In Pursuit of a H2 Economy for Mitigating Climate Change ... · Economics of H 2 from Coal with...

1

In Pursuit of a H2 Economy for Mitigating Climate Change...

How Important isAdvancing the State-of-the-Art inH2 Production from Fossil Fuels?

Tom KreutzPrinceton Environmental Institute

Princeton University

Presented at the GCEP Energy Workshop:“Carbon-Free Production of Hydrogen”

April 26, 2004, Stanford University, Palo Alto, California

2

Outline of Talk

• Overview of our work on production of carbon-free H2

and electricity from fossil fuels (primarily coal)

• Putting our work in perspective

• Areas of interest for future work

3

The Carbon Mitigation Initiative (CMI)at Princeton University, 2001-2010

• CMI Project Areas:

- Carbon capture (Kreutz, Larson, Ogden, Socolow, Williams)

- Carbon storage (Celia)

- Carbon science (Pacala, Sarmiento, GFDL)

- Carbon policy (Bradford, Oppenheimer)

- Integration (Socolow, Pacala)

• Funding: 15.1$ from BP, 5 M$ from Ford

4

World Consumption of Primary Energy

Oil

Coal

Natural Gas

From: http://www.bp.com/centres/energy2002/primary.asp#

5

Motivation for Studying Coal (vs. Gas)

• Plentiful. Resource ~ 500 years (vs. gas/oil: ~100 years).

• Inexpensive (low volatility). 1-1.5 $/GJ HHV (vs. gas at 2.5+ $/GJ).

• Ubiquitous. Wide geographic distribution (vs. middle east).

• Carbon intensive.

• Potentially clean. Gasification, esp. with CCS, produces few gaseous emissions and a chemically stable, vitreous ash.

• Ripe for innovation.

• Globally significant. For example: China: extensive coal resources; little oil and gas. Potential for huge emissions of both criteria pollutants and greenhouse gases.

6

Our Work on Low-CO2 Hydrogen and Electricity from Fossil Fuels

• Coal (entrained flow gasification at 70 bar):

- H2 / CO2 separation with WGS membrane reactors,

- Conventional H2 and CO2 separation: • Electricity-only (IGCC) plants• H2 + electricity plants

• Natural gas:- SMR and ATR with steam and combined cycles

7

Generic Process: Coal to H2, Electricity, and CO2

GHGT-6 generic process figure (9-25-02)

CO-richraw syngas

H2 product (60 bar)

N2

H2- andCO2-richsyngasQuench +

scrubber

Air Airseparation

unit

Coalslurry O2-blown

coalgasifier

95%O2

SupercriticalCO2 (150 bar)

Water-gas shift(WGS) reactors

CO + H2O <=> H2 + CO2

COdrying andcompression

Hydrogencompression

Syngas cleanup,gas separation

Electricityproduction

Heat recovery,steam generation

H2-richsyngas

CO2

Electricpower

2

• All work presented here is based on O2-blown, entrained flow, coal gasification (e.g. Texaco, E-Gas gasifiers).

8

Process Modeling• Heat and mass balances (around each system

component) calculated using:• Aspen Plus (commercial software), and• GS (“Gas-Steam”, Politecnico di Milano)

• Membrane reactor performance calculated via custom Fortran code

• Component capital cost estimates taken from the literature, esp. EPRI reports on IGCC

• Benchmarking/calibration:• Economics of IGCC with carbon capture studied by numerous groups

• Used as a point of reference for performance and economics of our system

• Many capital-intensive components are common between IGCC electricity and H2 production systems (both conventional and membrane-based)

9

Estimates of Overnight Component Capital Costs

0

1

2

3

4

5

6

7

8

9

1 0

1 1

1 2

0 50 100 150 200

Capital Cost (MM$)

SimbeckHoltDoctorChiesaHendriksPrudenEPRI3,000-6,000 $/m2

Solids handlingASUO2 compressionGasifier & quenchWGS reactorMembrane reactorRaffinate turbineFGDH2 compressionHRSG, steam turb.CO2 compression

Scale (HHV):1.5 GWth

coal,

• Significant variation found in cost values, methodology, and depth of detail.

• Our cost model is a self-consistent set of values from the literature.

• Cost database is evolving; less reliable values removed; range is narrowing.

• Uncertainty shown above leads to an uncertainty of ±10-15% in H2 cost.

