Next-Gen Hybrids

The Saturn Vue plug-in electric concept car is displayed at the North American International Auto Show in Detroit in January.

7, 2008 · The collaboration announced Tuesday between General Motors and more than 30 American utility companies may accelerate the introduction of plug-in hybrid electric vehicles.

GM plans to introduce the Chevrolet Volt and the Saturn Vue in 2010. If these cars and others in the works by Toyota and Nissan catch on, consumers stand to benefit from spending less on gas and gaining access to lower-priced electricity to fuel their commutes.
 

Here's a look at the impact that plug-in hybrids might have on consumers' pocketbooks and the environment.

What are the differences between a plug-in hybrid PHEV and a full hybrid, like the Toyota Prius or the Ford Escape?

Full hybrids like the Prius and Ford Escape can start and accelerate, up to a point, without engaging the combustion engine, but they rely on it to charge their batteries. In contrast, CalCars, California Cars Initiative for Plug-In Hybrids
The California Cars Initiative works to promote plug-in hybrids PHEV or plug-in hybrids. Plug-in hybrids use cleaner, cheaper, domestic energy a non profit advocacy group, describes PHEV as "an electric vehicle with a gas-tank backup."

A PHEV is similar to a full hybrid, except that it has an electrical cord that gets plugged into a standard 120-volt outlet to charge the battery. Plug-in hybrids will have larger and longer-lasting battery packs than hybrid cars now on the road. PHEV, which are still in development, would likely use lithium-ion battery technology similar to that used in consumer electronics to give them a longer electrical charge.

PHEV are being designed with the goal of providing an adequate electrical charge for a daily commute, somewhere between 20 to 40 miles each day. But designing a battery that carries enough energy for this type of commute is the major challenge facing the plug-in hybrid industry, says Mark Duvall, program manager of electric transportation for the Electric Power Research Institute, an industry research group.

By charging vehicles, aren't you just swapping out pollution from gas with pollution from power plants that generate electricity?

Not likely. A 2007 study by the Electric Power Research Institute and the Natural Resources Defense Council found the potential for reducing greenhouse gas emissions and improving air quality if the use of plug-in hybrid vehicles was widespread. A plug-in hybrid electric vehicle PHEV is a hybrid vehicle with batteries that can be recharged by connecting a plug to an electric power source. It shares the characteristics of both conventional hybrid electric vehicles and battery electric vehicles, having an internal combustion engine and batteries for power. Most PHEV on the road today are passenger cars, but there are also PHEV versions of commercial passenger vans, utility trucks, school buses, motorcycles, scooters, and military vehicles. PHEV are sometimes called grid-connected hybrids, gas-optional hybrids, or GO-HEVs.
 

The cost for electricity to power plug-in hybrids for all-electric operation in California has been estimated at less than one quarter of the cost of gasoline. Compared to conventional vehicles, PHEV can reduce air pollution and dependence on petroleum, and lessen greenhouse gas emissions that contribute to global warming. Plug-in hybrids use no fossil fuel during their all-electric range if their batteries are charged from nuclear or renewable energy sources. Other benefits include improved national energy security, fewer fill-ups at the filling station, the convenience of home recharging, opportunities to provide emergency backup power in the home, and vehicle to grid applications.

As of July 2008, plug-in hybrid passenger vehicles are not yet in production. However, Toyota, General Motors, Ford, Chinese automaker BYD Auto, California startups Fisker Automotive and Aptera Motors, and Volkswagen have announced their intention to introduce production PHEV automobiles. The PHEV-60 BYD F6DM sedan and F3DM hatchback are expected in 2009 the luxury Fisker Karma PHEV-50 sports car is slated for late 2009; and the Toyota Prius, GM's PHEV-40 Chevrolet Volt and Saturn Vue and the Volkswagen Golf PHEV50km plug-ins are expected in 2010. Conversion kits and services are available to convert production model hybrid vehicles to plug-ins. Most PHEV on the road in the U.S. are conversions of 2004 or later Toyota Prius models, which have had plug-in charging added and their electric-only range extended.

