Next-generation carbon capture technologies for coaltec o og es o coa

Toby LockwoodToby LockwoodIEA Clean Coal Centre

ECCRIA, 5-7 September 2016, Sheffield

Current status of power plant CCS

• Boundary Dam 3 (Canada): Started Oct 2014, 120 MW, amines• Kemper Country (USA): Start late 2016, 524 MW, pre-comb. w/ SelexolKemper Country (USA): Start late 2016, 524 MW, pre comb. w/ Selexol• Petra Nova at WA Parish (USA): Start 2017, 240 MW, amines

Kemper CountyBoundary Dam

WA Parish

Pl d ROAD N th l d ( t b ti ) Si Sh li ChiPlanned: ROAD, Netherlands (post-combustion); Sinopec Shengli, China (post-). Pre-combustion HECA and TCEP in the US are in trouble.

The high cost of carbon capture

• Current ‘1st generation’ technologies impose a significant energy penalty of at least 8%pts efficiency

• Equates to >70% increase in COE – both capex and opex increase• Pre-combustion – less increase but high cost IGCC• Cost of CO2: $60-90/tCO2

PreC

PostC

PostCPostC

Room for improvement…

Capture process Min. separation + compression work (GJ/t)

Currentprocess work (GJ/t)

Efficiency (%)

Post-combustion 0.39 1.17–1.43 27–33

Pre-combustion 0.19 0.85–1.43 8–14

Oxyfuel 0 39 1 08–1 32 29–36Oxyfuel 0.39 1.08–1.32 29–36

• Separation efficiency can be improved, but 0.23 GJ/t is for CO2p y p , 2compression alone (in post and oxy)

• Much more room for improvement in pre-combustion capture due to higher pressure and concentration of CO2 in shifted syngas

• Air separation is fundamentally similar to flue gas CO separation• Air separation is fundamentally similar to flue gas CO2 separation

• Potential for

Capture research targets

$40/t CO2$ 2

20% COEreduction

$20/t CO2

30% COE30% COEreduction

US and many other research programmes target 90% capture, >95% purity

New technologies

Post-combustion:Advanced solvents

Oxyfuel combustion:Chemical looping combustionAdvanced solvents

Solid sorbentsMembranesCa looping

Pressurised oxyfuelAir separation membranes

Supercritical CO2 cyclesGas turbine cyclesCa looping

Cryogenic separationSupersonic separationElectrochemical

Gas turbine cycles

Pre-combustion:Hot flue gas clean upElectrochemical

Hybrid systemsHeat integration

g pSorbent enhanced water gas shift

Membrane WGS reactorsDense membrane separation of H2

I d h d t biImproved hydrogen turbine

Key requirements:Key requirements: • Very high throughput required to process flue gas volume• High purity product (>95%) • No good lowering energy penalty if excessive material/equipment costg g gy p y q p

Post-combustion capture: solvents

Commercial post-combustion capture uses blends of amine solvents:• High energy penalty: high ΔH and 70% of solvent is water, but g gy y g

steadily improving• Environmental issues from degradation products and waste

New solvents:• Eliminate water• Regenerate with less heat or lower value (waste) heatRegenerate with less heat or lower value (waste) heat• Regenerate at pressure • Use more benign chemicals

Advanced solvents overview

• Precipitating solvents – eliminate water from regeneration step and allow high pressure regeneration, but challenging process. $ $$45/t estimated for U Melbourne K2CO3 process (1 tpd). $40/t for GE’s aminosilicones.

Ph h l t l d l t t $63/t• Phase-change solvents – also reduces volume to regenerate. $63/t estimated for IFPEn process. Bench scale.

• Ionic liquids too expensive and viscous but could be useful in• Ionic liquids – too expensive and viscous, but could be useful in blends: offer ‘tunability’. ION Engineering claimed $27/t possible.

• Microencapsulation lab-scale research sealing solvents in• Microencapsulation – lab-scale research sealing solvents in permeable polymer capsules

Microencapsulation

CO2-lean

Microencapsulation

CO2-richPhase separation

Enzyme-activated solvents

• Carbonic anhydrase catalyses CO2 to HCO3- in living cellsAll f l t i l t h t l• Allows use of lower energy, non-toxic solvents such as metal carbonates which normally react too slowly

• Lower grade heat for regeneration also possibleChallenges are en me stabilit and immobilisation in absorber• Challenges are enzyme stability and immobilisation in absorber

