The main tool for the government’s crusade to get one million plug-in cars on the road by 2015 is the “Qualified Plug-In Electric Vehicle Tax Credit,” a credit that returns between $2,500 and $7,500 to purchasers of a qualifying vehicle. To qualify for the minimum $2,500 credit, a vehicle must have a traction battery with a minimum of four kW/h, and the credit adds an additional $417 in credits for every kW/h above the minimum. Why? Well, you might think that it’s because the DOE has done its research and determined that larger battery packs deliver more social benefits… at least until the 16kW/h limit (the exact size of the Chevy Volt’s battery), where the credit tops out at $7,500. But according to new research by Carnegie Mellon’s Jeremy Michalek, that basic assumption doesn’t appear to be true at all. In fact, his latest paper argues that the government would actually be better off subsidizing smaller, not larger, battery packs.
In an in-depth evaluation [PDF] of plug-in hybrids (PHEVs), large-battery EVs, smaller-battery EVs, Hybrids and conventional cars, Michalek and his colleagues found that
Current subsidies intended to encourage sales of plug-in vehicles with large capacity battery packs exceed our externality estimates considerably, and taxes that optimally correct for externality damages would not close the gap in ownership cost. In contrast, HEVs and PHEVs with small battery packs reduce externality damages at low (or no) additional cost over their lifetime. Although large battery packs allow vehicles to travel longer distances using electricity instead of gasoline, large packs are more expensive, heavier, and more emissions intensive to produce, with lower utilization factors, greater charging infrastructure requirements, and life-cycle implications that are more sensitive to uncertain, time-sensitive, and location-specific factors. To reduce air emission and oil dependency impacts from passenger vehicles, strategies to promote adoption of HEVs and PHEVs with small battery packs offer more social benefits per dollar spent.
Back in 2009, Michalek made the core of this argument in an interview with Spectrum Magazine
Spectrum: So if you have to make a choice—big or small batteries for plug-in hybrids—which is best?
JM: From what we’ve found, if you have a higher-capacity plug-in, something like the Volt, it could lower greenhouse-gas emissions for some drivers, but that comes at a cost that wouldn’t be paid back by fuel savings. A $100-a-ton carbon tax doesn’t even do it.
On the other hand, a driver who is able to charge frequently would do well to buy a small-capacity plug-in. This person might not care at all about the environment or about the nation’s dependence on foreign oil, yet he or she would still benefit from buying such a vehicle.
Places where the economic, environmental, and national-security objectives are all well aligned—that’s where you’d want to break in a new technology. I would say to carmakers, go after those people. And to consumers: Buy small, charge often.
The Volt would be the poster-boy for Michalek’s critique: it has the minimum battery size needed to claim the full $7,500 tax credit, and yet its creators admit that it was developed for a consumer use profile rather than ultimate efficiency. Whether the Volt was developed to exactly hit the government’s kW/h credit limit, or if the limit was tailored to the Volt isn’t clear… but what is clear is that incentivizing smaller batteries will do more per dollar spent to displace oil. As Michalek tells Bloomberg
It’s not that large battery packs are bad, it’s that they are not providing as many benefits per dollar. Ordinary hybrids increase fuel economy substantially, and the incremental cost of those systems is getting relatively small.
Meanwhile, the timing of this report is very interesting: Reuters reports that the DOE is about to reveal its own research into EV incentives, and will be pushing to spend more money on Obama’s goal of putting a million EVs on the road.
Energy Secretary Steven Chu is due to unveil the results of a major review of research spending on Tuesday, one that could shift research dollars away from clean electricity and biofuels toward electric vehicles and modernizing the power grid.
The first-ever “Quadrennial Technology Review” prioritizes research that can be commercialized within 10 years, and research that could make a substantial dent in oil use and greenhouse gas production in the next two decades.
But will the DOE’s renewed push for EV proliferation reflect the sober analysis of scientists like Michelak, or will they be more wink-nudge games, in which the industry sets the policy agenda? After all, there are already plenty of reasons for the industry to keep electrified automobiles in a high-price ghetto, and the government has thus far been more than happy to play along with that game. But if this country is serious about reducing oil dependence, plug-in technology needs to be proliferated in the most efficient way possible. That means fewer handouts to luxury EV firms like Fisker and Tesla, and a more rational approach to consumer subsidies, as outlined by Michelak.