The study projected that in 2050, there would be more than an adequate supply of grid-supplied electricity for transportation uses. If PHEV were in widespread use by then, it predicted that greenhouse gas emissions could be reduced by the equivalent of removing 82.5 million passenger cars from roadways. And it suggested that petroleum consumption could be reduced by up to 4 million barrels per day.
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 PHEV 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 paragraph summary and a link to the first of several postings on the subject at CalCars-News
 EPRI-NRDC Definitive Study: PHEV Will Reduce Emissions If Broadly Adopted

The EPRI-NRDC studies finally give an environmental stamp of approval to PHEV. 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, PHEV 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 PHEV won't increase pollution. The main study shows that under all nine scenarios for both rates of market penetration of PHEV and the evolving power grid's characteristics capacity carbon intensity, PHEV 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.

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 renewable. A PHEV with only a 20-mile all-electric range is 62% lower.

Nationally, two government studies have found PHEV 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%. 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 PHEV using nighttime power reduce greenhouse gases by 46 to 61 percent.

Only PHEV 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. Finally, looking at the non-electric fuel, instead of using gasoline for long-trips, PHEV could run on bio-diesel, cellulose ethanol, or other bio-fuels to further reduce greenhouse gases.

PHEV 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. PHEV might one day actually help reduce it by providing power from parked PHEV' batteries during daytime hours.
3. PHEV Are Cheaper to Run and Cheaper to Maintain

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.

PHEV are meant to plug-in at night. In many areas of the country, overnight power is available at a lower cost. As PHEV start to enter the marketplace, we'll see increasing support from electric utilities, as they'll offer reduced nighttime rates to incentives 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.

Regardless, a 2003 EPRI battery study shows that mass-produced PHEV 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 PHEV offset the initial higher cost of batteries.

4. PHEV 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, cellulose 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 PHEV. 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. PHEV Already Exist

We use this section to track existing plug-in hybrids, to prove definitively that PHEV rely exclusively on existing technology -- no new advances are required. PHEV conversions are emerging at a frenzied rate to the point where it's no longer feasible to track every instance of a PHEV.

* Many automakers have built PHEV in private workshops, and DaimlerChrysler has publicly tested PHEV prototypes. They are converting up to 40 15-passenger Mercedes commercial vans into PHEV, 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.
* General Motors has announced its intention to mass-produce two PHEV 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
* 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 PHEV that have repeatedly won prizes in US Energy Department sponsored "Future Truck" competitions. Dr. Frank, widely known as the "Father of the Plug-In Hybrid," has been working on PHEV 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.
* Several companies are building plug-in hybrid school buses. 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.
How would the car communicate with the electric grid?

Integrating a plug-in hybrid with the electrical infrastructure is the second-biggest technology challenge, after creating an adequate battery, says Duvall. This requires coming up with a strategy of "smart charging," to establish synergy between the electrical grid and the car, he says. Ideally, a PHEV owner would be able to plug in the car whenever, but systems would be in place that prevent the car from charging up except when electricity usage is off-peak.

Utilities are already rolling out something called smart-metering technology, which is essentially a meter that enables someone's residence to relay consumption information back to the utility, so that power companies have the intelligence they need to manage electricity loads. By 2012, all of California will have smart meters in place, Duvall says.

What are the potential savings for consumers?

By charging at night, when many utility companies around the country offer more favorable power rates, consumers may save money. Duvall says it's likely that some utilities will offer consumers an "incentive" to charge at night. There are already special rates in place for electric-vehicle charging at some utilities, he says. PHEV typically draw the power equivalent of a dishwasher and require a charge of three to five hours.

These vehicles will use two-thirds less gasoline than full hybrids, says Duvall. CalCars California Cars Initiative for Plug-In Hybrids
The California Cars Initiative works to promote plug-in hybrids or plug-in hybrids. Plug-in hybrids use cleaner, cheaper, domestic energy estimates that drivers will be able to fill up their "electric tank" for less than $1 a gallon, based on the average U.S. electricity rate.
The California Cars Initiative calcars.org is a nonprofit startup of entrepreneurs, engineers, environmentalists and consumers promoting high-efficiency low-emission plug-in hybrid cars and harnessing buyer demand to help commercialize them.

