Renewable Energy

Prof. Peter Seligman, D.Eng

Inspired by Sustainable Energy – without the hot air byDavid MacKay FRSGoogle: withouthotair

Definitions:

Renewable: we can continue indefinitely

Sustainable: we can do it for a long time but eventually will have to come up with something different.

Zero carbon: we may run out in the foreseeable future but it’s still worth doing.

How much energy do we use?from ABARES

Australian Bureau of Agricultural and Resource Economics

abare-brs.gov.au

Primary energy:

Domestic: 5.8 exajoules per annum

Export: 13.8 exajoules per annum

Exajoule = 1018 Joule

Our domestic primary energy use:

Domestic: 5.8 exajoules per annum

= 5.8 x 1018 joules or watt seconds

divide by 3.6 x 106 = 1.6 x 1012 kWh/annum

divide by number of people: 22 x 106

= 73,200 kWh/annum/person

divide by hours in a year: 365 x 24= 8360 Watts/person

Our domestic primary energy use:

8360 Watts/personx by 24/1000

= 200 kWh/person/day

UK/Europe = 125 kWh/person/day

Primary energy: 8000 watts/person

Heating 80% efficientElectricity generation 30% efficientTransport 20% efficient

Average efficiency 50%

End-use energy: 4000 watts/person

Where do we use energy?• Personal

– Food – Electricity – Gas– Petrol– Flying– Stuff we buy– House construction

• Public– Factories– Offices– Shops– Hospitals– Schools– Universities– Public transport– Sporting facilities– Street lighting– Cinemas, theatres– Construction

About a quarter of our energy use is personal:

1000 watt/person

Three quarters of our energy use is public:

3000 watt/person

Our energy use

• Private 1000 watts (ten 100 watt globes)

Our energy use

• Public 3000 watts (thirty 100 watt globes)

Total end-use energy

• Per person: 4000 watts (forty 100 watt globes)

Elec industrial

Elec commercial

Elec domestic

Elec Misc

Fuels other than elec generation

Distribution of total energy use

Electricity use

National average electricity generation 25 GWover 22 million people:

1100 watts/person

Distribution of electricity use

Elec industrial

Elec domestic

Elec commercial

Elec misc

How much power can a 1000 watt photovoltaic system produce?

= 160 watts average

How much power per person?

= 40 watts average(remember we use 4000 watts each)

Output of a 1 kW solar panel

• 1000 watts nominal peak in bright sunlight• 800 watts under realistic conditions

(temperature and inverter efficiency)• 400 watts taking into account night time• 320 watts taking into account sun angle• 160 watts taking into account cloud• 40 watts each for a 4 person family

Role of domestic solar PV• Elec. price rises due to distribution, not

wholesale price• Increase distribution costs due to aircons• Each $1500 aircon adds $7000 to

infrastructure cost• PV can provide power locally when it is

most needed (best facing NW at steep angle)

We can’t solve a big problem by thinking small

Renewable energy system

• Wind• Solar• Geothermal• Wave• Utility scale energy storage• High voltage DC (and AC) links

How much power from the wind?

5 turbine diameter separation between turbines 2 watt/m2

2 – 3 turbine diameters in non-prevailing wind directions

Typically: 4.5 watt/m2

Land is still suitable for farming

Wind Power

• Turbines now up to 7.5 MW

• Technologically mature

• Capacity factor 30%

• Average output 2.3 MW per turbine

Turbine technology• Enercon E126 turbines• 7.5 MW• Gearless design • 138m hub height• 127m blade diameter

A question of storageWind power in South Australia and Victoria

From Wind farming in South Australia

Large scale solar - California 1984345 MW peak: 75 MW average

http://www.itas.fzk.de/deu/tadn/tadn013/image37.jpg

Andasol 1 to 3 Granada Spain50 MW turbines 20MW average

courtesy Ferrostaal AG.

Molten salt storage

Torresol Gemasolar Molten Salt Solar

• solar power at night• “Baseload” “Dispatchable” solar – better than coal

Gemasolar in Spain 201120MW turbines 12.5MW average

Large scale solar courtesy Ferrostaal AG.

Liquid salt storage tanks courtesy Ferrostaal AG.

How much power from the sun?

Solar radiation: 1000 watts/m2

• Taking into account night-time and cloud160 watts/m2

• Taking into account 15% efficiency24 watts/m2

• Taking into account shading and access4.5 – 15 watt/m2

How much of Australia?

• 200 km square

• 4.5 watt/m2

• 8000 watt/person

Geothermal energy from

hot dry rocks

http://sen.asn.au/renewables/geothermal

Geothermal resources in Australia

• Hot Dry Rocks• Heat build-up in radioactive granite

+ residual heat from earth’s core • Typical power flow 50 – 100 millwatts/m2

• Not renewable but usable over 400 years• Could supply about 800 watts per person

(end use)

Geothermal resources in Australia

http://www.ga.gov.au/image_cache/GA10036.pdf

How much power from waves?

• 2000 km of Australian south coast• 100 – 160 kW/linear metre• Extraction efficiency: 5 – 10%• Could supply about 900 watts per person

(end use)

Tidal power?

• North West Australia10 metre tides: 150 watts per person (end use)

• Port Phillip Bay 10 watts/Melbournian

Supply, demand and curtailment

From BZE Zero Carbon Australia Stationary Energy Plan

Nullarbor pumped seawater electricity storage

Bunda cliffs

From Google Earth

200 GWh battery

Okinawa pumped seawater electricity storage

High Voltage DC links• Low loss power transmission over long

distances• No current due to line capacitance• No eddy current losses is wires• Lower peak voltage (or higher average

voltage)

High voltage DC links

• 1700 km in the Congo, built 1982• Longest 2100 km, China• Highest power: 6400 MW, China and India

• Basslink: 300km cable, 600 MW

http://en.wikipedia.org/wiki/List_of_HVDC_projects

More HVDC details

• May use monopole (earth return)

• DC is the only practical solution to undersea cables

• Power loss: 2% / 1000km, 1.5% in converters

http://www.utilities-me.com/article-690-electricity-highway-powers-through-china/

AC-DC-AC Converter

http://www.energy.siemens.com/hq/pool/hq/power-transmission/HVDC/HVDC-Classic/TSQ-Valvehall-b.jpg

Transformer for High voltage DC power line

Courtesy Siemens AG

Wiring diagram for Oz

Resource Watts/person Proportion of resource

Hydro 73 Existing

Geothermal 682 Currently measured resource fully used

Wave 18 3% of coastline

Solar 909 0.06 % of country

Wind 909 0.13% of country compatible with farming

Total 2600 (end use

UK, Europe)

An energy strategy for Australia

Transport• Biofuels from algae?• Unwanted CO2 as feedstock for algae.• Hydrogen• Ammonia – NH3 ?!• Electrification of road transport• Use of transport batteries for large scale

energy storage

Efficiency and waste

Why do we need to do this?

We don’t have a Planet B!(Madeleine Trau – 8 years old)

Beyond Zero Emissions

ZCA2020 Available online and in print from

MEI: www.energy.unimelb.edu.au

or…

www.beyondzeroemissions.org