Highlight: CO2 solutions• K2CO3 and free-flowing enzyme• K2CO3 and free-flowing enzyme• Uses 80ºC water for regeneration• 10 tpd pilot near Montreal, 30 tpd planned

at pulp & paper mill• 30% cost reduction estimated over

amines

Solid sorbents

• Separation based on selective adsorption of CO2 to solids – usually higher CO capacity and lower regeneration energy than solventshigher CO2 capacity and lower regeneration energy than solvents

• Selectivity by physisorption, chemical reaction, or molecular sieving• High surface area materials studied include activated carbons,

zeolites, metal organic frameworks, amine-functionalised silica…zeolites, metal organic frameworks, amine functionalised silica…

• Biggest pilots use packed beds and pressure swings, but most research on temperature swing systemsresearch on temperature swing systems

• Need low cost, durable material

Structured monoliths

• Fixed beds pose problem of longer cycle times• A key strategy is to use monolithic, structured sorbents for lower y gy

pressure drop and faster heating than packed beds

CO2-deplsteam

CO2 depleted flue

gas

Flue CO2

Highlight: Inventys’ Veloxotherm• Rotating structured carbon based on an air preheater for fast TSA

gas

Rotating structured carbon based on an air preheater for fast TSA• FEED completed for 25 MW with NRG - $30/t CO2 target

Fluidised beds

• Better heat transfer allows for more CO2-selective sorbents: supported amines or solid carbonates

Highlight: ADA-ES• Layered bubbling beds for adsorber

A i iliHighlight: KEPCO• Metal bicarbonate• Amine on porous silica

• 1 MWe pilot operating since 2014• Problems with moisture uptake

Metal bicarbonate • 10 MW pilot with CFB• $30/t CO2 estimated

Adsorber Regenerator

Calcium looping

• Chemical looping system based on CaO + CO2 = CaCO3O f l fi d l i ti f C CO (>900ºC) i t f• Oxyfuel-fired calcination of CaCO3 (>900ºC) raises steam for power gen.

• Very low energy penalties possible, harnesses heat of reaction• Waste sorbent can be used for cement industry

C liCaolingpilot, La Pereda

Highlights: EU projects Caoling and Scarlet• 1.7 MWt pilot in Spain (Caoling) and 1 MWt at Darmstadt U (Scarlet)• High capture rate and sorbent lifetime achieved – efficiency penalties as

low as 2.9%pt (Scarlet)• $20-25/t CO2, 12% increase over non-capture plant estimated (Caoling)

Membranes

• Many polymer membranes show selective permeation of CO2 over N2• Simple, modular process with no chemicals or steamSimple, modular process with no chemicals or steam• Usually driven by vacuum pumping permeate side

High

Hollow fibre

Highselectivity

Lowselectivity

HHowever:• CO2 purity limited by practical pressure ratio• Need two separation stages

V l i d

Spiral-wound

• Very large areas required• Better suited to lower capture rates (40-60%)

Membrane Technologies Research

• MTR ‘Polaris’ membrane with high permeability• Second membrane stage is ‘swept’ with combustion air, raising g g

concentration of CO2 in flue gases: a ‘free’ gain in performance • $45/t at 90% capture, but $35/t at 60% capture rate• Final CO2 purification by liquefaction still required

1 MW rig at NCCC

Advanced membrane materials

• Amine-functionalised polymer membranes can provide ‘active transport’ of CO2: increased selectivity and permeance

• Highlight: NanoGlowa EU project. Test of 1.5 m2 amine membrane on real flue gas

• Mixed matrix membranes: polymer composites with zeolite or MOF

Mixed matrix membrane

filler material – increase CO2 permeability and selectivity• Supported ionic liquid membranes, poly(ionic liquids), enzymes…

• Improving selectivity is not very effective. Priority should be highly permeable membranes which need lower area/cost

Pre-combustion capture

A complex, multi-stage process with energy losses throughout:• Current CO2 and H2S solvents require cooled, dry syngas2 2 y y g• Water gas shift reaction uses lots of steam• Gas turbines not optimised for H2-rich gasBut, syngas is much easier to separate than flue gas.., y g p g

Coal syngas:2-7 Mpa

20-40% CO22

Strategies:• High-temperature

H S/CO lH2S/CO2 removal: retain H2O content for turbine

• Combine CO2 captureCombine CO2 capture step with water gas shift

• Sorbents, membranes

Sorbent-enhanced water gas shift

• High-temperature sorbent captures CO2 in WGS reactor: helps drive equilibrium to produce more CO and Hequilibrium to produce more CO2 and H2

• Reduces steam requirement for WGS and produces high temperature H2/water for gas turbine

• TSA and PSA systems studied, as well as Ca loopingTSA and PSA systems studied, as well as Ca looping