10

Economic Assumptions

~ 1 GWth H2 (LHV)Plant scale

12.0% of overnight capitalInterest during construction

Illinois #6Coal Type

2002U.S. dollars valued in year

5 $/mt CO2 (~8.6 ¢/kg H2)CO2 transport + storage cost*

4% of overnight capital per yearO&M costs

15% per yrCapital charge rate

80%Capacity factor

1.2 $/GJ (HHV)Coal price (2001 average cost to electric generators)

• “Best case” cost estimate for: 16,000 tonne/day CO2, 100 km pipeline, 2 km deep injection well (layer thickness > 50 m, permeability > 40 mDa)

11

Sensitivity of Cost to CO2 Storage Costs

0

2

4

6

8

10

12

0 10 20 30 40 50 60

CO2 Storage Cost ($/tonne CO2)

Ele

ctric

ity C

ost (

¢/kW

h)

Order of magnitude increase in CO2 storage costs increases electricity and H2 costs by 60-70%.

0

2

4

6

8

10

12

14

16

0 10 20 30 40 50 60

CO2 Storage Cost ($/tonne CO2)

H2 C

ost (

$/G

J LH

V)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

H2 C

ost ($/kg)

12

Disaggregated Cost of H2 Production

Net cost: 1.03 $/kg H2

-0.2

0.0

0.2

0.4

0.6

0.8

1.0H

ydro

gen

Cos

t ($/

GJ,

HH

V)CO2 Sequestration (5 $/mt CO2)

CO2 drying & compression

HRSG & steam turbine

Gas turbine

PSA and purge compressor

Selexol CO2 absorption, flashing

Selexol H2S removal, Claus, SCOT

WGS reactors, heat exchangers

Gasifier, quench, scrubbing

O2 separation & compression

Coal preparation & handling

Construction Interest (4 yr)

O&M (4% per year)

Coal (1.2 $/GJ, HHV)

Electricity revenue (at 6.2 c/kWh)

13

A Few Conversion Factors

• Thermal energy (LHV):

1 kg H2 ~ 1 gallon gasoline

(so $/kg H2 = $/gallon gasoline)

• 1 $/kg H2 = 7.05 $/GJ HHV = 8.34 $/GJ LHV

14

System Parameter VariationsSystem Performance:

- gasifier/system pressure- syngas cooling via quench vs. syngas coolers - hydrogen recovery factor (HRF)- hydrogen purity- sulfur capture vs. sulfur + CO2 co-sequestration- membrane reactor configuration- membrane reactor operating temperature- hydrogen backpressure- raffinate turbine technology (blade cooling vs. uncooled)

System Economics (Sensitivity Analysis):- membrane reactor cost (and type)- co-product electricity value, capacity factor, capital charge rate,

fuel cost, CO2 storage cost, etc.

15

Annual U.S. Carbon Emissions (2000)

0

100

200

300

400

500

600

700

Electricity Transportation Industrial Commercial Residential

Tonn

es C

per

Yea

r (x1

06 )

Natural Gas

Petroleum

Coal

Source: U.S. EPA Inventory of Greenhouse Gases, Apr. 2002

• Let’s focus for a moment on the power market...

16

“Commercially Ready” Coal IGCC with CO2 Capture

GHGT-6 conv. electricity, CO2 seq. (9-25-02)

Saturatedsteam

CO-richraw syngas

N2 for (NOx control)

H2- andCO2-richsyngas

Heat recoverysteam generator

CO2-leanexhaust

gases

Quench +scrubber

Air Airseparation

unit

Coalslurry O2-blown

coalgasifier

95%O2

Steamturbine

Gas turbineAir

Turbineexhaust

SupercriticalCO2 to storage

CO2 drying +compression

High temp.WGS

reactor

Low temp.WGS

reactorLean/richsolvent

CO2physical

absorption

Solventregeneration

Lean/richsolvent

H2Sphysical

absorption

Regeneration,Claus, SCOT

2

Syngasexpander

H -richsyngas

• CO2 venting: 390 MWe @ $1190/kWe, ηLHV = 43.0%, 4.6 ¢/kWh

• CCS: 362 MWe @ $1530/kWe, ηLHV = 36.8%, 6.2 ¢/kWh (no carbon tax)

17

Economics of Coal IGCC with Carbon Storage

4.5

5.0

5.5

6.0

6.5

7.0

0 20 40 60 80 100 120

Carbon Tax ($/tonne C)

