webinar 1 | mar-16 | renewable energy in small island grids: case study -tuvalu

Renewable Energy in Small Island Grids

Case study - Tuvalu

About ITP

•Specialist renewable energy consulting firm

•Over 30 years international experience and 1,000 projects

•Head office in UK

•Major regional offices in India, China and Australia

About ITP - Australia

• Head office in Canberra, offices in South Australia and

NSW

• Active in Australia and the Pacific region for over 10

years

• Involved in RE projects of all scales (1 kW to 50+ MW)

• Services

• Engineering Consultancy

• Project Engineering

• Energy Markets and Advisory

• International Aid and Development

Mini-grids – Tuvalu northern islands

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Case study – Tuvalu northern islands

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• Nine small atoll islands

• Total population approx. 10,000

• 6,000 on the capital, Funafuti

• Other islands populations 100-1,500

• Outer islands only accessible by boat, typically 24hrs by

boat to each island

• Irregular shipping (every 3-6 weeks)

• Shipping often disrupted by weather or boat unavailability

Case study – Tuvalu northern islands

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• Existing low voltage AC

electricity grids (diesel)

since 2001

• Grids operated by

electricity utility (Tuvalu

Electricity Corporation)

• Local operators (TEC

employees) deal with day

to day running

• Technicians from the

capital visit periodically or

for repairs when required

Why renewable energy?

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• Reduce reliance on

imported diesel

• Reduce running costs

• Cleaner

• Quieter

• Improve reliability

• But:

• Upfront cost can be high

• Storage required

• Can have integration

problems with generator

Generator efficiency

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Generators

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Nanumea power station

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Village

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Village

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Tuvalu northern islands- key issues

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• Reliability • Only 12-18 hours of power per day normally (down to 2-4 hrs

sometimes)

• Frequent diesel shortages due to shipping unreliability

• Generator breakdowns

• Long delays for repairs (can take weeks to send a technician from Funafuti)

• Cost• Estimated ~$1.20 to $1.50/kWh cost of supplying energy (possibly

more)

• Vulnerable to diesel price changes

• Vulnerable to utility cash flow issues

• Tariffs ~25c/kWh – outer islands heavily subsidised by main island and by government

• Remote diesel grids were built as a service to the community, but are very expensive for the government

Transportation

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Unloading

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Transportation

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Vulnerability to weather

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Aims of outer islands solar project

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• Outer islands 100% renewable energy

• 24hr power

• System to last 20 years without need for major

modification

• Reduce operating costs of outer islands power

systems

• Improve power reliability (and availability during

disasters)

• Grant-funded (NZ Govt)

• Eliminate need for aid fuel subsidies

Load curve – Nanumea island

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0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00 00:00

Load

(kW

)

After load growth

Assumed loads

From data logger

Load curve – Vaitupu island

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0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00 00:00

Load

(kW

)

From logs

From data logger

Assumed loads

Load estimate - Nanumea

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• Average 550 kWh per day

• Little seasonal variation, but some “busy” times of year.

• Highest demand around Christmas and special events

• 40% of demand during “solar” hours

• 60% evening/night time

• Allowance for extra days with poor sun – 2 days

• Use this to size battery bank

• Then size solar PV array to meet day time load plus

enough extra energy to fully charge the batteries.

Design schematic

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Design features

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• Modular

• if one unit fails, most of the system can be kept online

• Spares kept on island, easy to swap out

• Off-the-shelf inverter/controller, easy to order a new one

• Robust and corrosion resistant

• Cyclone proof structure

• No air conditioning required

• Because the air conditioner is often a failure point

• Low maintenance

Completed system

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Photo credit: Heather Logie

Display

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Modular inverter/chargers

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Sealed batteries

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Passive cooling

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Performance so far

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• System is very large for current loads – no diesel needed

• Batteries drop to 80% overnight, are fully charged before

midday if sunny

• Can go for 5 days of cloudy weather without generator

• 1 inverter failure – local operator successfully replaced it

and sent it back for warranty claim

Training and operation

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• Local operators involved from beginning of construction

• Training throughout construction and troubleshooting

• Other staff in Funafuti (capital) have been doing solar

training over a longer period and are adapting well with

support from the manufacturers

• Very challenging for the outer island operators to adapt to

the new technology

• Local operators call head office (if possible) for support

from more skilled technicians

Lessons/challenges

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Some challenges ITP has seen over the years:

• Skill level of staff on outer islands is usually low

• Systems becoming too reliable (operators stop maintaining

generators totally/ get lazy)

• Social problems with 24hr power (eg loud music at night)

• Logistics can be very complicated

• Getting accurate data and information is difficult (eg

powerhouse data, shipping schedules)

• Communications difficult

• Limited market for companies with experience in designing

and building renewable energy systems on island

environments

Southern Cross House,

6/9 McKay St, Turner, ACT

PO Box 6127 O’Connor, ACT 2602

info@itpau.com.au

p +61 (0) 2 6257 3511

f +61 (0) 2 6257 3611

itpau.com.au

IT Power Renewable Energy Consulting

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