Highlight: CAESAR project (ECN, Air Products etc.)• VSA with hydrotalcite clay – also acts as WGS catalyst• VSA with hydrotalcite clay – also acts as WGS catalyst• 25 kWth pilot tests: $25/t estimated• Scaling up to 14 t/d on blast furnace

Membranes and membrane reactors

Several materials possible:• Polymers: Only up to 300ºC, limited CO2 purity, cheapy y p , 2 p y, p• Pd alloys: High T, pure CO2, expensive, vulnerable to sulphur• Carbon and zeolite molecular sieves: high T, difficult to make

Polymer membranes: MTR• 1 stage of Proteus membrane1 stage of Proteus membrane• Use N2 as sweep• 1 tpd skid being commissioned• 15% COE increase estimated

Membrane reactors:• Same idea as SEWGS• Up to ~0 02 m2 Pd tested• Up to ~0.02 m2 Pd tested• Bench-scale carbon membrane project aims for $28/t (DOE)

Oxyfuel combustion

Coal combustion in O2 and recycled flue gases yields CO2-rich product• Cryogenic air separation has high energetic and economic cost• Product still requires removal of H2O, SOx/NOx, residual O2, N2 etc.

HUST35 MWt

Strategies:g• Exploit unique characteristics of oxyfuel combustion to improve

efficiency of power generation itself – minimise flue gas reycle• Combine with supercritical CO2 turbines• Oxygen from membrane-based air separation

Pressurised oxyfuel combustion

• Latent heat of vaporisation can be recovered at a useful temperature• Less CO2 compression needed, reduced fan power• Reduced equipment sizes, and reduced air ingress

Highlight: Washington Uni SPOC long flue gas recycleh t fl l

oxygeninjection

• Fuel introduced in stages - 16 bar• Almost zero recycled flue gas• 3.8%pt penalty possible

short flue gas recycle

to steampower cycle

pressurisedoxy-coalcombustor

blower

j

• 100 kW combustor pilot tempering USC boiler

coal water vitrified ITEAslurry slag

Highlight: ITEA Isotherm• Combustion of coal slurry at 10

ITEA

bar, tempered by recycled flue gas• 5 MWt pilot since 2007• 25% COE increase over non-

capturecapture• Recent DOE for pilot project with

SWRISPOC

Oxyfuel gas turbines

Several possible cycles for oxyfuel turbine with syngas/NG:Recycled H2O cooled (e.g. Clean Energy Systems) or CO2 cooled

Allam cycle CES

Highlight: 8 Rivers Capital Allam cycle• High P combustion (~300 bar) produces supercritical CO2 for turbine• 50 MWt NG pilot under construction by NET Powerp y• With gasification: 50.3% LHV achievable – more than SCPC w/o CCS• Zero cost of CO2, 15% reduction in COE over SC plant w/o CCS

Chemical looping combustion

• Oxygen delivered to fuel by a metal ‘carrier’• Inherently avoids any gas separation step• Inherently avoids any gas separation step• Two CFB reactors: heat from oxidiser raises steam• CO2 compression only significant energy penalty

Carrier material and ‘polishing O ’ are main costs• Carrier material and ‘polishing O2’ are main costs

Issues:• Solid fuel requires in-situ gasification (steam/CO2)• Need cheap carrier for solid fuels (material loss): waste, natural ores

Major CLC projects

Alstom’s limestone-based process• Uses CaSO3/CaSO4 produced in-situ from limestone + SO23 4 2• Dual CFB reactors• Largest CLC pilot at 3 MWth: autothermal operation achieved• Target 35.8% eff., 19.5% COE increase, $15/t CO2g , , 2

B&WAlstom

B&W iron oxide process• Fe2O3/FeO carrier2 3• Countercurrent moving beds: compact, reduced attrition• 25 kWt tests, funding for 10 MWe FEED

Conclusions

• Solvent-based CCS technologies are commercially available but costly • Next generation capture systems aim to achieve a step change in g y g

capture cost and energy penalty, with a capture cost of

Perspective

• High efficiencies often achieved with costly materials whichHigh efficiencies often achieved with costly materials which can require more upstream cleaning and maintenance: simple, cheap system may be more desirable

• Focus on >90% capture rate: suited to amines but other technologies (sorbents, membranes) can perform much better at reduced rates - sufficient for most carbon emission l i l ti ( US C UK)legislation (e.g. US, Can, UK)

• A range of new capture technologies will probably be required to meet other project specific factors (size reliability labourto meet other project specific factors (size, reliability, labour cost, water availability, waste disposal etc.)

• Even if cost of amine capture is significantly reduced by• Even if cost of amine capture is significantly reduced by optimisation and risk reduction, the huge energy penalty is a barrier to public/government acceptance