CO2 removal from the atmosphere

Lead authors: Mark Workman1 and Niall McGlashan1

Other contributors: Nilay Shah1, Mark Flower1, Jon Gibbins2 and Hannah Chalmers2,*

1Imperial College London2Imperial College London (visiting) and University of Edinburgh

*hannah.chalmers02@imperial.ac.uk, hannah.chalmers@ed.ac.uk

AVOID session 2, Earth Systems Science 2010Edinburgh, 12th May 2010

Context• A robust strategic plan is needed for 80% cuts in

GHG emissions by 2050– Need to allow for emissions that are difficult to

reduce in agriculture, some transport sectors etc– Useful to have options available for an ‘emergency’

where stock of CO2 in atmosphere is too high

• Some CO2 emissions abatement options are expensive, so search for alternatives continues

• A range of options for removing CO2 from the atmosphere have been identified

• Some approaches to CO2 removal from the atmosphere could increase options available due to potential flexibility in location for deployment

Preliminary illustrative numbers• Technical potential for CO2 abatement at prices

below $200/tCO2...• ...and could be (significantly?) below $100/tCO2

• Number of individual units depends on technology approach chosen, e.g. dispersed/centralised choice?

• Klaus Lackner artificial trees• Could need around 1.5million units for 10% of UK CO2 emissions• 1ppm global contribution estimated to require <2% of current global

electricity demand

• Biomass enhanced CCS (BECCS) could have ‘negative emissions’ potential of at least 10% of current UK CO2 emissions by 2030• Need to consider international trade for maximum contribution• Full lifecycle analysis remains challenging

Class 1 – Class 2 – Class 3 CCS projectsClass 1 = carbon positive CCS

Class 2 = (near) carbon neutral CCSClass 3 = carbon negative CCS

Class 1: Usually producing hydrocarbons, CCS gets the carbon footprint down to conventional hydrocarbon levels e.g. LNG, coal-to-liquids, oil sands

Class 2: Producing carbon free energy vectors: electricity, hydrogen or heat

Class 3B: Biomass plus CCS (takes CO2 from the air)Class 3A: Technology to process air directly to capture CO2

Enhanced oil recovery (EOR) and replacing natural gas reinjected in oil fields are grey areas.

Chalmers, H., Jakeman, N., Pearson, P. and Gibbins, J. (2009) “CCS deployment in the UK: What next after the Government competition?”, Proc. I.Mech.E. Part A: Journal of Power and Energy, 223(3), 305-319.

Class 3AA• CO2 removed directly from

the air and stored as CO2

• Large enough potential to pursue further

• Need to find sufficient low carbon energy sources

• Scale-up to be done

Sources for pictures: IMechE (2009), Keith et al (2006)

Class 3AA• CO2 removed directly from

the air and stored as CO2

• Large enough potential to pursue further

• Need to find sufficient low carbon energy sources

• Scale-up to be done

Sources for pictures: IMechE (2009), Keith et al (2006)

Also note some details can be missed in artistic impressions!- Need to handle/process caustic soda solution (including potential crashes)- Wind turbines have shed blades in other places (unusual, but has happened at Whitelee, Scotland this year)

Class 3AB• CO2 removed directly

from the air and fixed in a stable material

• Further work on monitoring, verification and reporting needed

• Co-benefits also being explored (reversing ocean acidification, soil improvement)

• Reasonable potential, but time needed for scale-up

Sources for pictures: Kruger (2010), Lehmann et al (2006)

Class 3B

• Biomass enhanced CCS (BECCS)• Can be stand-alone use of biomass or co-firing/gasification• Fuel diversity (geography and feedstock) important to

counteract seasonal availability and regional surpluses• Must be sensitive to competing uses and land use change• Can make non-trivial contribution now/soon and unlikely to

have CO2 storage capacity constraint in UK context

(b) Harvesting, Storage, Processing, Transport

(e) GHG Emissions

(a) Biomass Feedstock Production: (c) Bio Energy Power Plant

(f) Fossil Fuel Energy Displaced

(d) Carbon Capture and Sequestration

Emerging conclusions• A mix of options could be viable at reasonable

scale for removing CO2 from the atmosphere

• Flexibility in location could be helpful to avoid large CO2 transport systems

• Costs could be reasonable and may allow a cap on CO2 emission trading/tax costs

• Some options could be significant by 2030, while others may need longer to scale-up

• For technologies to be available asap, pilot and scale-up support will be needed