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All About Plug-In Hybrids (PHEVs)

On this highly popular but long page we address five fundamental topics:

1. What Are Plug-In Hybrids?

How does this sound: 100+ MPG in a regular vehicle?

We can achieve that -- today -- with a plug-in hybrid (PHEV). A PHEV is essentially a regular hybrid with an extension cord. You can fill it up at the gas station, and you can plug it in to any 120-volt outlet. It's like having a second fuel tank that you always use first -- only you fill up at home, from a regular outlet, at an equivalent cost of under $1/gallon.

You don't have to plug it in. But when you do, your car essentially becomes an electric vehicle with a gas-tank backup. So you'll have a cleaner, cheaper, quieter car for your local travel, and the gas tank is always there should you need to drive longer distances.

But wait, there's more:

  • If your driving is mostly local, you'd almost never need to gas-up.
  • Lifetime service costs are lower for a vehicle that is mainly electric.
  • A PHEV can provide power to an entire home in the case of an outage; A fleet of PHEVs could power critical systems during emergencies.

2. Plug-In Hybrids Are Cleaner (Even on a Coal Grid) [to top]

This entire section is finally obsolete -- because we now have a definitive study by the Electric Power Research Institute and the Natural Resources Defense Council. Here's our three-paragaph summary and a link to the first of several postings on the subject at CalCars-News:

July 2007 EPRI-NRDC Definitive Study: PHEVs Will Reduce Emissions If Broadly Adopted

The EPRI-NRDC studies finally give an environmental stamp of approval to PHEVs. Scientist have confirmed that unlike gasoline cars, plug-ins will get cleaner as they get older -- because our power grid is getting cleaner.

For people looking for the most effective way to end our addiction to oil, PHEVs have made sense because carmakers can build them now, with today's technology and using today's infrastructure. But they've needed definitive proof that PHEVs won't increase pollution. The main study shows that under all nine scenarios for both rates of market penetration of PHEVs and the evolving power grid's characteristics (capacity/carbon intensity), PHEVs will vastly reduce greenhouse gases for the next 40 years. In the second study, for the next 20 years, even if, worst-case, we still use lots of coal, nationwide air quality for other emissions will also improve.

Three more points: Both reports match up well with previous studies. They reinforce the Pacific National Lab's January 2007 findings that we won't have to build new power plants for cars that charge at night. And we're gratified that General Motors recognizes this study as validation of its decision to evolve to the electrification of transportation.

CA, NY, MA and other states have had Zero-Emission Vehicle programs since the early 1990s because battery electric vehicles in those states, taking into account power plants, are far cleaner than gasoline cars in reducing urban air pollution and smog. The comparison keeps being raised, though studies are conclusive:

The "well-to-wheel" emissions of electric vehicles are lower than those from gasoline internal combustion vehicles. California Air Resources Board studies show that battery electric vehicles emit at least 67% lower greenhouse gases than gasoline cars -- even more assuming renewables. A PHEV with only a 20-mile all-electric range is 62% lower (see printed page 95 in the 2004 study).

Nationally, two government studies have found PHEVs would result in large reductions even on the national grid (50% coal). The GREET 1.6 model in 2001 by the DOE's Argonne National Lab estimates hybrids reduce greenhouse gases by 22%, and plug-in hybrids by 36% (see table 2). An Argonne researcher reached consensus with researchers from other national labs, universities, the Air Resources Board, automakers, utilities and AD Little to estimate in July 2002 that PHEVs using nighttime power reduce greenhouse gases by 46 to 61 percent.

Only PHEVs and battery EVs get cleaner as they get older - because the electric grid gets cleaner every decade. Plus more people are installing rooftop solar photovoltaic systems, and clean wind power is vastly expanding nationally (see study by eminent environmentalist Lester Brown cited at CalCars Kudos). Finally, looking at the non-electric fuel, instead of using gasoline for long-trips, PHEVs could run on bio-diesel, cellulose ethanol, or other bio-fuels to further reduce greenhouse gases.

PHEVs will generally recharge at night using excess power from plants that can't shut down completely -- so they don't add to the peak load. PHEVs might one day actually help reduce it by providing power from parked PHEVs' batteries during daytime hours (see Vehicle-to-Grid in our FAQ).

3. PHEVs Are Cheaper to Run and Cheaper to Maintain [to top]

1/4 the Price?
At $3 for a gallon of gas, driving a non-hybrid car costs 8-20 cents/mile (depending on MPG).

With a PHEV, your electric local travel drops to as little as 2-4 cents/mile.
We say above that you can fill up your "electric tank" for less than $1/gallon. How? Using the average U.S. electricity rate of 9 cents per kilowatt-hour (kWh), 30 miles of electric driving will cost 81 cents. If we optimistically assume the average US fuel economy is 25 miles per gallon, at $3.00 gasoline this equates to 75 cents a gallon for equivalent electricity. Compared to a regular hybrid's real-world 45 miles per gallon, it's effectively $1.20/gallon.

PHEVs are meant to plug-in at night. In many areas of the country, overnight power is available at a lower cost. As PHEVs start to enter the marketplace, we'll see increasing support from electric utilities, as they'll offer reduced nighttime rates to incentivize off-peak charging. In some areas where wind and hydropower is wasted at night, the rate can be as low as 2-3 cents per kWh. That's 20-25 cents a gallon.

