The document discusses the design considerations and technologies involved in off-grid and island power systems, emphasizing the need for tailored solutions based on project-specific parameters. It covers fossil and renewable generation technologies, their operational and capital costs, as well as operational considerations like fuel types, maintenance regimes, and the importance of inertia for system stability. Key takeaways include the critical role of fuel in cost and equipment selection, and maintenance strategies to meet lifecycle and process requirements.

1. Powergen Pty. Ltd.
Off Grid / Island Power Supply
Rev - A
PGEN-COR-1015-PRE-008 - 0
hwright@pgen.com.au www.pgen.com.au

2. Contents
1. Island / Grid Power Systems
2. Island Operation Considerations
3. Fossil Generation Technology
4. Renewable Generation Technology
5. Capital Cost Considerations (CAPEX)
6. Operation Cost Considerations (OPEX)
7. Summary
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3. Island / Grid Systems
• An Island Power system is designed to control frequency 50Hz.
• A Grid Power system is designed to control power (MW, MVar).
• Island Power systems are designed to meet and maximise availability
and meet client load specifications.
• Grid Power systems are designed to maximise revenue for energy sales
under contract.
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4. Island Supply Operation Considerations
Availability
– Essential Services, typically 100% or by backup emergency
generation on essential services bus.
– Process Plant to be subject to product production and
processing, typically 50 – 100%. Optimisation of redundancy
and spinning reserve to match process.
Stability
– Frequency, Governor Droop settings to manage frequency
within equipment limits e.g. 47 – 52 Hz.
– Voltage to be linked to load and therefore frequency.
Controlled by AVR at generators.
Inertia
– Large consumer Starting / Stopping. Plant needs to be
designed to have sufficient rotating mass (Inertia) to
accommodate large drive starting. Mitigation measures by
FlexGen, Gigacell and Soft Start / VSD’s.
Voltage Drops and Losses
– System Design to keep high power centres closed to reduce
voltage drops and maintain smaller cable sizing.
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5. Island Supply Operation Considerations
Efficiency and Heatrate
– Equipment Selection, along with fuel availability will
determine heat rate. Improvement through co and tri
generation where applicable.
– Fuel types available for remote plants tend to be more
portable types, such as, liquid or compressed gas varieties.
Evaluation is required to determine storage and processing
costs over lifecycle against actual cost of fuel. E.g. cost of
LNG vaporisation or HFO heating and purification.
– FlexGen, CoGen and Trigen offer improvements to overall
fuel heat rate, however, only where water and steam can
be utilised. These improvements also have capital costs
attached, such as boilers, heaters and reticulation
equipment.
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6. Fossil Generation Technology
• Reciprocating Engines
– Generation, Conversion of fuel to electricity, ~ 47%
efficient at full load.
– Cogeneration, Conversion of fuel to electricity and
steam, ~ 70% efficient at full load.
– Tri generation, Conversion of fuel to electricity, steam
and hot water, ~ 80% efficient at full load.
• Engines based on standard 2 and 4 stroke cycles
require frequent maintenance due to high number
of friction surfaces.
• Side stream oil purification and slower rotational
speed (1,500 – 750 rpm) reduces ware.
• Can be easily containerised up to ~2MW
• Requires radiator cooling systems.
• Able to burn most liquid and gas fuels subject to
Hydrogen content (Causes Knocking).
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The Reciprocating Engine has become well established
for small power generation with high open cycle
efficiencies. Complexity and number of friction
surfaces increase maintenance costs.

7. Fossil Generation Technology
• Gas Turbines
– Open Cycle, Conversion of fuel to electricity, ~ 35%
efficient at full load.
– Combined Cycle, Conversion of fuel to electricity and
steam, ~ 60% efficient at full load.
• Scalable from 1MW to ~300MW
• Able to burn wide range of fuels, both liquid and
gas.
• Low maintenance costs due to small amount of
friction surfaces.
• May require injection water for NOx control.
• Can be trailer mounted up to ~3MW.
• Also commonly installed for mechanical drives.
• Available in Industrial and Aero derivatives.
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The Gas Turbine has increased in popularity due to its
high reliability. Gas Turbines also have capability to
burn less desirable fuels and blends. However, open
cycle efficiency is poor and impacted by temperature.

