TABLE 6.2 Hydrogen Supply Pathways Considered in This Analysis

Resource

Hydrogen Production Technology

Hydrogen Delivery Method to Station (for Central Plants)

Natural gas

Steam methane reformation (on-site)a

Steam methane reforming (central plant)

N/A

Liquid hydrogen truck

Compressed gas truck

Hydrogen gas pipeline

Coal

Coal gasification with carbon capture and sequestration (central plant)

Liquid hydrogen truck

Compressed hydrogen gas truck

Hydrogen gas pipeline

Biomass (agricultural, forest, and urban wastes)

Biomass gasification (central plant)

Liquid hydrogen truck

Compressed hydrogen gas truck

Hydrogen gas pipeline

 

On-site reforming of ethanol

N/A

Electricity (from various electric generation resources)

Water electrolysis (on-site)

N/A

NOTE: N/A = not applicable.

aOn-site refers to hydrogen production at the refueling station.

These scenarios are compared to a reference case, based on the Energy Information Agency (EIA) 2008 Annual Energy Outlook (EIA, 2008). The committee selected the AEO high-oil-price scenario for its reference case as being more representative of conditions under which HFCVs are promoted than the AEO reference case.1 This scenario includes improvements of gasoline ICEV technology to meet CAFE (corporate average fuel economy) standards, although fuel economy continues to grow slowly after 2020, and some use of biofuels (blending up to 10 percent ethanol) but no introduction of hydrogen or advanced ICEV technology. Gasoline taxes continue as per AEO 2008.

The time frame for analysis is 2008 to 2050. The committee agreed that HFCVs were not likely to make a large impact on U.S. oil use and greenhouse gas emissions by 2020, because they are unlikely to enter the market before 2012-2018, and then it will take time to build up a large enough number of vehicles to impact oil use and carbon emissions significantly. The committee recognizes that uncertainties increase in such a long-term analysis, but it was necessary for examining the time frame during which hydrogen could have a large impact.

Technologies Considered

Hydrogen and fuel cell technologies are based on technologies currently in development, as discussed in Chapter 3 and recently reviewed in the National Research Council (NRC) FreedomCar Fuel Partnership report (NRC, 2008). Available hydrogen supply pathways are listed in Table 6.2. Hydrogen production or storage technologies that would require fundamental scientific breakthroughs (for example, hydrogen storage in carbon nanostructures or biological production of hydrogen by algae) are not considered.

Cost and performance data for current and midterm (2015-2030) hydrogen infrastructure technologies are discussed in Chapter 3. Efficiency improvements in ICEVs and biofuels are described in Chapter 4.

Modeling Tools for Scenario Analysis

The committee developed two EXCEL-based models for infrastructure and scenario analysis:

  1. Hydrogen infrastructure model: designs and costs hydrogen infrastructure to meet a specified market penetration for HFCVs.

  2. Simplified transition model: estimates investment to bring HFCV costs to competitive levels, investment costs for building hydrogen infrastructure, oil savings, and greenhouse gas emission reductions,2 over time.

The models were developed at the University of California at Davis (UC Davis) and are described in detail in Appendix C. Given the time and resources available to the committee, the models were of necessity relatively simple, but they

1

In this scenario, imported low-sulfur crude oil is projected to cost about $79 per barrel in 2010, rising to $90 in 2015, $102 in 2020, and $119 in 2030 (all in 2006 dollars). Oil was over $130 per barrel in June 2008, but that does not necessarily mean that the AEO numbers are wrong. Other projections are both well above and well below this one.

2

Carbon dioxide is the main greenhouse gas of concern in this analysis, but other gases, especially methane and nitrous oxide, are emitted as part of the full fuel cycle. These are accounted for with global warming equivalency factors, taken from the literature and the GREET model.



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement