Hydrogen Scenario Impacts on Global Climate and Air

Pollution

Martin G. SchultzMax Planck Institute for Meteorology

Bundesstr. 53, 20146 Hamburg, Germany

IEW 2004, Paris, 22-24 June 2004 Martin G. Schultz et al., Hydrogen Scenario Impacts

Climate forcing impacts

from IPCC, 3rd Scientific Assessment of Climate Change 2001

IEW 2004, Paris, 22-24 June 2004 Martin G. Schultz et al., Hydrogen Scenario Impacts

Atmospheric CO2 concentration trend

IEW 2004, Paris, 22-24 June 2004 Martin G. Schultz et al., Hydrogen Scenario Impacts

Global CO2 budget

Net input of CO2 into atmosphere: ~ 3.5 Gt/yr

-1 +1+5.5 -2

IEW 2004, Paris, 22-24 June 2004 Martin G. Schultz et al., Hydrogen Scenario Impacts

Urban & Regional Air Pollution (Ozone)

Precursor trends (Waldhof, Germany) Peak ozone trend (UK)

from EUROTRAC S&I, chapter 3,2003

IEW 2004, Paris, 22-24 June 2004 Martin G. Schultz et al., Hydrogen Scenario Impacts

Background Ozone Trends

MOZAIC (aircraft)

MOZAIC (aircraft)

mountain station

coastal surface station

IEW 2004, Paris, 22-24 June 2004 Martin G. Schultz et al., Hydrogen Scenario Impacts

Monitoring Emission Trends from Space

A. Richter, F. Wittrock, Bremen University

IEW 2004, Paris, 22-24 June 2004 Martin G. Schultz et al., Hydrogen Scenario Impacts

Contribution of traffic to emissions of GHGs and ozone precursors

0%

20%

40%

60%

80%

100%

CO2 CO NOx CH4 VOC

bb

agriculture+natural

residential

power generation

industry

refineries

traffic

EDGAR 3.2, RIVM, data for 1995

IEW 2004, Paris, 22-24 June 2004 Martin G. Schultz et al., Hydrogen Scenario Impacts

Final energy consumption per traffic sector

0

200

400

600

800

1000

1200

1400

1600

1800

Air Road Rail Others Total World

1970 19801990 2000

OECD, 2000Mio. t oil equiv.

IEW 2004, Paris, 22-24 June 2004 Martin G. Schultz et al., Hydrogen Scenario Impacts

Why Use Hydrogen?• generates no emissions other than water vapour

• efficient energy storage

• suitable for mobile applications

• technology largely available (although improvements needed)

Hydrogen scenarios

• energy supply to isolated villages

• energy buffer to balance supply and demand (wind energy, solar)

• transport sectoro roado aircrafto ships

IEW 2004, Paris, 22-24 June 2004 Martin G. Schultz et al., Hydrogen Scenario Impacts

Hydrogen Perspectives

• WTW energy use of H2 fuel cell vehicle comparable to present-day gasoline vehicle (large-scale NG reformer)

• 2010 gasoline vehicle may realize 15% energy savings (hybrid technology) 735 Mt CO2/year in Europe

• H2 fuel cell car expensive to produce and expensive fuel (700-1600€/tCO2 reduction*)

• Short-term: H2 from natural gas reforming + fuel mix

• Longer-term: geothermal/solar/wind/hydropower H2

• Price and market penetration depend on oil price* 5% replacement scenario, crude oil price 25$/bbl

from JRC WTW analysis, 2004

Other scenarios are more sceptical (IIASA)

from JRC/IES well-to-wheels analysis, concawe, eucar, ec, 2004

sequestration window

IEW 2004, Paris, 22-24 June 2004 Martin G. Schultz et al., Hydrogen Scenario Impacts

Why Not Use Hydrogen?

• hydrogen generation requires a lot of energy

• hydrogen has a low energy density/volume

• coal or NG reforming lead to increased CO2 emissions (unless captured)

• hydrogen might leak into atmosphere with unknown consequences

• safety issues

IEW 2004, Paris, 22-24 June 2004 Martin G. Schultz et al., Hydrogen Scenario Impacts

Checklist Environmental Impacts

• perturbed hydrogen budget (greenhouse effect, oxidizing capacity)

• increased water vapour:

o stratospheric ozone depletion

o upper tropospheric greenhouse gas/cirrus formation

o boundary layer fog

• effects of associated emission changes:

o CO2

o NOx (oxidizing capacity, tropospheric ozone, air pollution)

IEW 2004, Paris, 22-24 June 2004 Martin G. Schultz et al., Hydrogen Scenario Impacts

