1. Off-main-grid systems for access to
electricity
Eng. Stefano Mandelli stefano.mandelli@polimi.it
Eng. Lorenzo Mattarolo lorenzo.mattarolo@polimi.it
UNESCO Chair in Energy for Sustainable Development
Department of Energy

2. Outline
1. Technologies and appropriateness
2. Centralized Vs off-main-grid electrification
3. Introduction to off-main-grid systems generation
technologies

3. Technologies and Appropriateness
NEW APPROACH
Importance of local resources and local human capital
Supported by Schumacher – “Small is Beautiful, Economics as if People Mattered” (1973)
Identification of technologies 1. small-scale
2. labour-intensive
3. energy efficient
4. environmental friendly
5. locally controlled
STARTING POINT - THE CONTEXT
Over reliance on colonial administration
Top-down approach to economic development
Low technological capacity development
TOP DOWN
BOTTOM UP
NEW CONCEPT OF DEVELOPMENT
Technology that fits in the country's infrastructure, affordable,
easy to properly maintain, not destructive to the environment.
(Kaplan, 1994)
SUSTAINABILITY

4. Importance of boundary conditions
• flexibility to adapt to local conditions
• not related to a defined technology mix
• scaled to the context
• tailored to the needed services
• accounting the local culture
Appropriate technologies
Economic feasibility
• business model enhancing sustainability
• counting the coverage and cost
The ‘space pen’ example!
Ownership/commitment
• involvement of final users
• end-users requirements
• installation, management and maintenance
• enhancing job creation
• strengthening of research institutions to support
local production

5. Replicability
• Increase access to new technologies of scale
• Innovative models to scale up technologies
• Preserving the environment
Functionality
• availability of local materials
• impact on human capacity
• final user ownership
Appropriate technologies
Impact
• Access to modern energy services and electricity necessarily need to be linked to
other social or economic strategy.
• The implementation of energy programmes have to be measured over socio-
economic indicators such as: quality of
life, education, health, information, agriculture, transport, promotion of small
enterprises.
(Asociación Argentina de Energía Eólica )

6. Centralised generation
Large power plants in central location
Huge transmission and distribution grids
Large number of consumers
Graphic representation of
centralized electrical system
Paradigm of centralised electrical systems
Centralized Vs Off-main-grid electrification
At the beginning of the electrification era
• System were decentralized
End of the first era of electrification
• System moved to centralised electrical system

7. Developed versus Developing countries
• In Developed Countries area has been electrified by the ‘70.
• In Developing countries the issue has not be solved yet (2013)
Little or no autonomy of monopoly enterprises vs government
Weak financial capacity
Aid (if any) is used for maintenance rather then capital investment
Huge transmission and distribution grids
The focus is more on urban then rural area (Low interest for utilities)
Liberalised Marked and Competition
• Around the ‘80s two mains drivers started the end of the centralised era
• Increase efficiency
• Attract private capitals (to reduce public burden)
Centralised generation
Centralized Vs Off-main-grid electrification

8. Five dimensions are promoting the spreading of decentralised
and distributed generation based on Renewable energies
1. Technological improvement (technical dimensions)
• increased performance of the small power technologies
• development of electronic metering and control equipment
• increased consumer demands for highly reliable power supply
2. Environmental concerns (environmental dimension)
• growing concern as for the greenhouse gases emissions
• public awareness of the impacts of the electric industry
• opposition to building new transmission lines
3. Economic opportunities (economic dimensions)
• to avoid transmission and distribution related costs
• To tackle the current risky nature of large scale plant investments
• to reduce power plants costs with combined heat and power generation
• to better exploit profit margins within the competitive market
Beyond Centralised generation
Centralized Vs Off-main-grid electrification

9. Five dimensions are promoting the spreading of decentralised
and distributed generation based on Renewable energies
4. Political asset (political dimensions)
• to decrease dependence from fossil fuels
• to increase primary source diversification (energy mix)
• to reduce vulnerability of the supply chain in centralized systems
5. Social issues (social dimension)
• increasing public desire to promote “green technologies”
• growing interest towards energy autonomy communities and sustainability
Two other issues essential for Developing Countries
• Accessibility (socio-economic and technical dimension)
• Poverty reduction (socio economic and political dimension)
Beyond Centralised generation
Centralized Vs Off-main-grid electrification

