Hydrogen Scenario Impacts on Global Climate and Air Pollution Martin G. Schultz Max Planck Institute for Meteorology Bundesstr. 53, Hamburg, Germany

IEW 2004, Paris, June 2004Martin G. Schultz et al., Hydrogen Scenario Impacts Climate forcing impacts from IPCC, 3rd Scientific Assessment of Climate Change 2001

IEW 2004, Paris, June 2004Martin G. Schultz et al., Hydrogen Scenario Impacts Atmospheric CO 2 concentration trend

IEW 2004, Paris, June 2004Martin G. Schultz et al., Hydrogen Scenario Impacts Global CO 2 budget Net input of CO 2 into atmosphere: ~ 3.5 Gt/yr

IEW 2004, Paris, June 2004Martin 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, June 2004Martin G. Schultz et al., Hydrogen Scenario Impacts Background Ozone Trends MOZAIC (aircraft) mountain station coastal surface station

IEW 2004, Paris, June 2004Martin G. Schultz et al., Hydrogen Scenario Impacts Monitoring Emission Trends from Space A. Richter, F. Wittrock, Bremen University

IEW 2004, Paris, June 2004Martin G. Schultz et al., Hydrogen Scenario Impacts Contribution of traffic to emissions of GHGs and ozone precursors EDGAR 3.2, RIVM, data for 1995

IEW 2004, Paris, June 2004Martin G. Schultz et al., Hydrogen Scenario Impacts Final energy consumption per traffic sector OECD, 2000 Mio. t oil equiv.

IEW 2004, Paris, June 2004Martin 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 sector o road o aircraft o ships

IEW 2004, Paris, June 2004Martin G. Schultz et al., Hydrogen Scenario Impacts Hydrogen Perspectives WTW energy use of H 2 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 CO 2 /year in Europe H 2 fuel cell car expensive to produce and expensive fuel ( €/tCO 2 reduction * ) Short-term: H 2 from natural gas reforming + fuel mix Longer-term: geothermal/solar/wind/hydropower H 2 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, June 2004Martin 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 CO 2 emissions (unless captured) hydrogen might leak into atmosphere with unknown consequences safety issues

IEW 2004, Paris, June 2004Martin 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 CO 2 o NO x (oxidizing capacity, tropospheric ozone, air pollution)

IEW 2004, Paris, June 2004Martin G. Schultz et al., Hydrogen Scenario Impacts Current hydrogen budget Unit: Tg H 2 /yr (=Mt H 2 /yr) Ref: Novelli et al., 1999; Hauglustaine et al., 1999 CH 4 VOC H2H2 biomass burning traffic industry soils, ocean ± ±15 reaction with OH soil uptake

IEW 2004, Paris, June 2004Martin G. Schultz et al., Hydrogen Scenario Impacts Projected Global H 2 Emission Changes * TgH 2 required to generate 380 EJ, factor 2 efficiency gain for fuel cell factored in † TgH 2 required to generate 250 EJ (based on 2025 projection from EIA) TgH 2 /year present 1:1 scenario* fossil 3% leakage 2025 oil replacement scenario† 3% leakage realistic 2025 scenario fossil Global leak rates larger 3% not plausible due to economic and safety considerations

IEW 2004, Paris, June 2004Martin G. Schultz et al., Hydrogen Scenario Impacts Consequences of twofold H 2 decreasing oxidizing capacity (increased methane lifetime) negligible* increased water vapour (greenhouse and chemistry impacts) negligible at surface potential problem (cirrus) in aircraft application stratospheric ozone loss (Tromp et al., 2003) negligible disturbed soil microbiology unlikely, but cannot presently be excluded * H 2 presently contributes ~10% to OH loss. However, changes in the oxidizing capacity are likely due to NO x emission reductions

IEW 2004, Paris, June 2004Martin G. Schultz et al., Hydrogen Scenario Impacts from Tromp et al., 2003 Tromp et al. assumption our estimate Stratospheric H 2 Impacts

IEW 2004, Paris, June 2004Martin G. Schultz et al., Hydrogen Scenario Impacts Consequences of associated emission changes potential CO 2 reduction up to 20% decreasing oxidizing capacity (increased methane lifetime) up to 10%* decreased urban air pollution (NO x, PANs, VOCs) highly significant decreased regional air pollution and background ozone significant (up to 4 ppb in northern hemisphere) * net greenhouse effect dominated by potential CO 2 reduction Results from a traffic replacement scenario (Schultz et al., 2003)

IEW 2004, Paris, June 2004Martin G. Schultz et al., Hydrogen Scenario Impacts OH changes in a hydrogen economy 100% traffic replacement OH(H 2 )/OH(ref) [surface]  OH = -5.2% from Schultz et al., 2003

IEW 2004, Paris, June 2004Martin G. Schultz et al., Hydrogen Scenario Impacts Ozone changes in a hydrogen economy 100% 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, June 2004Martin G. Schultz et al., Hydrogen Scenario Impacts Past, present, and future ozone simulated summer surface concentrations MOZART-2 (future: SRES A2)

IEW 2004, Paris, June 2004Martin G. Schultz et al., Hydrogen Scenario Impacts Future Ozone and Climate Change Tropospheric Ozone Stratospheric Ozone Transport Temperature Humidity Emissions (NOx, VOC, CO, CH 4 ) Chemistry NO NO 2 HO 2 OH VOC RO 2 Lightning (NOx) Deposition (O 3, HNO 3, NOx,...) aerosol

IEW 2004, Paris, June 2004Martin G. Schultz et al., Hydrogen Scenario Impacts Climate change and emission changes +  (2*CO 2 -1*CO 2 )/1*CO 2, emis [%] (emis.2100 – emis.2000)/emis.2000, 1*CO 2 [%] ( )/2000 [%] simulated summer surface concentrations MOZART-2 (future: SRES A2)

IEW 2004, Paris, June 2004Martin G. Schultz et al., Hydrogen Scenario Impacts Conclusions Hydrogen technology unlikely to play major role before 2030 We expect no severe consequences from H 2 release into atmosphere except for use in aircraft However: budget must be better understood and soil impact must be monitored If generated from renewables (or CO 2 is captured), H 2 would help reduce GHGs in spite of increasing methane Largest impact due to NO x 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)