Ele

ctric

ity C

ost (

¢/kW

h)

CO2 storage crossover:(93 $/tonne C)

Coal IGCC withCO2 storage

Coal IGCC withCO2 venting

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H2 Production: Add H2 Purification/Separation

GHGT-6 conv. electricity, CO2 seq. (9-25-02-a)

Saturatedsteam

CO-richraw syngas




CO2-leanexhaust

gases

Quench +scrubber

Air Airseparation

unit

Coalslurry O2-blown

coalgasifier

95%O2

Steamturbine

Gas turbineAir

Turbineexhaust



High temp.WGS

reactor

Low temp.WGS


CO2physical

absorption

Solventregeneration

Lean/richsolvent

H2Sphysical

absorption


H2-richsyngas

Syngasexpander

• Replace syngas expander with PSA and purge gas compressor.

• Reduce the size of the gas turbine.

19

Conventional H2 Production with CO2 Capture

GHGT-6 conv. hydrogen, CO2 seq. (9-25-02)

Saturatedsteam

CO-richraw syngas

High purityH2 product




CO2-leanexhaust

gases

Quench +scrubber

Air Airseparation

unit

Coalslurry O2-blown

coalgasifier

95%O2

Steamturbine

Gas turbineAir

Pressureswing

adsorption

Purgegas

Turbineexhaust


High temp.WGS

reactor

Low temp.WGS


CO2physical

absorption

Solventregeneration

Lean/richsolvent

H2Sphysical

absorption



• 1070 MWth H2 (LHV) + 39 MWe electricity, efficiency ηLHV=60.9%, 1.03 $/kg H2 (no carbon tax). [70 bar gasifier, quench cooling]

20

Economics of H2 from Coal with Carbon Storage

6.0

6.5

7.0

7.5

8.0

8.5

9.0

0 20 40 60 80 100 120Carbon Tax ($/tonne C)

Hyd

roge

n C

ost (

$/G

J, H

HV

)

CO2 storage crossover (39 $/tonne C,4.1 $/GJ NG,

4.6 ¢/kWh NGCC)

H2 from coal withCO2 storage

H2 from coal withCO2 venting

H2 from NG withCO2 venting

H2 from NG withCO2 storage

• Both the carbon tax and breakeven NG price needed to induce coal H2 with CO2 storage are significantly lower than those for electric power.

• Industrial H2 from coal might be the earliest CCS opportunity.

21

Conventional H2 Production with CO2 Capture

GHGT-6 conv. hydrogen, CO2 seq. (9-25-02)

Saturatedsteam

CO-richraw syngas





CO2-leanexhaust

gases

Quench +scrubber

Air Airseparation

unit

Coalslurry O2-blown

coalgasifier

95%O2

Steamturbine

Gas turbineAir

Pressureswing

adsorption

Purgegas

Turbineexhaust


High temp.WGS

reactor

Low temp.WGS


CO2physical

absorption

Solventregeneration

Lean/richsolvent

H2Sphysical

absorption



• Incremental cost for CO2 capture is less for hydrogen than electricity because much of the equipment is already needed for a H2 plant.

22

Capture (and Co-store) H2S with CO2

GHGT-6 conv. hydrogen, CO2 seq. (9-25-02-a)

Saturatedsteam

CO-richraw syngas





CO2-leanexhaust

gases

Quench +scrubber

Air Airseparation

unit

Coalslurry O2-blown

coalgasifier

95%O2

Steamturbine

Gas turbineAir

Pressureswing

adsorption

Purgegas

Turbineexhaust


High temp.WGS

reactor

Low temp.WGS


CO2physical

absorption

Solventregeneration

Lean/richsolvent

H2Sphysical

absorption



• Remove the traditional acid gas recovery (AGR) unit.

23

Conventional H2 Production with CO2+H2S Capture

GHGT-6 conv. hydrogen, co-seq. (9-25-02).FH10

Saturatedsteam

CO-richraw syngas



H2- andCO2-rich

syngas


CO2-leanexhaust

gases

High temp.WGS

reactor

Quench +scrubber

Air Airseparation

unit

Coalslurry O2-blown

coalgasifier

Low temp.WGS

reactor

CO2/H2Sphysical

absorption

Solventregeneration

Lean/richsolvent

95%O2

Steamturbine

Gas turbineAir

Pressureswing

adsorption

Purgegas

Turbineexhaust

CO2 + H2Sto storage

CO2/H2Sdrying andcompression

• Resulting system is simpler and cheaper.

