Breaker box
To distribute electrical current to the various circuits (if grid connected)
• Electric meter
To measure electric energy delivered to their customers for billing purposes
• Wires/cables
SPV SYSTEM COMPONENTS

15
TYPICAL SPV SYSTEM LAYOUT
1. STAND ALONE OFF GRID (WITH BATTERIES)

18
TYPICAL SPV SYSTEM LAYOUT
2. GRID CONNECTED

19
DESIGN / ASSESSMENT
Solar radiation is available at any location
The value of solar radiation depends on:
• The location (higher values closer to the Equator)
• 1400 to 2300 kWh/m2 in Europe and US
• around of 2500 kWh/m2 in Tanzania, East Africa
• Period of the year (seasonal climatic variations)
• Higher during warmer than in cold months
• Higher during the dry season then rainy season
Databases are available to obtain an estimation of annual plant
productivity
• Photovoltaic Geographical Information System (PVGIS)
• IRENA's Global Atlas
No Data
• Weather Modeling and Forecasting of PV Systems Operation
(radiometers)

20
SPV SYSTEM POWER DIMENSION AND NUMBER OF USERS
PICO PV SYSTEM HOME PV SYSTEM COMMUNITY PV SYSTEM
1-2 PRODUCTS 1 HOUSEHOLD 2-400 HOUSEHOLDS
1-10 W 10-200 W 200-5000 W

21
COSTS
Prices of SPV generation are
• in developed market around 2.5 €/Wp
• in emerging markets below 1 €/Wp
Stand Alone PV system
Family of 4-5 members
4.2 kW
5355 kWh/year - 35 m2
50000-100000 €
Solar Lanter
4+ hours of light
1-10 W
25-80 €
Solar Home Kit
10-20 hours of light,
recharging batteries
80-200 W
80-350 €

22
Solar water heating (SWH) is the conversion of sunlight into renewable
energy for water heating using a solar thermal collector.
It can be used to heat domestic hot water which promotes hygiene and
health, for space heating (e.g. solar driers and greenhouses) etc.
1. Solar Energy: water heating system

These systems are composed of solar thermal collectors, a storage tank
and a circulation loop.
23
HOW IT WORKS
Source Image: http://www.ashden.org/technologies

24
TYPES OF HEATERS
1. Integrated
collector storage
(ICS or Batch Heater)
2. Active systems with
pumps to circulate water
or a heat transfer fluid
3. Passive systems
with circulating water or
a heat transfer fluid by
natural circulation

25
COMPONENTS
Absorber
• metal,
• High conductivity
• High absorptivity
• Low emissivity
Copper/Steel with covered with
chromo, alumina-nickel, Tinox
Transparent coverage
• to reduce heat losses
• to maximize the efficiency of
the collector
Circulating tubes
• metal with good conductivity
The flat and closed collector
Insulating systems
• Low Thermal Conductivity
• Resistant to high temperature
Rock wool, polyurethane foam,
polystyrene ...

26
2. Wind Energy
Wind energy is site specific. A wind power generator (WPG) converts
kinetic energy of the wind into electric power through rotor blades
connected to a generator.

The force of the wind turns the
blades, converting the energy
of the wind into mechanical
energy of the rotating shaft.
This shaft is then used to turn a
generator to produce electricity
or to operate a mechanical
pump or grinding mill.
Most modern wind turbines are
used for electricity generation.
27
2. Wind Energy
HOW IT WORKS

There are two basic designs of
wind electric turbines:
• vertical-axis, or "egg-beater"
style
• horizontal-axis (propeller-
style) machines
Horizontal-axis wind turbines are
most common today
28
2. Wind Energy
HOW IT WORKS
Source Image:
http://www.hillcountrywindpower.com/wind-basics.php

- a rotor, or blades, which
convert the wind's energy into
rotational shaft energy;
- a nacelle (enclosure)
containing a drive train, usually
including a gearbox and a
generator;
- a tower, to support the rotor
and drive train;
- electronic equipment such as
controls, electrical cables, ground
support equipment, and
interconnection equipment.
29
2. Wind Energy
WIND POWER SYSTEM COMPONENTS
Source Image:
http://www.hillcountrywindpower.com/wind-basics.php

