The Transportation Challenge

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Transcript The Transportation Challenge

The Transportation Challenge
U.S. Greenhouse Gas
Emissions by Sector (2007)
Transportation Energy Use by Mode (2006)
Source: DOE, Transportation Energy Data Book, Table 4.17 and 4.18, 2008.
Source: DOE, Transportation Energy Data Book, Table 3.6, 2008.
Global Demand Projections
Source: Intergovernmental Panel on Climate Change (IPCC), "Transport and its infrastructure." In Mitigation of Climate Change
. Contribution of Working Group III to the Fourth Assessment Report. Cambridge: Cambridge University Press, 2007. Figure 5.3.
Alternative transportation fuels
hydrogen – fuel cells
efficiency of hydrogen as energy carrier
electric – batteries
hybrid vehicles
off-grid – e.g. Prius
plug-in hybrids
ethanol, methanol
Concept of ‘well-to-wheels’ efficiency as measure
Hydrogen fuel cell
Plug-in battery electric
Hydrogen sources:
steam – methane
2H2O + CH4 -> CO2 + 3H2
At high temperatures (700 – 1100 °C) and in the presence of a metal catalyst, steam
steam reacts with methane to yield carbon dioxide and water
hydrogen and carbon dioxide gases are compressed and separated
coal gasification
coal -> CO, CO2, CH4, H2 (syngas)
heating in absence of oxygen (in situ coal gasification, e.g.)
hydrogen is separated from compressed syngas
2H2O -> 2H2 + O2
requires direct electrical current; oxygen and hydrogen collect at anode and cathode
Plug-in hybrid
Grid-independent hybrid
“Hi-performance” plug-in
2009 Model S Base Price $49,900
Heavier fuel oil, coal(?) are feasible alternatives
biofuels - methanol, ethanol – lower energy density
biodiesel – experimentation is on-going
hydrogen – storage systems may be too heavy