Why Pay More for a PHEV?

Cost increments for a plug-in hybrid compact vehicle will be 10-20% more than a regular hybrid: $2000-3000 extra for a sedan; $5000 for an SUV. CalCars' mission is to narrow the cost gap through incentives, subsidies and rebates while making the case for paying extra to gain access to car-pool lanes, spend less time at gas stations, get home backup power, lower maintenance costs, and, most importantly, benefit society by reducing oil imports, greenhouse gases and pollution.

People routinely pay more for such options as sunroofs, automatic transmissions, V8 engines and leather seats. These are "features" -- and no one asks about the payback. A JD Power survey shows buyers will pay more for cars with the "environmental feature." How much more? The high demand for the Honda Civic hybrid tell us it's at least $3,000.

The Bottom Line

Plug-ins cost more mainly because batteries are expensive. But battery technology is improving steadily (especially lithium-ion, with nano-technology versions also looking promising), and in large quantities current options are acceptable.

Additional resources:

Plug In Partners: Economic Benefits
Wikipedia: Plug-In Hybrids (note graph at top)
Regardless, a 2003 EPRI battery study shows that mass-produced PHEVs have already reached lifecycle cost parity with gas-powered vehicles -- using gas prices from three years ago! This means the more maintenance-free electrical systems of PHEVs offset the initial higher cost of batteries.

4. PHEVs Are Domestically-Powered [to top]

The nationwide electrical grid is only 3% petroleum-fueled, whereas transportation is almost completely powered by oil -- 60% of which comes from foreign sources (and growing). Adoption of plug-in hybrids will transfer the overwhelming majority of our miles driven to nearly oil-free electricity. If all vehicles were plug-in hybrids we would cut our oil needs by 55%, nearly enough to eliminate foreign sources altogether.

The winning combination from an environmental and national-security perspective is the flexible-fuel PHEV -- one that runs on biofuels, cellulosic ethanol, methanol, or alternative liquid fuel in place of gasoline. This will reduce the transportation sector's use of oil to almost zero -- and cut the United States' annual oil needs by 2/3.

A growing coalition of bipartisan leaders and national security experts has emerged in vocal support of plug-in hybrids (and flexible-fuel PHEVs). These include former Secretary of State George Shultz, former CIA Director R. James Woolsey, former National Security Advisor Robert McFarlane, and senators and congressmen.

5. PHEVs Already Exist [to top]

We use this section to track existing plug-in hybrids, to prove definitively that PHEVs rely exclusively on existing technology -- no new advances are required. PHEV conversions are emerging at a frenzied rate (see the frequency of CalCars-News postings), to the point where it's no longer feasible to track every instance of a PHEV. See What Carmakers Say about PHEVs for the latest. In short:

  • Many automakers have built PHEVs in private workshops, and DaimlerChrysler has publicly tested PHEV prototypes. They are converting up to 40 15-passenger Mercedes commercial vans into PHEVs, with some vehicles using NiMH and others advanced lithium-ion batteries, plus diesel and gasoline engines. The program is in cooperation with California's Electric Power Research Institute (EPRI), South Coast Air Quality Management District, and Southern California Edison. See the press release, EPRI announcement and Daimler's description (with graphics).
  • General Motors has announced its intention to mass-produce two PHEVs -- a Saturn VUE SUV, and the Chevy Volt, a series hybrid (where only the electric motor powers the wheels and the gasoline engine recharges the batteries). See CalCars-News Archive for updates.
  • The advanced hybrid vehicle research center at University of California-Davis (founded and directed by the modern inventor of the PHEV, CalCars advisor Prof. Andy Frank) has converted nine sedans and SUVs into PHEVs that have repeatedly won prizes in US Energy Department-sponsored "FutureTruck" competitions. Dr. Frank, widely known as the "Father of the Plug-In Hybrid," has been working on PHEVs for thirty years, and building them with students for more than a decade.
  • CalCars produced the world's first plug-in Prius (the PRIUS+) in 2004. Since then a number of companies have emerged to offer conversions for sale to consumers and fleet buyers, and CalCars has worked to support a growing open-source conversion movement.
  • In 2003-04, the US Marine Corps demonstrated a diesel-electric PHEV-20 HUMVEE. (The military likes the silent, zero-heat "footprint" in all-electric mode, and appreciates saving fuel that can cost well over $100/gallon to deliver to front lines.) This advanced Shadow RST-V (Reconnaissance, Surveillance and Targeting Vehicle) PHEV, built by General Dynamics, uses lightweight lithium-ion batteries and motors in four wheel hubs. See details and photos and more descriptions.
  • Several companies are building plug-in hybrid schoolbuses (see bottom of page at Where-PHEVs-Are). And Long Island, NY has converted a city bus to a plug in hybrid with 40 miles of all-electric range. Many more heavy-duty vehicle conversions (including three recycling dump-trucks that will run in "silent" mode for pickups) are in progress.

See CalCars-News for the latest news on PHEV development, and Where PHEVS Are for a chronological list of (mostly) Toyota Prius conversions. For a more detailed history of plug-in hybrids, see Plug-In Hybrids: State of Play, History and Players.

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