Carbon footprint of electricity generation Stephanie Baldwin POST www.parliament.uk/post
What is POST s role? 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
26 Energy Review Policy context Climate change & energy security UK primary energy mix UK electricity mix 4% gas 39% gas 34% coal 33% oil 2% renewables & waste 8% nuclear & hydro 17% coal 1% oil 7% hydro, imports & renewables 19% nuclear Future policy maintain diversity of energy mix
Background 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?
Definitions What is a carbon footprint? The total amount of and other greenhouse gases emitted over the full life cycle of a product or process, from extraction of raw materials through to decommissioning Expressed as g eq/kwh account for different GWP of other GHG s Carbon footprints are calculated using Life Cycle Assessment (LCA) 1. Boundary definition 2. LCI Life Cycle Inventory the most objective result of LCA 3. LCIA Life Cycle Impact Assessment 4. Interpretation & improvement LCA cannot replace the decision making process itself
Full life cycle carbon dioxide ( ) and other greenhouse gases (e.g. CH 4 ) emitted by electricity generation technologies extraction transport processing decommissioning recycling construction maintenance operation (direct emissions)
Carbon footprints of electricity generation technologies (UK & European data 24-26) 12 1 8 6 4 2 175 (UK, AFBC plant) 823 (UK, IGCC plant) 65 Coal Gas Biomass PV Marine Hydro Wind Nuclear Oil Swedish plant 44 411 UK plant low-no X 237 25 58 35 5 25 1 3 5 4.5 5 3.5
Ranges in each electricity generation technology are due to: 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 (2 was cutoff date)
Carbon footprints of electricity generation technologies (global data, 24-26) 12 1 17 (West European UCTE average) 8 6 4 766 (Australian plant USCSC plant) 662 US plant 398 German plant 2 237 11 25 35 5 8 25 34 3 29 4 3 Coal Gas Biomass PV Marine Hydro Wind Nuclear
Carbon footprints variations 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 12 12 1 1 8 8 6 6 4 4 2 2 Coal Gas Biomass PV Marine Hydro Wind Nuclear Coal Gas Biomass PV Marine Hydro Wind Nuclear
Carbon footprint of electricity generation technologies (UK & Europe) 12 1 8 6 4 2 Coal Gas Biomass PV Marine Hydro Wind Nuclear
Carbon footprint of low carbon electricity generation technologies (UK & Europe) 2 18 16 14 12 1 8 6 4 2 237 straw direct combustion 25 woodchip gasification UK 58 35 southern Europe range for UK wave converters 5 25 Biomass PV Marine Hydro Wind Nuclear reservoir storage 1 run-of-river 3 offshore onshore UK, Torness Sweden, Ringhals 5.25 4.64 5.5 3.48
Biomass Carbon footprint range: Highest: 237 geq /kwh (direct combustion of straw) Lowest: 25 geq /kwh (gasification of wood chip) Issues: 2 18 16 14 12 1 8 6 4 2 Biomass PV Marine Hydro Wind Nuclear Biomass is carbon neutral absorbed (growth) = released (burning) Transport contributes the largest amount of life cycle, also fertilizers, harvesting Large range of carbon footprints related to differences in energy and density Co-firing biomass + fossil fuels can reduce the carbon footprint of fossil fuelled power
Photovoltaics Carbon footprint range: Highest: 58 geq /kwh (UK) Lowest: 35 geq /kwh (southern Europe) Issues: 2 18 16 14 12 1 8 6 4 2 Biomass PV Marine Hydro Wind Nuclear PV cells predominantly made of high grade silicon Silicon extraction and purification is most energy intensive phase (6% of ) Future reductions in silicon use (e.g. thin film) will lower carbon footprint Carbon footprint lower in southern Europe because greater operating hours
Carbon footprint range: Marine (wave & tidal) Highest: 5 geq /kwh (range for UK wave converters) Lowest: 25 geq /kwh Issues: 2 18 16 14 12 1 8 6 4 2 Biomass PV Marine Hydro Wind Nuclear Two main types of devices: wave energy converters & tidal stream/barrage devices Marine electricity generation still an emerging technology most still prototypes No commercial marine powered electricity generation in the UK yet Marine carbon footprint currently equivalent to PV, but may reduce to level of wind
Hydro Carbon footprint range: Highest: 1 geq /kwh (non-alpine reservoir storage) Lowest: 3 geq /kwh (non-alpine run-of-river) Issues: 2 18 16 14 12 1 8 6 4 2 Biomass PV Marine Hydro Wind Nuclear Two main schemes: reservoir storage (large scale), run-of-river (small scale) Storage schemes have higher carbon footprint since a dam is constructed Run-of-river schemes have the smallest carbon footprint of all technologies Hydro has small emissions, but some methane (CH 4 ) is also emitted
Lowest: Issues: Wind Carbon footprint range: Highest: 5.25 geq /kwh (UK offshore) 4.64 geq /kwh (UK onshore) 2 18 16 14 12 1 8 6 4 2 Biomass PV Marine Hydro Wind Nuclear Wind has one of the lowest carbon footprints 98% of emissions arise during manufacturing & construction (steel, concrete) Remaining emissions arise during maintenance phase of life cycle Footprint of offshore turbine is greater due to larger foundations
Lowest: Issues: Nuclear Carbon footprint range: Highest: 5.5 geq /kwh (UK, Torness plant) 3.48 geq /kwh (Sweden, Ringhals plant) 2 18 16 14 12 1 8 6 4 2 Biomass PV Marine Hydro Wind Nuclear Nuclear also has a very small carbon footprint Most emitted during uranium mining (4% of life cycle ) Global uranium reserves lower grades may cause footprint to rise in future 3 studies: AEA ( to 6.8g), Öko ( to 3-6g), Storm van Leeuwin ( 6 to 12g)
Future carbon footprint reductions (or increases!) 8 7 current footprint future footprint 6 Future carbon reductions are possible for all these technologies if the construction 5 phase (e.g. steel, concrete production) 4 3 2 coal with CCS gas with CCS future reductions in raw materials e.g. less silicon in thin film PV is fuelled by low carbon electricity 1-1 Coal Gas Biomass PV Marine Hydro Wind Nuclear -2 biomass with CCS Increasing future nuclear footprint due to lower grade uranium
Future carbon footprint issues Coal: Gas: co-firing with biomass CCS not yet demonstrated for electricity generation co-firing with biomass (where biomass is gasified) CCS not yet demonstrated Biomass: CCS unlikely since most biomass plants <5MW PV & Marine: Reduction in raw materials Nuclear: All: 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 Can reduce future carbon footprint if high life cycle phases are fuelled by low carbon energy sources
Conclusions All electricity generation technologies emit 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,geq /kwh) Low carbon technologies have low carbon footprints (<1geq /kwh) Future carbon footprints can be reduced for all electricitiy generation technologies if the high emission phases are fuelled by low carbon energy sources Thank You! Stephanie Baldwin www.parliament.uk/post