International hearing on Climate change and energy access for the poor

26th-28th March 2010, Limbé, Cameroon

MICRO-GRID POWER SYSTEMS BASED ON RENEWABLE ENERGY FOR RURAL ELECTRIFICATION:

BENEFITS, EXAMPLES AND STEPS TO PROMOTE THESE SOLUTIONS

Xavier Vallvé, Engineer International consultant

- Trama tecnoAmbiental, Barcelona,Spain –

xavier.vallve@tta.com.es

Battery

Conversion and control

Consumptions

Autonomous Electrification with RE

PV generator

BACKGROUND: Typical Design approach

Technical specification for PV-hybrid micro-power plants (<100 kW, LV) partially adapted from IEC 62257 TS series, IEA PVPS Task3 and Task11 recommended practices, etc

Demand analysis and segmentation

Monitoring of systems to validate technology and the service

10 yr. Service horizon with local operator and local capacity building

Standardized technical solutions with high PV penetration

Experience in Design and Project management of PV-hybrid micro-power plants in rural areas of southern Europe, Africa, Latin America, Pacific …

The diversification of the energy resources increase the quality of the service

The rational use of energy allows savings in the initial investment and in the maintenance costs

Energy access for the poor: current situation in SSA

Low population density

Remoteness from the public grid

Low demand in electricity but with very high value

High energy losses on the transmission lines

High costs of grid extension and connection

High Operation and Maintenance costs

Lack of adequate regulation/business models for decentralized electrification

Energy access for the poor: current situation in SSA

Existing micro grids running with Gensets (many are not working)

Many villages and households and villages not connected to the grid

But essential to access to electricity for basic needs (high value for the first few kWh)

Energy access for the poor: current situation in SSA

Autonomous RE cheaper than grid extension for remote areas

Comparison of investment costs for grid extension in selected countries. Source ESMAP 2000

Country Labour & other costs

Materials Total($/km)

Bangladesh 350 6 340 6 690

Laos 1 420 7 230 8 650

El Salvador 2 090 6 160 8 250

Kenya 6 590 5 960 12 550

Senegal 5 150 10 810 15 960

Mali 2 590 15 170 19 070

PV cheaper than grid extension for remote areas

Comparison of investment costs between grid extension and off-grid PV in Spain

RE Hybrid micro grids more sustainable than fossil fuelled Gensets

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Grupo electrógenodirecto

Grupo electrógeno+ baterías

FV híbrida (25%fracción solar)

FV híbrida (80%fracción solar)

FV (100% fracciónsolar)

€/k

Wh

0

4

8

12

16

20

€/m

es

us

ua

rio

me

dio

Combustible G&O&M Inversión (microplanta + microrred)

Levelized costs for PV and Diesel technologies in microgrid for 340 users in Peru

(D.R. 5%, Diesel: 1 €/l)

Source: http://www.esmap.org/filez/pubs/620200785630_Peru_Solar-Diesel_Amazon_111-07.pdf

From interim to permanent solutions

Typical load profilesProfile 1- Daily Cycle rigid slim loads

PROFILE LOAD

AVO

IDABLE

DEF

ERABLE

INTE

RRUPT.

MO

DULA

BLE

NO NO NO

NO NO YES NO

1100

TYPICAL DAILY RANGE

(Wh/day)

550 1100

NO

275 275

550 1100

2a

2b

2c

YES NO YES YES 0

A

A

Profile 2- Base Load

2a-Base Load 2b- Base Load Interruptible 2c- Base Load- Stand-by

From individual PV autonomous power plants to micro-grids

Application types Types of uses

Home applications LightingAudio/videoRefrigeratorSmall household appliancesWashing machineIronsFreezerOdd jobs

Public areas applications(places of collective life: worship halls, community centre, healthcentre, etc.)

The same appliances as above areused, but more and more powerful.

Public lighting.

Village water pumping.

Economic activities applications Process equipment supply (mainlymotors)

Individual PV micro plants in Europe

Multi-user micro grids (MSG) in Developing Countries

What is a Hybrid Mini Grid with RE?

A combination of different but complementary energy generation technologies based on renewable energies or mixed (RES + genset)

Hybrid powered mini-grids can provide steady community-level electricity service, such as village electrification, offering also the possibility to be upgraded through grid connection in the future

Total installed power up to 100 kW (according to IEC)

Distribution line in Low Voltage (up to 1.000V) (only distribution)

Single or 3-phase grid

PV Hybrid Mini Grid in West Bank, Palestine

From single user to villages: MSG (Multi user Solar Grid) up to 150 kWh/day

Typical layout (DC bus-bar micro power plant+AC single phase grid )

Comparison of PV Individual and Micro grids

Advantages Disadvantages

IndividualElectrificationMicro plants

• Consumption is user managed on a day to day basis.• Black outs affect only one user.• PV micro plants can be easily moved to a new location.

• Limited surge power capacity.• Monitoring individual plants can be expensive and difficult.• Maintenance and repair service complex to organize in rural areas.

Multiuser Solar Grids (MSG)

• Improved quality (surge power, load shedding, etc).• Lower investment for compact villages.• Energy saving can be practiced using improved management tools.• Lower maintenance costs.• Telemetry can be economic for monitoring plant’s status.

