Hymotion and tested under different use patterns.
How it works: you plug in a PHEV for charging at night just like a pure electric vehicle (EV) -- or like your cell phone. A Hymotion converted Prius can currently go on pure electric drive for 35-50 km, depending on how much air-conditioning is used (see Q8 in the Hymotion FAQ). Those are typical commuting distances for many people. But PHEVs can also switch to hybrid gas/electric for longer trips, becoming "regular" hybrids.
Here are the PHEV advantages:
- While you keep your PHEV in EV mode, you use 0 L per 100 km! For these trips:
- You'd cut carbon emissions from driving by an estimated 40% if you use conventional Ontario electricity today -- or 100% if you're on renewable Bullfrog Power. ("A car running on 100% green electricity: priceless!")
- You'd be "free at last" from rising gasoline prices, the oil companies, OPEC, tar sands, biofuel debates, oil spills, oil-related human rights abuses, and oil wars.
- For trips combining EV and hybrid mode, you'd still get over 100 MPG (US) or under 2.35 L/100 km in a PHEV car.
- The added range and ability to refuel at a regular gas station removes one of the usual objections to pure EVs: the fear of running out of battery and being unable to recharge quickly.
- For very long car trips, you'd get something like "regular" hybrid mileage. For example, the 2007 Prius is rated in Canada at 4.0 L/100 km (city) / 4.2 L/100 km (highway) or 71 MPG (city) / 67 MPG (highway) - as usual, "your mileage may vary".
PHEV technology is not perfect, but many of the down-sides would be temporary, or may be alleviated:
- Cost: larger batteries can be expensive. Hymotion projects a conversion cost of US $ 9,500 (see Q3 of their FAQ) -- on top of the cost of a 2004 or newer Prius. GM is projecting their Volt to be priced under US $30,000. That's more than a typical small car or even a regular Prius, but less than any highway-capable pure EV available today. Eventually, mass-production and/or kaizen (continuous improvement) may drive battery costs down. (That's already happening for "regular" hybrid technology like the one used in the Prius).
- Uphill struggle: for long uphill drives in "regular" hybrid mode, the extra weight of the large battery pack might offset the initial advantage of the EV mode. Regenerative breaking on the downhill drive would recapture some of the lost energy (a PHEV is not a perpetual motion machine :-)
- Cold emissions: catalytic converters require a certain minimum temperature to work properly in cutting down smog-forming gases. But after an extended EV-only drive, a PHEV would switch on the gasoline engine / exhaust system without warm-up. This can produce more emissions (at least initially) than a "regular" hybrid, which uses the gasoline engine frequently. Still, even "regular" hybrids have to takes other measures to heat the catalytic converter. Some people have suggested pre-heating the catalytic converter in a PHEV with an electric heater (see the comments below this Green Car Congress post). This which would use up some battery reserves to improve emissions performance on longer trips.
- Still Cars: "Regular" hybrids, pure EVs and PHEVs are still cars. They don't offer the health benefits of walking or cycling, or the sociability of public transit. PHEVs would also not encourage higher-density development that would make walking and public transit easier (more in my previous blog post). Having said this, PHEV cars would be a great transitional technology for urban and suburban areas, and may be a longer-term technology for rural areas. Carpooling in a PHEV would be greener and more social than driving one alone. PHEV buses would better yet.
- In "Beta": PHEV technology is still in experimental or prototype stages. Focusing on PHEVs exclusively might obscure the usefulness of current technologies like "regular" hybrids. For example, Toronto is unwilling to mandate the conversion of its entire taxi fleet to "regular" hybrids, a move which is expected to help New York City to reduce emissions signigficantly over the next few years.