30
2. Wind Energy
WIND POWER GENERATOR DIMENSION
Energy need for a family: ca. 5 kW
• Micro-Wind generator
• Tower height 9 meters
• Blades (or rotators) diameter 3
meters

31
2. Wind Energy
Energy need for a farm or an
isolated group of houses: ca.
60-75kW
• Mini-Wind
• Tower height 10-20 meters
• Blades (or rotators) diameter
15 meters

32
2. Wind Energy
Energy need for 200 families:
from 600 kW
• tower height 50-100 meters
• 2/3 blades (or rotators)
diameter 50-100 meters

33
2. Wind Energy
DESIGN / ASSESSMENT
Wind power is site specific
Energy produced depends on wind speed at the site:
• Wind speed is highly influenced by topography and obstacles
Wind power changes during the day, and the seasons.
• Wind speeds of 4-5 m/s are required to achieve economic
sustainability
Data all along the year are required.
• Direct measure can be taken with meteorological towers with
anemometers and wind vanes to have speed and directions
• Secondary data can be taken from other measuring
meteorological or airport installations, together with appropriate
calculation models

34
2. Wind Energy
COSTS
The price depends on the size, material and construction process.
• Costs of Small Wind systems include
• turbine and components: tower or pale, battery storage,
power conditioning unit, wiring, and installation
• Maintenance: turbine requires cleaning and lubrication, while
batteries, guy wires, nuts and bolts, etc. require periodic
inspection
• Costs depend on the cost of local spares and service
• overall costs are in the range 3000 – 6000 €/kW
User 1 family household
Power 5 kW Micro Wind
Cost From 15.000-30.000€

35
3. Hydro Energy
Hydro resources are site specific. Hydro power plants transform
kinetic into mechanical energy with a hydraulic turbine.

36
The power available in a river or
stream depends on the rate at
which the water is flowing, and
the height (head) which it falls
down.
Mechanic energy drives devices
or is converted in Electric
Energy via an electric generator.
Electricity production is
continuous, as long as the
water is flowing.
3. Hydro Energy
HOW IT WORKS

• Weir and intake channel
where water is diverted from the natural
stream, river, or perhaps a waterfall
• Forebay tank
Artificial pool to contain water
• Penstock
Canal to bring water to the turbine
• Power Group:
the turbine converts the flow and
pressure of the water into mechanical
energy. The turbine turns a generator
connected to electrical load, directly
connected to the power system of a
single house or to a community
distribution system
37
3. Hydro Energy
HYDRO POWER SYSTEM COMPONENTS

38
3. Hydro Energy
DESIGN / ASSESSMENT
Hydro resources are site specific
Hydro Power is the most mature REs technology and has conversion
efficiency up to 90%
• Best geographical areas: presence of perennial rivers, hills or
mountains
• the right combination of flow and fall is required to meet the
desired load
• a river flow can vary greatly during the seasons
• detailed information are required to estimate production potential
• infrastructures are required: a canalization system is necessary to
send the flow to the turbine and a building to protect the
generator
• require low maintenance

Hydro Power plant costs depend on:
• site characteristics, terrain and accessibility
• (for micro-systems) the distance between the power house and
the loads can have a significant influence on overall capital costs
• the use of local materials, local labor, and pumps
• operational costs are low due to high plant reliability, proven
technology
• overall costs are in the range ca. 3000 €/kW
3. Hydro Energy
DIMENSION AND COSTS
User/energy need Power/ dimension Cost
1 family household 1 kW Family-Hydro ca. 3.000€
3-5 families household 3-5 kW Pico-Hydro ca. 9.000-15.000€
5-100 families
connected
5-100 kW Micro-Hydro ca. 15.000-300.000€

40
4. Biomass Energy
Bioenergy is made available from materials derived from biological
sources. Biomass is any organic material which has stored sunlight
in the form of chemical energy.
Source Image: Africa Biogas Company

