Carbon footprint of electricity generation

Stephanie Baldwin

POST

www.parliament.uk/post

Provides information on S&T based issues to Parliamentarians

NOT party political

Independent, impartial, balanced – no recommendations

Seek input from industry, academia, government, NGO’s

Peer reviewed by these external experts

What is POST’s role?

2%renewables

& waste

8%nuclear& hydro

17%coal33%

oil

40%gas

Policy context

34%coal

39%gas

19%nuclear

7%hydro, imports& renewables

1%oil

2006 ‘Energy Review’

Climate change & energy security

UK primary energy mix UK electricity mix

Future policy – maintain diversity of energy mix

No electricity generation technology is ‘carbon free’

All electricity generation technologies have a carbon footprint

8 different electricity generation technologies analysed

In the context of fossil fuelled electricity generation…

where they are now? – current carbon footprint

where are they going? – future carbon footprint

how do they compare with other technologies?

Background

What is a carbon footprint?The total amount of CO2 and other greenhouse gasesemitted over the full life cycle of a product or process,from extraction of raw materials through to decommissioning

Expressed as gCO2eq/kwh – account for different GWP of other GHG’s

Carbon footprints are calculated using Life Cycle Assessment (LCA) 1. Boundary definition2. LCI – Life Cycle Inventory – the most objective result of LCA3. LCIA – Life Cycle Impact Assessment4. Interpretation & improvement

LCA cannot replace the decision making process itself

DefinitionsCO2

CO2CO2

CO2

CO2

CO2

decommissioning

maintenance

transport

CO2

recycling

extraction

construction

operation(direct CO2 emissions)

CO2

CO2

CO2

CO2

CO2

CO2processing

Full life cycle carbon dioxide (CO2) and other greenhouse gases (e.g. CH4) emitted by electricity generation technologies

0

200

400

600

800

1000

1200

Coal Gas Biomass PV Marine Hydro Wind Nuclear

1075

Oil

650

823

440 411

25 3558

237

(UK, AFBC plant)

50 25 10 3 5 4.5 3.55

Carbon footprints of electricity generation technologies(UK & European data 2004-2006)

(UK, IGCC plant)

UK plant low-NOX

Swedish plant

Differences between individual plants – some older and/or less efficient

Different technologies – e.g. run-of-river vs. reservoir storage

Different LCA input (boundary definition) parameters

Different studies – some studies older, so had older data (2000 was cutoff date)

Ranges in each electricity generation technology are due to:

0

200

400

600

800

1000

1200

Coal Gas Biomass PV Marine Hydro Wind Nuclear

Carbon footprints of electricity generation technologies(global data, 2004-2006)

1070

766

662

398

25 35110

237

(West European UCTE average)

50 25 34 3 29 4 380

(Australian plant – USCSC plant)

US plant

German plant

Carbon footprints variations

0

200

400

600

800

1000

1200

Coal Gas Biomass PV Marine Hydro Wind Nuclear

Ranges are larger in the global data for 2 main reasons:

Older vintage technologies – less efficient

Use of LCA not as established – LCA identifies less efficient processes

UK & European data Global data

0

200

400

600

800

1000

1200

Coal Gas Biomass PV Marine Hydro Wind Nuclear

Carbon footprint of electricity generation technologies(UK & Europe)

0

200

400

600

800

1000

1200

Coal Gas Biomass PV Marine Hydro Wind Nuclear

Carbon footprint of low carbon electricity generation technologies(UK & Europe)

020406080

100120140160180200

Biomass PV Marine Hydro Wind Nuclear

237

25

58

3550

2510

3 5.25 4.64 5.05 3.48

strawdirect combustion

UK UK

, Torness

offshore

onshore

southern Europe

run-of-river

reservoir storage

range for UKwave converters

woodchip gasification

Sweden, R

inghals

020406080

100120140160180200

Biomass PV Marine Hydro Wind Nuclear

Carbon footprint range:Highest: 237 gCO2eq/kWh (direct combustion of straw)Lowest: 25 gCO2eq/kWh (gasification of wood chip)

Issues:Biomass is ‘carbon neutral’ → CO2 absorbed (growth) = CO2 released (burning)Transport contributes the largest amount of life cycle CO2, also fertilizers, harvestingLarge range of carbon footprints → related to differences in energy and densityCo-firing biomass + fossil fuels can reduce the carbon footprint of fossil fuelled power