We're demonstrating the immediate opportunity and benefits of "plug-in hybrids" . Based entirely on existing components, they're like current hybrids but with larger batteries and the ability to re-charge conveniently. So local travel is electric, yet the vehicle has unlimited range. They are the pathway to future zero-emission multi-fuel and bio-fuel PHEV.

Our "PRIUS+" prototypes prove we can have "100+MPG of gasoline hybrids." We're working with others to develop fleet orders from utilities, government private companies and early adopters.

We're also involved in advocacy and public policy, educating the large market of buyers who will pay extra for green cars. We're presenting the benefits of PHEV, along with wind and solar power, as a coordinated response to two of our greatest challenges: global warming and energy security. We're exploring with public officials ways to provide incentives to auto makers to build PHEV.
www.calcars.org - basic info
Will plug-in hybrids overburden the electrical grid?

Not likely. A few decades from now, analysts estimate there will be a 60 percent market share for plug-in hybrids. "It would add 6 to 7 percent to electrical demand," says Duvall. "We can handle most of this with existing capacity if we've got smart charging dialed in correctly."

Philip Rein, an engineering professor at the University of Illinois and an expert in electric and hybrid cars, says excess capacity already exists, especially at certain hours of the day. "To the extent that rates or other incentives can be used to make sure people are charging vehicles at night, there is very little problem," he says. "You just don't want them to be competing with air conditioning during a hot summer day."

Next-Gen Hybrids

California Cars Initiative for Plug-In Hybrids
The California Cars Initiative works to promote plug-in hybrids  PHEV or plug-in hybrids. Plug-in hybrids use cleaner, cheaper, domestic energy

Calcars.org 100 MPG + Toyota Prius Plug In is re-built and test driven in a weekend at the Oreille Maker Fair in Sunnyvale CA Fairgrounds in front of an audience.

Key CalCars personnel

Felix Kramer, Founder, is a marketing strategist and communicator with an entrepreneurial track record with startups; in the environmental realm, he has managed major events and run campaigns and organizations. After founding, running and selling a small Internet company, since 2001 he has volunteered his time to CalCars.

Ron Gremban, Technology Development Lead for PRIUS+, moderator of the PRIUS+ Plug-In Hybrid Conversion Group and electrical and software engineer involved in sales of solar energy systems, has long experience with electric cars -- he helped design and drive the Caltech entry in the transcontinental 1968 Great Electric Car Race.

Gail Slocum, Senior Advisor, former Mayor, Menlo Park and Regulatory Attorney at Pacific Gas and Electric Company.

CalCars is helped and advised by the entire EV community, including many members of the Electric Auto Association and the groups working to keep the remaining electric cars on the roads instead of being "recycled". Don't Crush succeeded as is apparent by Toyota's welcome decision to allow the cars to be purchased by their leaseholders; this group has now become Plug In America.

GM and Toyota have been taking public shots at each other, each claiming that their plug-in hybrid technology not yet brought to market is the best, and implying that the other's plans are poorly thought out, to say the least.

We at CalCars, if anything, are thrilled to see the two biggest automakers in the world touting their upcoming PHEV wares and paying significant attention to each other's. But what is the science behind the dispute? What follows is a discussion that is aimed at engineers, but we think will be quite informative also to non-technical audiences. Thanks to Dr. Andy Frank of UC Davis and Efficient Drivetrains Inc.

A preview of my conclusion: It turns out that different battery sizes have different optimum PHEV architectures, and each company’s claims are basically accurate, but only for its vehicle’s battery size. Since each type of PHEV has its own advantages, disadvantages, costs, and optimum driving regimes, our expectation is that during the first few years maybe a decade of PHEV production, all types of PHEV will compete well in the marketplace.