24

Co-Capture and Co-storage of CO2 and H2S

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Conv. tech. base case

H2 C

ost (

$/kg

)

CO2 venting Pure CO2 sequestration Co-sequestration

25

Economics of H2 from Coal with H2S-CO2 Co-Storage

6.0

6.5

7.0

7.5

8.0

8.5

9.0

0 20 40 60 80 100 120Carbon Tax ($/tonne C)

Hyd

roge

n C

ost (

$/G

J, H

HV

)

Co-storage crossover (19 $/tonne C,3.8 $/GJ NG,

4.2 ¢/kWh NGCC)

H2 from NG withCO2 storage

H2 from NG withCO2 venting

H2 from coal withCO2 venting

H2 from coal withH2S-CO2 co-storage

• H2S-CO2 co-storage further reduces both the crossover carbon tax and breakeven NG price.

26

Produce “Fuel Grade” H2 with CO2+H2S Capture

GHGT-6 conv. hydrogen, co-seq. (9-25-02-a).FH10

Saturatedsteam

CO-richraw syngas



H2- andCO2-rich

syngas


CO2-leanexhaust

gases

High temp.WGS

reactor

Quench +scrubber

Air Airseparation

unit

Coalslurry O2-blown

coalgasifier

Low temp.WGS

reactor

CO2/H2Sphysical

absorption

Solventregeneration

Lean/richsolvent

95%O2

Steamturbine

Gas turbineAir

Pressureswing

adsorption

Purgegas

CO2 + H2Sto storage


• Remove the PSA and gas turbine; smaller steam cycle.

27

“Fuel Grade” (~93% pure) H2 with CO2/H2S Capture

GHGT-6 Fuel grade H2, co-seq. (9-25-02)

Saturatedsteam

CO-richraw syngas Low purity

H2 product(~93% pure)

N2

H2- andCO2-rich

syngas


CO2-leanexhaust

gases

High temp.WGS

reactor

Quench +scrubber

Air Airseparation

unit

Coalslurry O2-blown

coalgasifier

Low temp.WGS

reactor

CO2/H2Sphysical

absorption

Solventregeneration

Lean/richsolvent

95%O2

Steamturbine

CO2 + H2Sto storage


• Simpler, less expensive plant. No novel technology needed.

28

Production of “Fuel Grade” H2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Conv. tech. base case Fuel grade H2

H 2 C

ost (

$/kg

)CO2 venting Pure CO2 sequestration Co-sequestration

• Fuel grade H2 more competitive with gas and oil in the heating sector, and might be adequate for transportation (H2 ICEVs; barrier to PEM FCEVs?)

29

Change H2-CO2 Gas Separation Scheme

GHGT-6 conv. hydrogen, co-seq. (9-25-02-b)

Saturatedsteam

CO-richraw syngas



H2- andCO2-rich

syngas


CO2-leanexhaust

gases

High temp.WGS

reactor

Quench +scrubber

Air Airseparation

unit

Coalslurry O2-blown

coalgasifier

Low temp.WGS

reactor

CO2/H2Sphysical

absorption

Solventregeneration

Lean/richsolvent

95%O2

Steamturbine

Gas turbineAir

Pressureswing

adsorption

Purgegas

CO2 + H2Sto storage


• This work uses a membrane to separate H2 from the syngas instead of CO2.

30

H2 Separation Membrane Reactor System

GHGT-6 uncooled turbine, co-seq. (9-25-02)

CO-richraw syngas


N2

H2- andCO2-rich

syngasHigh temp.WGS

reactor

Quench +scrubber

Air Airseparation

unit

Coalslurry O2-blown

coalgasifier

95%O2

Hydrogencompressor

Uncooledturbine

MembraneWGS

reactor

O2 (95% pure)

CO2 + SO2to storage

CO2/SO2drying andcompression

Catalyticcombustor

Water

Pure H2

Raffinate

• Employ a H2 permeable, thin film (10 µm), 60/40% Pd/Cu (sulfur tolerant) dense metallic membrane, configured as a WGS membrane reactor.

