town power management

8/6/2019 Town Power Management

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POWER MANAGEMENTPOWER MANAGEMENT

FORFORSUSTAINABLE ENERGY SYSTEMSSUSTAINABLE ENERGY SYSTEMS

Graham Town

Electronic Engineering

Macquarie University.



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OVERVIEWOVERVIEW• The need for

– decreasing reliance on fossil fuels

– increased reliance on sustainable sources of energy

– efficiency in energy conversion and use

• Sustainable energy systems

– source, storage, load, power management…

• Efficiency in sustainable energy systems

– solar cells, wind turbines, batteries, converters

• Integrated circuits for

– power conversion & management

– energy harvesting



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ENERGY 2010ENERGY 2010• Fossil fuels (oil, coal) are main source of energy in modern society.

• Advantages: high energy density (45MJ/kg, approx. twice ethanol)

relatively easy to transport safely, easy to use.



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ENERGY 2010ENERGY 2010• CO2 emissions are mainly from burning fossil fuels for:

– Electricity generation (coal)

– Transport (oil)



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PROBLEMS WITH FOSSIL FUELSPROBLEMS WITH FOSSIL FUELS2. CO2 emissions causing environmental change

– Global warming caused by greenhouse gases in atmosphere climate change, extreme weather events, etc.

– Ocean acidification caused by absorption of CO2

potential threat to marine food chain



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ENERGY OPTIONS TO 2050+ENERGY OPTIONS TO 2050+1. Reduce fossil fuel usage

i) for the environment, ii) to make resource last longer

To use less energy (esp. for transport, heating/cooling)….• reduce population and/or living standards

increase energy efficiency

Campbell, “Petroleum and People”,

Pop’n and Environ.,24 , 193 (2002).



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ENERGY OPTIONS TO 2050+ENERGY OPTIONS TO 2050+2. Replace fossil fuels with sustainable energy sources (i.e. no

compromise to the needs of future generations)

– Nuclear energy – “Renewable” (naturally replenished) sources of “green” (unpolluting)

energy

• solar

• wind

• wave & tidal

• hydropower

• biomass

• geothermal

– Energy harvesting

International Energy Agency, “KeyWorld Energy Statistics,” p6 (2009).



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PRACTICAL ENERGY MATTERSPRACTICAL ENERGY MATTERS• Available on demand?

• e.g. solar power not available at night, wind power often variable

• Storage? (if not available on demand)• e.g. thermal, mechanical, chemical, electrical

• Transport? (if source and load not colocated)

• e.g. electrical, chemical

• Efficient conversion (for storage, transport)• e.g. chemical electrical (e.g. battery)• e.g. thermal mechanical (e.g. steam turbine)

• e.g. mechanical electrical (e.g. wind turbine)• e.g. electrical electrical (e.g. DC-AC, DC-DC converters ~95% efficient)• conversion efficiency particularly important for harvesting small amounts of

energy from the environment (ambient light, vibrations) for mobile devices.



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POWER SYSTEM MANAGEMENTPOWER SYSTEM MANAGEMENT• Any electric power system has a source, load, and usually storage

• Each of the components have a preferred operating point

– e.g. maximum power point (V and I for max. power transfer) – e.g. charge/discharge rate for max. lifetime

• Power management is req’d to maximise system performance,especially in energy harvesting (ambient sources: small, variable)



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SOLAR CELL ARRAYSOLAR CELL ARRAYCHARACTERISTICSCHARACTERISTICS

• For a given irradiance, the power extracted from a solar cell (oruniform array) depends on the voltage across it, up to a maximum – the maximum power point, or MPP

http://www.innovativesolar.com/images/File/BSE_What_is_MPPT.pdf



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SOLAR CELL ARRAYSOLAR CELL ARRAYCHARACTERISTICSCHARACTERISTICS

• The MPP varies with irradiance, temperature, etc.

• Arrays of cells are often used to boost voltage or current – BUT shadowing of any cells in array can cause large reduction in avail. power

• Need smart and efficient power conversion & combining

Organic (polymer) solar cell array fabricated and characterised by the author at St Andrews University (2009)



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ENERGY STORAGE TECHNOLOGYENERGY STORAGE TECHNOLOGY• Many different technologies available, different characteristics

http://www.mpoweruk.com/performance.htm

http://www.batteryuniversity.com/parttwo-34.htm

Longevity

of lithium-

ion as a

function of

charge and

discharge

rates.

A moderate charge and discharge

puts less

stress on

the battery,

resulting in

a longer

cycle life.



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GREEN TRANSPORTGREEN TRANSPORTThis?

……….. or this?

http://www.gizmag.com/lexus-hybrid-bicycle-concept/14938/



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GREEN TRANSPORTGREEN TRANSPORT

http://www.gizmag.com/lexus-hybrid-bicycle-concept/14938/



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ENERGY HARVESTINGENERGY HARVESTING• e.g. “wireless switch” technology

The effort made in pushing the switch powers a small and efficient wireless

transmission system to activate remote equipment• e.g. power generators in your shoes

The act of walking generates electricity by flexing a piezoelectric materialembedded in a shoe, e.g. to charge a battery for mobile communication, etc.

https://reader009.{domain}/reader009/html5/0515/5afa17f0248c2/5afa17f82a975.jpg



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POWER TECHNOLOGYPOWER TECHNOLOGY• Will follow same evolutionary path as wireless communication

technology (i.e. to smaller, more mobile systems)



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““POWER SUPPLY ON A CHIPPOWER SUPPLY ON A CHIP””• Research sponsored by local company, Sapphicon Semiconductor

– Only IC manufacturer in Australia

– Silicon-on-sapphire CMOS platform• Transparent sapphire substrate low loss, high speed, efficient heat x’fer

• Better than standard CMOS for power management and energy harvesting



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CONCLUSIONSCONCLUSIONS• We need to change energy usage patterns

develop different sources of energy

use available energy more efficiently

• Integrated electronics provides reliable, low cost, and

compact technology for efficient energy conversion and utilisation

smart management of power systems…

and the battery on your mobile phone will last longer !

town power management

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