Impact of Battery Weight and Charging Patterns on the Economic and Environmental Benefits of Plug-in Hybrid Vehicles
The mellonheads at Carnegie Mellon University have taken a long. loving look at the whole plug-in electric hybrid vehicle (PHEV) thing and reached a shocking conclusion: smaller is better. “Across the scenarios examined, the small capacity PHEV outperforms larger capacity PHEVs on cost regardless of the consumer’s discount rate, and the larger PHEV40 and PHEV60 are not cost effective in any scenario, although they provide GHG reductions for some drivers and the potential to shift air pollutant emissions away from population centers. The dominance of the small-capacity PHEV over larger-capacity PHEVs across the wide range of scenarios examined in this study suggests that government incentives designed to increase adoption of PHEVs may be best targeted toward adoption of small- capacity PHEVs by urban drivers who are able to charge frequently.” Golf carts! I mean, city cars! Not the, uh, Volt! Never mind. As the E85 debacle proves, politics trumps science every time. Until the free market has its say. If it’s allowed one.
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Poor whittle free market. Those bad ol' politicians won't let you talk no more. If they just you do your thing, you'd fix everything!
I think this one was aimed at the Volt. PHEV40 is their jargon for a PHEV that can go 40 mi without using its ICE. They found that PHEV7 was a better balance. Shooting for that level, GM could have used NiMh batteries, and saved themselves a load of grief. It is probably academic, because GM will not live long enogh to sell any Volts. Will Toyota's rumored PHEV Prius be PHEV7?
Electric cars were very common at the beginning of the last century. They could not compete with gas powered ICE cars due to their limited range. Do you see a pattern?
I'd point out that GM may have come to the same conclusions, since at least one briefing said that the 'son of Volt' will have a smaller capacity battery. Note that the cost effectiveness argument is heavily dependent on the price of gas, and batteries, they used $3 per gallon for their main analysis, and $1000 /kWh for the batteries. As gas prices increase, and batteries get cheaper, the optimum battery size will increase. Finally I'd observe that the methodology is a little suspect. GREET 1.7 seems to overstate the mpg of Prius (51 mpg), and underestimate the mpg of conventional IC cars (their baseline car gets 28 mpg). Adding batteries to an optimised system like Prius is not the going to result in an optimised system, if you want a PHEV40 it might involve a whole different set of compromises. They've just simulated adding batteries, not reconfiguring the whole car.