Then, eventually as batteries become a cheaper, longer-life, commodity item, liquid fuels become more dear, renewable electricity generation proliferates, and CO2 emissions are increasingly targeted the PHEV with the most EV power and range will come to dominate.

First, let’s establish what, in our opinion, are the most important characteristics of a PHEV. Though PHEV technology can improve overall power train efficiency, decrease criteria emissions, provide full zero-emissions capabilities part of the time, etc. and other technologies can and ought to be used to significantly reduce vehicle mass and drag the most profound capability of any PHEV is its ability to displace some of the vehicle’s consumption of liquid fuel  usually gasoline with stored electricity from the grid, and to do so without introducing new overall vehicle limitations  e.g. the high cost, extra weight, and range limitations of pure EVs.

It is this fuel displacement from which all the most important advantages of PHEV arise: dramatically reduced oil consumption and greenhouse gas emissions, low enough liquid fuel consumption that biofuels may someday fully substitute for fossil fuels, and energy storage that can eventually enable increased deployment of intermittent renewable electric generation from sources such as wind. Therefore, the very most important measure of a PHEV is the extent of its ability to displace liquid fuels, to do so during normal US driving cycles, and to do so cost effectively. All else is frosting on the cake.

When we look at “normal US driving cycles”, there are several areas of general agreement. The average mileage driven per day is around 30 miles. There is a curve available showing percentage of daily driving vs. distance. Though there is a continuum, driving is broken down into city and highway driving; standard drive cycles, UDDS  a city driving cycle and HWY, have been designed to emulate each. These standard cycles are obsolete and grossly underestimate required vehicle energy and capabilities, but are used as the basis of all EPA and CARB testing anyway. The US06 combined drive cycle is a much more realistic standard cycle.

Since the first standards for testing and measurement of PHEV performance are still being written, general references to these three standard cycles that the upcoming SAE J1711 standards will reference are our best bet for measuring and comparing PHEV performance. Dr. Andy Frank suggests that a new “Annual Driving Cycle” be designed to model annual electricity and gasoline usage, but for now that doesn’t exist.

There are series hybrids, where the internal combustion engine  ICE drives only a generator; parallel hybrids, where both the ICE and electric motor are always connected to the wheels; and power-split or series/parallel hybrids, where either the motor or the ICE or both drive the wheels at various times.

Though the Chevy Volt is presented as a series PHEV, and the Toyota Prius  as well as the 2-mode Saturn Vue, too! is power-split, the specific architecture is actually fairly irrelevant to the main issue that GM and Toyota are addressing. Incidentally, my calculations lead me to believe that the inherent efficiencies of each of the architectures are close enough to each other that the quality of engineering that goes into each vehicle is more likely than the architecture chosen to determine overall vehicle efficiency.

Though the details can vary and/or the mode distinctions blur, all plug-in hybrids basically have a charge-depletion mode and a charge-sustaining mode. After a grid charge, the charge-depletion mode is activated first, during which time as much of the vehicle’s propulsion energy as possible is pulled from the battery, while as little liquid fuel as possible is used. If this charge-depletion mode is 100% electric, the vehicle is considered a “pure-EV PHEV”, otherwise, it is a “blended-mode PHEV”. Once the battery is discharged to its target depth-of-discharge  DOD, the battery’s state-of-charge  SOC is maintained at this level and the vehicle functions in charge-sustaining mode, just as an ordinary hybrid.

A PHEV can either have some pure EV range, be “blended mode”, or, of course, employ some combination of the two. For example, a PHEV may start out with some pure EV range. Near the end of that range, the ICE may be started more and more often, providing some blended-mode driving before full DOD, at which time the vehicle shifts to charge-sustaining mode. Or charge-sustaining mode may consist of alternating periods of pure EV driving and significant ICE power, causing the SOC to vary rather than stay steady at maximum DOD.

Also, there are various kinds and degrees of power blending. A PHEV may be able to drive purely electrically only up to a specific speed, such as the 34 mph/55 kph limit imposed by the hybrid system on converted Prii. Also, only limited electric propulsion power may be available, like the 21 kW limit also imposed on converted Prii by the hybrid system.

