Plug-in hybrids v. conventional hybrids: New study shows benefits as well as losses
This article in the Christian Science Monitor reports on a recent study conducted by the American Council for an Energy-Efficient Economy (ACEEE) which examines the environmental benefits and costs of a plug-in hybrid when compared to a conventional hybrid. According to their figures, the results aren't as plainly evident as you may have thought.
First, the economics. By definition plug-in hybrids require a larger, beefier battery pack. That's how they achieve a decent electric-only range. And of course, as a consumer, you'd be paying for the privilege up front. The ACEEE estimates that the average time it will take the owner of a plug-in hybrid with a 40-mile electric range to begin to realize savings due to fuel costs is about 6.4 years while conventional hybrids recover their costs in about 3 years. Until battery prices significantly drop, this is one of those factors that we always expected (or at least we should have.)
Now, on to the environmental side of the examination. The report states that the impact of plug-in hybrid electric vehicles (PHEV) varies dramatically by region. For instance, a PHEV located in California would lower carbon dioxide (CO2) emissions by one-third compared to a conventional hybrid because of the low-pollution facilities generating electricity for the grid in the eco-friendly state. That same plug-in charged in the Midwest would hardly see any reduction in CO2 emissions, though the nitrogen oxide (NOx) levels would fall slightly. However, sulfur dioxide emissions which contribute to acid rain would quadruple.
Overall the gains and losses are still mixed. On a national average, the ACEEE found that CO2 emissions would be reduced by 15 percent with PHEVs, yet sulfur dioxide pollution would go up by 157 percent.
Therese Langer, ACEEE's transportation program director and coauthor of the report, notes the significance of the anti-optimism of the study in that it's dangerous to place full faith in any new technology without knowing the consequences. She says, "We want government policy based on reality, not overstating what [plug-in technology] can achieve and when."
As plug-in hybrids are relatively new to our landscape, this is just the beginning. There will undoubtedly be a lot more news, reports, estimates, debates and predictions and hopefully, they'll sprout some answers. This study should be seen as a wake-up call to get moving and clean the electrical grid as more cars in our near-future begin to use it as a source for energy.
[Source: Christian Science Monitor]
Reader Comments (Page 1 of 1)
loikll 12:11PM (9/29/2006)
I like PHEV concept in principle, but as long as it costs an up-front additional $17,500 it's 100% dead on arrival. Wonder how much cheaper it can get.
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just 12:19PM (9/29/2006)
when in commercial use will be this develop?
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charlie 12:26PM (9/29/2006)
Plug in hyrbids won't make sense until they're dramatically lighter and more compact, and then at that point, most people would probably be better off buying a pure electric car and renting something like a plug in hybrid for long road trips.
The reason is just simple engineering logic. A plug in hybrid has to carry as large of an electric motor as a full electric car, it has to carry as many batteries as a full electric car, and then it still has to carry a relatively large (at least as large as in a non-plug in hyrbid, probably marginally larger because the car is heavier) internal combustion engine, transmission, and all related systems. The result is that for trips within the battery range, you're carrying around hundreds of pounds of ICE stuff you're not using, and for trips outside battery range, you're carrying around hundreds of pounds of electric powertrain stuff you're not using. This is simply too mechanically innefficient, and is not a good solution.
The reason regular hybrids like the Prius work is because their parts are relatively light- the electric motor in the prius, unrestricted, will only take the car to 34mph (under ideal conditions) so obviously a plug in would need a considerably larger electric motor to be able to run completely on electricity for daily driving. I've also read that at that speed, the prius batteries would only be able to power the car for less than 5 minutes- so you'd need exponentially more batteries for a plug in, that adds over a thousand pounds in weight.
I'm much more confident that regular hybrids (like the prius), diesels, diesel hyrbids, new innovations to traditional gasoline engines, and even pure electric cars will be more successful in the long term than plug in hyrbids.
Theres still so much that can be done to a regular car without adding a electric engine to increase fuel efficiency. Theres direct injection, HCCI, more effective variable displacement and variable valve timing technology, theres regenerative braking just to make power for onboard electrical needs, theres using an electric coolant pump instead of having it draw directly from the engine, theres really cool technologies like BMW's Turbosteamer (which runs exhaust gases over a heat exchanger to produce steam in a closed loop water system to drive a steam engine to assist the motor, they've seen 15% increase in highway efficiency) and then if the Crower 6-cycle could work, that would be HUGE.
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jcwinnie 1:07PM (9/29/2006)
The propaganda would seem predicated on the samo-samo.
I would accept the ACEEE finding, given present conditions, AND, would suggest looking at it a bit differently. Do we wish to continue to depend upon oil (conventional hybrid) or accept alternative personal transportation utilizing electricity (plug-in hybrids)?
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Jimmy 1:51PM (9/29/2006)
There is a scale of increasing cost and reduced improvements. Mild hybrid systems give you fairly good fuel savings for the least cost and complexity. Full hybrids are more complex, expensive and impressive on the test drive, but are only slightly better in the real world. Plug-in Full Hybrids are even more expensive and complex.
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charlie 3:12PM (9/29/2006)
"There is a scale of increasing cost and reduced improvements."
That would be called decreasing marginal returns. I'm saying that by the time you go from full hyrbid to plug in hyrbid, you're talking about negative marginal returns.
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