• In a general power plant failure, everybody is cut off.• Social rules required to distribute energy availability.• Local management required.• Plants generally need to be serviced on site.

Challenge: sharing the energy available without conflicts

Energy distribution and metering issue!

VISION: Universal electrification-individual plants and micro grids under one operational scheme

Individual Micro-Power PlantsMSG

MSG

Examples MSG (Multi user Solar Grids)

Akkan, Morocco, Africa

Akkan, Morocco

PV HYBRID POWER PLANT

PV GENERATOR

Installed PV capacity 5.760 Wp

Module type 80 Wp 36 cell – mono crystalline

Number of modules 72

Inclination / orientation 43º / +5º S

PV CHARGE CONTROLLER

Rated power 6.000 Wp

Control algorithm MPPT - Boost

BACK UP GENSET

Rated power 8,2 kVA single phase

Fuel Diesel

BATTERY

Number of elements (voltage) 24 (48V)

Model Hawker 2AT1500

Capacity (C100) 1.500 Ah

Autonomy 4 days

INVERTER

Voltage input / output 48 V DC / 230 V AC

Rated power 7.200 W

Harmonic distortion < 2,5%

DATA LOGGER

Memory / log frequency 300 kbyte / hourly

Type of data Energy, voltage, radiation, etc.

ELECTRICITY DISPENSER – METER

Input 230 V AC 50 Hz

Maximum current 10 A

Algorithm Configurable Daily Energy Deliverability

STREET LIGHTING

Number of lamps 13

Type 70 W hp sodium / 2 level electronic ballast

Total power - high 910 W

Total power - low 683 W

INDIVIDUAL LOADS

Households 275 Wh/day 23

Households 550 Wh/day 3

School 550 Wh/day 1

Mosque 550 Wh/day 1

Diakha Madina, Senegal, Africa

Diakha Madina, Senegal

PV ARRAY

PV installed power 3.150 Wp

PV Module model PW750 75 Wp 12V

Nº PV modules 42

Orientation/Inclination 0º S / 10º S

PV Area 46 m2

AVAILABLE ENERGY

Available Energy (Wh/day) 4.803

Irradiation (ḠpHp) 5 HPS

Month of design December

BATTERY

Nº elements 24

Battery type Tudor 6 OPzS 420

Capacity (C100) 672 Ah

Day of autonomy 4 days

CHARGE CONTROLLER

Regulation capacity 4.000 Wp

Mode of charge control MPP Tracker

INVERTER

Input / Output voltage 48 V DC / 230 V AC

Nominal Power 3.600 W

DC/DC Converter (12 V) 10A máxima de corriente

Harmonic distorsion < 2%

DATA LOGGING

Memory / freq. of logging 300 kbyte / hourly

PUBLIC LIGHTING

Number 2

Type of lamp 70 W / electronic ballast

PUMPING SYSTEM

Power of the pump 1.100 W

Flow 5m3/h

Deep 49 m

Height of the tank 7 m

Tank capacity 20 m3

BACK-UP GENSET

Nominal power 4,2 kW single phase

Fuel Diesel

Civil works of multi purpose building

Agreements with users

Local kick-off meeting

Floreana island (Galapagos), Ecuador, South America (I)

Building entry

Data download

Battery

Floreana island (Galapagos), Ecuador, South America (II)

San Lorenzo, Ecuador, South America (I)

Typical household

San Lorenzo, Ecuador, South America (II)

San Lorenzo, Ecuador, South America (III)

Electricity Dispenser / meter

Metering and invoicing interface

Energy and power limitation and guidance according to energy allowance contracted

User pays for availability of energy, not for the consumed energy

Community based scheme vs Utility based scheme

Ownership and Operation

User’s fees can sustain operation and replacement during the horizon of the project

Typical cash flow for MSG of 20 households and monthly fee of 8 USD

Flujo de caja en el ciclo de vida (20años)

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2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027

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Anual

Present and future potential for Renewable Energy Micro grids

Villages not connected to the grid, where the grid extension is too expensive and not cost effective: micro-grid for basic needs (health, school, water, etc)

Villages with obsolete diesel generator because of the high running costs (Operation and Maintenance): refurbishing distribution grid, electrical installations, etc

Short-term (0-2 years)

Medium-term (5-6 years)

Long-term (10 years onwards)

Villages not connected to the grid: extension of the mini-grid to private applications and productive uses

Villages not connected to the grid: interconnection of several mini-grids between them or/and the national grid

Constraints and limitations

Training and capacity building

High costs of investment

Critical density for adequate maintenance

Management of accumulated money

Social organization may be a critical issue depending of the management scheme

Unfair existing regulation (unfair regulations that discriminate against technologies that are especially suited to rural areas)

New technologies available with Renewable Energy hybrid micro-grids

Possibility of decentralised productive electricity uses

MSG little knowledge and often not considered

Very good local governance capacity building

Lack of demonstration and monitoring

Existing barriers:

• Conventional tariff structure

• Institutions and infrastructure

• Engineering and social experience

SOME CONCLUSIONS

xavier.vallve@tta.com.es

Thanks for your attention!