2011-03 - sustainable energy - without the hot air - cx

8/7/2019 2011-03 - Sustainable Energy - Without the Hot Air - CX

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David JC MacKaySustainableEnergy without the hot air

Chaojun Xu, 2011-03-12

http://www.withouthotair.com/http://www.uit.co.uk/

Department of Physics, University of Cambridge

David MacKay is a Professor in the Department of Physics at the University of

Cambridge. He studied Natural Sciences at Cambridge and then obtained his PhD

in Computation and Neural Systems at the Cal ifornia Institute of Technology. He

returned to Cambridge as a Royal Society research fellow at Darwin College . He is

internationally known for his research in machine learning, information theory, and

communication systems, including the invention of Dasher, a software interface thatenables efficient communication in any language with any muscle. He has taught

Physics in Cambridge since 1995. Since 2005, he has devoted much of his time to

public teaching about energy. He is a member of the World Economic Forum Global

Agenda Council on Climate Change.

Why did he write this book?

Hes concerned.

He wants to give us numbers we understand.

He burns for this.
http://www.withouthotair.com/http://www.uit.co.uk/http://www.uit.co.uk/http://www.uit.co.uk/http://www.withouthotair.com/


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Do you know

how many tons of CO2 you produce per year?

how many kWh you consume per day?

Numbers, not adjectives!Some number we should know

CO2 emissions per person per year

World: 5 tons /y /p

EU: 10 t /y /p

US: 24 t /y /p

CO2 emissions per one litre of gas

2,3 kg

CO2 emissions for airfare

Inter-European: 200 kg

Inter-Continental: 2000 kg

Power consumption per person per day

Europe: 125 kWh /d /p

US: 250 kWh /d /p

For CO2 emission, divide by 10: 100 kWh /d = 10 t CO2 /y


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Per capita emissions of CO22000

World avg.

EU avg.

Balance sheetCan we live on renewables?


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The balance sheetCan we live on renewables, i.e. without fossile fuels?

Convert to simple numbers! Figures will be imprecise and be based on

reasonable assumptions and physics.

The balance sheetCan we live without fossile fuels?

Bad news! Good news?

Easy!

Difficult!

Not really.


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Start building both pilesCan they match? At what price?

Cars

Assumptions

Distance travelled is 50 km per day

Distance per unit of fuel 12 km per litre

Energy per unit of fuel 10 kWh per litre

Additional questions (not taken into account)

Energy consumed to produce the cars fuel?

Energy consumed to manufacture the car?


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Wind (onshore)

power per person = wind power per unit area x area per person

Typical windspeed is 6 m/s

Power per unit area 2 W/m2

People density (UK) 250 people /km2 = 4000 m2 /person

If wind mills are packed across the whole country;

2 W/m2 x 4000 m2 / person = 8000 W per person

Power is 200 kWh/d

Lets cover 10% of the country:

Power is 20 kWh/d

Offshore wind, larger mills etc. are discussed later

Renewables are diffuse

ToTo makemake aa differencedifference renewablerenewable facilitiesfacilities havehave toto bebecountrycountry--sizedsized!!


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Planes

One intercontinental trip per year how much energy?

Boeing 747-400 has 240.000 litres of fuel for 416passengers and flies 14.200 km.

Fuel caloric value is 10 kWh/litre

Overestimation, therefore use 30 kWh/d Equals leaving a 1 kW electric fire non-stop for one year!

Flying enough for silver frequent flyer status; 60 kWh/d

Solar

Power of raw sunshine at midday on a cloudless dayis 1000 W per m2

This is theory, in practice we get 100 W per m2

Different usage of power:

Solar thermal (13 kWh/d per person) using 10 m2per person (roof towards the south)

Solar photovoltaic (5 kWh/d per person) using 10m2 per person (roof towards the south); (50 kWh/dper person) using solar farms in 5% of the UK*

Solar biomass (24 kWh /d /p)**

Food (...) no contribution, we need it to eat

*This is ca. 100 x all PV installed today world-wide!