8. Fossil Generation Technology
• Boilers and Steam Turbines
– Pulverised Fuel, Traditional Boilers ranging to 320Bar @ 620°C
Steam in the ultra critical region. SOx, NOx removal by
Limestone and SCR.
– Circulating Fluidised Bed, able to burn wide range of low CV
fuels / Biomass and low NOx emissions due to combustion
temperature. SOx removal by injection.
– Biomass, available in smaller sizes to burn low CV fuels such
as Municipal waste, coconut and raid growth timber.
• Complex systems requiring high levels of maintenance and
skill for management.
• Require clean water for boilers and cooling.
• Clean coal drives construction costs are higher.
• Lifecycle costs can be cheaper as size increases.
• Fuel costs typically low for coals and low CV Bio waste.
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The Steam Boiler and Turbine have been developed
for many years leading to ultra critical cycles reaching
43% Efficiency levels. Recent trends have been towards
clean coal combustion.

9. Renewable Generation Technology
• Wind Turbine
– Sizing to >3MW
• Load profile is not dependable.
• Wind Generation requires a
backup of fossil generation for
both generation stability and
availability.
• Couples well with Hybrid Power
systems inclusive of solar PV and
Fossil Generation.
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The Wind Farm is one of the first commercialised
renewable sources of generation. In recent years visual
amenity has become and issue, and farms are starting to
be moved off shore. Prices falling for wind generation.

10. Renewable Generation Technology
• Hydro
– Storage | Water is stored in an elevated reservoir and released
to a turbine. Options are available for returning water to
elevated reservoir.
– Run of River | Weir is installed to divert water through
penstocks to a turbine. Discharge is returned to the river.
– Cost of civils for Hydro plants is extremely high, however fuel
cost is extremely low.
– Subject to rainfall and inflows.
• Tidal
– Submerged “wind” Turbine, Sub sea variant of wind turbine,
high stress in blades due to water density.
– Shrouded Turbine, Compact units fouling issues with shroud.
• Predictable generation based on ocean tides and currents.
• Resource often close to urban centres (Buka Passage).
• Immerging Technology still subject to R&D.
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The Hydroelectric power station is available from only
a few hundred kW to 700 MW (32 installed at Three
Gorges). Available as Kaplan, Pelton and Francis types.
Construction costs are high due to civil engineering.

11. Renewable Generation Technology
• Solar PV | using Photovoltaic panels solar
radiation is converted to electrical charge,
coupled with inverters and batteries.
• Solar Concentrating | For larger installations
solar radiation is concentrated using mirrors
on to heat absorbing surfaces. These are also
used for cogeneration pre heating.
• Dependent on solar radiation.
• Require back up systems for night time.
• Coupled with Small Reciprocating engines
and FlexGen or Gigacell provides a robust
Hybrid Power option.
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The Solar power station is a distributed power system.
Available as Photovoltaic or Concentrating types. Now very
common as a supplement to grid connected systems.
Limited by daylight hours, mitigated by batteries.

12. Renewable Generation Technology
• Energy Storage
– Raid Charge and
Discharge.
– Able to damp short
term power spikes.
– Reduce spinning
reserve.
– Reduce Spare
Capacity.
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Island and Renewable power systems lack inertia which is
critical for system stability. Utilisation of modern battery
Inverter systems such as Flexgen and Gigacell allow rapid
charge / discharge power banks to replicate inertia.

