The House Committee on Energy and Commerce (2007) is considering enacting policies to subsidize the production of transportation fuel from coal-to-liquid projects (CTL), which would enhance national security by lowering oil imports. However encouraging plug-in hybrids is a less costly policy that also reduce oil imports and does more to lower greenhouse gas (GHG) emissions. A paper, by Carnegie Mellon Electricity Industry Center (CEIC), compares GHG emissions of CTL gasoline to the emissions of plug-in hybrid vehicles powered with electricity generated with coal as well as various fuel usage scenarios. A life cycle approach was used so that all stages of the life cycle of each fuel, from production to use, are included.
Quoting from the report:
Figure 1 shows the annual life cycle GHG emissions for conventional sedans using CTL gasoline and for plug-in hybrid vehicles. It can be seen that gasoline derived from CTL plants with no CCS could increase GHG emissions from vehicles by almost 60%. If CCS is available, then a reduction of less than 6% could be obtained. It is important to note, once again, that in this best-case CTL scenario, not only is there CCS at the CTL plant, but also a low-carbon electricity source is used for CTL production. This might not be a very realistic assumption, but is presented here to show that at best we could only obtain a very small reduction in GHG emissions following a path of increased CTL production.
Plug-in hybrids look more promising as a pathway for reduction of GHG emissions. Even if coal electricity without CCS is used, plug-in hybrids could lead to a GHG emissions reduction of almost 25%. This demonstrates the worst case for plug-in hybrids, as GHGs would be further reduced with a low-carbon electricity portfolio. It is important to note however, that this analysis does not include the emissions from manufacturing the storage battery used in plug-in hybrids. If GHG emissions from lithium-ion batteries for plug-in hybrids are included, total annual GHGs from plug-ins would increase by about 800-1,500 pounds of CO2 Equivalents, depending if a twelve or eight-year vehicle life is assumed (Samaras and Meisterling 2007). Battery technologies are difficult to predict, but even when emissions from current battery production are included, plug-in hybrids result in substantially lower emissions than CTL pathways.
In this analysis we assumed that conventional sedans have achieve an efficiency of 34 mpg, while plug-in hybrids have an gasoline efficiency of 44 mpg and an electric range of 60 miles. Fuel efficiency and vehicle types will affect the results, however a conventional sedan would have to achieve 69 mpg before emissions from coal-to-liquids gasoline are comparable with plug-in hybrids at their current fuel efficiency. Similarly, electrical efficiency of plug-ins would have to fall by 50% to 1.6 kWh per mile for emissions from plug-ins to be comparable to coal-to-liquids.
Enhancing energy security is the main argument in favor of supporting CTL developments. CTL will help the U.S. decrease its demand for foreign sources of oil. We find, however, that plug-in hybrids could also help the U.S. achieve this goal. Since about 60% of passenger vehicles travel less than 30 miles per day (USDOT 2003), plug-in hybrids can travel on electricity for nearly all of daily travel, displacing up to 85% of gasoline use in vehicle travel each year. For these reasons, plug-in hybrids are better suited than CTL fuels to simultaneously achieve the goals of energy independence and reducing GHG emissions, and a major program to subsidize CTL may not make much sense.
One thing that their analysis leaves out is the time it would take to implement CTL production, which has already been started vs the time to implement, on a significant scale the use of PHEVs. As most readers know the large auto companies claim that the battery technology for PHEVs is not yet available. As was discussed in a recent post some claim that PHEVs could be produced, on at least a limited scale, now. It is rather clear to me that accelerating PHEV production, by intensifying battery research and production, is the best use of government funds.