Current hydrogen budget

Unit: Tg H2/yr (=Mt H2/yr)Ref: Novelli et al., 1999; Hauglustaine et al., 1999

CH4

VOC H2

biomassburning

trafficindustry

soils, ocean

40

16

15±10

6

19

56±15

reactionwithOH

soil uptake

IEW 2004, Paris, 22-24 June 2004 Martin G. Schultz et al., Hydrogen Scenario Impacts

Projected Global H2 Emission Changes

*1400-1800 TgH2 required to generate 380 EJ, factor 2 efficiency gain for fuel cell factored in† 940-1200 TgH2 required to generate 250 EJ (based on 2025 projection from EIA)

50

100

150

Tg

H2/y

ea

r

present 1:1scenario*

fossil

3% leakage

2025 oil replacement

scenario†

3% leakage

realistic2025

scenario

fossil

Global leak rates larger 3%not plausible due to economicand safety considerations

IEW 2004, Paris, 22-24 June 2004 Martin G. Schultz et al., Hydrogen Scenario Impacts

Consequences of twofold H2

• decreasing oxidizing capacity (increased methane lifetime)negligible*

• increased water vapour (greenhouse and chemistry impacts)negligible at surfacepotential problem (cirrus) in aircraft application

• stratospheric ozone loss (Tromp et al., 2003)negligible

• disturbed soil microbiologyunlikely, but cannot presently be excluded

* H2 presently contributes ~10% to OH loss. However, changes in the oxidizing capacity are likely due to NOx emission reductions

IEW 2004, Paris, 22-24 June 2004 Martin G. Schultz et al., Hydrogen Scenario Impacts

from Tromp et al., 2003

Tromp et al.assumption

our estimate

Stratospheric H2 Impacts

IEW 2004, Paris, 22-24 June 2004 Martin G. Schultz et al., Hydrogen Scenario Impacts

Consequences of associated emission changes

• potential CO2 reductionup to 20%

• decreasing oxidizing capacity (increased methane lifetime)up to 10%*

• decreased urban air pollution (NOx, PANs, VOCs)highly significant

• decreased regional air pollution and background ozonesignificant (up to 4 ppb in northern hemisphere)

* net greenhouse effect dominated by potential CO2 reduction

Results from a traffic replacement scenario (Schultz et al., 2003)

IEW 2004, Paris, 22-24 June 2004 Martin G. Schultz et al., Hydrogen Scenario Impacts

OH changes in a hydrogen economy100% traffic replacement

OH(H2)/OH(ref) [surface]

OH = -5.2%from Schultz et al., 2003

IEW 2004, Paris, 22-24 June 2004 Martin G. Schultz et al., Hydrogen Scenario Impacts

Ozone changes in a hydrogen economy100% traffic replacement

Annual mean surface ozone change

The total tropospheric ozone burden (below 100 hPa) is reduced by 3%

ppb

from Schultz et al., 2003

IEW 2004, Paris, 22-24 June 2004 Martin G. Schultz et al., Hydrogen Scenario Impacts

Past, present, and future ozone

1890 2000

2100simulated summer surface concentrationsMOZART-2 (future: SRES A2)

IEW 2004, Paris, 22-24 June 2004 Martin G. Schultz et al., Hydrogen Scenario Impacts

Future Ozone and Climate Change

TroposphericOzone

StratosphericOzone

Transport

TemperatureHumidity

Emissions(NOx, VOC, CO, CH4)

Chemistry

NO

NO2

HO2

OHVOCRO2

Lightning

(NOx)

Deposition(O3, HNO3, NOx, ...)

aerosol

IEW 2004, Paris, 22-24 June 2004 Martin G. Schultz et al., Hydrogen Scenario Impacts

Climate change and emission changes

+

(2*CO2-1*CO2)/1*CO2 , emis. 2000 [%] (emis.2100 – emis.2000)/emis.2000 , 1*CO2 [%]

(2100-2000)/2000 [%]

simulated summer surface concentrationsMOZART-2 (future: SRES A2)

IEW 2004, Paris, 22-24 June 2004 Martin G. Schultz et al., Hydrogen Scenario Impacts

Conclusions

• Hydrogen technology unlikely to play major role before 2030

• We expect no severe consequences from H2 release into atmosphere except for use in aircraftHowever: budget must be better understood and soil impact must be monitored

• If generated from renewables (or CO2 is captured), H2 would help reduce GHGs in spite of increasing methane

• Largest impact due to NOx emission reductions (improved air quality, reduced background ozone, reduced oxidizing capacity)

• Future emission changes must be viewed in conjunction with climate change (coupled model experiments needed)