13. Capital Cost Considerations
• Power Island
– Modularisation | Packaging of equipment in
to pre assembled fast. Connection reduces
construction site costs.
– KINA/kW (EPC)
• Gas Turbine, 2,200 (1,100 AUD)
• Reciprocating, 2,900 (1,450 AUD)
• Solar, 5,000 (2,500 AUD)
• Hydro, 6,000 (3,000 AUD)
• Coal/ Biomass, 6,000 (3,000 AUD)
• Balance Of Plant (BOP)
– Air Systems
– Fire Systems
– Water Systems
– Transmission & Distribution (T&D)
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14. Capital Cost Considerations
• Fuel Logistics
– Gas transportation by Pipeline, LPG, CNG or LNG. Each has
issues relating to volumes required and capital cost of pre
process equipment. Worldwide Bulk transport by LNG. CNG
expensive due to compression, LPG low volume.
– Fuel oil, readily available from world market for delivery by
ship to port. Access to docks and inland transport may be an
issue.
• Transmission Systems
Typically more cost effective than fuel transport. Initial capital
outlay can be high, subject to terrain and distance.
• Financing (BOO, BOOT)
– In order to reduce balance sheet costs, build own operate
plants are marketed where the provider delivers energy for
the duration of a contract. Pricing is typically split into a
capacity payment and a generation payment (CAPEX, OPEX).
Terms range from 5 to 25 years.
– An enhancement of the BOO adds transfer. In these cases the
equipment is given a residual value to the client after a period
of time (Concession Period). In some cases assist in overall
Kina/kW costs.
– Both BOO and BOOT contracts require some form of offtake
guarantee to allow successful financing by supplier.
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10MW Reciprocating
Engine will burn:-
~ 0.374kg/s (900 t/m)

15. Example Finance Model for BOO
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16. Operational Cost Considerations
• Fuel / Heatrate (1MW Plant @ 92.5% per year)
– Liquid 8,400 kJ/KWh (43%)
• Diesel, 1,542t @ AUD 1,010 t (23.32 $/GJ) = $1,557,000
• HFO, 1,584 t @ AUD 625 t (14.64 $/GJ) = $990,000
– Gas 7,763 kJ/KWh (46%)
• CNG, 62.1 TJ @ AUD 10 $/GJ (Ex Trans) = $621,040
• LPG, 666 t @ AUD 980 $/t (Ex Trans) = $1,315,000
– Coal 10,800 kJ/KWh (30%)
• Thermal, 4,405 t @ AUD 80 t (Ex Trans) = $352,428
– Biomass 14,000 kJ/KWh (26%) Price Subjective
• Waste (25% MC), 7,717 t @ AUD 100 t (Ex Trans) = $717,714
• Timber (5% MC), 7,032 t @ AUD 200 t (Ex Trans) = $1,406,596
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17. Operational Cost Considerations
• Labour
– Local Staff | Always preferable to utilise local resource. Allocation
should cover allowances for shifts. Communities are family orientated
and most locals do not have personal transport. Allocate costs for
relocation, accommodation and transport.
– Expatriate Staff | Expats should focus on the transfer of knowledge
and skill. Where possible, tasks should be procedure based for local
transfer. Costs for expat workers in PNG are high. Skillsets are required
initially and for ongoing support.
– Training | Key to project success and integration with social groups is
the upskilling and utilisation of local teams. Training needs to form an
initial and ongoing part of project delivery and operation.
– Accommodation | Lack of affordable accommodation in PNG is an
issue. Locals tend to live away from urban centres adding additional
camp costs. Hotel pricing in the Capital are very high.
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18. Operational Cost Considerations
• Maintenance Regime
– Reciprocating engine (Subject to speed, fuel, duty) (O&M ~$39.5 MWh)
• Weekly / Monthly service for filters and oils
• 6,000 hrs, turbos and top end
• 12,000 Hrs, bearings, pistons and liners
• 24,000 Hrs, rebuild
– Gas Turbine (Subject to environment, duty) (O&M ~$17.8 MWh)
• 10,000 Hrs, Borescope
• 30,000 Hrs, 1st, 2nd row replacement (hot Sec)
• 60,000 Hrs, 3rd row replacement (hot Sec)
– Boilers & Turbines (O&M ~$19.5 MWh)
• 8,000 Hrs, Boiler Inspection, Ash System, Firing Equipment
• 24,000 Hrs, Boiler overhaul
• 48,000 Hrs, Turbine Inspection
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19. Summary
• One solution does not fit all - expect a tailored solution specific to the
project parameters;
• Fuel is critical to cost, equipment selection, operation and maintenance;
• Know your loads and load schedule to allocate spinning reserve and
implement load management strategies;
• Inertia is critical for power stability, especially in larger drives. Design to
accommodate or mitigate;
• Maintain equipment to meet process requirements and life cycle;
• Construct where possible away from site and modularise; and
• Reciprocating engines and gas turbines each have pros and cons which
may best suit differing situations.
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Additional information available at :
http://www.pgen.com.au

20. 240MW CCGT on Island Grid
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