Biomass

PhotovoltaicsCarbon footprint range:Highest: 58 gCO2eq/kWh (UK)Lowest: 35 gCO2eq/kWh (southern Europe)

Issues:PV cells predominantly made of high grade siliconSilicon extraction and purification is most energy intensive phase (60% of CO2)Future reductions in silicon use (e.g. thin film) will lower carbon footprintCarbon footprint lower in southern Europe because greater operating hours

020406080

100120140160180200

Biomass PV Marine Hydro Wind Nuclear

Marine(wave & tidal)

Carbon footprint range:Highest: 50 gCO2eq/kWh (range for UK wave converters)Lowest: 25 gCO2eq/kWh

Issues:Two main types of devices: wave energy converters & tidal stream/barrage devicesMarine electricity generation still an emerging technology – most still prototypesNo commercial marine powered electricity generation in the UK yetMarine carbon footprint currently equivalent to PV, but may reduce to level of wind

020406080

100120140160180200

Biomass PV Marine Hydro Wind Nuclear

Carbon footprint range:Highest: 10 gCO2eq/kWh (non-alpine reservoir storage)Lowest: 3 gCO2eq/kWh (non-alpine run-of-river)

Hydro

Issues:Two main schemes: reservoir storage (large scale), run-of-river (small scale) Storage schemes have higher carbon footprint since a dam is constructedRun-of-river schemes have the smallest carbon footprint of all technologiesHydro has small CO2 emissions, but some methane (CH4) is also emitted

020406080

100120140160180200

Biomass PV Marine Hydro Wind Nuclear

Issues:Wind has one of the lowest carbon footprints98% of emissions arise during manufacturing & construction (steel, concrete)Remaining emissions arise during maintenance phase of life cycleFootprint of offshore turbine is greater due to larger foundations

WindCarbon footprint range:Highest: 5.25 gCO2eq/kWh (UK offshore)Lowest: 4.64 gCO2eq/kWh (UK onshore)

020406080

100120140160180200

Biomass PV Marine Hydro Wind Nuclear

Issues:Nuclear also has a very small carbon footprintMost CO2 emitted during uranium mining (40% of life cycle CO2)Global uranium reserves – lower grades may cause footprint to rise in future3 studies: AEA ( to 6.8g), Öko ( to 30-60g), Storm van Leeuwin ( 60 to 120g)

NuclearCarbon footprint range:Highest: 5.05 gCO2eq/kWh (UK, Torness plant)Lowest: 3.48 gCO2eq/kWh (Sweden, Ringhals plant)

020406080

100120140160180200

Biomass PV Marine Hydro Wind Nuclear

Future carbon footprint reductions

-200

-100

0

100

200

300

400

500

600

700

800

Coal Gas Biomass PV Marine Hydro Wind Nuclear

current footprint

future footprint

coalwithCCS

gaswithCCS

biomasswithCCS

Future carbon reductions are possiblefor all these technologies if the construction

phase (e.g. steel, concrete production)is fuelled by ‘low carbon’ electricity

future reductions in raw materialse.g. less silicon in thin film PV

Increasing futurenuclear footprint due to

lower grade uranium

(or increases!)

Future carbon footprint issues

Coal: ▪ co-firing with biomass▪ CCS – not yet demonstrated for electricity generation

Gas: ▪ co-firing with biomass (where biomass is gasified)▪ CCS – not yet demonstrated

Biomass: ▪ CCS – unlikely since most biomass plants <50MW

PV & Marine: ▪ Reduction in raw materials

Nuclear: ▪ Footprint may rise if lower grade ores are used,but will only rise to level of other ‘low carbon’ technologies,not as large as current fossil fuelled electricity generation

All: ▪ Can reduce future carbon footprint if highCO2 life cycle phases are fuelled by lowcarbon energy sources

Thank You!Stephanie Baldwin

www.parliament.uk/post

Conclusions

All electricity generation technologies emit CO2 at some point during their life cycle

None of these technologies are entirely ‘carbon free’

Fossil fuelled electricity generation has the largest carbon footprint (>1,000gCO2eq/kWh)

‘Low carbon’ technologies have low carbon footprints (<100gCO2eq/kWh)

Future carbon footprints can be reduced for all electricitiy generation technologies if

the high CO2 emission phases are fuelled by low carbon energy sources