31

Hydrogen Separation Membrane Reactor (HSMR) Concept

Membrane Reactor 5 5-3-03

Porous (optionally asymmetric) ceramic orstainless steel (SS) supporting substrate

Optional oxide layer (needed for metallicmembrane with SS substrate)

Catalyst pellets

Thin film membrane

Entering highpressure syngas

Exiting raffinate

Permeatinghydrogen

High pressure syngas

Shell-tube membrane module

Thin film membrane

Membrane Structure:

Low pressure hydrogen permeate

Porous substrate

Low pressurehydrogen permeate

• Alternative HSMR design: high pressure, WGS reaction, and membrane outside supporting tube, with H2 permeating to the interior of the tube

32

Typical Membrane Reactor Performance

0

5

10

15

20

25

0

20

40

60

80

100

0 5 10 15 20 25 30 35

H2 P

artia

l Pre

ssur

e (b

ar) H

2 Recovery Factor (%

)

Membrane Area (103 m2)

→ →

a)

0

10

20

30

40

50

60

70

0

10

20

30

40

50

60

70

0 20 40 60 80 100

Aver

age

H2 F

lux

(kW

/m2 )

Mem

brane Material C

ost ($/kW)

H2 Recovery Factor (%)

→

→

b)

10 µm thick Pd-40Cu membrane475 C; 1000 ppm H

2S; 67 bar syngas

Tube length →

• H2 Recovery Factor (HRF) = H2 recovered / (H2+CO) in syngas

• HRF increases with membrane area diminishing returns

• Membrane costs rise sharply above HRF~80-90% (no sweep gas)

33

Cost of H2 Compression and HSMRvs. H2 Backpressure

0.0

0.1

0.2

0.3

0.4

0 2 4 6 8 10H2 Backpressure (bar)

Cos

t Com

pone

nt ($

/kg

H2)

Total cost

HSMR capital

Compressor

Number of compression

stages:

Compressor capital

Cost minimum

34

5

34

Membrane System with Cooled Raffinate Turbine

GHGT-6 cooled turbine, co-seq. (9-25-02)

CO-richraw syngas


N2

H2- andCO2-rich

syngasHigh temp.WGS

reactor

Quench +scrubber

Air Airseparation

unit

Coalslurry O2-blown

coalgasifier

95%O2

Hydrogencompressor

Cooledturbine

MembraneWGS

reactor

O2 (95% pure) CO2 + SO2to storage

CO2/SO2drying andcompression

Catalyticcombustor

Water

Pure H2

Raffinate

(for bladecooling)

Steam(for bladecooling)

Uncooledexpander

Steam

• Blade cooling with steam enables higher TIT (1250 C vs. 850 C), and higher electrical conversion efficiency. Requires much lower HRF (~60%).

35

Membrane System Results Summary

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

70HCQ LU-F LU HU HU-S HC-1 HC-2

H2 + Electricity Plant

H2 C

ost (

$/kg

H2)

0

10

20

30

40

50

60

70

Effective E

fficiency (% LH

V)

6.3

4

5

3

¢/kWh

Cooledturbine

Conventialtechnology

6.3

Starting case(70 bar, uncooled

Base case(120 bar,

uncooled turbine)

36

Part 1 Summary

• No matter how hard we try, H2 costs $1/kg!

• Question: Would the world’s outlook be significantly enhanced if H2 cost 90 ¢/kg? 80 ¢/kg?

0.0

0.2

0.4

0.6

0.8

1.0

Hyd

roge

n C

ost (

$/G

J, H

HV)

CO2 Sequestration (5 $/mt CO2)

CO2 drying & compression

HRSG & steam turbine

Gas turbine

PSA and purge compressor

Selexol CO2 absorption, flashing

Selexol H2S removal, Claus, SCOT

WGS reactors, heat exchangers

Gasifier, quench, scrubbing

O2 separation & compression

Coal preparation & handling

Construction Interest (4 yr)

O&M (4% per year)

Coal (1.2 $/GJ, HHV)

Electricity credit (6.42 ¢/kWh)0 2

37

Outline of Talk





38

Where Might H2 be Used?

0

100

200

300

400

500

600

700


Tonn

es C

per

Yea

r (x1

06 )

Natural Gas

Petroleum

Coal


39

Production Cost of H2 (Scale=1 GWth HHV)

0

1

2

3

4

5

NG Coal

Cos

t of H

2 ($/

kg)

Non-fuel O&M (4%/yr of OC)

Feedstock (NG=$4/GJ, coal=$1.2/GJ)

Plant capital (15%/yr CCR)

Electricity credit

40

Add CO2 Transport and Geologic Storage...