41
4. Biomass Energy: biogas digester
Biogas, a mixture of methane and carbon dioxide, is produced by
breaking down wet organic matter like animal dung, leftover food or
human waste.
Image Source: Africa Biogas Company

42
Source: Africa Biogas CompanySource: Ashden Why biogas is brilliant?

43
• A large container to hold the
mixture of decomposing
organic matter and water
(which is called slurry)
• another container to collect the
biogas
• Opening to add the organic
matter (the feedstock)
• Opening to take the gas to
where it will be used
• Opening to remove the residue.
In fixed dome biogas plants (the
most common type), the slurry
container and gas container are
combined.
HOW IT WORKS

44
Anaerobic digestion of organic
matter produces a mixture of
methane (CH4) and carbon
dioxide (CO2) gas that can be
used as a fuel for cooking,
lighting, mechanical power
and the generation of
electricity replacing firewood or
other fuels
APPLICATION

45
TYPE OF BIOGAS DIGESTER
1. Floating Gas Holder 2. Fixed Dome
3. Flexible Bag

46
The cost of biogas plants varies greatly from country to country, depends
on:
- the costs of both materials (brick, concrete and plastic)
- labor can be very different
The cost per cubic meter of digester volume decreases as volume rises.
Using plastic or steel to pre-fabricate biogas plants usually increases the
material cost but can substantially reduce the labor needed for installation.
DIMENSION AND COSTS
No. of family members
(cooking and lighting
requirement)
3-4 members 18-24 members
Size of digester 1 m3 6 m3
Av. Daily Fresh Bovine
Dung and Slurry
Requirement
25 kg 150 kg
Number of Cattle 2-3 12-18
Cost / Cost Tubular Type 150 € 355 €

47
4. Biomass Energy: biomass gasification
Gasification is a process that
converts biomass through
partial combustion in the
presence of a limited supply of
air into a combustible gas
mixture known as producer gas
(sometime called ‘wood gas’).

48
In small-scale gasifiers, the reactions
take place in a stationary or fixed
‘bed’ of biomass, a closed vessel,
cylindrical in shape.
It takes place in four stages:
• Drying
• Pyrolysis
• Reduction
• Combustion
HOW IT WORKS
Updraft gasifier:
Air blown in at the bottom
Gas contaminated by tar and too
dirty for internal combustion engine
Downdraft gasifier:
Air is drawn downwards through the
biomass
Cleaner gas

49
Source: Africa Biogas CompanySource: Ashden Husk Power Systems, electricity from crop waste

50
4. Bio-Energy: biomass gasification
Initial capital cost to buy/build the gasifier
• €1,500 per kW (electrical) for plants up to 100 kW
• €1,200 per kW for plants between 100 kW and 1000 kW
Running costs to maintain the gasifier
• €0.05 per kWh generated
The cost of a 1 kW Husk Power systems for 1 family is around 1.500€ or
lower.
COSTS

51
5. Environmental impact
Is Renewable Energy zero impact?

52
5. LCA comparison of some renewable and non-
renewable energy systems
Method: Eco-indicator 99 (H) V2.07 /Europe EI 99 H/A / Single score
RENEWABLE ENERGY SYSTEMS NON-RENEWABLE
ENERGY SYSTEMS
1kWh electricity

53
TOTAL REDUCTION OF
99%
1kWh electricity

54
TOTAL REDUCTION OF
90%
1kWh electricity

55
References
- Open Seminar: Distributed Renewable Energy System opportunities for
All, POLIMI and UNESCO, Politecnico di Milano, English, 2014:
• 2.3 Renewable and distributed energy for a local and sustainable
development
• 2.4 Off main-grid systems for access to electricity
• 2.5 Off main-grid technologies for power generation in rural contexts
- Renewable Energy for Unleashing Sustainable Development, E. Colombo, S.
Bologna, D. Masera, 2014
- LeNSes Pilot Course: System Design for Sustainable Energy for All, CPUT,
POLIMI LENSes Team, Cape Peninsula University of
Technology, English, 2014:
• 4.5 Renewable Energy
- Ashden Technologies
- Energypedia

56
Thank you!
emanuela.delfino@polimi.it

5.4 dre technologies

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