Plug-Ins Have Higher CO2 Emissions Than Traditional Hybrids Car When Coal Fires Grid, Study Shows


Life Cycle Analysis (LCA) study results can seem counter-intuitive, even preposterous, until one spends hours pouring over the details. That said: it's generally possible to find a take-away message that makes immediate sense. A recently published LCA study - Life cycle assessment of greenhouse gas emissions from plug-in hybrid vehicles: Implications for policy - makes especially timely, important points about the fit of coal fired electricity and Plug-In Hybrid vehicle use in North America. In a word: we really must clean up the grid to make PHEVs worthwhile. To quote one of the authors:

When upstream impacts from fuel extraction, production, processing, and transportation are included, total GHGs per kWh get closer to ~670. Using power that looks like this still affords PHEVs a 32% reduction in life cycle GHGs compared to a regular sedan, and a 5% reduction compared to efficient gasoline-electric hybrids. In areas where coal is or could be the dominant fuel for charging (~950 g/kWh), PHEVs would still edge out sedans on GHGs but they would have 9-18% higher GHGs than hybrids. On the other hand, with a low-carbon portfolio of ~ 200 g/kWh, PHEVs would have large GHG reductions compared to sedans and hybrids (51-63% and 31 to 47%, respectively).
Our take on the coming election: a politician who supports PHEV R&D; and coal power is self contradicting. By definition, if you support more coal power you should not support electric vehicles of any kind. [See important "update" below the fold.]Update: The original post overlooked a factor that shapes how readers might react to its provocative Title and political conclusion: the regional upward effect on electricity pricing of a national GHG Cap and Trade system.

If a US Cap and Trade is implemented in synchrony with wide-scale marketing of PHEVs, prospective PHEV owners in regions of the US that are predominantly powered by coal will realize that they would be paying more to charge their cars that owners in other regions. Therefore, it is reasonable to expect that the PHEV market will be "tipped" to portions of the grid where less carbon intensive forms of electricity are available.

This points out how important public policy making is. (And, how much lobbying against Cap & Trade there will be from coal-dependent states.)

Additionally, as the comments below point out, the PHEV/coal power promotion contradiction for coal-heavy grid areas is resolved for independent consumers, businesses, or for local coops which produce renewable power on their own: e.g. distributed renewables.

Via::Sustainable Research AND Environmental Science and Technology, Abstract. Image credit::Mondovista, power lines.

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