The extent of a blended-mode PHEV’s blending is expressed as a “Utility Factor” that is a percentage of the wheel energy that is not supplied by the ICE. A vehicle’s Utility Factor can be quantified over each of the standard drive cycles talked about above. Its “Effective EV Range” is its depletion-mode range multiplied by its Utility Factor, which is conceptually the EV range it would have if its depletion mode were pure EV.

A PHEV with pure EV range has a Utility Factor of 100% and an Effective EV Range equal to its real EV range. Of course, this is also complicated by the fact that Utility Factor and Effective EV Range can each be very different when measured using each of the three standard driving cycles. In general, both parameters will be highest on the UDDS cycle and lowest on US06.

Another measure of a PHEV’s capability&mashing some ways even more useful than Effective EV Range is the usable capacity of its battery pack in kilowatt-hours or kWh, as this indicates how much energy is available after each charge to displace liquid fuel. A 12.5 kWh battery pack, allowed to charge fully but discharge only to 80% DOD, will have 10 kWh usable capacity.

Since a gallon of gasoline holds about 33 kWh of heat energy and the most efficient hybrid drive trains approach 30% efficiency, 10 kWh of usable battery capacity can potentially displace a gallon of gasoline after each  often <$1.00 grid charge, or up to 365 gallons/year when the vehicle is charged every night and driven to the end of depletion mode every day. However, a PHEV whose battery is regularly not fully depleted between charges is leaving money on the table  the battery could have been smaller and less expensive, and a PHEV that is regularly driven significantly beyond charge depletion mode into charge sustaining mode could potentially gain from having a larger battery.

What we want, of course, is, on the average, the most displacement of liquid fuels for the least incremental cost over that of a standard ICE propulsion system. Motor, power electronics, and ICE costs are all fairly proportional to maximum power output. Battery cost, which for now dominates PHEV costs, is set by energy storage capacity, maximum input/output power, and cycle life, which is itself dependent on maximum DOD and other factors.

As everyone else does  but without acknowledging it, we will ignore the fact that until PHEV become ubiquitous, people who buy and drive PHEV will in general be those whose driving regimes are most suited to them, meaning that generalizations based on average US driving patterns will, possibly greatly, underestimate the amounts of liquid fuels likely to actually be displaced by a particular model of PHEV.

Now we can finally get to the meat of the matter. GM’s Volt is reportedly capable of driving all three standard cycles, including the US06, purely electrically. GM states, accurately no doubt, that a PHEV that cannot do that is really a blended-mode PHEV, with one or more engine starts during most people’s normal driving. The company goes on to say that only a PHEV with 40 miles of pure EV range  which it calls an Extended Range EV or ER-EV can obtain maximum PHEV benefits. Toyota, who admits that its prototype Prius PHEV are blended-mode, does not disagree but says that pure EV PHEV are too expensive and not cost-effective.

Let’s look at two PHEV, as much like a Volt and a possible Prius PHEV as I can estimate based on public data  but both, for ease of calculation, with a 250 Wh/mile US06 power requirement at the wheels and estimate US06 performance. Note, as we explain below, that this is not an apples-to-apples comparison, since the battery capacity is different:

Note that, just as GM claims, the Volt-like PHEV’s ICE remains unused for average daily driving, making the PHEV’s benefits very often perfect: no cold ICE starts, no liquid fuel use, and no ICE emissions when daily use does not exceed 32 mi. On the other hand, though it never displaces liquid fuel 100%, the Prius-like PHEV provides approximately as much fuel displacement per usable battery capacity  88-117% as the Volt-like PHEV.

A Volt-like PHEV with a Prius-sized battery could do a better on daily driving distances up to 16 miles, but at a high cost of double the relative battery power requirements: 12.5C vs. 6.25C. And Prius-like PHEV with a Volt-sized battery would make poor use of the battery capacity below a daily driving range of 48 miles, 160% of the 30 mile US average. This means that different battery sizes have different optimum PHEV architectures, and each company’s claims are basically accurate, but only for its vehicle’s battery size.