10. Classification of electrification systems
• Large power plants in central location
• Huge transmission and distribution grids
• Size effect
• Large number of consumers
Centralised systems
Off Main Grid Systems
Centralized Vs Off-main-grid electrification

11. • DECENTRALISED SYSTEMS
• Built by autonomous units (one single source)
• Locally based and Need oriented
• Restricted number of consumers
• DISTRIBUTED SYSTEMS
• Based on a number of decentralised systems
• Interacting trough a transmission distribution grid
• Virtual power plant
Off Main Grid
Systems
Centralized Vs Off-main-grid electrification

12. Decentralised and Distributed generation
• Decentralised (single unit single source) can be:
• Consumer/need oriented
• Home based system => for household
• Community based systems => for community needs
• MSEs or SMEs based systems => for micro/small/medium enterprises
• Multipurpose
• Micro Grid
• Distributed can be:
• Hybrid system (renewable + diesel)
• Size is limited < 5 MWel
• No connection to the main grid (“off-main-grid” microgrid)
bottom up & top down approach can be mixed
A network of smart minigrid that can be connected….
1 source, 1 component, 1 customer
1 source, multi component, multi customer
multi source, multi component, multi customer
Electrification via “off-main-grid systems”

13. Off-main-grid Systems for rural areas
Off-main-grid systems
Centralized Vs Off-main-grid electrification

14. Off-main-grid Systems for rural areas
Generation technologies can be identified as follows
Off-main-grid systems generation technologies

15. Off-main-grid Systems: conventional
Conventional systems are mainly diesel-powered generators (gen-sets).
Widely used to improve the access to electricity and for emergency.
Advantages
- dispatchable on demand
- simple technology
- require reduced civil work and time for installation
- meet low rural power demand
- have a low capital cost per kW
Disadvantages
- high maintenance and fuel costs (including transportation),
- high noise generation,
- low efficiency when operating far from nominal conditions (they operates at 20-
30% of the nominal conditions
- environmental implications
Off-main-grid systems generation technologies

16. Off-main-grid Systems: non-conventional
Non-conventional energy systems are Renewable Energy Technologies (RETs) :
photovoltaic (PV), wind, pico and micro-hydro (PH, MH) systems. These technologies are
selected based on existing practices, policies, and technological maturity
Advantages
- Energy security
- lower energy prices in the long term:
- efficiency are increasing prices are decreasing
- flexibility and modularity,
- low maintenance, and reduced environmental impact
Disadvantages
- aleatory nature of the sources, especially solar and wind,
- storage is a mandatory component
- increasing cost, complexity and maintenance)
- high dependence on weather conditions (solar, wind), seasonal (hydro, wind
technologies) and daily cycles (solar)
attention to the peak load demand and to the temporal load distribution is required
Off-main-grid systems generation technologies

17. Off-main-grid Systems: non-conventional
Non-conventional energy systems
biomass-based technologies are not included even if biomass is considered one of the
most important renewable sources in the near future.
Two are the reasons:
- the minimum plant size for electricity production
- The minimum scale for electricity production from biomass is estimated to be 10-100 kW,
fitting the Microgrid scale but not the home-based and community-based typical scale
- The steam cycle technology is available for loads higher than 5 MW, suitable for grid-
connected generation plants
- the complexity of the supply chain.
- Biomass is largely used on small-scale energy systems for thermal applications, while for
power generation a large-scale combustion/gasification plant is necessary
- The extremely complex and multidisciplinary biomass supply chain requires specific deep
analyses that are not tackled in this chapter.
- Good management of the whole supply chain is required
Off-main-grid systems generation technologies

18. Off-main-grid Systems: hybrid
Hybrid systems are often built up with diesel generator technology coupled
with RET-based system.
Advantages
• high reliability and continuity of supply
• reduction of the storage system size
• batteries lifetime and operation costs benefit
Disadvantages
• higher investment and maintenance costs than pure RET use.
• hybrid solution increases the complexity of the system
• the management and maintenance of different technologies is required
Off-main-grid systems generation technologies