0

1

2

3

4

5

NG Coal

Cos

t of H

2 ($/

kg)

CO2 injection wells

CO2 injection site piping

CO2 pipeline (100 km)




Electricity credit

41

Add H2 Storage and Distribution Pipelines...

0

1

2

3

4

5

NG Coal

Cos

t of H

2 ($/

kg)

City gate H2 booster compressor

H2 local distribution pipelines

H2 pipeline from plant to city gate (100 km)

Central H2 storage (1/2 day's output)

CO2 injection wells






Electricity credit

42

Add H2 Refueling Stations...

0

1

2

3

4

5

NG Coal

Cos

t of H

2 ($/

kg)

H2 refueling station





CO2 injection wells






Electricity credit

43

Add the Incremental Vehicle Cost...

0

1

2

3

4

5

NG Coal

Cos

t of H

2 ($/

kg)

PEMFC-EV cost increment ($2,460)

H2 refueling station





CO2 injection wells






Electricity credit

44

Where Else Might H2 be Used?

0

100

200

300

400

500

600

700


Tonn

es C

per

Yea

r (x1

06 )

Natural Gas

Petroleum

Coal


• Displacing traditional H2 from NG (1% of global primary energy).

• At 200 $/tonne C, H2 for industrial boilers, furnaces, and kilns becomes competitive with gas at 4 $/GJ. Oil?

45

Outline of Talk





46

What is this Curve?

Time

Con

sum

ptio

n

47

The “Elephant-in-the-Snake” Problemor

“How does Ohio absorb a 1 GWth H2 plant?”

“Le Petit Prince”, Antoine de Saint Exupéry

49

H2 DEMAND DENSITY (kg/d/km2): YEAR 1: 25% OF NEW Light Duty Vehicles = H2 FCVs

Blue shows good locations for refueling station

50

H2 DEMAND DENSITY (kg/d/km2):

YEAR 5: 25% OF NEW LDVs = H2 fueled

51



52



53

What is Required to Enable a H2 Economy?

• Safe / effective / low cost CCS

• H2 safety

• Better H2 storage?

54

From Multiple Targets and Baselines to The Stabilization Wedge in Three Steps

Step One: Restrict attention to 50 years (the Goldilocks time frame)Step Two: Choose just one goal and one baseline

Yearly Emissions of Carbon

6789

101112131415

2000 2010 2020 2030 2040 2050

Year

Em

issi

ons

(GT

Carb

on)

IS92A BAUS500

Step Three: Abstracting further, take the goal to be flat emissions and the baseline to be doubling linearly in 50 years.

55

The Stabilization Wedge

2004 21042054

GtC/yr21

14

7

0

Easier CO2 target ≈ 750 ppm

Tougher CO2 target ≈ 500 ppm

Business As Usual

56

Seven “Slices” Fills the WedgeIt is irresistible to divide the wedge into seven

equal parts. We call these “slices.”

7 GtC/yr

20542004

57

What is a “slice”?A “slice” is an activity reducing the rate of carbon build-up in the

atmosphere that grows in 50 years from zero to 1.0 Gt(C)/yr.

1 GtC/yrTotal = 25 Gigatons carbon

50 years

Cumulatively, a slice redirects the flow of 25 Gt(C) in its first 50 years. This is 2.5 trillion dollars at $100/t(C).

A “solution” to the Greenhouse problem should have the potential to provide at least one slice.

58

Filling the WedgeThe strategies available to provide the slices to fill the wedge are grouped

below. All strategies are based on technologies already in use.

Coal to Gas

CCS

Nuclear

Renewables

Efficiency

Natural Sinks

62

Parting Thoughts/Questions

• Lowering the cost of H2 from fossil fuels is hard work!

• The cost of H2 production per se may be only a small fraction of the cost of a H2 economy.

• Thus, how useful is it to try to squeeze production costs via novel technology?

• Other (e.g. system) issues may have greater leverage.

• How soon will H2 play an important role in carbon mitigation?

• How can we best use our talents to forestall global climate change?

In Pursuit of a H2 Economy for Mitigating Climate Change ... · Economics of H 2 from Coal with...

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