Toyota claims that blended PHEV like its 2.5 kWh-capacity prototype Prius PHEV provide more liquid fuel displacement per battery capacity and power than those like the Volt that have pure EV range, that a blended-mode PHEV’s motor and electronics can cost less, and that the battery pack may see an easier and therefore a longer life. What the chart above shows is that Toyota’s claim of more displacement per battery capacity is true only for PHEV with EV range less than the US daily average driving distance of 30 miles. What a blended-mode system can do, with only proportional disadvantage, is allow the proportional scaling down of battery and electronics power requirements for vehicles, like Toyota’s Prius PHEV prototypes, with Effective EV Range of less than 30 miles.

Dr. Andy Frank states that the GM and Toyota cost arguments are not very meaningful at this stage because of unsteady costs due to low volume production of all parts, especially the batteries.

In conclusion, it is clear that PHEV with pure EV range of at least the average US daily driving range of 30 miles can displace the most liquid fuel, as well as have other advantages like zero tailpipe emissions in normal daily driving. However, these examples do bear out Toyota’s claims that the relative power requirements of blended-mode PHEV batteries can be much less than for pure EV PHEV but only for PHEV with very short Effective EV Range. On the other hand, Toyota’s claim of better utilization of expensive battery resources can be true, too.

What neither company has stated is that it is following its quickest and least expensive way to build its first PHEV by taking advantage of its own existing hybrid and/or EV technologies and tooling. For each to do this is highly desirable for all of us. Since each type of PHEV has its own advantages, disadvantages, costs, and optimum driving regimes, our expectation is that during the first few years maybe a decade of PHEV production, all types of PHEV will compete well in the marketplace. Then, eventually as batteries become a cheaper, longer-life, commodity item, liquid fuels become more dear, renewable electricity generation proliferates, and CO2 emissions are increasingly targeted the PHEV with the most EV power and range will come to dominate.

There is no doubt that it will be completely dominated by the cost of oil. Remember that the cost of oil doubled in the last five years and it will double again in less than five years and double again in even less time! So we can reach $20/gallon in the time frame that these guys are arguing over. At that time  6 to 8 years from now it means an SUV 30 gallon tank will cost $600! This costs will make all this nit-picking costs argument seem insignificant! I agree that at this time, let the big guys argue about who is better or more cost effective, we need to focus on what is good for the people on earth as the cost of fossil fuel rises.

That is the main reason for the PHEV! To displace fossil fuel with electricity that can be generated from a plethora of sources including renewable at a very high efficiency with low to zero emissions!

The Oil companies will eventually throw their wishes into the pot as well soon. And I think they will be much more vocal because they have the money! This may be where we should be bracing ourselves! The [recent] USA today article [inaccurately claiming PHEV cause higher emissions] is an example! Ron Gremban of CalCars has written an interesting guest piece over on Green Car Congress examining the debate between General Motors and Toyota that started last fall about the best approach to plug-in hybrid vehicles. The debate started when Toyota executives criticized the whole series-hybrid/extended range EV approach of the Chevy Volt. Gremban does a good analysis of the numbers looking at each type of power train over different driving cycles. So the obvious question is: Who's right, GM or Toyota? Both. As the old saying goes, tell me which side of the argument you're on and I'll give you the statistics to prove you're right.

The bottom line is that the better configuration depends on which driving cycle you use. For the foreseeable future as batteries remain expensive, getting maximum benefit depends how far you drive and at what speeds. For shorter driving cycles and lower speeds, the less expensive blended PHEV approach used in the plug-in Prius and Saturn Vue get the most benefit from a smaller battery. People who drive at higher speeds or longer distances will get more benefit from an E-REV like the Volt, which comes at a higher cost. The bottom line is that there is no one right answer for everyone. The replacement of petroleum will require a diverse approach to energy. The best answer will depend on where you live and how you use the vehicle.

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