** There is no way to power cars 100% by biofuels!


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Heating and cooling

Hydroelectricity


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Light

Street lights are negligible

Energy-saving bulbs aregood for economy

Total cumulative cost of using atraditionalincandescent 100W bulbfor 3 hours per day, compared withreplacing it now withan OsramDulux Longlife Energy Saver(pictured).Assumptions: electricitycosts 10p per kWh;replacementtraditionalbulbs cost 45p each;energy-saving bulbs cost 9.

Offshore Wind Requires60 Miotons ofsteel and

concrete(UK) andspecial

ships


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Offshore wind kills 30,000 birds per year!How media can influence opinions

Gadgets


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TryingTrying toto savesave energyenergy withwith phonephone chargerschargers isis likelike bailingbailing thethe TitanicTitanic withwith aa teatea spoonspoon..


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Wave

Efficiency at best 25%

Food and farming

Energy for producingfood see below.


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Tide

Stuff (=industrial production)Raw Material Production Use Disposal


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Geothermal10 kWh/d/p if all land area

was used (at 15 km

depth!

Very large in Iceland,Phillipines, (ca. 25%of national electricity)

Public ServicesEnergy for making bullets,bombs, nuclear weapons;

Making devices fordelivering bullets, bombs,and nuclear weapons;

Roaring around keeping intrim


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Can we live on renewables?A close race

Consumption 195 kWh /d /p

Production 180 kWh /d /p

But:

economic, social, environmental constraints have beenneglected

energy conversion losses have been neglected

energy exists in different forms

renewables compete for resources and area

It would be very difficult to live on our own renewables

- at least, as we currently live


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18 kWh /d /p

= 14.4 %

The situation today


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Conclusion so far

A typical European country cannot live

on (own) renewables

- at least not as we currently live.

To make a difference,

renewables have to be country-sized.

The same is true for most other

European countries (except for Norway)

We cannot live on renewablesWhat now?


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Every BIG helps

66 000? Wow, what a lot of homes! Switch off the chargers!

66 000 is just 0,26% of 25 million homesin the UK.

How to make an energy plan that adds up

Demand side

Reduce population

Change life style

Technology, efficiency

Supply side

Clean coal

Nuclear power

Use other countriesrenewables


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Reduce population!

???

this is for politics (and the pope?)

Change lifestyle!


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Technology & Efficiency


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Better transport!

3 kWh per 100 km


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Better heating!

Reduce temperature difference

move to the south

hmmm

turn the thermostat down

change lifestyle (a bit)

Reduce leakiness

costs 8 kWh /d /C

insulate better

Increase coefficient of performance of heat creation

install heat pumps

Better electricity use!


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Sustainable fossil fuels

Clean coalis only a stop-gap

Nuclear fission

Leave safety and disposal of waste aside (only here!)

World nuclear power production today 1.2 kWh /d /p


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Nuclear fusion the MessiahWait but act!

Living on other countries renewables

www.desertec.org

With all problems that still needto be solved

political social

Basic technology isavailable and proven
http://www.desertec.org/http://www.desertec.org/


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Energy storageBalancing supply and demand

Important quantities: amount

of energy to store and rate of

energy to store

Total output [MW] of all wind farms ofIreland(www.eirgrid.com).

Electricity demand in Great Britain[kWh /d /p in 2006.]

Future energy plansCommon features

Transport is electrified

Public transport is better

Electric fleet serves for energy storage

Large areas of the country need toserve renewables

Insulation of buildings and heat pumpsare standard

The need for electric energy will risedramatically

For this, the book describes fivedifferent scenario plans
http://www.eirgrid.com/http://www.eirgrid.com/


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Conclusions

A typical European country cannot live

on renewables

- at least not as we currently live.

To make a difference,

renewables have to be country-sized.

Every BIG helps. Do not spend effortfor little.

2011-03 - sustainable energy - without the hot air - cx

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